CCD-world: More QE questions for SONY ILX511 and ILX526A

[Sutherland, Scott]

The following was posted to CCD-world:

Don Groom wrote:


> Scott,
> 
	  	 I agree with Craig Mackay that you will have to measure the
QE yourself,
	  	 or go by that of similar devices. 


	Okay, I'll bite.  How does one measure the QE of a CCD?  I would
assume I
	need an NIST calibrated light source and a very controlled geometry.
Unfortunately,
	these are things I do not have handy.  My goal here is to get a feel
for the QE shape,
	not exact QE.  For instance, is the MAX QE 10% or 75%.  I am doing a
rough,
	back-of-the-envelope comparison with other CCD's I have been using.
Do you have
	any suggestions of 'similar devices' for which the QE curves ARE
available?

	 	 --"Relative sensitivity" for photodectors is often given in
	  	 current/incident power. I'm not sure about the curve given
in the ILX511
	 	 spec sheets, but conversion from current/incident power to
relative QE
	 	 would raise the value at 700 nm by 1/0.64 relative to 450
nm. I suspect QE
	 	 of this device peaks in the red, as you expect.

	SONY does not provide units on its Relative Sensitivity curve.
However,
	in the Electro-optical Specifications, sensitivity is given in
V/(lx*s) for
	a uniform intensity illumination with a 3200 K light source AND for 
	an LED with a 660 nm center wavelength.The latter is 12.3 X higher
for
	the ILX526 and 9X higher for the ILX 511.

	In addition, even with the 'correction factor' of 1/0.64 above (~
1.5 X),
	the 'relative sensitivity' of the ILX511 at 450 would be 1.0 and
that
	at 700 would be 1.5*0.55, or 0.83, still less, indicating a peak
	sensitivity still at or near 450.  It is NOT clear if the CM-500S
filter,
	used for the electro-optical data, is also use in the relative
sensitivity
	measurement, and if so, how much it affects the shape of the curve.
	Based on the published transmission curve of the 1.0 mm thick
	CM-500S filter, if it is used, the relative sensitivity beyond 750
nm
	would be 0, since the transmission of the filter between 750 and 
	1100 nm is < 10-4.  Still confusing.


> --In any case, response dies completely as the bangap is approached; this
> is at about 1100 nm at 300 K and drops by about 30 nm at 153 K.
> 
	That's okay.  My region of interest is 850-1000 nm.

	[Sutherland, Scott]  Thanks for the information.

	Dr. Scott Sutherland
	Senior Scientist
	GAMMA-METRICS 
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