RECOMMENDATIONS ON
     DETECTOR TYPE, INTENSIFIED VS. UNINTENSIFIED IMAGING
                AND VIDEO CAMERA SIZE FOR THE
  GOMER (Global Ozone Monitoring for the Earth - Rocket) PROJECT
                              by
                James Giesbrecht, M.Sc, P.Eng.
                      September 27, 1996
                                
  BACKGROUND
  
     The following data has been compiled from the references listed at the end of the
  report.
  
  1) Detector Type
     -The most common solid state imagers are:
          a) CCDs (charge coupled devices);
          b) CIDs (charge injection devices);
          c) CPDs (charge priming devices); and
          d) MOS (metal-oxide semiconductor).
     -Imagers with 500 x 800 pixels are available.
     (Ref. [3])     
          
     -If CCD saturation becomes a problem in the intensified system, the gain of the
  intensifier should be reduced to the point where the detection of a single photoevent is
  not possible above the lowest quantization level .
     -Intensified CCDs are capable of photoevent counting of weak airglow signals of
  a few rayleighs.
     (Ref. [5])
  
     -The dynamic range of the system can be increased by summing successive image
  frames. Moreover, SNR is improved and cooling requirements are eased by this
  technique.
     -It is desirable to keep integration time short and the readout rate as high as
  possible.
     (Ref. [1])
  
  2) Intensifier
     -There are three basic considerations for selecting an intensifier:
          a) achievable gain;
          b) mechanical and power requirements; and
          c) spectral response.
     (Ref. [3])
  
     -Typical MCP signal gain is from 10^4 to 10^7 with temporal resolution <100ps
  and spatial resolution limited by interchannel spacing and channel diameter (typically
  10um diameter channels on 12um centres)
     -Ion feedback is a problem in straight channel MCPs (gain 10^3 to 10^4) - it
  degrades the SNR.
     -MCPs operate in a linear fashion until output current reaches 10 to 15% of the
  bias current (10 to 100 uA).
     -The most ut systems are the:  phosphor screen/photodiode array,      or phosphor
  screen/CCD.
     -To maximize performance between the intensifier and the imager, the spectral
  response and persistence of the intensifier must match that of the imager.
     (Ref. [2])
  
  3) Video Camera
     -The spectral response of the Xybion Intensified Video Camera (model ISS-250-GQR-3) peaks at 40-45 mA/W in the 550nm to 750nm band of wavelengths.
     -The response of the camera is nonlinear.  The system quickly saturates when the
  brightness of light exceeds 100kR.
     (Ref. [4])
  
  RESULTS
  
     I contacted the companies below.  All have associations with low-light level
  cameras, CCDs, and/or image intensifiers.
  
          Eastman Kodak Co.        E-mail:  masdkodak@aol.com
          k-Space Associates Inc.  E-mail:  kspace@dial.cic.net
          Electro-Physics Corp.    E-mail:  73353.3272@compuserve.com
          GTFS Inc.           E-mail:  info@gtfs.com
          Johnson Scientific Corp. E-mail:  72360.1715@compuserve.com
          Hamatsu Corp.       E-mail:  hamacorp@interramp.com
          L.O.T Oriel Ltd.         E-mail:  100613.1325@compuserve.com
          EMR PhotoElectric        E-mail:  pietras@princeton.wireline.slb.com
          Instruments SA      E-mail:  systems@isainc.com
  
     So far, I haven't received any useful information from them.
  
  RECOMMENDATIONS
  
  1) Detector Type
     -A CCD is a good choice for a detector because
          1) its use is widespread and hence there should be stable suppliers and a
  wide variety of sizes;
          2) its characteristics are well known and there are CCDs sensitive to the
  band of wavelengths that we are interested in.
     -The CCD should be capable of frame tranbe high so that multiple frames can be
  summed.
  
  2) Intensified vs. Unintensified Imaging
     -It seems that an intensified system is needed (gain should be <1000 to prevent
  the CCD from saturating).  Perhaps a straight through MCP should be used because of its
  lower gain characteristics.
  
  3) Video Camera Size
     -Available camera sizes are:  N/A
     -A video camera of a size less than 4 in. X 4 in. X 4 in. should be chosen because
  of small payload space.
  
  4) Acronym
     -Use GOMER as the project acronym:
          Global
          Ozone
          Monitoring for the
          Earth -
          Rocketpar 
  REFERENCES
  [1]  Babey, S. K.; Anger, C. D.; Green, B. D.; "Digital Charge Coupled Device (CCD)
  Camera System Architecture", SPIE:  Solid State Imaging Arrays, vol. 570, 1985.
  [2]  Corbett, Michael B.; Then, Alan; "Microchannel Plates:  Principles of Using MCPs
  for Efficient Detection", The Photonics Design and Applications Handbook, 1995.
  [3]  Hofmeister, Richard A.; "Intensified Solid State Cameras:  Amplifying Photoelectric
  Energy in Low-Light Imaging Devices", The Photonics Design and Applications
  Handbook, 1995.
  [4]  Moorhouse, Peter G.; "An Attitude Video Camera Using Stellar Images for the
  Gemini Experiment", M. Sc. Thesis, University of Saskatchewan, 1994, pp. 38 & 41.
  [5]  Sandel, B. R.; Broadfoot, A. L.; "Statistical Performance of the Intensified Charge
  Coupled Device",  Applied Optics, November 1986, vol. 25, no. 22.