RENISHAW RAMAN MICROSCOPE STANDARD OPERATING PROCEDURE

Transcription

1 RENISHAW RAMAN MICROSCOPE STANDARD OPERATING PROCEDURE 09DJ00 CHRIS BUXEY (TECHNICIAN) X2715 V5.0 OCTOBER 2008

2 RENISHAW MICRORAMAN STANDARD OPERATING PROCEDURE 1.0 Foreword Chris Buxey: This guide is intended as a reference and a reminder for those already familiar with the microraman. If you have never used the microraman before or are trying to do something complicated or unusual, then please contact me for training and/or assistance. Oh, and please REMEMBER TO BOOK and to FILL IN THE LOG BOOK! Dr Henryk Herman: Warning, this is a delicate and expensive instrument. If it is abused, the user will be banned, and disciplinary proceedings may be instigated. Use the log book. It enables us to keep track of the state of the instrument. Any problems or queries, contact: Chris Buxey, x2715 Dr Richard Curry, x2713, or Dr. Henryk Herman, The Renishaw Raman Microscope (Systems 2000) is a compact laser Raman microprobe/microscope that can collect both Raman spectra and global images. The collection optics are based on a Leica DMLM microscope. The samples are placed underneath the microscope objective (x5, 20, 50) and are excited by the laser directed through the microscope. The scattered light is collected (180 degree backscattering) along the same optical path as the incoming laser. Raman scattered light passes through a notch filter (used as one of the reflective elements for the incident laser beam) into the monochromator that disperses the scattered light over a CCD array detector. The spectrometer is controlled by PC using two software packages, instrument control software (Renishaw WiRE ) and data analysis software (Galactic GRAMS/32 ). Safety Procedure: Both lasers in this system as classified Class 3B, which denotes lasers or laser systems that can produce a hazard if viewed directly. This includes intrabeam viewing or specular reflections. The arrangement is such that hazardous conditions are only present within 2 mm of the focal plane, so in normal operation there will be no material hazard. Servicing, or change of laser, will require access to the spectrometer and laser beams. Under no circumstances should unsupervised, untrained users attempt to gain access. You have been warned!

3 2.0 Switching On Procedure Fig1. Renishaw System 2000 microraman Spectrometer. See schematic in Appendix. Sign and date the microraman instrument log book; The Raman system is normally left switched on. Check the illuminated Raman system power switch; if it is off, switch on. The PC controller is normally left on. Check the power button; if it is off, switch on. The PC flat screen monitor is normally off. Switch on. The software is normally left running. If it isn t, click on the shortcut Renishaw Wire. The Raman software starts. Always Check motors. If this process hangs on Focusing Motor for several minutes, contact Chris Buxey. Whilst the system is going through the switch-on procedure (about 5 minutes) switch on microscope illumination. Decide which laser, 514 or 782 nm, you require. Note that changing from one to the other is an involved process that requires opening and working within the spectrometer. It MUST NOT be carried out by anyone unfamiliar with the necessary alignment procedure and you must have authorisation from R Curry or H Herman. The CCD detector could be destroyed, and your group will be billed. There is a tell-tale on top of the spectrometer. The 782 nm laser (white housing) is associated with LASER1 on the safety interlock box. The 514 nm laser (black housing) is associated with LASER2 on the safety interlock box. Most operations are performed with LASER1.

4 LASER1 switch-on procedure: o Turn key switch on LASER1 quarter-turn clockwise; o There are three lights: INTERLOCK, TEMP and POWER. Under normal switch-on INTERLOCK and POWER are green, and TEMP will turn from red to green once correct internal laser parameters have been established (about three minutes). o If INTERLOCK is red, check The laser interlock switch is set to LASER1 The spectrometer housing is fully closed. o Wait until all lights turn green. If they do not: Log the event Switch off the laser at the key switch Get assistance. o Check LASER1 power by moving the slide on top of LASER1 from LASER to ADJUST. The reading should be 15 to 21 mw. If it is not: Switch-off the laser at the key switch. Wait two minutes. Restart the switch-on procedure. If after several attempts the laser is still not producing power, get assistance. o Maximise the power reading by using the correct Allen key (on top of LASER1 housing through hole A. Engage the Allen key and move gently anti- and clockwise. LASER2 switch-on procedure: o Turn on LASER2 Power at the wall switch o Turn on POWER at the square black power supply o Turn key-switch quarter turn clockwise o Wait 2 minutes o On laser operator panel ensure toggle switches are set for POWER, 50mW and STANDBY o On laser operator panel turn key switch quarter-turn clockwise o Wait 5 minutes o Set toggle to RUN. o No checking is required for LASER2 operation.

5 3.0 Beam Positioning Procedure The Beam Positioning Procedure is required to ensure that the visible and laser beams are collinear and co-focal: o Set microscope turret to x5 OBJ o Put SILICON CALIBRANT slide in position on the microscope stage o Ensure MICROSCOPE MIRROR is set to 2 on the rotary bezel, and MICROSCOPE FILTER is set to 1. This allows the microscope CCD to see the sample o Click on the video tool in the Grams/32 software panel o Using the manual adjusters on the microscope, focus on the silicon surface. Note that the big outer ring on the adjuster is coarse, whilst the inner knob is fine o Adjust level of illumination via ILLUMINATION ADJUST rotary at base of microscope o Set microscope turret to x20 OBJ o Refocus o Set microscope turret to x50 OBJ o Refocus o Allow laser light onto calibrant/sample by setting MICROSCOPE MIRROR to 1 on the rotary bezel, and MICROSCOPE FILTER to 2 o A bright tightly focussed laser beam should be visible. If not contact Chris Buxey. A Warning on the Focusing Motor: Please do not use the microraman control software to adjust the internal laser spot focusing motor. This has already been set correctly, so if your sample is focused optically, the laser spot should also be in focus. Fine adjustments may be made using the fine focus dial on the microscope. If you believe there to be a problem then please contact Chris Buxey on x2715.

6 4.0 Spectrometer Calibration Procedure Spectrometer calibration o In the Toolbox/Experiment Set-Up, ensure Type is Grating, Spectrum and Static. Centre at Set (Detector) Time to 1.00, Gain High, (Misc.) Accum 1, Cos. Ray Rem. Off, Power Obj 50 and Focus 0. Set Descriptor to Silicon Calibration: date. Click OK. o Click the Spectrum Acquire button twice. o Using Windows technique, expand peak so display shows approx. 460 to 550 cm -1. o Click Arithmetic, Curve_Fit. Right click ONCE on peak of spectrum. Then DONE, ITERATE, Start Fit and OK. o Click View Peaks, and Parameters. o The center value should be (+/-0.5). If it is, log it, as well as Height and Width. The Height value should be at least 2000, and the Width, 6 or less. o If the Center Value is not within bounds, note it and quit the curve fit procedure by Parameters, Exit, Quit and Exit. Now Collect, Applications, Calibrate System, Calibrate Grating and Offset Correction. Compute ( Center value) and enter this in Required Shift, then Apply, Done. Repeat the Spectrum Acquire procedure. o If the Height value is low, or the Width is too high, check the beam quality at the sample. If necessary, repeat the Beam Positioning Procedure. The system will operate with these parameters out-of-bounds, but data will be degraded. o Note the values for the Centre Value, Height and Width in the log book.

7 5.0 Sampling Procedure Measuring samples is very similar to the Beam Positioning Procedure. Always start at the lowest magnification and work up. Remember to move mirror and filter wheels to allow laser to fall on sample before acquiring spectrum. If the objective touches the sample, get assistance. o If you can, place sample on Al foil (wrapped round microscope slide) o The optical arrangement of the system is such that only about 400 cm -1 can be acquired in the static mode of the grating. For larger scans, within Toolbox/Experiment Set-Up, ensure Type is Grating, Spectrum and Extended. o This option brings up an extra box, which provides three choices: Continuous this is the favoured option, which synchronises the movement of the grating with the CCD readout speed. It provides the best quality spectra. However, it can only be used for Detector Time of 10 seconds or greater. Step & Repeat acquires spectra in approximately 400 cm -1 blocks, and displays them. Matched Step & Repeat as Step & Repeat but joins the spectra by overlapping them and averaging the overlap region. o This option also changes the Centre option to Range, providing From and To boxes. Note that there is no sensible data below 170 cm -1 with the current apparatus. o Note that the combination of LASER1 (782 nm) and the silicon-based CCD detector means that signals above about 2,500 cm -1 are weak. o The dynamic range of the CCD detector is about 30,000 counts. To obtain the best signal to noise use the highest possible power, and adjust the Detector Time to ensure the dynamic range is filled. o However, be careful about power density. Although the laser only produces a maximum of 13 mw at the sample, the spot size is submicron. If in doubt, choose a small bit of sample, and subject it to the laser for 2 minutes. Check its physical appearance. Especially in dark samples, it will be advantageous to reduce the power and increase the integration time. o The laser power can be adjusted in steps via the Power option 100%, 50%, 25%, 10% and 1%. These values are approximate. o Spectra are NOT automatically saved. Ensure that you save what you want into YOUR folder.

8 6.0 Exporting Your Work The procedure for exporting your data is as follows. Note that only spectra that have been saved may be exported. o Select the File menu, then Import/Export. o Choose ASCII_XY from the list and click the Export button. o Select the data you wish to export and click OK. o Change the name of the exported file if you wish, then click OK. o Your ASCII data will be exported as a.prn file to the same directory as the saved data file that it was generated from. o You can now copy the exported data to either 3½ floppy disk or zip disk. 7.0 Shutting Down Procedure Shut down procedure: o Switch off laser o Replace samples with the silicon calibrant o Leave software and PC running o Switch off screen only o Sign instrument log-book with time out

9 8.0 Appendix 8.1 Version History Version: 1.0, dated 3 rd September, 2003, Author: Henryk Herman Version: 1.1, dated 19 th November, 2003 Added Beam Positioning Procedure, HH Version 2.0, dated 15 th October, 2005 Modified Sampling Procedure, HH Version: 3.0, dated 24 th October, 2006 Acknowledge changed of location to 09DJ00, HH Version 4.0, dated 25 th October, 2006, HH Inserted additional restriction on changing laser permission must be sought from RJC or HH. Version 5.0, dated 10 th October, 2008, Author: Chris Buxey Minor updates to procedures to bring them into line with current practise. Additional foreword and reformatting added. Section on exporting data files added.

10 8.2 Internal Schematic Microscope Illumination Microscope Manual Z-axis Raman System Power Switch Microscope Mirror Microscope Filter