Future Army Future Army Applications for Presentation Applications for Presentation Dr. A. Fenner Milton IR Focal Plane IR Focal Plane Title Title Director Night Vision & Electronic Sensors Directorate Arrays Arrays Presented by Dr. Don Reago Presented to Name Principal Deputy By Name Technology and Countermine Presenter ’ s Title Night Vision and Electronic Sensors Directorate Presentation Date 19 March 2008 Approved for Public Release, distribution unlimited. Purpose • To discuss potential applications of IR FPAs to future Army needs – Cooled and Uncooled
Imaging IR FPA Technology Roadmap Long Range Airborne (at altitude) 1 InSb InSb Very Large LWIR QWIP ? Arrays MWIR MCT on Si? PtSi 3 Helo and Ground to Ground MCT on Si/GaAs ? Scanning Staring Multiband MWIR InSb LWIR MCT MBE MCT Large Multiband Common for Smaller on CdZn Te Arrays Modules SADA I/II Optics SLS ? TE Cooled MCT Small InSb Pixel MCT Compact Systems 25 µ m 17 µ m Uncooled Uncooled 2 Manportable/Low Cost 1990 1995 2000 2005 2010 Future Application #1: Pilotage for Utility and Lift Rotocraft Goal: Affordable Day/Night/IR pilotage and situational awareness for two pilots and crew UH - 60, CH47 Approach: Distributed Aperture Sensor using stitching software (no gimbal) feeding multiple head mounted displays, multiple cameras covering wide field of regard with high resolution forward and lower resolution side/rear coverage High Resolution Forward Low Cost Side/Rear Night + Imaging (IFOV TBD) Baseline (0.8 – 0.9 mR IFOV) H 90 ° - 180 ° V 60 ° – 90 ° For forward sector: Need two low cost cameras with large (1.5K x 1.5K) arrays (MWIR or LWIR) with short integration time (t = 2- 3 msec) For side cameras: Need low - cost night imaging with short integration time (2 - 3 msec). Possibilities include fast uncooled, I2TV and/or SWIR
Future Application #2: Large Format Gen 3 FLIR (Dual Band MW/LW) Goal: Achieve current 2 nd Gen FOVs with new 3 rd Gen dual band staring focal plane arrays (improve range and maintain FOV) Current 2 nd Gen: Future 3 rd Gen: 480x4 Scanning MCT 720x1280 MCT 480x1153 Effective on Si (1.5 S/D) Gen 3 B - Kit Current 3 rd Gen: 640x480 MCT on CZT MBE Grown LW/MW Reduction in cost required for larger dual band arrays Future Application #3: SWIR Overlay on the Head Goal: SWIR Increase soldier ’ s passive situation I 2 awareness using SWIR imagery combined with existing image intensifier goggle and uncooled IR IR • IR for long range targeting • I 2 for high resolution exterior mobility and low light levels • Passive SWIR for WFOV situational awareness 20 o 20 o FOV FOV ‘ Urban ’ ENVG (UENVG) SWIR Camera • IR 20 o /27 o X 15 o /20 o FOV 320 X 240 VOx 40 o FOV Microbolometer ENVG • I 2 Circular 40 o /46 o FOV – 18mm 3rd GEN Image Tube - 55 o FOV Direct View • SWIR 55 o X 41 o – Miniature Camera Inexpensive, large format SWIR camera needed for wide FOV applic ation
Future Application #4: IR Sensors for Airborne Persistent Surveillance • Persistent Surveillance : 24 - hour Operational airborne imagery of entire urban Concept battlespace • Potential Capabilities : Very Large Areas : > 25 km 2 – 64 km 2 – – Moderate Resolution : • 1 – 0.5m for vehicle tracking • 0.5 – 0.25m for dismounts – Moderate Update Rate : 1 – 2 Hz for MWIR Night image low - speed urban targets – Altitude : Aircraft must remain above 0.5m GSD 15,000 ft for survivability • Potential Solutions: – Very large staring FPAs – Large scanning or step/stare FPAs New application with many possible detectors (HgCdTe, InSb, QW/S LS) Image size is the dominant characteristic (moderate resolution/f# demands) Future Application #5: Distributed Aperture Sensor (DAS) Goal: Provide vehicle occupants a simultaneous, real time, 360 o x 90 o dome of situational awareness coverage of the immediate surroundings, enabling visibility, day or night while on the move . Sensor Design Trade Study Challenges: IR FPA 640 x 480 1280 x 1024 1280 x 1024 • Affordability for ground vehicle Slices / 7 + 4 4 + 2 OH 5 + 2 OH overhead • High optical flow rates IR cameras • Resolution Horz. FOV 73 º 115 º 70 º (Front) per camera 105 º Potential Solutions: (Side/Rear) • Fast uncooled IR (low t c ) Azimuth 2 mrad 1.6 mrad 0.95 mrad • Near IR/SWIR TV Resolution (Front) 1.4 mrad • Image Fusion (FLIR/I2) (Side/Rear) Current 73 º - 11 cameras 115 º - 6 cameras 105 º / 70 º - 7 cameras Inexpensive, large format uncooled IR camera with short time con stants critical for full performance in moving ground vehicle
Low Cost Substrate Alternatives to CdZnTe Potential advantages of Si or GaAs over CdZnTe • Availability 6 inch Si: 120 640 x 480 or 37 1280 x • Lower cost/cm 2 720 with 20 micron pitch • Scaleable technology To 1 st order, processing cost is not dependent on • size • Better thermal match to readout circuit • Mature processing capability • Improved durability and toughness Biggest Disadvantage • Higher dark current than CdZnTe The Army needs low cost, high performance LW/MW/SW IR FPAs irrespective of material system (II - VI or III - V) or detector type (p/n or SLS) 6 x 6 cm CdZnTe 6 ” (15 cm) diameter silicon Number of die/wafer drives end cost HgCdTe/Si Hybrid FPAs Technical Approach In situ doped p - type cap layer In situ doped p - type cap layer Si Readout Circuit Si Readout Circuit Si Readout Circuit n - type HgCdTe base layer n - type HgCdTe base layer Buffer layer lattice - matched to HgCdTe Buffer layer lattice - matched to HgCdTe n- type n- type n- type HgCdTe HgCdTe HgCdTe CdTe Buffer Layer CdTe Buffer Layer CdTe Buffer Layer ZnTe layer - controls CdZnTe orientation ZnTe layer - controls CdZnTe orientation Si Substrate Si Substrate Si Substrate Vs Vs Vs Si substrate - automatic thermal expansion CdZnTe CdZnTe CdZnTe match to Si ROIC match to Si ROIC Need to mitigate lattice and thermal mismatch which cause dislocations in MCT
Comparison: MCT vs. MCT LWIR (Si vs. CdZnTe) LWIR Parameter MCT/Si MCT/CZT QE (%) 80 - 90 85 - 95 RoA (ohm - cm 2 ) 100 - 200 200 - 500 Waveband ( µ m) 10.5 10.5 Operability (%) 95 - 99 >99 Dark Current (A/cm 2 ) 3.4 - 6.7e - 5 1.3 - 3.4e - 5 Operating Temp (K) 80 80 7x7 cm 2 CZT Substrate & Max Size 6 - in 0.3X for 2000 2 Approx cost pixel (2000 2 ) 1x (Enables > 3000 2 ) MCT/Si enables very large FPAs, allows lower cost and increased reliability -- Need to improve MCT/Si operability Comparison: MCT and InSb MWIR MCT/Si MCT/Si MWIR InSb Parameter 80K 110K 99 (w/o CO2 notch) QE (%) 80 - 90 80 - 90 ~97 w / notch RoA (ohm - cm 2 ) 1e7 >1e5 1e6 Waveband ( µ m) 5.3 5.3 5.3 640x480 99.9 Operability (%) >99 - 99.6 >99 2k 2 99.7 Dark Current (A/cm 2 ) <7e - 9 <9.5e - 8 7e - 9 Operating Temp (K) 80 110 80 4 ” in production Substrate & Max Size 6 - in Si 6 - in Si 6 ” available from foundry, estimate 2 yrs to production Approx cost pixel (2000 2 ) 0.6x 0.6x 1x MCT/Si allows multiple bands, higher operating temperatures and lower cost -- InSb currently in production with large FPAs
Progression in TWS Technology 1998 2003 2004 2005 MCT • 5.5 – 4.5 lbs BST (TFFE) • TE Cooled MWIR 320 X 240, 2 mil • Remove scanner • Remove cooler Monolithic VOx • Reduce size/weight 320X240, 2 mil • 4.5 – 2.7 lbs • Improve performance Monolithic VOx • Remove chopper 320X240, 1 mil • Smaller optics Monolithic VOx • 1.9 lbs 640X480, 1 mil • 18 ° FOV • Longer range enables M/HTWS • 2.5/3.9 lbs • 18 ° /9 ° FOVs Use Uncooled IR (LWIR) to Maintain Range Performance with Lower Weight Improved Performance with Continued Technology Developments Uncooled Applications: Current and Future VO x – 640x480 Future Applications: Current Applications: 25 um • Far Target Locator • Rifle Sights • Distributed Aperture • Helmet Mounted Imagers • Aviation Pilotage • Driving Sensors • Missile Seekers • UGS • Threat Warning Improvements Required For Future Applications: Application Higher Shorter Time Higher Frame Multi - band / Resolution Constant Rate wavelength Far Target Locator Distributed Aperture Aviation Pilotage Missile Seekers Threat Warning Keys to future application expansion are FPAs with smaller pixel s and shorter time constants without reducing S/N performance
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