NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head

Transcription

1 NTEGRA Spectra Probe NanoLaboratory SNOM Measuring Head Instruction Manual 16 April 2010 Copyright NT-MDT Web Page: General Information: Technical Support: NT-MDT Co., building 100, Zelenograd, , Moscow, Russia Tel.: Fax:

2 Read me First! Observe safety measures for operation with devices containing sources of laser radiation. Do not stare into the beam. A label warning about the presence of laser radiation is attached to the measuring head (Fig. 1) as well as to the laser sources. Fig. 1 Before you start working with the instrument, get acquainted with the basic safety measures and the operation conditions for the instrument! If you are a beginner in scanning probe microscopy, we recommend you to familiarize with basic SPM techniques. Fundamentals of Scanning Probe Microscopy by V.L. Mironov gives a good introduction to the subject. This book is available on the Internet, Feedback Should you have any questions, which are not explained in the manuals, please contact the Service Department of the company (support@ntmdt.ru) and our engineers will give you comprehensive answers. Alternatively, you can contact our staff on-line using the ask-online service (

3 User s documentation set The following manuals are included into the user s documentation set: Instruction Manual is the guidance on preparation of the instrument and other equipment for operation on various techniques of Scanning Probe Microscopy. The contents of the user s documentation set may differ depending on the delivery set of the instrument. SPM Software Reference Manual is the description of the control program interface functions, all commands and functions of the menu and, also a description of the Image Analysis module and the Macro Language Nova PowerScript. Control Electronics. Reference Manual is the guide to SPM controller, Thermocontroller and Signal Access module. Some equipment, which is described in the manuals, may not be included into your delivery set. Read the specification of your contract for more information. The manuals are updated regularly. Their latest versions can be found in the site of the company, in the section Techsupport (

4 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Table of Contents 1. BASIC INFORMATION OVERVIEW PRINCIPLE OF OPERATION DESIGN Optical Measuring Head Optical Tube Laser beam delivery system Photomultiplier Module BASIC SAFETY MEASURES OPERATING CONDITIONS STORAGE AND TRANSPORT INSTRUCTIONS ASSEMBLING OF THE SNOM MODULE EXCHANGING THE REPLACEABLE PANEL OF THE BASE UNIT MOUNTING THE OPTICAL TUBE MOUNTING THE LASER BEAM DELIVERY SYSTEM PREPARING FOR OPERATION PREPARING AND INSTALLING THE SAMPLE PREPARING AND INSTALLING THE APERTURE PROBE INSTALLING THE PROBE HOLDER INSTALLING THE MEASURING HEAD PRELIMINARY APPROACHING AND SELECTING SCAN AREA PRIMARY ADJUSTING THE DETECTION CHANNEL LAUNCHING THE CONTROL PROGRAM ADJUSTING THE OPTICAL CANTILEVER DEFLECTION DETECTION SYSTEM PERFORMING MEASUREMENTS APPROACHING THE SAMPLE AND FINE ADJUSTING THE DETECTION CHANNEL ADJUSTING THE DELIVERY CHANNEL SCANNING SAVING DATA FINISHING THE WORK... 51

5 1. Basic Information Chapter 1. Basic Information 1.1. Overview SNOM measuring head serves for measurements with the scanning near-field optical microscopy (SNOM) with the instrument NTEGRA Spectra PNL (configuration Upright) 1. This head is an optional part of the instrument. SNOM functionality is enabled by aperture probes which operates both as microsized apertures and as SPM cantilevers. Optical resolution of data is determined by diameter ( nm) of an aperture. SNOM technique provides study of surface optical properties (spatial distribution of reflectivity and transmittivity over the sample surface, distribution of fluorescent characteristics, etc.) of various objects with resolution several times higher the diffraction limit. For high resolution, the probing radiation is focused on an aperture of size much less than the radiation wavelength, passes through it as an evanescent electromagnetic wave, and reaches the sample located in the near field vicinity of the aperture. The operating aperture-sample distance is of order of several nanometers and so the light spot on the sample is approximately of the size of the aperture. This eliminates diffraction smearing of images taken with scanning the sample with the SNOM probe Principle of Operation SNOM measuring head used with the NTEGRA Spectra PNL (Upright configuration) operates in the optical scheme of the Transmission Illumination Mode, which is used for transparent or semitransparent samples. Fig Transmission Illumination Mode 1 For details on design and operation of the PNL, refer to manual NTEGRA Spectra Probe NanoLaboratory (Upright Configuration with Renishaw Spectrometer) 5

6 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual The primary laser beam is focused by the objective on the probe aperture. The sample surface stays as close to the probe as to be in the near field of the aperture. Radiation emitted by the aperture and scattered by the sample is collected with the optical system and directed to the PMT detector. The PMT output serves for formation of the sample optical bitmap. The instrument can perform the following scanning modes: scanning-by-sample; scanning-by-laser. In the scanning-by-sample mode, the sample is moved in the XY plane with the tubular XYZscanner. It is important for SNOM techniques that the probe aperture stays on the axis of radiation delivery and detection. In the scanning-by-laser mode, the sample and the probe are fixed. Scanning is provided by the mirror scanner of the radiation delivery and recording system. Scanning-by-laser is used for fine adjustment of the instrument that implies alignment of directions of the primary beam and of the detector. Analytical measurements use the mode of scanning-by-sample Design Fig. 1-2 shows the delivery set of the SNOM measuring head: Optical measuring head; Probe holder. Fig SNOM measuring head 1 measuring head; 2 probe holder 6

7 Chapter 1. Basic Information Fig. 1-3 shows parts of the SNOM module: 1. Replaceable panel; 2. Optical tube; 3. Positioning device; 4. Laser beam delivery system KineFlex; 5. Photomultiplier module (PMT); 6. Hollow sample holder; 7. Set of substrates; 8. Fixing screws. Fig Parts of the SNOM module 1 replaceable panel; 2 optical tube; 3 positioning device; 4 laser beam delivery system KineFlex;5 PMT module; 6 hollow sample holder; 7 set of substrates; 8 fixing screws Optical Measuring Head The optical measuring head (hereafter, measuring head) consists of the following parts: Optical detection system; Universal objective; Universal objective holder; Probe holder. The optical cantilever deflection detection system 1 is mounted on the objective holder 2 (Fig. 1-4). The objective is suspended in an arrangement of elastically deformed arms. This arrangement provides high accuracy of focusing and mechanical stability of the device. The head mount 3 is equipped with microscrews for positioning the probe. 7

8 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Fig Basic parts of the measuring head 1 optical detection module; 2 objective holder; 3 base unit with the probe holder and positioning mechanisms Basic parts of the measuring head are shown in Fig Fig Measuring head 1, 2 screws for XY probe adjusting; 3, 4 photodiode mirror adjusting screws; 5 screw for fine focusing of the lens; 6, 7 screws for XY lens adjusting; 8 lens positioning device spring stop; 9 entrance aperture; 10, 11, 12 screw legs; 13 lens; 14 probe holder; 15 spring stop of the probe holder positioning device The main functional component of the measuring head is the Mitutoyo M Plan Apo 100 lens (pos. 13). The numerical aperture of the lens is 0.7 and the focal length is 2 mm while the working distance is 6 mm. The lens provides the following options along with conventional AFM techniques: Viewing the sample with resolution limited by 0.4 μm (at wavelength 550 nm); Delivery and focusing the exciting laser radiation; Aiming the laser beam at the probe aperture; Detecting the probe deflection (needs an additional semiconductor laser diode to generate radiation of 650 nm or 830 nm wavelength). 8

9 Chapter 1. Basic Information The screw for fine focusing of the lens 5 is located in front of the lens. The microscrews 1 and 2 move the probe holder relative to the lens. Moving the probe holder provides directing the laser beam of the optical cantilever deflection detection system (hereinafter referred to as detection system) to the cantilever reflective surface. The photodiode mirror is adjusted with the screws 3 and 4 so that the beam reflected from the probe could come directly to the centre of the photodiode. For adjusting the measuring head in angle and height, three screw legs 10, 11, and 12 are used. The microscrews 6 and 7 provide positioning of the lens against the probe and external optical devices. ATTENTION! Height adjustment of the legs 10, 11, and 12 is not recommended as this can misalign the optical system. Cantilever deflection in AFM modes is detected with the detection system operating a semiconductor laser (with =830 nm or 650 nm) that supplies radiation through the lens. The system dichroic mirror selectively reflects the radiation of the semiconductor laser. It provides a wide spectral range (400 < < 800 nm for the laser with =830 nm) thus allowing for observing the sample through the optical microscope and for optical exciting the sample surface. High sensitivity of the detection system is due to a special design of the laser formation system. This measuring head is distinct in design from others in that its cantilever deflection detection system operates with a nearly horizontal probe. For SNOM measurements, the probe stays at low angle to horizontal (2 3 ). Specification of the measuring head is presented in Table 1-1. Table 1-1. Specification of the optical measuring head Parameter Value Scanning type By sample Objective numerical aperture 0.7 Optical resolution 0.4 m (at wavelength 550 nm) Objective focal distance 2 mm Visual field ~70 m Laser wavelength of the cantilever deflection 830 nm detection system 650 nm Dimensions (L W H) mm Weight 1.5 kg Aperture probe Structurally, the aperture probe is an elastic beam or cantilever (see pos. 2 in Fig. 1-6) fixed on a silicon base (probe chip). The sensitive element of the probe is located in the free end of the probe. 9

10 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Mostly, probes of two following types are used: with a straight rectangular cantilever (Fig. 1-6 a); with a triangular cantilever formed by two beams (Fig. 1-6 b). a) triangular cantilever b) triangular cantilever Fig AFM probe 1 chip; 2 cantilever; 3 tip (sensitive element) The aperture probe tip is a hollow pyramid with a hole at its apex that serves as aperture (Fig. 1-7). The desired size of the aperture can be manufactured with a focused ion beam. a) diagram 1 cantilever; 2 tip; 3 aperture b) SEM image Fig Tip of the aperture probe Probe holder The aperture probe holder (Fig. 1-8) is exchangeable. It can be installed on the measuring head and later replaced with another one. Fig Aperture probe holder The aperture probe is equipped with a magnetic substrate that fixes the probe on the magnet of the holder (Fig. 1-9). 10

11 Chapter 1. Basic Information Fig Fastening magnet for mounting the aperture probe The aperture probe holder is placed in the mount of the measuring head and then secured with the spring stop 1 (see Fig. 1-10). The screws 2 and 3 serve to move the probe holder for adjusting the optical cantilever deflection detection system. The aperture probe holder is connected electrically to the slot 4 in the measuring head. Fig Aperture probe holder installed on the measuring head 1 spring stop; 2, 3 screws for X and Y movement of the probe; 4 probe holder connector Optical Tube The optical tube (Fig. 1-11) serves either for redirecting the transmitted radiation and delivering it to the laser beam delivery system or for delivering the exciting radiation coming from the laser beam delivery system to the sample. Fig Optical tube 11

12 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Diagram of the optical tube is shown in Fig For measurements, the sample surface is located in the focal plane of the lens 1. The reflecting prism 2 redirects the laser beam to the objective for delivering radiation to the tube or to the laser beam delivery system for collecting the transmitted radiation. Fig Diagram of the optical tube 1 lens; 2 reflecting prism Positioning device The positioning device (Fig. 1-13) is a mount of the optical tube. It can move the tube in three coordinates to position the tube so that the sample surface is in the focus of the lens. Fig positioning device 1 X movement screw; 2 Y movement screw; 3 Z movement screw; 4 supporting bracket The screws 1, 2, and 3 provide displacement of the optical tube in the ranges of 11 mm for corresponding degrees of freedom. The supporting bracket 4 is screwed on the replaceable panel of the base unit thus fixing the positioning device. 12

13 Chapter 1. Basic Information Laser beam delivery system Laser beam delivery system (hereinafter LBDS) (Fig. 1-14) is designed for easy, safe and secure transfer of the laser radiation to the entrance of the PMT module or to the sample. Fig Overall view of LBDS 1 «Input» socket; 2 polarization key, 3 «Output» socket; 4 cover plugs Polarization plane of the radiation is defined by the line mark on the Output socket of LBDS (see Fig. 1-15). Rotate the socket to the desired position when installing LBDS. Fig Output socket. Line mark indicates the polarization plane Table 1-1. LBDS technical characteristics Parameter Value Fiber type single-mode Pigtail length 2 3 m Beam diameter at entrance 0.65 mm Transmission efficiency > 65 % Output beam divergence diffraction limit Maximum input power 100 mw 13

14 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Photomultiplier Module Photomultiplier module (PMT module) (Fig. 1-16) serves for converting optical radiation acquired from the sample into electrical signals. Fig PMT module ATTENTION! The photomultiplier is highly sensitive to light. Never illuminate the PMT (even when it is off) with high intensity to prevent its damage or degradation. Avoid overloading the PMT. The detected radiation comes to the PMT module through the laser beam delivery system that connects with the slip bushing 1 (Fig. 1-17). The module is equipped with an adapting bushing that corresponds to design of the laser beam delivery system in use. Spectrum of the radiation acquired by the PMT can be transformed (by suppression, extraction, or shifting of the desired band) with filters. For example, the fluorescent component of the scattered radiation can be detected if the primary wavelength is suppressed. The desired filter (diameter 25.4 or 25.0 mm) is placed in the cartridge 2 and secured with the fixing nut 3. Fig PMT module 1 slip bushing; 2 cartridge; 3 fixing nut 14

15 Chapter 1. Basic Information 1.4. Basic Safety Measures General Safety Measures Ground the instrument before operation! Do not disassemble any part of the device. Disassembling of the product is permitted only to persons certified by NT-MDT. Do not connect additional devices to the instrument without prior advice from an authorized person from NT-MDT. This instrument contains precision electro-mechanical parts. Therefore protect it from mechanical shocks. Protect the instrument against the influence of extreme temperature and moisture. For transport, provide proper packaging for the instrument so as to avoid its damage. Electronics To reduce possible influence of power line disturbances on the measurements, we recommend supplying the instrument units with a surge filter. Before operation, set the power switch of the SPM controller to the position corresponding to value of the local electrical power line (this is only done with the controller being off!). Switch the SPM controller off before connecting/disconnecting its cable connectors. Disconnecting or connecting the cable connectors during operations may cause damage to the electronic circuit and disable the instrument. A warning label is attached to the SPM controller of the instrument (Fig. 1-18). Fig Laser Observe safety measures for operation with devices containing sources of laser radiation. Do not stare into the beam. A label warning about the presence of laser radiation is attached to the measuring head (Fig. 1-19), laser sources. 15

16 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Fig Scanner Do not apply to the scanner forces bigger than it is necessary for installation of a probe or a substrate with a sample. Avoid impacts on the scanner and its lateral displacement. Remember that thickness of the scanner walls makes only 0.5 mm. Optical components Optical components include the following units and elements: optical elements in the spectrometer unit; laser. To avoid contamination of the optical elements with dust or moisture, keep the room clean and never disperse sprays or other substances near the instrument. Do not touch the optical elements. For cleaning the optical components, use special cleaning sets. ATTENTION! Never uncover the spectrometer without extreme necessity. Only an authorized person is permitted to clean elements of the spectrometer. In the case of contamination, request for help to the manufacturer. Radiation detectors When storing or handling the CCD-camera, avoid ingress of contamination into the camera. Before connecting the water cooling system, turn off the computer and disconnect the camera from the computer. Prevent ingress of moisture into the camera case. Keep the vent holes on the case open when using the camera. Prevent too intensive illumination of the camera. Make sure that the camera is at the room temperature when finishing the work. 16

17 Chapter 1. Basic Information 1.5. Operating Conditions To provide for the normal operation of the device, it is recommended to observe the following conditions: environment temperature: (25 ± 10) C; temperature drift less than 1 C per hour; relative humidity at +25 С less than (65 ± 15) %; range of purity 7 8 (by ISO ); vibration amplitude in the band Hz less 0.5 m; atmospheric pressure 760 ± 25 mm Hg; the work area should be supplied with a protective grounding circuitry and with grounded electric mains (110/220 V); electric mains: - voltage 110/220 V (+10 % / 15 %), - frequency 50/60 Hz; the room should be protected from mechanical vibrations and acoustic noises, either internal or external; vibration criterion VC-C, 12.5 µm/s (one-third octave band criterion); the device should be protected from the direct sun radiation impact; to provide solid stability against vibrations, SPM modules should be placed on self-leveling floor with marble covering alongside bearing components of the building (pillows, beams etc.); the measuring unit of the instrument (the base unit with the measuring head) should be placed on a separate table away from computers and monitors, to eliminate electromagnetic interference; 17

18 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual the table intended for installation of the measuring unit of the instrument must be stable and, whenever possible, massive. The operation of the device is susceptible to heat flows, draughts and sudden alternations in temperature and humidity Storage and Transport Instructions Storage Instructions The instruments should be stored packaged in clean and dry premises with low ambient temperature variations: Acceptable temperature inside the premises is plus (20 ± 10) C; Acceptable humidity inside the premises is < 80 %. Transport Instructions The instrument should be carefully packaged to avoid damage during transport. 18

19 2. Assembling of the SNOM Module Chapter 2. Assembling of the SNOM Module Before assembly, the PNL should be prepared for operation and interconnections of all electromechanical parts are done. Make sure that the controllers, the spectral unit< and the laser source are off. Assembly of the SNOM module and its installation on the base unit of the PNL include the following procedures: 1. Exchanging the replaceable panel of the base unit; 2. Mounting the optical tube; 3. Mounting the laser beam delivery system. These operations will be explained in details below Exchanging the Replaceable panel of the Base Unit To exchange the replaceable panel of the base unit, perform the following steps: 1. Unscrew two fastening screws 2 and remove the mirror mounting frame 1 (Fig. 2-1). 2. Unscrew three fastening screws 3 and remove the replaceable panel. Fig Base unit 1 screws for fastening the mounting frame; 2 mirror mounting frame; 3 screws for fastening the replaceable panel 3. Take the replaceable panel in the spare parts set of the SNOM module (Fig. 2-2) and mount it on the base unit. Secure the replaceable panel by screwing three screws 1 with a cross-point screwdriver to fix the panel on the base unit and by screwing two M4 16 screws (pos. 2 in Fig. 2-2) with Allen key wo fix the panel on the exchangeable mount. 19

20 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Fig Replaceable panel mounted on the base unit 1 screws for fastening to the base unit; 2 screws for fastening to the exchangeable mount This completes mounting the replaceable panel on the base unit Mounting the Optical Tube To mount the optical tube on the base unit, perform the following steps: 1. If necessary, mount the scanner in the positioning device as follows: a. Release the spring stops of the exchangeable mount (Fig. 2-3) and place the scanner in the positioning device as shown in Fig Fig Spring stops Fig Scanner mounted in the positioning device b. Lower the scanner to its extreme by rotating the approach knob clockwise (Fig. 2-5). This is necessary for mounting the optical tube. 20

21 Chapter 2. Assembling of the SNOM Module Approach knob c. Connect the scanner to the base unit: Fig Approach knob of the base unit - When using a scanner with sensors, connect the scanner slot to the SCAN+SENSOR located on the base unit. - When using a scanner without sensors you may connect the scanner connectors to the SCANNER slot or to the SCAN+SENSOR slot. ATTENTION! Switch the instrument off before any operation on connecting/disconnecting its cable connectors. Disconnecting or connecting the cable connectors during operations may cause damage to the electronic circuit and disable the instrument. 2. Secure the optical tube on the positioning device with four M2 6 screws as shown in Fig Fastening screws Fig Optical tube mounted on the positioning device 21

22 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual 3. Mount the positioning device with the optical tube on the base unit as follows: a. Loosen nuts of the guide pins 1 (Fig. 2-7). a) b) Fig Positioning device 1 nuts for fastening the guide pins; 2 guide pins; 3 slots of the M4 8 fastening screws b. Carefully place the positioning device so that the guide pins match the seats of the replaceable panel (Fig. 2-8). Seats of the positioning device Fig Replaceable panel mounted on the base unit c. Secure the positioning system with three M4 8 screws (pos. 3 in Fig. 2-7), with Allen key. 22

23 Chapter 2. Assembling of the SNOM Module Fig Optical tube mounted on the base unit 1 X movement screw; 2 Y movement screw 4. Tighten two nuts of the guide pins (pos. 1 in Fig. 2-7) with hexagonal box wrench. Fixing the guide pins enables the positioning device to take its initial state if it is remounted on the base unit. 5. With the movement screws 1 and 2 (Fig. 2-9), find the position of the optical tube where the center of the tube lens is aligned with the center of the exchangeable mount. This completes mounting the optical tube on the base unit. 23

24 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual 2.3. Mounting the laser beam delivery system The LBDS connects either the laser with the optical tube for adjusting the detection channel ar the optical tube with the PMT module for adjusting the delivery channel or for measurements. Here, mounting the LBDS for adjusting the detection channel is explained. ATTENTION! Do not look through the laser exit aperture or the LBDS. Direct or scattered laser radiation is hazardous and may cause eye injuries. To mount the LBDS, perform the following steps: 1. Take the LBDS and insert its Input socket into the optical tube against the stop (Fig. 2-10). Fastening screws Fig LBDS Input socket mounted 2. Secure the Input socket by screwing two fastening screws with Allen key 1.5 mm (Fig. 2-10). 3. Close the laser source exit shutter if it is open. 4. Take the Output socket of the LBDS with your right hand while, with your left hand, press and hold the central backing-up screw of the radiation feedthrough. Insert the Output socket into the slot of the radiation feedthrough against the stop (see Fig. 2-11). Fig Radiation feedthrough This completes mounting the LBDS for adjusting the detection channel. 24

25 3. Preparing for Operation Chapter 3. Preparing for Operation ATTENTION! Familiarize with the manual NTEGRA Spectra Probe NanoLaboratory (Upright Configuration) before starting operation with the SNOM measuring head. Preparation of the instrument for operation includes the following operations: 1. Preparing and Installing the Aperture Probe (sect. 3.2 on p. 28). 3. Installing the Probe Holder (sect. 3.3 on p. 29). 4. Installing the Measuring Head (sect. 3.4 on p. 30). 5. Launching the Control Program (sect. 3.7 on p. 34). 6. Preliminary Approaching and Selecting Scan Area (sect. 3.5 on p. 32). 7. Primary Adjusting the Detection Channel (sect. 3.6 on p. 32). 8. Adjusting the Optical Cantilever Deflection Detection System (sect. 3.8 on p. 35). These operations will be explained in details below Preparing and Installing the Sample The instrument allows for measuring samples of 5 18 mm in diameter and up to 1.5 mm in thickness. For mounting the sample, non-magnetic metallic substrates (Fig. 3-1) are used. A substrate is a rectangle with an internal orifice of diameter 5, 10, or 15 mm. The substrate with the sample mounted on it is placed in the hollow sample holder (Fig. 3-2) that is fixed in the magnetic fastener of the scanner. Fig Substrates Fig Hollow sample holder To prepare and install the sample, perform the following steps: 1. Prepare a clean metal substrate of diameter close to diameter of the sample. Cut off a strip of a double-sided adhesive tape, slightly wider in size than the sample. 2. Stick the adhesive tape to the substrate, smooth its surface out with the back of the tweezers to remove air bubbles between the substrate and the adhesive tape. Remove the portion of the tape inside the substrate orifice. 25

26 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual 3. Put the sample on the adhesive tape and carefully press it with tweezers in several places (not touching the area intended for the investigation). NOTE. After the sample is fixed on the substrate, a noticeable vertical drift of the sample can occur within one hour (due to the slow relaxation of sticky tape). This drift should be taken into account. If the task requires the minimum drift, prepare the sample beforehand (at least, an hour before the investigation). 4. Place the substrate with the sample on the sample holder. Insert the substrate from aside under the spring clips (Fig. 3-3). Magnetic disk for fixing on the scanner Fig Substrate mounted on the sample holder ATTENTION! When working with a thick sample, you need to account for its height in the program. The default value of the sample is set to 0.5 mm (For more details how to set up the sample height see page below). 5. Place the sample holder on the scanner (Fig. 3-4). To this purpose, take the holder with its larger hole being directed to you and carefully pin it on the end of the optical tube avoiding contact with the tube lens. Then, mount the sample holder on the magnetic fastener of the scanner (Fig. 3-4). Make sure that: - the holder magnetic disk comes to the center of a magnetic holder and lays on the three support balls; - axis of the optical tube is horizontal and comes to the center of the lateral orifice of the holder. This ensures that the spring clips of the holder will not damage the probe and will not obstruct approaching the sample. - Notice that with proper alignment of the sam ple holder, the clips are slightly turned to the axis of the optical tube. 26 Fig Sample holder installed on the scanner

27 Chapter 3. Preparing for Operation This completes installing the sample. Setting the sample height The sample thickness influences the geometrical dimensions of the acquired image. With the same elongation of the scanner tube, a thicker sample will move to a larger distance from the probe in the XY plane (Fig. 3-5) thus increasing size of the image. To account for this effect, the height of the sample above the scanner should be taken correctly. Fig Increase of the image size with height of the sample When defining the sample thickness, be careful not to miss thickness of the sample used for XY calibration of the scanner. To define the sample height, perform the following steps: 1. Open the Scanner Calibration Setup dialog (Fig. 3-6) by selecting the Main menu command Settings Calibrations Change Calibrations. 2. In the Sample Height input field of any of the tabs, enter the sample height (Fig. 3-6). - If the substrate is of the same thickness as that of calibration, enter thickness of the sample itself. - If the substrate is thicker than that used for calibration, enter the sample thickness increased by the height difference of the substrates. 27

28 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Fig Scanner Calibration Setup dialog 3. Click OK to save the changes and close the window. For another sample, value of the Sample Height field of the Scanner Calibration Setup dialog can change Preparing and Installing the Aperture Probe The aperture probe is fixed in its holder with a magnetic support. The support is a metallic plate with a protrusion inclined to the plate. The aperture probe is sticked on the support with epoxy resin or with cyanoacrylate glue. ATTENTION! Be careful when handling cantilever or the tip with glue. the probe. Avoid contamination of the To prepare and install or exchange the aperture probe, perform the following steps: 1. Check that the support is clean. If necessary, wipe it with lint-free tissue moistened with alcohol. 2. Place the support on a clean smooth surface with its protrusion up. 3. Apply a small amount of glue on the support protrusion. Use epoxy resin or cyanocrylate glue for sticking. 4. Take the probe from the container with the tweezers. Make sure that the working side of the chip with cantilevers is directed to you during the installation. Do not turn the chip over because probes in the container are packed with their tips pointing upwards. 28

29 Chapter 3. Preparing for Operation 5. Carefully place the probe on the support protrusion (covered with glue) so that the chip projects outside the protrusion to distance of 0.5 mm (Fig. 3-7). Wait for 10 minutes until the glue contact gets firm. Fig Layout of installing the probe 1 probe support; 2 probe; 3 protrusion of the probe support Fig Probe installed on the support 6. Place the holder with the probe in the middle of the holder magnetic fastener (Fig. 3-9, Fig. 3-10). Using tweezers align the support so that the cantilever is strictly perpendicular to the edge of the holder. Support magnetic fastener Fig Probe holder Fig Probe installed in the holder Now, the probe is installed into the holder Installing the Probe Holder To install the probe holder on the measuring head, perform the following steps: 1. Place the measuring head with its bottom up on a plane surface. 2. Pull the spring stop (Fig. 3-11). Place the probe holder so that support balls of the holder stand on sapphire seats on the base of the measuring head (Fig. 3-11). Screws of the measuring head must come to the corresponding slots with their caps. 3. Release the spring stop to secure the holder. 29

30 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Spring stop Fig Probe holder installed 4. Connect the probe holder electrically to the measuring head (Fig. 3-11). This completes installing the probe holder on the measuring head Installing the Measuring Head To install the measuring head, perform the following steps: 1. Rotate the manual approach knob clockwise until the scanner comes to its lowest position (pos. 1 in Fig. 3-12). This will secure the probe and the sample during installation of the measuring head. ATTENTION! When lowering the scanner, avoid contact of the sample holder with the optical tube to prevent damage of the tube lens. To keep the desired distance, adjust Z position of the optical tube. 30 Fig approach knob; 2 seats of the measuring head

31 Chapter 3. Preparing for Operation 2. Place the screw legs of the measuring head down to the seats 2 of the exchangeable mount (see Fig. 3-13). Observe that the probe tip does not contact with the sample surface or with parts of the microscope. Fig Measuring head installed on the base unit ATTENTION! Length of the measuring head legs is adjusted during the installation procedure. Do not re-adjust it as this will result in inclination of the objective and thus in misalignment of the optical detection system. 3. Tuck in the head cable into the cable holder. Connect the measuring head to the HEAD socket in the base unit of the instrument. This completes installing the measuring head. 31

32 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual 3.5. Preliminary Approaching and Selecting Scan Area 1. Watch from aside and rotate the approach knob 1 (Fig. 3-14) counterclockwise to approach the sample to the probe to distance of 0.5 mm. Fig approach knob; 2 fine focusing screw of the objective 2. Switch on the illuminator of the videomicroscope, the CCD-camera, and the monitor of the optical viewing system 3. Turn the fine focusing screw 2 (Fig. 3-14) to focus the objective on the sample surface. Watch quality of the focus with the image on the monitor of the optical viewing system. With proper focusing, the monitor displays a contrast image of the sample surface. 4. To select an area for investigation, rotate the microscrews of the positioning device to move the scanner with the sample to a position where the desired area is in the viewing f ield of the objective. Monitor the surface by inspecting image on the monitor of the optical viewing system. This completes preliminary approaching and selecting the scan area Primary Adjusting the Detection Channel Primary adjusting serves for aligning the sample surface with the focal plane of the lens. This procedure needs the sample to approach the probe to distance of 0.5 mm. Proper focus of the lens on the sample surface is required for efficacy of collection and detection of radiation transmitted through the sample. To adjust primarily the detection channel, perform the following steps: 1. Direct the primary laser beam from the source to the radiation feedthrough by changing adjustments of the spectral unit in the Control program (see manual on the Control program). 2. Switch on the laser. Open the laser exit shutter. The laser beam will go through the LBDS and the optical tube and come to the sample. 32

33 Chapter 3. Preparing for Operation 3. Decrease intensity of the laser beam coming from the LBDS to prevent overloading the video camera. To this purpose, move the LBDS away from the axis of the laser beam by rotating the adjusting screws of the radiation feedthrough (Fig. 3-15) until the surface image on the monitor becomes contrast. Fig Radiation feedthrough 1 horizontal adjusting screws; 2 vertical adjusting screws 4. Using screws 1 and 2 (Fig. 3-16) of the positioning device, move the optical tube in the XY plane so that the laser spot comes to the viewing field of the objective. The monitor of the optical viewing system will display a smeared image. Fig Screws for moving the optical tube 1 X movement screw; 2 Y movement screw; 3 Z movement screw 5. Focus the laser beam on the sample surface by moving the optical tube along Z with the screw 3 (Fig. 3-16) until diameter of the laser spot image is at its minimum (Fig. 3-17). 33

34 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Fig Image of the focused laser spot 6. Move the optical tube in the XY plane to place the laser spot slightly below the center of the screen (Fig. 3-18). Fig Image of the focused laser spot located slightly below the center of the screen 7. Close the exit laser shutter. This completes primary adjusting the detection channel Launching the Control Program Before this procedure, all interconnections of electromechanical units of the instrument are to be done according to the manual NTEGRA Spectra Probe NanoLaboratory (Upright Configuration with Renishaw Spectrometer). ATTENTION! Tighten up all connectors before turning the controllers on. Disconnection of connectors during operation may cause damage to the electronic components. 1. Switch the spectrometer on. 34

35 Chapter 3. Preparing for Operation 2. Switch on the main and the slave controllers with the toggle switches on the front panel. 3. Switch on the computer. ATTENTION! The controllers and the spectrometer must be on before starting the Control program. 4. Start the Nova program Adjusting the Optical Cantilever Deflection Detection System Adjusting the optical cantilever deflection detection system can be performed in one of two ways: by the spotlight from the illuminator; by laser beam coming from the spectrometer. In both cases, the adjustment procedure is the same. So, only adjustment with the illuminator is described below. 1. Watch the probe and move it with the screws 1 and 2 (see Fig. 3-19) to the position where the light spot appears on the probe chip (pos. 1 in Fig. 3-20). a) b) Fig Adjusting elements of the detection system 1, 2 screws for X and Y positioning of the probe;3 screw for fine focusing of the lens; 4, 5 screws for positioning of the photodiode; 6, 7 screws for X and Y movement of the lens 35

36 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Fig Aiming the laser spot at the cantilever 2. Using the screw 1 move the probe away from you, thus moving the light spot to the edge of the chip (pos. 2 in Fig. 3-21), until a specific image appears on the monitor of the optical viewing system ( Fig. 3-21). Here, the bright portion corresponds to the edge of the probe chip while dark areas display the chip surface and the sample surface which are out of focus of the objective. Fig Chip edge imaged by the light spot 3. Rotate the screw 2 to move the probe along the light spot until the spot comes to the cantilever (pos. 3 in Fig. 3-20). The monitor will display alternating dark and bright areas (Fig. 3-22). Fig Chip edge and the cantilever imaged by the light spot 4. Move the light spot to the free end of the cantilever (pos. 4 in Fig. 3-20) by moving the probe away from you with the screw 1. Watch the image on the monitor of the optical viewing system. 36

37 Chapter 3. Preparing for Operation Fig Free end of the cantilever imaged by the light spot Focus the objective on the cantilever by turning the screw 3 ( Fig. 3-19). Watch quality of the focusing on the monitor of the optical viewing system. Move the probe in the XY plane to a position at which the bottom of the tip is viewed slightly below the center of the monitor (Fig. 3-24). Fig Objective focused on the cantilever. Tip bottom is viewed slightly below the center of the screen 7. Focus the objective on the probe aperture by rotating the screw 3 counterclockwise until the image of the hollow apex is contrast (Fig. 3-25). Fig Objective focused on the probe aperture 8. Further steps on adjusting the optical cantilever deflection detection system are performed within the Control program. So, switch to the Aiming tab with the button in the Main Operations panel. 37

38 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual The laser of the optical detection system turns on or off with the button located at the right of the Main Parameters panel. When the Control program starts, the laser turns on automatically. Fig Spot of the detection system laser on the cantilever 9. For fine aiming the laser beam at the end of the cantilever, use adjusting the total signal of the photodiode. With laser positioning screws 1 and 2, move the beam a little against the cantilever and find the position at which the total signal (Laser) is at its maximum. Expected level of the Laser signal is in the range na. 10. Adjust the laser spot at the center of the photodiode (see Fig. 3-27) by moving the photodiode with the screws 4 and 5. For higher precision, find a position where the signals DFL and LF are close to zero, with the total signal Laser being sufficiently high. Recommended level of the signal Laser 15 na (it depends on reflectivity of the cantilever and on factory adjustments of the measuring head). Fig Laser spot adjusted at the center of the photodiode This completes adjusting the optical cantilever deflection detection system. The PNL is now prepared for measurements with the aperture probe. 38

39 4. Performing Measurements Chapter 4. Performing Measurements Initial state Before measurements, components of the instrument should be prepared as follows: 1. Control program is running; 2. Instrument is on; 3. Probe is installed; 4. Sample is installed; 5. Measuring head is installed; 6. Sample is approached to the probe to distance of 0.5 mm; 7. Scan area is selected; 8. Detection channel is preliminarily adjusted; 9. Optical cantilever deflection detection system is adjusted; 10. Turret with exchangeable mirrors (in the radiation delivery and recording system) is in position M2, that is, no reflection in the turret is applied (see manual NTEGRA Spectra Probe NanoLaboratory (Upright Configuration with Renishaw Spectrometer)); 11. Proper set of calibration parameters (corresponding to the scanner with the hollow sample holder) is activated (see manual NTEGRA Probe NanoLaboratory. Performing measurements, Appendix). Basic operations 1. Approaching the Sample and Fine Adjusting the Detection Channel (sect. 4.1 on p. 40). 2. Adjusting the Delivery Channel (sect. 4.2 on p. 41). 3. Scanning (sect. 4.3 on p. 48). 4. Saving Data (sect. 4.4 on p. 50). 5. Finishing the Work (sect. 4.5 on p. 51). These operations will be explained in details below. 39

40 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual 4.1. Approaching the Sample and Fine Adjusting the Detection Channel Approachin g the sample to the probe Perform approaching the sample to the probe according to the procedure of contact AFM. For details, refer to manual NTEGRA Probe NanoLaboratory. Performing measurements, Part 3. Here, only the procedural sequence is presented: Adjusting the Contact controller configuration; Adjusting the initial level of the DFL signal; Approaching the sample to the probe; Adjusting the working level of the feedback gain. Fine adjusting the detection channel After the sample approaches the probe, the sample surface appears shifted out of the focal plane of the optical tube. So, the detection channel needs some further (fine) readjustment. To adjust the detection channel precisely, perform the following steps: 1. Open the feedback loop by releasing the button in the Main Operations panel. The probe-sample distance will be 10 m. 2. With one of the movement screws (pos. 1 or pos. 2 in Fig. 4-1), carefully move the probe away from the viewing field of the objective. Watch the probe image on the monitor of the optical viewing system. Notice position of the probe to enable its easy return to the initial position later. Fig Adjusting elements of the detection system 1, 2 screws for X and Y movements of the probe; 3 screw for fine focusing of the objective; 4, 5 screws for positioning the photodiode; 6 screw for Z movement of the optical tube 3. Focus the objective on the sample surface by rotating the screw 3 (Fig. 4-1). Watch the surface image on the monitor of the optical viewing system. 4. Open the laser exit shutter. The laser beam will go through the LBDS and the optical tube and come to the sample. 40

41 Chapter 4. Performing Measurements 5. Focus the lens of the optical tube on the sample surface by moving the optical tube along Z direction with the screw 6 (Fig. 4-1) of the positioning device. With proper focusing, the laser spot will be of the least diameter (Fig. 4-2). Fig Image of the focused laser spot 6. Mark the centre of the focused laser beam on the monitor of the optical viewing system using a mark pen. 7. Close the laser exit shutter. This completes fine adjusting the detection channel Adjusting the Delivery Channel Adjusting the laser beam delivery channel should provide proper positions of the laser beam and of the probe for the sample surface to be irradiated at that point where the transmitted radiation is collected by the optical detection system. For adjusting, the laser beam is directed to the focus of the detection system and then the center of the probe aperture is moved to the focus of the laser beam. For adjusting the delivery channel, the optical scheme of the Transmission Collection Mode, that is, the optical tube is connected to the PMT module through the LBDS while radiation from the laser source is directed to the spectral unit. Arranging the optical scheme of the Transmission Collection Mode 1. Remove the Output socket from the radiation feedthrough. To this purpose, press and hold the backing-up screw of the feedthrough with your left had (Fig. 4-3) and pull the Output socket with your right hand. 41

42 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Fig Radiation feedthrough 2. Insert the Output socket in the bushing of the PMT module against the stop (Fig. 4-4). Secure the Output socket be screwing the fixing screws of the bushing of the PMT module. Fig PMT module 3. Direct the beam from the laser source to the spectral unit within the Control program of the spectral unit (see manual on the Control program). 4. Open the exit laser shutter. The laser beam will go through the spectral unit and come to the radiation feedthrough. 5. Turn the turret of exchangeable mirrors to position M0 (totally reflecting mirror). The laser beam will come to the sample and the monitor of the optical viewing system will display the laser spot focused on the sample surface. Fig Image of the laser spot focused on the sample surface 42

43 Aligning the laser beam with the focus of the detection system Chapter 4. Performing Measurements 1. Go to the Spectra tab in the Main window of the Nova program. This runs the auxiliary version of the Nova program. All operations on scanning are performed in the main version of Nova. Select the Scan (Slave) tab for scanning-by-laser mode. 2. For directing the laser beam to the focus of the detection system, place the marker of the 2D Viewer (Fig. 4-6 a) at the location corresponding to the mark on the monitor of the optical viewing system (Fig. 4-6 b). The mark has been made by mark pen on the monitor of the optical viewing system during fine adjustment of the detection channel. Watch position of the laser beam on the monitor of the optical viewing system. The marker of the 2D Viewer will follow the actual position of the mirror scanner. Mark a) 2D Viewer b) Image on the monitor of the optical viewing system Fig Viewing mirror scanning 3. Adjust the PMT output as follows: a. In the drop-down list of the Main Parameters panel, select PMT1 (Fig. 4-7). Fig. 4-7 ATTENTION! When using the PMT module, monitor level of the PMT output (Ext2 signal) on the oscilloscope. At level >5 V, the PMT may be damaged. b. Open the Auxiliary Operations Area by clicking the button at the right top of the Main window. 43

44 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual c. Go to the software oscilloscope at the bottom of the Auxiliary Operations Area. In the drop-down list of the Signal field, select Ext2 corresponding to the PMT output (Fig. 4-8). Fig. 4-8 The oscilloscope is expected to display a noisy curve with RMS level of noise of order If noise is noticeably higher, check connectors between the PMT and the controller for bad connection, test ground ing of all electrical components, and eliminate sources of strong electromagnetic interference. d. Adjust the PMT control voltage (PMT1 parameter) by gradually increasing the voltage until modulus of the PMT output is 1 V. Monitor the output level on the oscilloscope. NOTE. The optimal level (in modulus) of the PMT output for measurements is 1 V. Higher output results not only in direct raise of the noise level RMS but also in heating the PMT module that contributes to noise. On the other hand, lower output may result in insufficient sensitivity. 4. Scan an area around the focus of the detection system by the laser beam as follows: a. Define the following values of the scan parameters: - X and Y pixel dimensions of the scan area (Point Number parameter) 100; - Metrical size of the scan area (Scan Size parameter) 20 m; - Detection signal (in the list of available signals Select Signals) PMT; - Time of measuring at a point (Time/point parameter) 62.5 s. b. Using the tool, select the scan area so that the green cross of the marker in the 2D Viewer is at its center. 44

45 Chapter 4. Performing Measurements Fig Selecting the scan area c. Start scanning the selected area. Intensity distribution of the detected signal will be acquired (Fig. 4-10). Fig Intensity distribution of the detected signal The dark region in the acquired image corresponds to the light-transmitting region of the optical tube, that is, light coming to this region will be detected by the PMT module. 5. To improve positioning of the laser beam, perform scanning over a smaller area. Repeat the step 4 with value of the Scan Size parameter being 10 m. Again, intensity distribution of the detected signal will be acquired (Fig. 4-11). 6. Direct the laser beam to the point where the detected signal is maximal. To this purpose, place the marker to position where the PMT output is maximal (Fig. 4-11). Monitor the output level on the oscilloscope. 45

46 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual Fig Arrow indicates the position of the maximum of the detected signal 7. Mark the centre of the laser spot on the monitor of the optical viewing system using a mark pen. Position of the new mark will most likely differ from the previous one. 8. Define the PMT control voltage (PMT1 parameter) to be 0 V. Aligning the probe aperture with the focus of the laser beam 1. Turn the turret to the position M2 (no reflection applied). The laser beam will not illuminate the sample and the image of the sample on the monitor of the optical viewing system will be formed by ambient light. 2. Carefully move the probe to the viewing field of the objective with the screws 1, 2 (Fig. 4-12). Watch the probe on the monitor of the optical viewing system. Fig Adjusting elements 1, 2 screws for X and Y movements of the probe 3 screw for fine focusing; 4, 5 screws for positioning the photodiode 3. If the probe aperture is out of the objective focus, focus the objective on the aperture by turning the fine focusing screw 3 until the aperture image is contrast. 4. Carefully move the probe to match the aperture image on the monitor of the optical viewing system with the second mark (Fig. 4-13). 46

47 Chapter 4. Performing Measurements Mark F ig Probe aperture image matches the second mark Tuning the photodiode position With the delivery channel adjusted, align the photodiode as follows: 1. Switch to the Aiming tab with the button in the Main Operations panel. 2. Rotate the photodiode positioning screws 4 and 5 (Fig. 4-12) to place the laser spot position indicator at the center of the photodiode indicator (Fig. 4-14). Fig Laser spot adjusted at the center of the photodiode 3. Close the feedback loop by pressing the button. 47

48 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual 4.3. Scanning Before taking a scan, turn off the illuminator and all sources of ambient light in the work room and close windows of the room with dense curt ains to protect the PMT from any undesirable interference. Scanning includes two stages. First, scanning-by-laser of the probe interior is used to align the laser beam at the center of the probe aperture. Then, the surface landscape and the transmitted light intensity distribution are measured with scanning-by-sample. Scanning-by-laser uses the Scan(Slave) tab while scanning-by-sample uses one of the tabs Scan(Master) or Scan. Here, scanning-by-sample will be explained with the Scan tab. Tuning position of the laser beam 1. In the Auxiliary Operations A rea (accessible through the button at the right top of the Program window), select the Scheme tab to open the block scheme. 2. Click the secondary mouse button on the button of the scheme window. In the popped-up list (Fig. 4-15), select Save to lock the position of the Z-section of the scanner. Fig Selecting the Save item NOTE. Be aware that leaving the probe in the Save state for long time is risky because the probe can be damaged due to the scanner drift. 3. Turn the turret of exchangeable mirrors to position M0 (totally reflecting mirror). The laser beam will fall onto the probe and then, after passing the aperture, onto the sample. 4. Gradually increase the PMT control voltage (PMT1 parameter) until one of the following events occurs: - the PMT control voltage achieves the level of 1250 V; - modulus of the PMT output achieves the level of 1 V. Monitor the PMT output on the software oscilloscope (Ext2 signal). The PMT control voltage is adjusted properly if the PMT output changes with turning the laser beam on and off. The PMT output is expected to be 0 V with the exit laser shutter closed and to be 1 V with the shutter open. 5. Perform scanning-by-laser of the probe surface around the aperture. First, scan a larger area (of size, for instance, 8 8 m) and then repeat with a smaller area (of size, for instance, 3 3 m). 48

49 Chapter 4. Performing Measurements 6. Aim the laser beam at the center of the probe aperture by placing the marker to the position of the maximal PMT output (Fig. 4-16). Monitor the PMT output on the software oscilloscope. Fig Arrow indicates position of the maximal intensity of the laser signal 7 With the laser beam aimed at the center of the aperture, the monitor of the optical viewing system will display the distinct image of the laser s pot with rays radiating in vertical and in horizontal ( Fig. 4-17). Fig Distinct image of the laser spot. The laser beam is aimed at the center of the probe aperture Scanning-by-sample 1. Switch on the feedback by clicking the button in the block scheme and selecting On in the drop-down list (Fig. 4-18). Fig Selecting On item 49

50 NTEGRA Spectra Probe NanoLaboratory. SNOM Measuring Head. Instruction Manual 2. Switch to the Scan tab by clicking the button in the Main Operations panel to activate scanning-by-sample. Open the scanning parameters window by clicking the button. Select the following detection signals for the forward pass: - for ADC#1 PMT; - for ADC#2 Height. 3. Perform scanning-by-sample of the selected area. The optical intensity distribution and the surface landscape will be acquired (Fig. 4-19). For the example, the test structure Alprojection pattern m on the cover glass (produced by Kentax.de) was used. Images are presented with a color scheme that displays more transparent regions with darker colors. Fig Optical intensity (left) and surface landscape (right) 4.4. Saving Data Data collected during the scanning procedure are stored in the RAM. They can be viewed and analyzed in the Data tab (by clicking the button in the Main Operations panel). To save the data on the hard disk, perform the following steps: 1. Select the File Save Main menu command. 2. A dialog box will appear. Define the folder to store the data (by default, it is C:\Program Files\NT-MDT\Nova). 3. Type in a filename and save it with the extension *.mdt. NOTE. By default, the images obtained are stored in files NoNameXX.mdt, where XX is the file index in the folder Nova. 50