I'm testing the setup and a code for extracting scattered light from the images.
I used a red laser pointer to test the scattered light setup. Then took a picture with no light (fig1) and a picture with the incident light (fig2). The scattered light can be extracted by subtract fig1(background) from fig2.
The snapshots saved by SampleViewer are in .bmp file. When it is read by MATLAB, the file will contain 480x752x3 matrix element, Each are varied between 0 and 255. The values are proportional to the brightness (how many photons hit the cell). 480x752 is the resolution of the image, x3 are for R G B color. In our case, the image is greyscale and the values are identical. The code can be found in the attached file.
fig1: The test mirror without incident beam taken as a background image. The image is enhanced by a factor of 5 (by matlab).
fig2: The test mirror with a red incident beam around the center. The image is enhanced by a factor of 5.
fig3: the image is created by subtracting data of fig1 (background) from fig2 (scattered light) and enhanced by a factor of 100. The scattered light on both surfaces can be seen clearly around the center.
==To do next==
- From fig 3, the background can be seen even after subtraction, so some black curtains and beam dumps should be added behind the mirror.
- A room light filter should be installed in front of the camera.
- I'll see if we can find a sample with known scattering loss, so that we can compare how accurate the measurement is.