March 12, 2022
...
At 808 nm:
| angle (degrees) | Rp | Rs |
|---|---|---|
| 0 | 0.041365 | 0.041365 |
| 5 | 0.040948 | 0.041784 |
| 10 | 0.039693 | 0.043069 |
| 15 | 0.037593 | 0.045301 |
| 20 | 0.034640 | 0.048630 |
If angle of incidence is 10 degrees, reflected beam rotates by 20 degrees. If beam of diameter D rotates by theta, distance it must travel to not have incident and reflected overlap obeys tan(theta)=D/L so L/D=1/tan(theta)
...
Using https://lightmachinery.com/optical-design-center/more-optical-design-tools/prism-designer/
| apex angle | incidence angle | 300 nm angle | 1100 nm angle | difference |
|---|---|---|---|---|
| 1 | 1 | 0.487 | 0.449 | 2.2 arcmin |
| 1 | 10 | 0.4981 | 0.4589 | 2.35 arcmin |
| 10 | 5 | 4.904 | 4.523 | 22.86 arcmin |
...
notional system diagram:
RACBP Spring 2024 Parts List:
...
We note the reflective designs in this paper which document a 4-element system that adequately* preserves the initial polarization / phase of light.
Status updates:
An initial version of the RACBP was constructed in the benchtop lab setup on Feb. 22.
Initial testing with a 532nm laser unfortunately showed strong and tightly spatially located double-bounce propagation through the system, indicating that the 30-arcmin wedge on the wedge windows purchase would be insufficient for canceling double-bounce issues.
Consequently, plano-convex lenses of the fastest f-ratio were ordered and installed the following week as replacements to the wedge windows; initial observation reveal that this modification
appears to successfully cancel out double bounces, representing a step closer to taking controlled flux measurements through the system at this proof-of-concept stage.
In-progress/next steps: finalizing modelling results for system ; angular alignment tolerance, verification of polarization effects.
Reworking physical layout and installing double monochromator system and operation with expanded beam profile.
Kane To-Do:
polarization state output as fxn of angle of incidence for BK-7 and Fused Silica ... quantitative calcns
sol'n: circular polarization?
python script to compute aggregate throughput
incidence / reflection angle tables / program
n(lambda) – check
labjack with mac mini
(Galvez, E. (2001). Achromatic polarization-preserving beam displacer. Optics Letters, 26(13), 971–973. https://doi.org/10.1364/OL.26.000971)
References
Large optical wedge vendor, example: https://www.precisionoptical.com/precision-optics/optical-flats/unmounted-reference-flat/
...
polarization-preserving configuration with 4 reflections ol-26-13-971.pdf; (Galvez, E. (2001). Achromatic polarization-preserving beam displacer. Optics Letters, 26(13), 971–973. https://doi.org/10.1364/OL.26.000971)
We note the reflective designs in this paper which document a 4-element system that adequately* preserves the initial polarization / phase of light.
| title | link | |
|---|---|---|
| Theory of the optical wedge beamsplitter | The_Theory_of_the_Optical_Wedge_Beam_Spl.pdf | |
| Achromatic polarization-preserving beam displacer | https://doi.org/10.1364/OL.26.000971 | |