Zeiss beam splitter's photocell purpose and related equipment

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Lambda 6
Posts: 3
Joined: Mon Jan 23, 2023 11:09 am
Location: High Plains Scientist Wyoming

Zeiss beam splitter's photocell purpose and related equipment

Post by Lambda 6 »

Searching for information about the purpose and related equipment for the 7 pin photocell in the Zeiss Beam Splitter 47 60 25.

The 7 pin Caesium/Antimony photocell is manufactured by Phillips, Mullard, and VALVO
as " 90 AV" which indicates its' a vacuum photocell. Sensitive to blue and daylight incident light.
Va max = 100V, Ia max 5 mA
Phillips Tuba Handbook lists the specs, pin configuration etc. but has no indication for use by Zeiss.
The vacuum tube 7 pin socket has a single coax cable ending with a banana plug. Photocells generally act as triggers to activate another device. So a power supply is required as is the acted-on device. Shutter maybe?
Beyond that I am in the dark - no pun intended. Any information would be greatly appreciated.
A picture of the tube with another showing the internal component. The cathode is sprayed onto the inside of the glass envelope. The two rods are the anode. The round structure near the base is the getter holder. ya got me on that. http://www.r-type.org/pdfs/90av.pdf lists more tube data but no function of how Zeiss used it. circa 1953
Attachments
VALVO photoflah.jpg
valvo 90 AV.jpg

g4lab
Posts: 1437
Joined: Fri May 23, 2008 11:07 am

Re: Zeiss beam splitter's photocell purpose and related equipment

Post by g4lab »

The photocathode looks like it is selenium.
These were used for exposure meters for photomicrography as well as ocassionally being used for microscope spectrophotometry. They need a power supply of several tens of volts probably at least 50 and maybe as much as 400 depending on the application.
Both Zeiss and Leitz had these things which were probably either completely custom or produced in such small numbers that they didn't get into the catalogs.
Because the amount of light available if trying to do spectrophotometry of a spot in a microscope image, is tiny often in that application photomultiplier tubes were used. But before they were available (mostly post WWII) tubes such as this used.

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