November 22, 1996

Tom Sertic

EEV Canada

6305 Northam Drive Unit 3

Mississauga, Ontario L4V 1H7

Tel: (905)678-9811

Fax: (905) 678-7726

Re: Faxes concerning EEV CCD25 and CCD47

Dear Tom:

Thanks again for the information you sent me yesterday and today. As I mentioned, we have a requirement for the largest active area possible, within our budget. The price you mentioned, i.e., about C$28 - 30K for a scientific-grade CCD25, is acceptable, but anything on the high side of C$35K would have to offer major advantages over the CCD25.

I do have the following questions about the CCD25.

1. Is the CCD available in a back-thinned version? If so, would this increase the quantum efficiency at all, especially at the shorter wavelengths?

2. Is it capable of operation in MPP mode? (If this information is provided in the sheets you sent me, I apologize for asking, but I didn't see it mentioned.)

3. What are the dark current characteristics as a function of device temperature in MPP mode, for temperatures between 215 K and 285 K?

4. What is the nominal read noise (over the above temperature range) for a readout frequency of 1 frame per second (769600 bytes per second for a 740x520 image)? Is the device intended to be read at this rate?

5. It appears (§2.1 viii) that the output register and output amplifier are intended to allow on-chip binning of up to 4 pixels into one superpixel without saturating? Do I understand this correctly?

Thank you for your help with these questions, Tom. I look forward to hearing from you soon. If there is another EEV CCD with the larger pixels of CCD25 and the high quantum efficiency and other favourable characteristics of CCD47 I would be very pleased to hear about it.

With best regards, I am

Yours truly,

David Steele, Ph.D.