FTIR. Far - Infrared Teraher t z. Tests. Instruments. Terahertz Spectrometer

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1 FTIR Far - Infrared Teraher t z Modular Spectral Analyzer Material Transmission/Reflectance Spectrometer In The Far-Infrared and THz Spectral Region A simulation of what the sky will look like to the Planck satellite (Image: ESA) Far-Infrared and terahertz (THz) radiation falls in the spectral region at the long wavelength end of the infrared and the short end of the microwave region. It is also known as sub-millimeter wavelength spectral region. In the last few years, there has been an explosion of interest in THz applications as the radiation can penetrate many materials. THz light is now used in materials science research, security, pharmaceutical compound analysis, biomedical imaging, superconducting materials research, astronomy and particle physics research. Sciencetech is a pioneer in THz spectroscopy, having supplied its SPS-200 Far Infrared FTIR for over 10 years to the sub-millimeter wavelength research communities in astronomy and particle physics. Sciencetech has recently upgraded its SPS-200 into the truly commercial grade SPS-300 THz spectral analyzer and spectrometer, thanks to the support of the European Space Agency which is using the SPS-300 to calibrate the detectors for its Planck/Herschel Mission to analyze the origins of the universe. Main Features Modular design for use as far-infrared/thz spectral analyzer or materials spectrometer Dual polarizing Martin-Puplett and Michelson interferometer configurations depending on beam splitter used Industry s finest 4μm Mylar grid beam splitter for Polarizing Mode Supports external third party light sources and detectors Supports external custom designed sample chambers Standard precision step scan and rapid scan modes Large 90mm gold coated optics Wide 2~2000cm-1 (5μm~5mm) spectral range 0.12cm-1 resolution for standard model with 50mm stage 0.02cm-1 for high resolution model with 300mm stage upgrade Technical Specifications Spectral Range 2 to 2000cm -1 (5μm to 5mm, 60GHz to 60 THz ) Standard Resolution High Resolution 0.12 cm -1 with 5cm translation stage 0.02 cm -1 with 30cm translation stage SPS-300 FTIR Vacuum sealed housing supporting pressures up to 10-3 Torr to eliminate spectral effects of atmospheric water vapor. Thermocouple vacuum gauge Model SPS-300 Far-Infrared THz FTIR The SPS-300 is Sciencetech s latest modular polarizing Fourier Transform Spectrometer (FTS), designed specifically to operate in the far infrared or THz spectral region. While standard FTS and FTIRs are based on the Michelson configuration, the SPS-300 operates in the Martin-Puplett configuration as well, which provides polarization division for a significantly wider bandpass when measuring normal transmission, and improved signal to noise ratio for circular dichroism and linear dichroism measurements. The SPS-300 can be configured as a THz spectral source analyzer by mating to an external bolometer detector at the output port, or it can be configured into a THz materials spectrometer by mating to an external light source at the input port and a sample chamber with detector at the output port. Model SPS-200 Far-Infrared FTIR The Model SPS-200 is Sciencetech s older generation THz polarizing Fourier Transform Spectrometer (FTS). Although no longer in production, many new upgrade accessories are available for existing systems; for example the Rapid Scan upgrade, a new highly stable mercury arc lamp, a new slower chopper system, etc. THz Scanning Services Sciencetech provides THz spectral analysis and scanning services on various materials in solid, liquid and gas form. Both transmission and reflectance measurements can be taken in the spectral range 20μm to 3.3mm. Please contact the Special Development Group for details at: Sciencetech s SPS-300 is a modular polarizing Fourier Transform Spectrometer/Interferometer (FTS or FTIR) designed specifically to operate in the far-infrared and THz spectral region (operating wavelength from 5μm to 5000μm, frequency from 0.06 to 60 THz or 2cm-1 to 2000cm-1). The modularity of the SPS-300 allows it to be configured as a far-infrared/thz light source spectral analyzer or as a materials transmission and reflectance spectrometer. The SPS-300 has large 90mm optics and can be operated in both classical Michelson mode and polarizing Martin-Puplett Mode for superior sensitivity and broad spectral range. The SPS-300 comes with a grid polarizer beam splitter and a Mylar beam splitter. The grid polarizer beamsplitter allows the SPS-300 to operate in polarizingmartin-puplett mode, and cover a wider range than the standard Michelson mode using the Mylar beam splitter. The Polarizing mode also has other advantages in spectroscopy, biophysics, surface science, electrochemistry, materials science, and infrared ellipsometry. Signal-to-Noise Ratio Optics Grid Polarizer Beam Splitter Body Source Controls Ports Scan Dimensions Weight (with internal lamp) in Michelson mode: 250:1 in Martin-Puplett mode: 50:1 Large 90mm beam optics coated for maximum infrared reflection fast f/2.35 off-axis paraboloid condensers for high light throughput 90 ±3 roof mirrors Martin-Puplett optical configuration 2μm lines with 4μm pitch aluminum on Mylar substrate Vacuum steel housing capable of maintaining 10-3 Torr Internal 75W Hg arc lamp (water cooled) with external DC stabilized power supply and igniter Motorized alignment for roof mirror tilt, rotary shear, lateral shear) to fine tune inter ference at the beam splitter External source input port Converging and parallel beam output ports Vacuum purge port Inlet and outlet ports for water cooling of internal light source and stepper motors Step and Integrate (standard): Data collection is coordinated with the translating roof mirror position. The mirror is stepped to each specific position and stops while a reading is taken. Rapid Scan Mode: The roof mirror moves continuously during data collection without stopping at each position. 98cm x 63cm x 38cm (39 x 25 x15 ) Steel body: 180kg (397lb)

2 SPS-300 System The base system of the SPS-300 includes: SPS-300 Body consisting of: Servo motor chopper 75W ultra quiet Hg arc lamp source Vacuum gauge Motorized roof mirror alignment system Mylar beam splitter for Michelson operation mode Grid polarizer for polarizing Martin-Puplett mode Steel or optional stainless steel casing External Components: Vacuum pump system to maintain 10-3 Torr vacuum inside SPS-300 Recirculating water cooler Arc lamp power supply and igniter Servo motor electronics for choppers and translation stage Stepper motor electronics for roof mirror alignment Host PC with SPS control softwaremylar beam splitter for Michelson operation mode Grid polarizer for polarizing Martin-Puplett mode Steel or optional stainless steel casing Components required but not included in base price: Detector, GPIB, Lockin amplifier. For Spectral Analyzer configuration: Additional detector; light input port with flipping mirror For Materials Spectrometer configuration: Additional detector; sample chamber Standard Features Internal Source and External Input Port The SPS-300 has a built-in 75W Hg arc lamp for use as a broadband THz source. When the user wants to use his own THz source, an optional internal flipping mirror can be switched to bypass the internal lamp source and allow external radiation to enter through the input port. The optional input port is ~4cm (1.5 ) in diameter and can accept a f/2.5 converging input beam focusing just inside the housing. The port is capped with a polyethylene window that transmits THz radiation but maintains the vacuum conditions inside the SPS- 300 body. In Spectral Analyzer configuration the external source to be analyzed is introduced through the input port and the internal light source is only used as a reference. In Materials Transmission/Reflection Spectrometer configuration either the internal 75W Hg arc lamp or an external source can be used. If the user prefers an external light source, Sciencetech does manufacture a glow-bar source and a Gunn oscillator source that can be mounted to the external input port. A user may also use a third party light source. Output Ports The SPS-300 has two output ports. One produces a focused output beam for mating to a detector while the other produces a collimated output beam for mating to an external sample chamber. Normally, only the focused detector port is used in Spectral Analyzer configuration while only the output external sample chamber port is used in Materials Transmission/Reflectance Spectrometer configuration; however with an extra beam splitter both can be used at the same time. Detectors Three THz detector choices are available from Sciencetech. The most common is a DTGS (pyro-electric) detector, which operates at room temperature. More sensitive liquid helium cooled bolometer and liquid helium cooled hot electron bolometer detectors are also available. The user may also choose to use a third party THz detector. Vacuum Environment The SPS-300 FTS maintains a 10-3 Torr vacuum environment in its optics chamber to minimize the spectral absorption effects of atmospheric water vapor. Due to this internal vacuum environment, the input port and the two output ports are sealed withmetal cover to prevent leakage. The polyethylene windows transmit THz radiation while maintaining a sealed internal vacuum environment. The windows can be removed for those cases where the vacuum environment includes light sources and/or output detectors and/or sample chambers. The top lid is removable for maintenance and for changing the beam splitter and choppers to switch between polarizing and Michelson modes. While the SPS-300 can operate in a vacuum environment, the equipment required to produce the vacuum is sold as a separate upgrade option. Optics One of the most important optical features of the SPS- 300 is our exclusive polarizer grid beam splitters, which are nearly 100% efficient for all wavelengths up to the cut-off frequency set by the grid separation of 4μm. The SPS-300 also features large 90mm optics for high light throughput, a high precision translating stage, large roof mirrors, and large input/output off-axis paraboloids to support a 10cm (4 ) diameter output beam. The Model SPS-300 also operates in both polarizing and Michelson mode. Each mode has its own computer-controlled chopper (input Mylar beam splitter chopper for Michelson mode, output grid polarizer chopper for Polarizing mode). Changing modes involves demounting the unused chopper and selecting the correct chopper settings on the external electronics controller. Cooling System Since heat does not dissipate well inside the vacuum optics chamber, a 6mm (¼ ) diameter water cooling loop with external recirculation is used to cool all internal heat generating components such as electric motors and the Hg light source. Other heat dissipating electronics such as motor controllers and light source power supply are located outside for operation in the ambient environment. Host PC A PC with flat screen monitor is supplied as the host computer with the SPS-300 control software fully installed and operational. A copy of the software is also provided on CD. Scanning Mode The SPS-300 generates an interferogram by taking multiple detector readings as a mirror translates across a known distance.. In standard Step and Integrate Mode, the mirror stops at a prescribed position for each detector reading. By stopping, the detector can take long readings for better signal-tonoise ratio, and the relationship between the detector reading and mirror position is known precisely. An upgrade is available to allow a Rapid Scan Mode in which the mirror does not stop translating while the detector is read. Instead, it keeps moving while the detector captures as many readings as possible along the way. The advantage of rapid scan mode is that there is no dead time between readings due to the stop and go motion of the translating mirror, resulting in faster scans. This is useful when making a draft or preview scan across a wide spectral region. The disadvantages of rapid scan mode are short detector reading times and a less precise relationship between the readings and the mirror positions. A typical rapid scan 15~60 seconds. Due to the speed requirement the optical chopper and lock-in amplifier are not used. Instead, the signal from the detector is filtered and amplified, and then fed directly to the computer through a 16-bit AD board. Software The SPS-300 control software is a LabView based application that operates on a Windows PC. An executable version of the software is supplied so the user does not require the Lab View development environment. Although Sciencetech only supports the Windows version of the SPS-300 control software, a Mac-OS version is also available through a third party vendor. Main Software Features: Step and Scan or Rapid Scan operation Data acquisition and automatic log-keeper Data stored in ASCII format text files for easy importation into other data analysis software Multitasking for simultaneous scan and analysis

3 Data Processing and Manipulation: Phase correction by Mertz-Forman method Apodizations: Bessel, boxcar, cosine, triangular Digital filtering of the rapid scan signal Add, subtract, normalize, multiply (interferograms or spectra) Average and standard deviation (interferograms or spectra) Fitting of data by user-specified functions: functions are analytically specified and new functions are automatically saved on the hard disk for easy retrieval Display: Fast Scan Mode: display of interferogram, spectrum and the relative sigma of the spectrum Step and Integrate Mode: display of interferogram and contents of lock-in amplifier buffer Display of spectra, interferograms, ratios, fit results and other data Print selected data Multitasking The software is capable of simultaneous scanning and data analysis. The SPS-300 software runs in its own window and is undisturbed by other Windows applications running in the background. Batch Processing: Automated data acquisition can be achieved with simple command scripts. This is useful for organizing unattended automated measurements Modular LabView VI structure: Users may add application specific lab view virtual instruments (VI s) without recompiling the SPS-300 software. This is useful for experiment automation where scanning operation needs to be integrated with external features (from sample chambers, light sources, temperature controllers, magnetic field sweeps, etc.) Performance Spectral Range The SPS-300 Spectral Range (both Standard and High Resolution Models) is 2 to 2000cm-1, (5μm to 5mm). Although the SPS-300 optics can cover a spectral range from 2 to 2000cm-1, the practical range is generally limited by the source and detector combination used. For example, the 2cm-1 low wavenumber spectral range cutoff can only be obtained with a high powered source such as that of a synchrotron entering through the external light source port and a 1.7k helium cooled bolometer detector. Using the internal Hg arc lamp provided, the low wavenumber spectral range cutoff is limited to approximately 4cm-1 using the bolometer. This low wavenumber cutoff increases to about 8cm-1 with a 4k helium cooled bolometer and the internal Hg arc lamp. At the high wavenumber end the grid spacing of the polarizer is a limiting factor. Since Sciencetech uses a close pitch 4μm grid polarizer, compared to other polarizers of 12.5μm or 25μm pitch, the SPS-300 is capable of reaching 2000cm -1 if the detector and source allow. More commonly the cutoff is closer to 1000cm- 1. Resolution : Standard: 0.12cm -1 with 5cm translation stage High: 0.020cm-1 with 30cm translation stage The resolution quoted for the SPS-300 is not the theoretical limit as determined by the length of the roof mirror translating stage, quoted by some manufacturers. The the abrupt stopping of data collection at the ends of the interferogram produces oscillations in the Fourier transformed spectrum (that look like feet at the sides of strong lines). So Sciencetech uses an apodization function which multiplies the interferogram by a factor that goes to zero smoothly at the scan ends - but this degrades the resolution somewhat. Although there are several alternatives, we quote the resolution for Bessel apodization, which is degraded by from the theoretical limit. In general, resolution is given by: Resolution = A/(2*2*0.80*L) [cm -1 ], where L = stage length [cm], A = Apodization factor 0.80 is the zero path location factor (zero is 20% from the translation stage end position) Four different apodizations can be selected on the SPS-300 software, each with its own factor A affecting the resolution: Bessel: A = Boxcar: A = Cosine: A = Triangular: A = The recommended apodization for the very far infrared and THz domains is the Bessel function. Configuration Options Depending on options selected, the SPS-300 can be configured into the following: Spectral Analyzer The SPS-300 is used as a spectral analyzer by mounting an external THz light source at the external input port, and an external THz detector at the condensing beam output port. Sciencetech provides multiple detector options: a room temperature pyro-electric detector, a room temperature DTGS detector, and a helium cooled bolometer. A user can also opt to attach a third party detector to the output port. Materials Transmission/Reflectance Spectrometer The SPS-300 is used as a materials transmission/reflectance spectrometer by mounting an external sample chamber at the collimated beam output port and an external THz detector at the sample chamber detector output port. For example the SPS403 sample chamber and detector allows both transmission and reflectance measurements. The source is the broadband Hg arc lamp inside to the SPS-300 body. However, other types of broadband THz sources such as a glow-bar or Gunn oscillator can be mated to the external input light port. Please note that the SPS-300 base system does not include these additions. THz Circular/Linear Dichroism Spectrometer In polarizing mode operation, the SPS-300 can also be used for transmission, circular dichroism, and linear dichroism investigations with good signal-to-noise ratio. The measurement of vibrational circular dichroism (VCD) below ~600 cm -1 is a modern experimental challenge. Polarizationdivision interferometry is considered to be the most efficient approach for realizing these measurements. A crucial component for successful applications of this interferometry is the beam splitter that divides the incoming beam according to polarization. The Sciencetech large area FIR grid polarizers consisting of metallic lines deposited on a mylar substrate are effective beam splitters for the 500cm -1 ~ 2.0 cm -1 frequency range. Upgrades Optical Layout for Spectral Analyzer Configuration Optical Layout for Materials Spectrometer Configuration Rapid Scan Upgrade (code: SPS200RS) In the standard Step and Integrate Mode, detector data acquisition coordinates with to the translating roof mirror position. The control software sets the mirror position via fire wire commands and acquires the corresponding detector data via a GPIB interface of the lock-in amplifier. Since this standard scan mode can be time consuming, a faster but less precise rapid scan mode is available

4 What limits scan time and does using Rapid Scan mode help? In Rapid Scan mode the roof mirror moves continuously and does not stop at each reference position for detector data acquisition. An interferogram is generated immediately after the mirror completes its translation, typically in 15~60 seconds. The detector signal is not synchronized with a modulated source using an optical chopper and lock-in amplifier because the optical chopper is too slow for the data acquisition process. Instead, since the incoming detector signal is weak, it is amplified and filtered using an electronic signal processing unit and then fed directly into the computer using a 16-bit AD board. Rapid Scan Mode operates only if the detector and electronic processing unit (amplifier & AD board) is purchased with the system, Otherwise, only the software is included and the user must supply their own detector, amplifier, and 16-bit AD board to take advantage of this feature. In Martin-Puplett polarizing mode Rapid Scan works only with a fixed polarizer analyzer placed at the output beam (or with the polarizing output chopper in a non-rotating position). Main Features Rapid Scan software upgrade 16-bit AD board for detector to computer interface Electronic signal processing unit to filter and amplify detector signal before computer interface Technical Specifications Uses separate AD Board Interface instead of lock-in amplifier to keep up with fast data acquisition Includes a signal amplifier to boost pyroelectric/ bolometer signal before digitization supports stage scan speed of 0.5cm/s (10 seconds on standard 5cm stage). Speed limited by detector Detector sensitivity in capturing a good signal is what truly limits scan speed, much more than the difference between using step & scan mode or rapid scan mode. After all, rapid scan mode only eliminates the dead stage translation time between scan data points, which becomes irrelevant if the detector integration time must be increased beyond ~1/2 second to obtain adequate S/N. So in situations with long detector integration time, standard Step and Integrate is as efficient as rapid scan mode. Using bolometer as the detector and the internal 75W Hg light inside the SPS-300 as the source, the typical bolometer integration time is about 100ms. However, the step time, or time between measurements, is about 200ms. So in typical Step and Integrate the scan time is about 300ms x the number datapoints required. In rapid scan mode using the same detector and source the mirror speed is limited to about 0.5cm/s due to detector signal to noise issues. Any faster scan speeds (though mechanically possible) would not yield enough signal for decent detector reading. At this stage speed a scan at the highest resolution would take 10 seconds to complete, collecting 100 detector readings and resulting in a data-point density of 2 points/mm. By comparison, Step and Integrate would require 30 seconds. These numbers assume we are looking at very thin samples or gases. If the material is thick or has low transmission coefficient, longer integration times may be needed and the fastest stage speed in rapid scan mode will be even slower. High Resolution Upgrade (code: Hi-Res(SPS300) The standard SPS-300 has a 50mm translating stage, which can obtain resolutions to 0.12cm -1. This high-resolution upgrade option extends the translating stage to 300mm, allowing the SPS-300 to reach a resolution of 0.020cm-1. Due to the increased stage length, an extension is required to the vacuum sealed body to accommodate the extra travel. SCANNING FAQ If we only want to get a spectrum within a relatively small spectral range, for example THz (10cm -1 to 16.7cm -1 ), What happens to the required scanning time and the spectral resolution? This is a very good question to understand how an FTIR works. In general, the resolution is set by the traversing the length of the mirror stage and the short wavelength limit of the spectral region is set by the spacing density of the mirror positions within that length (data-point density). The base SPS- 300 has a stage length of 50mm, which allows it to achieve 0.12cm -1 resolution regardless of the spectral region. If we want to scan a larger spectral region, we would scan more points along this 50mm stage length, resulting in a higher datapoint density. If we want to scan a smaller spectral region, we could scan fewer points along this 50mm stage length resulting in a lower data-point density. The total travel distance of 50mm remains the same in both cases, assuming we want the highest resolution of 0.12cm -1. Please note that regardless of desired spectral region, we always start from 0cm -1 and scan upwards to the selected cut off frequency. For the spectral region from 0.3 to 0.5THz (10cm-1 to 17cm -1 ), we would typically scan the spectral range 0~20cm -1 as a rounded setting. For this spectral region, we need a data point density of 1.6points/mm. So if we want the highest resolution, we would scan at this data-point density for 50mm resulting in 80 detector readings. If we want half the resolution, we would scan at this data-point density for 25mm resulting in 40 detector readings. In regular Step and Integrate Mode, each scan point takes about 300ms: the bolometer detector integration time is about 100ms (for scanning thin films or gases) and the dwell time, which is defined as the time between scan points, is about 200ms. This 200ms is required for the mirror to move and settle before taking the next detector reading. So an 80-point scan would take about 24 seconds in the highest resolution mode. If the high-resolution stage is used which would result in a 30cm mirror travel, 480 data-points are required for this spectral region, which would require 144 seconds to scan. Stage Positional Accuracy The 300mm stage has a built-in encoder that provides the absolute position of the translating roof mirror to the SPS- 300 host computer. This encoder has been individually calibrated at the factory using a laser interferometer for accurate positioning. Vacuum Operation Upgrade (code: V-Pump) The standard SPS-300 housing is itself vacuum grade and can maintaining a 10-3 Torr vacuum environment inside its optics chamber. However the pumps, seals, valves, gauges, and port caps to maintain this vacuum are sold separately should the user wish to take advantage of this capability. Maintaining a vacuum allows the spectral absorption effects of atmospheric water vapor and carbon dioxide to be minimized so that they do not affect the spectra measured. This vacuum upgrade contains all of the necessary parts for vacuum operation including: seals, valves, gauges, and port covers. With a typical roughing pump, the SPS-300 can reach a vacuum of 10-5 Torr. For vacuum pump options please consult a Sciencetech application Specialist. Acoustic Noise The SPS-300 is very sensitive to acoustic vibrations - even a conversation can be measured - and a vacuum environment of even 0.1 Torr is effective in preventing acoustic noise pollution. Vacuum System Components Both standard vacuum and ultra vacuum options include the same vacuum proof housing, a digital vacuum gauge, and computer controlled vacuum gates and release valves. Vacuum tight Removable Lid The lid is removable for maintenance and for changing the beam splitter and choppers between Polarizing and Michelson modes. However, the housing needs to be brought back to atmospheric pressure before the lid can be removed. Vacuum Gauge A vacuum gauge is included with this option. The vacuum reading is displayed in real time (refresh rate of once per second) on a computer via a 12-bit AD data acquisition board. The readings are displayed in Torr (or mtorr) via an ActiveX software module. This software interprets the data from the AD board and calculates

5 the actual Torr (or mtorr) value. Since it is an Active-X module, the functionality can be incorporated into a larger Visual C++, Visual Basic, Excel, Java++, or even LabView based application. It can also be used as a standalone application as part of the SPS-300 software feature set. Vacuum Release Valve The SPS-300 vacuum release valve to relieve the vacuum chamber inside should the user wish to bring the unit back to atmospheric pressure for internal maintenance or changes to its optical configuration. Vacuum Testing In addition to the pumps, a substantial portion of this cost is in vacuum testing to qualify the instrument for vacuum use. Accessories External Source Selector (code: SPS601) Available for both the Spectral Analyzer and Spectrometer configurations, this option adds an internal motorized mirror such that an external THz source entering through the external input port can be selected instead of the internal Hg arc lamp source. The internal Hg arc lamp source is turned off when the external light source is selected. Without this option, the only available light source is the built-in internal Hg arc lamp source. This option is required in the Spectrum Analyzer configuration where an external source spectrum is measured. It is also required in the Materials Spectrometer configuration if the user wishes to use an external source to illuminate the sample other than the built-in internal source. Simultaneous Dual Output Ports (code: SPS602) The SPS is typically configured to use only one output port - either the converging output for mating to a detector when the instrument is used as a spectral analyzer or the parallel output for mating to a sample chamber if the instrument is being used as a materials spectrometer. This option allows the instrument to use both outputs simultaneously. The internal mirror that directs the parallel beam to the converging output is replaced by a large beam splitter which sends half the radiation to the converging output & the rest to the parallel output. SPS403 Optical Layout Sample Chamber (code: SPS403) This is an external transmission/reflectance sample chamber that can be mated to the output port of the SPS200/SPS-300 FTIR when it is being used as a Materials Spectrometer. This sample chamber allows small samples such as liquid in a cuvette or thin films to be studied under both transmission/ reflectance modes. The sample chamber is totally isolated from the SPS-200/ SPS-300 vacuum environment by a sealed polyethylene window at its input port (output port of the SPS FTIR) thereby enabling the user to change samples without upsetting the SPS-200/SPS- 300 vacuum housing. The sample chamber can be operated independently in vacuum (optional up grade code: PSPS403-VAC) or in atmospheric conditions. The sample chamber utilizes reflective aspheric optics with gold coating for far infrared and THz operation. A manual flipping mirror inside the sample chamber allows the user to select between transmission and reflective modes. In transmission mode, an internal mirror focuses the sample onto the detector, whereas in reflective mode, a secondary internal mirror focuses onto the sample. All optics are pre-aligned and focused for a specific detector positions at the sample chamber output port. An optional peltier cooler is also available to maintain the temperature of the sample holder(code: SPS403-C). For this option, a water-cooling loop inside the sample chamber is required. This water-cooling loop can be connected to the same water re-circulating system as the main SPS-200/ SPS-300 body or though a separate independent cooler such as the Sciencetech Model 160- REC water recirculation. A Helium cooled sample chamber is also available (code: SPS403-He). SPS403 Top View SPS403 Sample Chamber Sciencetech can customize a sample chamber to meet your specific needs, speak to a Special Development Assistant at Gunn Oscillator (code: Gun-Os) Sciencetech can supply a demountable Gunn oscillator light source that can be mounted to the external source port of the SPS-300 for Materials Spectrometer applications. When the SPS-300 external source mirror is set to the external source port, the Gunn oscillator becomes the excitation source rather than the internal arc lamp. The Gunn oscillator remains at atmospheric pressure and does not share the vacuum space of the SPS-300. The external source port is sealed with a quartz window cap that is part of the Gunn oscillator structure. The Gunn oscillator is a narrow band source and the user will need to select a model whose frequency matches the desired application. Globar (code: GLO-Li) Sciencetech can supply a demountable globar light source that can be mounted to the external light source port of the SPS-300 THz Spectrometer. When the internal light source flipping mirror of the SPS-300 is set to the external light source port, the globar becomes the excitation source rather than the internal arc lamp. The globar is enclosed in its own vacuum housing (sharing the same vacuum space of the SPS-300) and with water-cooling lines that interconnect to the SPS-300 cooling circuit. The power supply is sold separately. DTGS Detector - Detector Only Ver.(code: DTGS -base) This is a room temperature based far-infrared detector for use with SPS-200 and SPS-300 THz FTIR spectrometers. This detector option includes the DTGS detector with mounting flange. A Dual Phase lockin amplifier, required for improved signal- to-noise ratio, is sold separately. This detector can be mounted directly to the SPS-200/SPS-300 body at the detector port, or on the Modular Sample Chamber. Liquid Helium Cooled Bolometer Detector (code: Bo-Det) Liquid Helium Cooled Bolometers are far more sensitive than room temperature DTGS or Pyro-Electric detectors in the far-infrared/thz spectral region. However, they are more expensive and tedious to operate, as liquid helium is required. This detector option includes a customized silicon composite bolometer, preamplifier electronics, a helium dewar and interface flange to the SPS-300. The helium dewar cools the detector to 4.2K or 1.7K (depending on version purchased) for high sensitivity. In the 1.7K version an added helium pump connected to the dewar is required. In Rapid Scan Mode, the bolometer interfaces to the AD board, and in Step and Integrate mode, it interfaces to the lock-in amplifier, which in turn has a GPIB interface to the. However, if this bolometer is purchased separately from the SPS- 300, a lock-in amplifier data acquisition system is required. Liquid Helium Cooled Hot Electron Bolometer (code: Bo-HEB) A helium cooled hot electron bolometer has a much faster response time than a standard helium cooled silicon bolometers (picoseconds vs. milliseconds) allowing it to measure the peak power and temporal profile of pulse type THz sources. Please note that these additional measurement capabilities are not required for the SPS-300 to derive a THz spectrum. Quite often the SPS-300 can measure the spectrum of pulse THz source using just the standard helium cooled silicon bolometer despite its slow response time. This is because the detector measures the average power of many pulses spread over time. The advantage of measuring pulse power with the hot electron bolometer is that the spectrum can be measured at specific times within the pulse profile. For example, the THz spectrum at the beginning of a pulse may differ from the spectrum at the peak of the pulse. Non-Magnetic Housing Upgrade (code: H-Up) The S.PS-300 system is enclosed in a steel housing. However, the housing can be reconstructed in nonmagnetic stainless steel-304 should it be placed in a magnetic environment. This option is important in superconducting material and MRI applications where the instrument needs to be placed close to a large magnet

6 Pricing Table Product Code Number Far-Infrared THz FTIR Upgrades SPS-300 Rapid Scan Mode SPS200RS High Resolution Vacuum Operation Ultra Vacuum Operation Accessories Hi-Res(SPS300) V-Pump-stdvac V-Pump-ultravac Water Recirculating Cooler External Light Source Port Dual Output Port 160-REC SPS601 SPS602 Sample Chamber SPS403 Peltier Cooled Option Liquid Helium Cooled Option Vacuum Operation Option SPS403-C SPS403-He SPS403-VAC Gunn oscillator Globar DTGS Detector Liquid Helium Cooled Bolometer Detector Liquid Helium Cooled Hot Electron Bolometer Detector Non-magnetic Housing Gun-Os Glo-Li DTGS-base Bo-Det-2.4k Bo-HEB H-Up