[Dsg-rich] Moving RICH reflectivity test station from EEL 108A to EEL 121b

[Tyler Lemon]

Hello Bert, 

Since you are Laser Safety Officer, we have a question regarding the test set-up we are using to measure RICH mirror's reflectivity. The tests use a laser to align the optics of the test set-up before taking data. I submitted the BList (http://devweb.acc.jlab.org/CSUEApps/hblist/task/1555) for this tasks last week and it has since been approved. 

During the tests, we have found that the actual spherical mirrors for RICH are too big to fit in the existing darkbox in EEL 108A. Would we be able to operate the test set-up without the dark box enclosure? 

To solve the problem of the mirrors being to big, we would like to move the entire test set-up into the small clean room in EEL 121b and remove the darkbox. The dark box is not needed in the small cleanroom because the room has already been darkened for other RICH mirror tests. Without its dark box, the beam of the test set-up's alignment laser and also the test lamp beam would no longer be completely enclosed. 

The alignment laser specifications and test lamp details are below. 

Alignment Laser 
WITHOUT NEUTRAL DENSITY FILTER: 
Class : 3R 
Central Wavelength : 635 nm 
Power : 2.7 mW 

WITH NEUTRAL DENSITY FILTER OF OPTICAL DENSITY 1.0: 
Central Wavelength : 635 nm 
Power : 0.27 mW 

Test Lamp: 
Wavelength: ranges from 300nm - 650 nm during test. 
Max Power : ~10 nW at ~600 nm 
Test Beam Diameter : 1 mm 
Test Beam Divergence: 10 mrad 
Description: Test lamp is a 50-W quartz-tungsten halogen lamp that passes through a monochromator. The internal optics of the monochromator diffract the lamp's light into the desired wavelength and collimate the light into a test beam diameter of 1 mm. Power of test beam ranges from ~2 nW to ~10 nW over range of wavelengths used. 

Please let us know whether we can operate the test set-up without the dark box enclosure. It is urgent that we complete these tests as soon as possible because we need to get back to the mirror's manufacturers on the quality of their coating. 

If you need to take a look at the test set-up, I will be available tomorrow morning. 

Best regards, 
Tyler 


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