Spectral Response Curves for 3EB,
thinned Loral CCDs at various stages
with/without UV Flooding

Device W7-4 CCD has been measured at various temperatures, in imaging AND diode mode. We now use a stable Cadmium source (with a strong line at 228nm) for flooding rather than Mercury. This was prompted by a mail message from Mike stating that Cadmium was to be prefered to Mercury as it produced a better more stable response. We measure the response at room temperature using either-
  1. a stable light source and a set of filters with 5nm band-pass, from 330nm to 1060nm, in what is termed Diode Mode. This mode connects ALL electrodes on the chip together except RD and OD which are paralleled and returned via a sensitive pico-ammeter to substrate. We generally measure currents in the range 2-3nA in the UV to 200nA in the mid-band,
  2. By using a monochromator with a stable source, measuring about every 5nm across the band 400nm to 1000nm, this feeds the same pico-ammeter and works fine. A second order filter goes in at 700nm, the light path is direct, i.e. there is no integrating sphere.
  3. We have used a phase sensitive detector to measure the signal BUT we can not get the large chips to work at the lowest chopping frequency we can use (10Hz). By large chips I mean the thin Tek1024 and the Loral 2kx2k. Going to somewhat smaller (EEV) devices enables us to obtain a signal but this signal depends on the chopping frequency - the higher the chopping frequency the lower the measured signal. At 10Hz the Tek and Loral CCDs dont produce any signal at all. I was attempting to use this particular method of measurement (a) because background interference is automatically accounted for in the way the PSD operates and (b) it was a completely independent way of measuring the response. It appears only to work for smaller format devices which I suppose have lower total capacitance than the larger devices. It is intruiging though...

The 'recipe' we use for pre-flooding is the standard one
recommended by Mike Lesser.

  1. With the detector at ambient pressure in air, DRY air ONLY is used now (19/9/95),
  2. a period of UV flood using a Cd lamp (strong 228nm line) placed 10cm from the detector. We have tried times from 5 minutes to 30 minutes without any noticable change in the response to the UV flood,
  3. measure the response straight away if required,
  4. Pump the cryostat to 10-4,
  5. Cool the chip to operating temperature and measure the response in the way out-lined above. Now a few hours after UV flooding.

Loral Data #1 - 24/05/95

Data from the current (June 1995) room temperature and cold (-140C) measurements are on the next Loral page-

View Loral Page - 1

Loral Data #2 - 19/09/95

Data from the current (August 1995) room temperature and cold (-140C) measurements are on the second Loral page-

View Loral Page - 2

Loral Data #3 - 28/03/96

Data from the current (March 1996) room temperature and cold (-120C) measurements are on the third Loral page-

View Loral Page - 3

This is for the Passivated Platinum Film (PPtF) Device

Loral Data #4 - 23/1/97

Data from an Engineering chip to proof the RGO monochromator rig. View Loral Page - 4

This is for a Passivated Platinum Film (PPtF) Device

Life, dont talk to me about life, brain as big as a planet and they ask you to open the door.... Life....

Don't you wish you were here....

I am... apo