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Which budget Laser Power Meter for measuring telescope mirror reflectivity?

Tatsu

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Jan 4, 2020
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I am an amateur astronomer and would like to test the reflectivity of my telescope mirrors. My idea is to use one of my laser pointers (nominal 20mW and 100mW) and measure the intensity before and after the reflection in the mirror. Typical mirror reflectivities in astronomy are 96-99%, which means that the laser power meter (LPM) should have an accuracy of at least 1%. Is there any affordable LPM on the market that would do the trick? Affordable in my case would mean max around 250 US$.
I have the possibility to buy a second hand Sanwa LP-1 / Sper Scientific 840011.
rebrand.ly/nrdep6
Will this LPM be able to do what I want?
 



paul1598419

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Sep 20, 2013
Messages
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This is a duplicate thread to one you posted here today. That is not something that is acceptable here. There are no LPMs that have an accuracy of 1% or less. Not even professional ones. So, the laser test won't work. This could likely be done in a number of other methods.....and has likely been done. So, do a search and find another way to measure the reflectivity of your mirror.
 




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