What is this optical component made of??

Mon Jul 22 14:21:38 EST 1996

Its easy to tell the difference betweent these substances:

Plastic is lightweight, easily scratched, and susceptible to solvent and 
heat damage.... hence it is highly unlikely that it is made of plastic.
Also, plastic only transmits light with wavelengths longer than maybe 500nm.
(I've never heard of *serious* optics, like what you describe, being
made of plastic... they would need lots of special coatings, and become
almost as expensive as the better substances.

Glass will transmit shorterwavelenghts of light, but it cuts-off around
-400nm, depending on the quality of glass.  

Quartz cuts off around 210nm, unless it is a Suprasil-type quartz, which
is somewhat more expensive but can get down to about 175nm.... by this 
point, however, the water and oxygen in the atmosphere will be absorbing 
more than the optics.... so purging with N2 gas is necessary..... 

And for completeness:
for shorter wavelengths, you would probably need CaCl2 or MgCl2 crystals....
these can go down to ~120nm, but they are extremely expensive and fagile.

My guess is that your optics are made of a cheap quartz or better quality
glass (the distinction is only one of amounts of impurity), as are most
optical devices.  My reasoning is this: Even though fiberglass can only 
transmit longer wavelengths, the kind of optics you are describing are 
worthy of reasonable quality to ensure complete transmition, durability 
and accurate optical properities.

You can test all this with a simple UV-Vis Absorbance spectrometer, or
in honor of Archimedes you could even measure the relative density/specific 
gravity.(I'm sure the CRC Handbook has densities for glass/quartz).

More info than you needed, and probably someone else has the actual
specs on the machine.... but what the heck!


Gary D. Strahan, Ph.D.
Department of Pharmaceutical Chemistry
University ov California, San Francisco
San Francisco, CA 94143-0446
(415) 476-4378

strahan at picasso.ucsf.edu

> From BIOSCI-REQUEST at net.bio.net Fri Jul 19 20:48:24 1996
> Hi,
>    I salvaged some parts (optical & electronic) off a chemistry
> analyzer that was going to be scraped. The analyzer was a 
> Toshiba medical system.
>   The part in question is the mirror used to relay the light source
> via fiber-optics to the cuvette with the analyte in it. Another mirror
> relays the transmittance or absorption of the light source to the 
> detector. The mirror is a small oval inside a clear cube.It is similar
> to a cube beamsplitter(2 right-angle prisms cemented @ their hypotuse
> faces), but small -- 10mm x 7mm x13mm.
>   Anyone  know what  these are made of? Quartz,glass, or plastic?
> 		Thanks, rimshot at worldnet.att.net

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