User:Pranav Rathi/Notebook/OT/2010/08/02/x & y Signal Drift Issue
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| + | ===Goal=== | ||
| + | The goal has been achieved today. The drift problem is solved by imaging the beam waist (1.26mm; exists inside the AOM) with 1:1 telescope on the QPD. I am very positive that this works, but I am still verifying that it is not happening due to small beam waist at the QPD. I will right the full detail later ; how we achieved it. | ||
| + | Investigate the x & Y signal drift: What is causing it; AOM or the laser (most probable it’s the AOM), magnitude of the effect, and possible solution. | ||
| + | |||
===Setup & procedure=== | ===Setup & procedure=== | ||
| + | The setup is fairly simple; laser --> AOM --> two mirrors (down and upstream) --> telescope (1:1)--> QPD. | ||
| + | |||
| + | ====Procedure==== | ||
| + | under work | ||
====Steps==== | ====Steps==== | ||
# Measure the beam waist (2 x W=1.5) at the eyepiece lens of the telescope. | # Measure the beam waist (2 x W=1.5) at the eyepiece lens of the telescope. | ||
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# Measure the beam waist again (2 x W =1.5) at QPD, to make sure that the ratio is 1:1. | # Measure the beam waist again (2 x W =1.5) at QPD, to make sure that the ratio is 1:1. | ||
# Straighten the beam after the telescope, using two aperture techniques [[http://openwetware.org/wiki/User:Pranav_Rathi/Notebook/OT/2010/04/20/Super_easy_way_to_straighten_and_align_two_laser_beams_simultaneously]]. | # Straighten the beam after the telescope, using two aperture techniques [[http://openwetware.org/wiki/User:Pranav_Rathi/Notebook/OT/2010/04/20/Super_easy_way_to_straighten_and_align_two_laser_beams_simultaneously]]. | ||
| - | # Setup the QPD | + | # Setup the QPD on the xyz translation stage. |
| - | [[Category:Optical | + | [[Category:Construction of Optical Tweezers and devices]] |
Current revision
Contents |
Goal
The goal has been achieved today. The drift problem is solved by imaging the beam waist (1.26mm; exists inside the AOM) with 1:1 telescope on the QPD. I am very positive that this works, but I am still verifying that it is not happening due to small beam waist at the QPD. I will right the full detail later ; how we achieved it. Investigate the x & Y signal drift: What is causing it; AOM or the laser (most probable it’s the AOM), magnitude of the effect, and possible solution.
Setup & procedure
The setup is fairly simple; laser --> AOM --> two mirrors (down and upstream) --> telescope (1:1)--> QPD.
Procedure
under work
Steps
- Measure the beam waist (2 x W=1.5) at the eyepiece lens of the telescope.
- Setup the (1:1) telescope: In this case two planoconvex lenses (f=38.1mm of both) are used.
- Measure the beam waist again (2 x W =1.5) at QPD, to make sure that the ratio is 1:1.
- Straighten the beam after the telescope, using two aperture techniques [[1]].
- Setup the QPD on the xyz translation stage.
