Laser scanning microscopes are useful for all kinds of tiny investigations. As it turns out, you can build one using parts salvaged from a Blu-ray player, as demonstrated by [Doctor Volt].
The trick is repurposing the optical pickup unit that is typically used to read optical discs. In particular, the build relies on the photodiodes that are usually used to compute focus error when tracking a disc. To turn this into a laser scanning microscope, the optical pickup is fitted to a 3D printed assembly that can slew it linearly for imaging purposes.
Meanwhile, the Blu-ray player’s hardware is repurposed to create a sample tray that slews on the orthogonal axis for full X-Y control. An ESP32 is then charged with running motion control and the laser. It also captures signals from the photodiodes and sends them to a computer for collation and display.
[Doctor Volt] demonstrates the microscope by imaging a small fabric fragment. The scanned area covers less than 1 mm x 1 mm, with a resolution of 127 x 127, though this could be improved with finer pitch on the slew mechanisms.
While it’s hardly what we’d call a beginner’s project, this technique still looks a lot more approachable than building your own scanning electron microscope.