Interestingly CD/DVD/BluRay optical pickup units can be used to build fluorescence [0]/laser [1] scanning microscopes, atomic force microscopes [2], nanoscale 3D printers [3], interferometers [4] etc, due to their high precision, low cost and high availability.

  [0] https://www.sciencedirect.com/science/article/pii/S2950435X24000283
  [1] https://pmc.ncbi.nlm.nih.gov/articles/PMC6066758/
  [2] https://hackaday.io/project/186604-low-cost-and-high-speed-nanoscale-imaging-tool
  [3] https://www.nature.com/articles/s42005-021-00532-4
  [4] https://opg.optica.org/ol/abstract.cfm?uri=ol-24-10-670