CCD-world: What is an interline transfer CCD and why does it require a lens?

[Hagan, Vern]

The following was posted to CCD-world:


There is an article on interline devices located at
www.prist.com/bioprod.htm
Article on CCD Information.



Vern A. Hagan
Camera Systems Specialist
Roper Scientific: Tucson
tel:  520.547.2726
fax: 520.573.1944
email vhagan at photomet.com
http://www.roperscientific.com



-----Original Message-----
From: Sutherland, Scott [mailto:ssutherl at gammametrics.com]
Sent: Tuesday, July 27, 1999 4:38 PM
To: 'CCD-world at cfht.hawaii.edu'
Subject: CCD-world: What is an interline transfer CCD and why does it
require a lens?


The following was posted to CCD-world:

Hello all:
 
In my continuing quest to get sensitivity and QE information
on SONY linear CCD's, I ran across 2 web sites that have
QE data on SONY area CCD's.  The area CCD's have 
a similar wavelength-dependent sensitivity as the linear
CCDs (according to the curves on their respective data
sheets, with greatly supressed red response.  In a response
to an earlier posting I made here, it was suggested
that the reason for this was that 
the tests were performed with a CM500S filter in front of the 
light source, greatly supressing the red/NIR light.  However,
the, QE data I found shows the same low red/NIR sensitivity
as the Relative Response data.

When I called up the first company, Apogee, they told me that the
the SONY AREA sensors are interline transfer and require some sort
of lens on the chip.  It was not clear to me what this meant.  I further
found mention of a new SONY area CCD chip (ICX083AL) on the
on the Starlight Xpress web site.  Starlight states: "The latest in
'microlens'
technology from Sony has almost eliminated the 'dead area' from this
CCD and has increased the quantum efficiency to more than 60%
over much of the visible spectrum."

Could someone explain to me (or point me to references) what
an interline transfer CCD is (and how it differs from a Kodak KAF0400,
TI TC241, or EEV type CCD), and why the microlens is needed and
what it does?  Does this type of CCD have inherently lower red/NIR
sensitivity?

On another page of the Starlight Xpress web site, they describe
another CCD that, according to the QE curves provided, has low
red/NIR sensitivity.  This is the Philips FT12.  Starlight claims
that this CCD was designed to have low red/NIR sensitivity:

" As the reader will know, almost all conventional CCDs have a
very high red / infra-red sensitivity, combined with a poor blue
response, and the thermal dark current is often very high. Other
undesirable effects can be the lack of an effective anti-blooming
control and the need for a mechanical shutter to prevent 'smearing'.
Fortunately, the large electronics company, Philips, have now
released a series of advanced technology 'frame transfer' sensors,
which have none of the unwanted problems listed above."

I do not know if the SONY chips have been designed this way (e.g.
with low red/NIR response) as well, and all my inquiries to SONY
have revealed nothing (they cannot even tell me with whom I should
speak).

Any insights as to what might be going on here would be 
helpful.

Thanks,

Dr. Scott Sutherland
Senior Scientist
GAMMA-METRICS
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