Table A.1.
Low-cost alternatives to specialized optical testing components, avoiding an estimated total investment of approximately US$1504 in equivalent entry-level commercial devices. This estimate does not include the mandatory investment in the laser source (approximately US$500 for the Spyder Wicked model used here), the non-polarizing beam splitter (approximately US$54), or the generic data acquisition system (camera and computer).
| Device (entry-levelcommercial cost) | Provenance of the alternative | Details |
|---|---|---|
| Mirrors with kinematic motion (4 × US$180) | Fragmented first surface mirror from a laser printer scanner | Mirror glued onto a three-screw tip–tilt mount |
| Short focal length lens (2 × US$80) | Disused smartphone camera | Mounted on plastic bottle caps, typically used for fragrances or generic liquids. A 5 mm hole in the base enables beam alignment with the bottle axis to facilitate collimation |
| Holders for the laser and the two lenses (3 × US$150) | Sky-Watcher adapter from digital camera to telescope eyepiece | It allowed fine adjustments in two axes |
| Holder for non-polarizing beam splitter (US$24) | Walls of stackable plastic blocks with a magnet in the base | It was fixed firmly on an iron plate whose orientation was also adjusted by three vertical screws |
| Linear polarizer (US$150) | Disused camera polarizer | Placed at the laser exit to block the horizontal polarization component of the light |
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