1. ‘High Sensitivity, Confocal, Fibre Optic Based Raman System’ EM Technology UK City University UK Bradford University UK Verhaert Be ESA – Contract No: 18498/04/NL/MV ESA ITI CONCEPT Project FINAL PRESENTATION

2. 21/11/05- EM Technology - Partners & Expertise EM Technology Optical Systems: UK– SME specialising in advanced opto-electronic prototype developments; City University Electronic Eng: UK– experience in fibre optic sensor research and development; Bradford University Chemistry & Forensics: UK– experienced in applications and analysis & interpretation of Raman spectroscopy – inorganic & organic; Verhaert Space Systems: Be – specialists in development of space-deployable opto-electronic & hardware systems;

3. 1. SCOPE OF ACTIVITY

4. 21/11/05- EM Technology - Space Problem To search for signs of planetary life e.g. on Mars; Propose Use of improved fibre optic Raman Spectroscopy; Much less fluorescence at longer NIR wavelengths (>1um); Conventional Si multi-channel array Raman systems: –Problems with auto-fluorescence at visible wavelengths; –Higher sensitivity but lower resolution - limited to <1um; Raman FTIR systems – use of NIR wavelengths: –Eliminate/greatly reduce fluorescence at >1um but are: –Lower in sensitivity although have higher resolution –Large, heavy laboratory instruments - not space compatible

5. 21/11/05- EM Technology - Solution Concept Develop system with potential for compact size, light weight, low power Raman spectroscopy system for NIR use (>1um); Use dispersive multi-channel array spectrometer design for high sensitivity; Use InGaAs multi-channel array detector sensitive to NIR wavelengths (~0.8um to 1.7um); Use flexible NIR fibre optic network & probe-head for sampling in inaccessible areas e.g. sub-soil, etc; Use wavelength stabilised fibre pigtailed NIR telecomms laser diode LD e.g. 980nm >100mW.

6. 21/11/05- EM Technology - Background Raman Spectroscopy Established at Visible wavelengths Analytical Tool Provides characteristic spectral fingerprint Uniquely identifies chemical species Raman Advantage No sample preparation or special cells required Works in back-scatter mode on sample surface –With stand-off distance e.g. for use through protective window Relatively low power laser excitation required (<100mW) Useful for organic as well as inorganic specimens

7. 21/11/05- EM Technology - Space Application Space Applications Mount on Planetary Rover –Free-Space optical system for surface studies –Fibre optic probe for subsurface (burrowing ‘mole’) studies Biological & Geological Investigations –Investigate planetary geology –Look for signs of life – previous or existing e.g. cyano-bacteria –Initial search based on known carbon life-form e.g. look for »  -Carotene - anti-oxidant »Scytonemin - UV protection »Chlorophyll? –Otherwise what? Silicon? Want know what else to look for!

8. 21/11/05- EM Technology - Planetary Use – e.g. Mars Martian Climate Low, arid temperatures; high UV solar radiation Martian Surface Surface region ‘sterilised’ by strong UV radiation Depths of > a few meters needed to avoid UV effects Antarctica Analogue Antarctica Dry Valleys provide analogue environment Cyani-bacteria survives in harsh Antarctic environment Cyani-bacteria adapts –Developed scytonemin near surface exposed - UV blocker –Can survive inside surface region of rocks (e.g. sandstone), etc –Enough Light penetrates for photosynthesis but protection from UV

9. 21/11/05- EM Technology - Raman Spectra: Cyanobacteria Showing UV screening pigment scytonemin and Collema, a desert dwelling cyanolichen which synthesizes scytonemin (lower)

10. 2. Raman System Design Analysis Work Carried Out

11. 21/11/05- EM Technology - Raman System Configuration ‘ Confocal’ - Minimum System Configuration - for testing new NIR approach 50um GI multi-mode fibre network

12. 21/11/05- EM Technology - System Power Budget Analysis Raman Scatter Power  -4 : P R (980nm)/P R (780nm) ~1/4

13. 21/11/05- EM Technology - Design Analysis Compared Raman techniques - Dispersive Array most efficient Analysed multi-mode fibre optic ‘Confocal’ configuration; Analysed use of InGaAs diode array detector »NIR response – use 1020nm to 1180nm range Use of Telecomms 980nm LD for Raman Excitation (50mW) »Fibre pigtailed, in fibre FBG grating stabilised »Line narrowed (<0.25nm) & -stabilised (<0.1nm/hr) Use Achromatic Fibre Optic Components »Fibre couplers & probe-head focusing optics: ~950nm to >11800nm

14. 21/11/05- EM Technology - InGaAs Array Noise Analysis Conclusion: Max. Dark Curent Integration Time ~10secs - before saturation.

15. 21/11/05- EM Technology - NIR Raman Design Specifications –Specifications for Planetary Geology/Biology Raman excitation LD wavelength – 980nm Spectral resolution <10cm -1 (<1nm) Wavenumber range: 400cm -1 to 1180cm -1 LD line-width/stability requirements <1nm LD excitation power at sample 50mW S/N >100 Measurement time – typically 5 min; <1hr Raman (anti-Stokes) edge-filter >12-OD at 1um Sample/probe-head focus control: <1um

16. 3. Raman System Build

17. 21/11/05- EM Technology - Specifications for Prototype InGaAS Spectrometer

18. 21/11/05- EM Technology - Breadboard System Layout

19. 21/11/05- EM Technology - LD & Probe-Head Units

20. 21/11/05- EM Technology - InGaAs Spectrometer & Halogen Filter Source

21. 4. Fibre Optic System Testing

22. 21/11/05- EM Technology - Fibre Optic - Optical Probe System Power Budget 17% of Raman signal from sample reaches the spectrometer (in agreement with design analysis)

23. 21/11/05- EM Technology - Raleigh Scatter Focus Control Using LD Power Modulation (1) Sample Back-Scatter Focus Response; (2) Fibre Back-Reflection (0.6%); (3) Mirror Sample Reflection (100%) (4) White Paper (4.7%) (5) Black-Tape (2%) (6) Paracetamol Tablet (2.7%)

24. 21/11/05- EM Technology - LD: Line-Width Stability (1)LD Line Spectrum – L/W = 0.15nm @ 10mW (2) LD Central Mode Stability - <0.01nm/hr @ 10mW (3) LD Line Spectrum – L/W = 2.3nm @ 50mW (4) LD Line-Width Stability - <0.1nm @ 10mW

25. 21/11/05- EM Technology - LD: Fluorescence Tail LD Spectrum showing small fluorescence tail - (taken using laboratory OSA)

26. 5. System Characterisation Tests

27. 21/11/05- EM Technology - Optical Transmission Tests (1) Launch Optical Spectra (2) Transmitted Optical Spectra (at Source input) ( at Spectrometer input) Optical System Transmission ~ Near Achromatic Spectral Performance System Optical Transmission Losses ~x10 (Resolution 10nm)

28. 21/11/05- EM Technology - InGaAs Spectrometer Comparison Spectral Response to broadband Tungsten- Halogen light –& interference filters: Reference Spectrometer. (Resolution ~0.5nm) Spectral Response to same tungsten-Halogen light– showing wavelength dependence response. (Resolution 0.7nm) 3msec Integration Time Laboratory OSA InGaAs Array Spectrometer

29. 21/11/05- EM Technology - InGaAs Array: Dark-Noise InGaAs Array Dark Noise Response /Integration Time (I t ) Anomalous dark noise response (~0 values): Dark noise saturation I t >500msec

30. 21/11/05- EM Technology - InGaAs Array: Signal Response (1) 1100nm Interference Filter @ I t =3msec (2) Ditto OD Filter Attenuation @ I t =100ms showing acceptable pixel response showing anomalous pixel response Array Response Only Good for Short Integration Times I t < 5msec Array Sensitivity Limited ~ 0.02pW/pixel: Raman Minimum (at I t =100ms)

31. 21/11/05- EM Technology - InGaAs Array: Signal Response (1) Pixel linearity against input intensity (2) Noise reduction against  (sample number) (3) Pixel Dark Noise: Estimate to be ~x20 higher than analysis

32. 21/11/05- EM Technology - Signal Integration Time: Anomalous Effects (1) Increased Integration Times – Halogen Light (2) Filtered Raman Spectra for I t =100ms

33. 6. Attempted Raman Spectrum Tests

34. 21/11/05- EM Technology - Raman Spectra: Background Raman background Spectrum (wavelengths) from fibre optic network with no sample – signal due to LD fluorescence tail: I t =3ms; 10000 samples

35. 21/11/05- EM Technology - Raman Spectra:Ascorbic Acid - 1 Attempted Raman spectrum – 50mW; 3ms; 10,000 samples: - In Wavenumbers. (inset – typical vitamin C Raman spectra)

36. 21/11/05- EM Technology - Raman Spectra:Ascorbic Acid - 2 Ditto as Attempt spectrum vitamin C: with increased I t =100ms, 1,000 samples; showing anomalous pixel response across array

37. 21/11/05- EM Technology - Raman Spectra: Paracetamol Attempted Raman spectrum of Paracetamol: 50mW; I t = 3ms; 1,000 samples

38. 7. Conclusions

39. 21/11/05- EM Technology - Conclusions - 1 –Work analysed fibre optic Raman system with InGaAs detector array spectrometer; –Developed bench-top NIR fibre optic Demonstrator system; –Demonstrated stabilisation/line-narrowed LD: <0.25nm –Developed modulated LD Raleigh scatter probe focusing method; –Demonstrated good transmission and spectral performance of the fibre optic and optical probe-head design; –Demonstrated fibre optic Raman system met the design specifications for power budget and spectral performance;

40. 21/11/05- EM Technology - Conclusions - 2 –Took delivery of state-of-the-art prototype InGaAS array spectrometer from leading manufacturer: Optical performance good: resolution =0.7um Problems with electronic/software processing –Acceptable performance for short integration time only Dark current processing problems Dark noise ~x20 higher than expected –Further effort needed to develop InGaAs array spectrometer: Overcome electronic/soft-ware processing problems Select InGaAs array detector for low dark noise operation –Re-design probe-head optics for higher collection efficiency

41. 21/11/05- EM Technology - Activity Benefit to Partners EMT - Prototyping design experience gained in new opto-electronics space area; CU – Developed new space research activity in novel fibre optic sensor system development; Bradford University – New application area for Raman spectroscopy analysis; Verhaert – Assessment of new Raman spectrometer design to widen space expertise. Partnership has potential for future space systems collaboration.