I'm setting up a scattered light measurement for AlGaAs samples. The methods are summarized below.

I discussed with Manasa about the setup and how to do the measurement. The goal is to measure  scattered losses from AlGaAs samples from a normal incident beam. The setup is shown below.

==setup==

The setup is in the ATF lab, on the unused optical table. It is too crowded on CTN table. So I will need a to borrow a 1064 laser from somewhere. 

The incident beam will have to be slightly angle from the normal angle in order to dump the beam properly. 

The arm holds the camera, it can rotate to change the angle to cover the measurement from around 10 degrees to ~70 degrees.

==calibration method==

• We can take a picture from a diffuser plate, make sure it is not saturated. 
• Then use a power meter, measure the power fall on the camera.
• compare the output of the camera and the measured power
• I have to think about how to make sure the solid angle of the camera aperture and the power meter are the same.

==measurement and data analysis==

• For each position, take one picture without the beam on the mirror and one with the beam on the mirror. The first one will be used for subtracting the ambient noise from a picture when the beam is on the mirror. 
• Make sure that no pixel is saturated
• For each pair of picture, we will use Matlab to count the output, then use the calibration to convert to power.
• integrate over half the sphere. I have to think about this to make sure I get it right.