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Entry  Tue Jun 28 07:46:54 2011, Suresh, Update, IOO, Power incident on REFL11 and REFL55 
    Reply  Tue Jun 28 10:11:13 2011, steve, Update, IOO, Power incident on REFL11 and REFL55 
    Reply  Tue Jun 28 14:21:41 2011, kiwamu, Update, IOO, something wrong ? : Power incident on REFL11 and REFL55 
       Reply  Thu Jul 7 14:27:16 2011, Suresh, Update, IOO, something wrong ? : Power incident on REFL11 and REFL55 
Message ID: 4894     Entry time: Tue Jun 28 07:46:54 2011     Reply to this: 4896   4898
Author: Suresh 
Type: Update 
Category: IOO 
Subject: Power incident on REFL11 and REFL55 

I measured the power incident on REFL11 and REFL55.  Steve was concerned that it is too high.  If we consider this elog the incident power levels were REFL11: 30 mW and REFL55: 87 mW. (assuming efficiency of ~ 0.8 A/W @1064nm for the C30642 PD).  However, currently there is a combination of Polarising BS and Half-waveplate with which we have attenuated the power incident on the REFL PDs.  We now have (with the PRM misaligned):

REFL11:  Power incident = 7.60 mW ;  DC out = 0.330 V  => efficiency = 0.87 A/W

REFL55:  Power incident = 23 mW ;  DC out = 0.850 V  => efficiency = 0.74 A/W

and with the PRM aligned::

REFL11:  DC out = 0.35 V  => 8 mW is incident

REFL55: DC out = 0.975 V  => 26 mW is incident

These power levels may go up further when everything is working well.

The max rated photo-current is 100mA => max power 125mW @0.8 A/W.

 

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