March 12, 2022
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From https://refractiveindex.info/?shelf=glass&book=BK7&page=SCHOTT
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)
| theta_incidence | theta_refl | L/D |
|---|---|---|
| 5 | 10 | 5.7 |
| 10 | 20 | 2.7 |
| 15 | 30 | 1.7 |
Purchases
Lambda optics 2 inch concave mirror blanks, polished both sides.
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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 |
This wedge pair needs to be tilted relative to incident beam. Five degree wedge angle seems good, as a pair. That gives us variation from zero to around 30 arcmin. For any sensible focal plane array of 4K x 4K
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RACBP Spring 2024 Parts List:
| Description | Qty | Part # | Details | Purchase Date |
|---|---|---|---|---|
| Ø2" UVFS Wedged Window, Uncoated | 8 | WW42012 | 8/8. | 01/30/24 |
| 60 mm Cage Cube | 8 | LC6WR | 8/8. | 01/30/24 |
| Light-Tight Blank Cover Plate for 60 mm Cage Cube, 1/4"-20 Tap | 10 | LB1C | 10/10. | 01/30/24 |
| SM2-Threaded Cover Plate for 60 mm Cage Cube | 4 | LB2C | 4/4. | 01/30/24 |
| Kinematic Prism Platform for 60 mm Cage Cube, Imperial Taps | 6 | LB4C | 6/6. | 01/30/24 |
| 60-mm-Cage-Compatible Rectangular Filter Mount | 2 | LFFM1 | 2/2. | 01/30/24 |
| Ø2" Optic Mount for 60 mm Cage Cube with Setscrew Optic Retention | 8 | LB5C1 | 8/8. | 01/30/24 |
| 60 mm Kinematic Cage Cube Connector | 8 | DFM2-CC | 8/8. | 01/30/24 |
| 6mm cage connector rods of various lengths | all received. | |||
| fast plano-convex lenses | various | all received. | ||
| optical shutter? Thorlabs | ||||
| optical chopper following monochromator | ||||
| condensing lens for photodiode | ||||
| order blocking filter, controller servo |
We note the reflective designs in this paper which document a 4-element system that adequately* preserves the initial polarization / phase of light.
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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.
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