L3Vision CCD Technology Explained
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The document discusses L3Vision CCD technology, which provides low light sensitivity through an electron multiplication gain process within the CCD that can amplify signal electrons up to 1000 times. Key factors that determine a CCD's low light sensitivity are the number of photons per pixel per unit time, how well light is converted to signal electrons, and how low the noise floor is. L3Vision CCDs reduce noise to improve sensitivity and have applications in scientific imaging and surveillance due to their ability to detect very low light levels.
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L3Vision CCD Technology Explained
- 1. L3Vision CCD Technology Click to edit Master title style INTRODUCTION
- 2. L3Vision Technology How sensitive is atitle style Click to edit Master CCD? Three key factors determine the low light sensitivity of a CCD: • Number of photons / pixel / unit time Dependent on pixel area Frame With all else equal, a 16 µm square pixel gathers 4x the transfer light of an 8 µm square pixel • How well light is converted to signal electrons High quantum efficiency Back illuminated CCDs convert over 90% of 550 nm light to signal electrons • Maximum open area ratio Frame transfer CCDs are 100% fill factor Interline transfer CCDs are not 100% fill factor Interline • How low the noise floor is transfer Noise sets the limit to the minimum detectable signal
- 3. L3Vision Technology MaximizingMaster title Noise Click to edit Signal to style Main Sources of Noise • Shot Noise on the Dark Signal Cool sensor to eliminate dark current • Noise from the CCD Output Amplifier Reduce readout rate Benefit from L3Vision • Noise added by the video chain electronics Technology Optimise design of electronics Reduce the noise = Improve the CCD Sensitivity
- 4. L3Vision Technology What to edit Master title style Click L3Vision is… • Low Light Level Technology • A CCD technology that provides <1 photo-electron equivalent read noise at video rates or higher • An impact ionisation gain process within the CCD that amplifies signal electrons up to 1000 times so that they may be detected above the CCD output and electronics noise. • A unique technology developed by e2v technologies
- 5. L3Vision Technology What to edit Master NOT… Click L3Vision is title style • L3Vision CCDs do NOT use image intensifiers • L3Vision CCDs are NOT electron bombarded CCDs (EBCCDs). • L3Vision CCDs are NOT CMOS image sensors … L3Vision CCDs are simply CCDs … and are sometimes known as EMCCDs (Electron Multiplying CCDs)
- 6. L3Vision Technology Conventional CCD style Click to edit Master title φ Iφ1 φ Iφ2 Image/Store Areas φ Iφ3 Charge to Voltage Conversion Readout Register φ φ φ Rφ1 Rφ2 Rφ3
- 7. L3Vision Technology L3Vision CCD Click to edit Master title style φ Iφ1 φ Iφ2 φ Iφ3 Multiplication Register φ φ φ Rφ1Rφ2Rφ3 φ Rφ2HV
- 8. L3Vision Technology How the gain processstyle Click to edit Master title works • The charge multiplication elements
- 9. L3Vision Technology Other noise sources style Click to edit Master title • Dark current The CCD must be cooled to completely eliminate dark current – even at 1000 frames per second • Clock-induced charge or spurious charge Can be almost eliminated by reducing clock rise times & careful voltage adjustment <0.1 e/pixel/frame is possible in inverted mode, <0.003 e/pixel/frame is possible in non-inverted mode See L3Vision Technical Note #4 for more details…. • Excess Noise Factor… The gain process adds noise due to the gain probability distribution. σout2 = σin2 x Gmean2 x F 2 Where σout2 = variance of output signal σin2 = variance of input signal Gmean = mean gain F = excess noise factor
- 10. L3Vision Technology CCD to edit Master title style Click Quantum Efficiency 100 90 Back-illuminated w/ midband AR coating 80 Back-illuminated (-20C) w/ broadband AR 70 coating (-20C) 60 QE (%) 50 Front-illuminated (+20C) 40 30 Front-illuminated 20 with lumogen coating (+20C) 10 0 200 300 400 500 600 700 800 900 1000 1100 Wavelength (nm)
- 11. L3Vision Technology L3Vision CCDs vs ICCDs Click to edit Master title style ICCD Advantages • Gated operation • Mature and accepted technology Image Intensifier • Low power consumption ICCD Disadvantages CCD • Poor daylight performance • Susceptible to damage • Poor resolution • High excess noise factor Fiber optic coupling
- 12. L3Vision Technology L3Vision CCDs vstitle style Click to edit Master ICCDs L3Vision CCD Advantages • Increased spatial resolution & SNR giving greater dynamic range • No halo from bright sources allowing visible detail in adjacent pixels • Not susceptible to damage from bright lights • No scintillations giving improved image quality • High photo-sensitivity (QE up to ~95%) • Solid state giving lower life-cycle cost • No high voltages required • Excellent for day and night operation L3Vision CCD Disadvantages • Moderate power consumption
- 13. L3Vision Technology Cameraedit Master title style Click to Features • High Dynamic Range
- 14. L3Vision Technology Cameraedit Master title style Click to Features • Fast recovery from bright lights
- 15. L3Vision Technology Cameraedit Master title style Click to Features • Spot light performance is far superior to Gen III ICCD
- 16. L3Vision Technology Featureedit Master title style Click to Summary • Electron Multiplication allows even the smallest signals to be seen • Back-illumination means superb quantum efficiency ~95% QE at 550 nm with mid-band AR coating • Square pixels, scientific format sensors are available • Large pixels for high signal to noise ratio available High full well capacity and dynamic range • Cameras are available that fully exploit the L3vision features Automatic level control Digital image enhancement (filtering, dynamic gamma) Digital & analogue outputs Ultra-low light level performance
- 17. L3 Vision Technology Cameraedit Master title style Click to comparison Quarter Moonlight e2v e2v L3C95 L3C65 Digital Analogue Omni-4 Sony Gen3 ICCD Ex-view
- 18. L3 Vision Technology Cameraedit Master title style Click to comparison Sub Starlight (0.5 mlux) e2v e2v L3C95 L3C65 Digital Analogue Omni-4 Sony Gen3 ICCD Ex-view
- 19. Custom L3Vision camera for C130-J upgrade Click to edit Master title style
- 20. L3 Vision - Defence & Aerospace Market Click to edit Master title style •Reconnaissance Pod Images courtesy of Thales Optronics UK
- 21. L3Vision Technology Legacy edit Master title style Click to Camera Products L3C60 128(H) x 128(V) 500 frames per second Analog video output Internally cooled CCD for reduction of dark current IMO for reduced dark current Automatic gain control adjusts to varied lighting L3C65 576(H) x 488(V) or 576(H) x 576(V) Analog video output Internally cooled CCD for reduction of dark current Automatic gain control adjusts to varied lighting L3C95 / L3C85 768(H) x 488(V) or 768(H) x 576(V) Analog or Digital video output Internally cooled CCD for reduction of dark current Digital control of operating modes – USB2.0 or RS232 Real time digital image enhancement Extremely low minimum usable light level (10x lower than L3C65) Fully automatic operation over NINE decades of illumination. Customization available
- 22. L3Vision Technology New Video Master title style Click to edit Camera Product L3C216 768(H) x 488(V) or 768(H) x 576(V) Analog or Digital video output Internally cooled CCD for reduction of dark current (fan-less) Back-thinned L3Vision CCD with QE up to ~95% Digital control of operating modes – Camera Link or RS232 Real time digital image enhancement Extremely low minimum usable light level (10x lower than L3C65) Fully automatic operation over NINE decades of illumination. Reduced power consumption (6W typical, 12W max) Reduced size (and modular design version planned) RoHS Compliant Customization available
- 23. L3Vision Technology Video Camera Customization Click to edit Master title style • Camera customisation to meet military specifications and airborne applications • Also available as a sensor-head board and driver board-set and as CCD sensors Please send us you requirements!
- 24. L3Vision Technology Scientific CCD products Click to edit Master title style • Back-illumination and sub-electron-equivalent read noise Basic process mid-band and broadband AR coatings available QE up to ~95%. Near theoretical detection limit • CCD201 (BI and FI) • CCD39 (BI and FI) 1024 x 1024 frame transfer 80 x 80 split frame transfer 13um square pixels 24um square pixels Up to 15MHz readout Up to 1000 Frames per second Dump drain for fast ROI readout Particularly suited for the tracking of point source objects • CCD97 (BI and FI) 512 x 512 frame transfer 16um square pixels Up to 10 MHz readout Dump drain for fast ROI readout • CCD60 (BI and FI) 128 x 128 frame transfer 24um pixels Up to 1000 fps Dump drain for fast ROI readout
- 25. L3Vision Technology ApplicationMaster title style Click to edit areas • Scientific imaging Single molecule fluorescence High throughput screening Adaptive optics / wave-front sensing Photon counting Ground based astronomy See www.ing.iac.es/~smt/LLLCCD/marcl3.htm • Surveillance and Reconnaissance TV format Airborne & Ground-based surveillance Underwater Imaging Driver view enhancement Commander’s night-sight Pushbroom imagers
- 26. L3Vision Technology Click to edit Master title style The End Thank you for listening, do you have any questions?