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Message ID: 1154     Entry time: Mon Apr 22 02:25:58 2013
Author: Chloe 
Type: DailyProgress 
Category: ECDL 
Subject: ECDL Grating/Current Controller 

Grating choices:

In the literature, people seem to use 1800/mm spacing. Attached are efficiency graphs found on Thorlabs for 1200/mm and 1800/mm spacing. At 1064nm (which is where we are interested in tuning to), the efficiency drops off for the 1800/mm spacing grating. This could be fixed if we use an angle close to perpendicular, or we may be better off using the 1200/mm grating, which has an average efficiency of about 35% at 1064nm, vs an average of 20% for the 1800/mm grating. It is a question of efficiency vs. resolution. 

Current Controller:

We are currently examining a current controller designed by Libbrecht and Hall (1993), since it has been shown to have lower noise than before. There is a commercially available controller based on the design from their paper (http://www.vescent.com/products/electronics/d2-105-laser-controller/). I did some literature search and it seems that there was a design by Erickson (2008) which is an improvement on the design by Libbrecht and Hall. This paper is attached... we may try to use this design instead. Tara and I will meet on Thursday to determine if the requirements we want to have on our experiment to have low noise, and then choose whether to pursue the Erickson controller further. 

Attachment 1: 1200mm_grating.PNG  41 kB  | Hide | Hide all
1200mm_grating.PNG
Attachment 2: 1800mm_grating.PNG  40 kB  | Hide | Hide all
1800mm_grating.PNG
Attachment 3: Erickson08au.pdf  175 kB  | Hide | Hide all
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