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From: ftpam1@acad3.fai.alaska.edu (MUNTS PHILLIP A)
Newsgroups: sci.electronics
Subject: UV Detectors (was Need help ... is there any inexpensive device that)
Summary: Bias of phototube or photomultiplier can change spectrum
Message-ID: <1990Jul22.013627.19744@hayes.fai.alaska.edu>
Date: 22 Jul 90 01:36:27 GMT
References: <14380@venera.isi.edu> <1990Jul21.023806.12927@hayes.fai.alaska.edu> <5350@milton.u.washington.edu>
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In article <5350@milton.u.washington.edu>, whit@milton.u.washington.edu (John Whitmore) writes...
>In article <1990Jul21.023806.12927@hayes.fai.alaska.edu> ftpam1@acad3.fai.alaska.edu writes:
>>In article <14380@venera.isi.edu>, sllu@jenny.isi.edu (Shih-Lien Lu) writes...
>>>will detect UV light only (200nm to 400 nm wave length)?
>>>If not, is there any device that will detect light down to 200 nm wave
>>>length?
>>
>>     Photomultiplier tubes (possibly with optic filtering).
> 
>	Or perhaps simple photocells.  The bias voltage on a
>photomultiplier (PMT) tube's first cathode can be deliberately
>degraded (run low) so that only energetic photons (UV) generate
>electrons... this is the 'photoelectric effect' that Einstein
>got his Nobel for explaining.  Photocells, while having MUCH
>lower currents, are easier to bias.  Look up 'stopping potential'
>in any discussion of photoelectricity.
> 
>		John Whitmore

     Hmmm... an interesting idea that I wouldn't have thought of.  There are
some problems, however.  First ordinary glass doesn't pass UV.  Second you need
a photocathode designed for high quantum efficiency at UV.  I am afraid you can
only satisfy these with a PMT or photocell specifically designed for UV.  Still,
I wonder if anyone still makes non-PMT phototubes?  It's worth a test.

     Anyway, I just found a blurb in the August 1990 "Modern Electronics" that
lists a G3614 UV (260 to 400 nm) detector (solid state GaAs) from Hamamatsu
Corp, 360 Foothill Road, POB 6910, Bridgewater NJ 08807.  (Note that I left out
a "ma" from the name before.)

Philip Munts N7AHL
NRA Extremist, etc.
University of Alaska, Fairbanks