The maker (Lötlabor Jena), who has made a variety of hardware himself, draws attention by revealing how to make a laser microscope with a DVD drive and the photos actually taken.
He said that DVD drives are being scrapped in large quantities recently, so if you’re a hardware enthusiast, you can get DVD drives almost for free. It means that you can build hardware using a DVD drive, which can be obtained inexpensively. It makes a laser microscope with a laser sensor capable of discriminating 440nm pit heights placed at 780nm intervals on a DVD disc.
According to him, the DVD drive device is suitable for making a laser microscope because it includes not only a precise laser sensor, but also an optical element such as a lens mirror prism, and a motor that moves the sensor to an appropriate position. However, it is equipped with a unique microprocessor and circuit designed by the DVD drive manufacturer, so users cannot rewrite the operation at will. Therefore, he decided to reverse engineer the hardware and design his own software and hardware to add the ability to adjust the focus function and sensor position necessary for a laser microscope.
The DVD drive is equipped with a photodiode integrated circuit PDIC to detect and process laser light. He took micrographs to understand the PDIC structure and found that the PDIC is equipped with at least eight independent photodiode channels. Later, he measured the PDIC voltage and irradiated light to confirm the role of each photodiode channel.
Having understood the PDIC design, he designed a board that handled the information received from the PDIC and handled the motor control and power supply, which controls the sensor position. The board he designed is equipped with the TPIC2050, an IC chip that Texas Instruments sells for 2.5 euros each. It also developed software to control the sensor position to create a laser microscope on a DVD drive.
If you look at an image taken with such a laser microscope, you can also shoot at 500μm×500μm at 1mm×1mm or higher magnification. He publishes the blueprint and source code he developed to create a laser microscope in his GitHub repository. Related information can be found here.