1. Optical Position Sensor: Radiation Hard glasses for lenses and new electronics Jose Luis Sirvent Blasco Student meeting 26-11-2012

2. 1. Issues due to radiation A) Lenses goes dark as they are irradiated – Reduce the life time of the system – Possibility of unavailability of this important subsystem. – Decrease of the transparency: Irradiation conditions Wavelength used Glass material – Recovery (Annealing) Time Temperature *3rd Europa Jupiter System Mission Instrument Workshop, ESA ESTEC January 2010, D. Doyle, ESTEC, Optical Materials 8KGy (8 years of WS operation 1KGy year)

3. 1. Issues due to radiation B) In general: – Decrease of transparency in NIR & IR is not as strong as in VIS or UV – Dopants such as Cerium in the glasses stabilizes Radiation effects – Numerous studies of radiation damage in glasses (literature) – *Best ‘standard’ materials: Fused Silica, Sapphire & Quartz (Very Expensive) Quite few elements available in the market for our design – Other Solutions: RadHard Glases (Schott & Ohara) No commercial lenses availables with this RadHard materials (lens done under demand) Need of lens design with my friend Zemax. * A study of neutron and gamma radiation effects on transmission of various types of glasses, optical coatings, cemented optics and fiber. S.M. Javed Akhtar *, Mohammad Ashraf, Shaukat Hameed Khan Optics Laboratories,Islamabad, Pakistan. 22 September 2006 2.4KGy (2 years)

4. 2. Irradiated glass comparison

5. 3. What happens with the lens of our design for the WS_OPS? Materials: – Corning Eco-550 (Asphere Thorlabs 352440) – Corning Co-550 (Aspheres Schaffter+Kirchhoff) – No reports about radiation damage! (I cannot quantify the damage in our environment for the moment). Previous Studies: Optical Design Considerations for Astronomical and Space Applications Simon Thibault (2002 INO, Sainte-Foy, Québec, Canada): – “Standard component for ground communication system as collimator can not be used for space application because it may happen that the glass material will be sensitive to radiation. By example, the molded Corning glass CO550 used for aspherical lens is sensitive to radiation. Corning has developed a stabilized CO550-G20 with 2%of CeO2 with a greater radiation stability.” – “The coupling efficiencies have to remain high once the system is in space, i.e. in vacuum and at a temperature ranging from 25 to 55 °C. For this space applications, we used only a single glass type which is the stabilized BK7-G18 from Schott” Optical system design and integration of the Mercury Laser Altimeter (L. Ramos-Izquierdo 2004 MESSENGER mission to mercury) – “The collimating lenses are 11mm focal-length Geltech aspheres with 2% cerium added to the Corning C0550 substrate material to prevent adiation darkening” – “The beam expander is a Galilean optical design with a Corning 7980 fused-silica negative lens, a BK7G18 positive lens group, and a Sapphire exit window.” Radiation Hardness study on fused silica (M. Hoek, Ed. Bennet, D.Branford Nuclear instr. And Methods in Physics Research 2008) – “Normalised transmission difference DTnorm for (a) Corning 7980 and (b) Lithosil Q0 for 1 and 10 Mrad dose spots. No distinct features corresponding to the irradiation spots are observed within the obtained precision. “

6. 4. After reading: Conclusion about best materials: – Corning CO550-G20  Aspheric lens provider: LightPath “We cannot supply a specialty glass for only 3 lenses. I am not sure about the possibility of 60 lenses either since I don't know the level of effort involved but I will ask.” (John Luvera, LightPath) – Schott BK7-G18  Needed to fabricate lens: Optimax Systems “We do have experience with RadHard materials and have worked quite a bit with space applications. Most recent being the Mars Curiosity for NASA JPL. We fabricated the lenses for the MARDI, MAHLI, and Mast Cameras aboard Curiosity. Send us the characteritics of your lens and we’ll quote.” (Jess Dennie, Optimax) – Corning C79-80 / Schott Suprasil, Lithosil (F_Silica)  “Standard” “Search in Edmund-Optics/Thorlabs/Newport/Asphericon/Melles Griot & many other companies” – Sapphire  Quite expensive Spectral Transmission of Schott Lithosil Q0/1 F_Silica Near our working wavelength 1310nm

7. 5. Design criteria 1. Magnification Factor=2  Ligh spot 20um – Measurable slits 5um (-6dB), 10 um (-3dB), 20um (0dB) 2. Tolerance Disk/Lens  ~ 150um 3. System Diameter  Compact system (12mm optics) 4. System Length  As short as possible 5. Usage of Zemax – Physical Optics Propagation  Gauss beam Waist = 0.0046um (SMF output 1310nm) – Optimization tool to adapt parameters to our criteria and maximize coupling eff.

8. Prop 1 Commercial Asphericon C7980/ Lithosil Q1 F_Silica – 2 X A12-15FPX Two Identical lenses F=15mm Coupling=70%, Decrease in 100um=30%

9. Prop 2 Commercial Asphericon C7980/ Lithosil Q1 F_Silica – 1 X A12-15FPX – 1 X A12-20FPX Two different lenses F=15mm & F=20mm Coupling=72%, Decrease in 100um=20%

10. Prop 3 Custom lens designed with Zemax and BK7-G18 (Schott RadHard Glass) Only one Bi-Aspheric Lens (Mag. Factor=2 2*F1=F2) Minimize Aberrations and maximize coupling eff Should fit in Holder (Optics 12mm and Thickness <=10mm) Coupling= 78%, Decrease in 100um= 20%

11. Prop 3 Custom lens designed with Zemax and BK7-G18 (Schott RadHard Glass) Only one Bi-Aspheric Lens (Mag. Factor=2 2*F1=F2) Minimize Aberrations and maximize coupling eff Should fit in Holder (Optics 12mm and Thickness <=10mm) Coupling= 78%, Decrease in 100um= 20% To give you a rough I idea on cost for a bi-asphere at quantity 6: -Commercial Quality ($900 each) -Precision ($2000 each) -Hi Precision ($3600 each) (Optimax Systems mail Jess Dennie 28-12-12)

12. Prop 4 Commercial Edmund Optics Aspheric Lens F_Silica – 1x NT49-593 – 1x NT67-280 Two Aspheres 0.5NA & 0.63NA (25mm Diam) Coupling= 71%, Decrease in 100um < 20% In my opinion it’s maybe too big

13. 6. Remarks Prop 1 & 2 Selected as the best ones Material already ordered Physical test to be done  Vacuum & Temperature Assembly materials  Aluminum & Co7980 The Optics will also be tested in the TestBench and compared with Schaffter+Kirrchoff (CO550) Some electronics should be developed and fitted in a “Nice Box 2.0” – Laser driver with digital power control (Voltage controlled current source DAC 0-1V) – Photodiode driver for ADC 0-1V (PD Signal  Offset 4V & 0.8Vpp, Differential to Single ended signal + Gain control) – Optical circulator included in “The Box” The current Box (Face A: 1Ch 850nm, Face B: 2Ch 1310nm, Face C: Driver for Heidenhain Ron225) On Off LD PowerF.Optic I/O LD Power ADC PD DAC The New and final box (Only one face two channels 1310nm & prepared for DAC & ADC)

14. 7. Drivers for DAC & ADC

15. 7.1 Driver for DAC (Limited current source for LD)

16. 7.2 Driver for ADC (First Tests with AD 8608) AD 8608  I/O Rail to Rail 5V, 10MHz High Impedance buffers Differential ampliffier (G=1) Non Inverting ampliffier (G  1 – 5) Final Op_Amp_ AD 8028 (190MHz)