Simon

I have set up a measurement bench in TAMA to easily and fastly take reflection data of a 1064nm laser on samples (mostly optics, I guess) as a function of the angle of incidence (from 0 to 90 degrees) and input polarization.
The system works fine but it still not entirely finished. For example, we plan to install a rotation-gear on the angular rotator to compensate the 2*AoI effect, so that a manual change of the PD won't be necessary anymore.

Especially today, I was trying to further understand the laser. I recognized that the used PD cannot measure powers more than 8mW (which is strange as there is a threshold of 50mW written on it...). But putting the laser at such low power-gains, the stability of the laser is not good at all. Therefoe, I was inserting a ND-filter in front of the laser and increased the gain so that the laser-power is stable (change of power after 10 minutes <1%).

After setting up the laser, I tested the system with a Brewster-polarizer (TFP-1064-pw-2037-uv) which we use for the PCI. The input power for the measurements was set for both S and P polarization to 6.53mW.
Please see the attached graphic which illustrates the results. For P-pol, a minimum at 63 degrees was found (R = 3.5%), while for S-pol, the reflectance did not change much at all over the entire measured range (which is somehow expected, I guess).

Please note that the data taken at 80 degrees AoI are probably not very accurate, since I believe that the beam was clipped (I need to check this further, maybe installing a lens is better).