= Optical Lever Improvement Project =

||'''Task Description'''||'''Who'''||'''Status'''||
||Review LHO elogs for information on Optical lever Problems||EG|| ||
||Review LLO elogs for information on Optical Lever Problems||MT|| ||
||Meet with Suresh||EG & MT||Discussed||
||Learn how to download data from Observatories and 40m|| || ||
||Try to understand if the power normalization is working|| || ||
||Download and analyze free space He-Ne Op lev data at 40m||MT||Retrieved data Sept23 to Oct 2||
||Fiber coupled He-Ne Op lev experiment at 40m || || ||
||Test the new fiber coupled He-Ne using the fiber power meter||MT||Do not have a FPM @633nm; Free space: 0.07mW||
||Select and purchase adjustable fiber collimator||MT||Will be using Thorlabs CFC-2X-C for now||
||Select and purchase mount for fiber collimator||MT||Available and ready||
||Fiber coupled diode laser Op lev experiment at the 40m ||MT||Setup on Oct15. Last data retrieved did not show enough resolution. Modify channels to 16bit ADC||
||Trade between free space solution and fiber solution|| || ||
||Make a design once a solution is selected|| || ||

== Procurements list ==

||'''Component'''||'''Quantity needed/procured'''||'''Part Number'''||'''Order status'''||'''Last updated'''||
||Fiber coupled Diode laser||1/1|| ||Procured||Oct 9||
||Kinematic fiber mount||1/1||Unknown||Available||Oct 9||
||Fiber collimator||1/1||Thorlabs CFC-2X-C||Available||Oct 9||
||Fiber collimator mount||1/1||Thorlabs AD9.5F||Available||Oct 9||

== Oplev QPD circuit ==
[[https://dcc.ligo.org/LIGO-D980325/public|D980325-C1]] (added GV 23 Jun 17 - I believe the transimpedance resistance is 97.6k, see [[https://nodus.ligo.caltech.edu:8081/40m/9975|elog 9976]])

== Oplev QPD ==
[[http://www.allpartsdata.com/show_allpartsdatasheet.php|Centronic QD-100-0]] (added GV 23 Jun 17)

According to the datasheet, the typical (maximum) crosstalk between quadrants is 1% (5%), although this is quoted at 900 nm. This number should be kept in mind when trying to decouple PIT and YAW motions on the QPD.

== References ==

'''LLO elogs'''
 *[[https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=14809]]
 *[[https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=13125]]

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''Page archived content (Before Oct 8 2014)''
## page was renamed from 40m Optical lever lasers
Right now we use cheapo diode lasers.

We may in the future use HeNe lasers:

http://www.mi-lasers.com/he-ne.html