Choosing the right OPU

A project log for Scanning laser microscopy made by CD-ROM OPU

CD-ROM Optical Pickup Unit (OPU) used for homemade scanning laser microscope

Roland VargaRoland Varga 04/17/2018 at 12:510 Comments

When I originally started to working on this project, I sacrificed a lot of CD and DVD drives to find the right OPU. For the better resolution a blue-ray drive would be ideal, but as most modern gears, these are not very well documented. On the other hand old CD-ROM driving ICs have a very detailed datasheets with the pin outs, but as the wavelength is in the 780 nm range, the resolution wont be as good as the blue-ray, or even a DVD-ROM.

As I started this project only as a proof-of-concept, I decided to use a CD-ROM which build around the SONY CXD3045R digital signal processor and the SONY CXA2581N RF signal processor. I removed all unnecessary hardware components, ( i.e.: all DC motors and rails, and the disc rotatory elements), and I am only using the main board, including the DSP, RF signal processor connected to the OPU itself.

From the datasheet of the RF processor I was able to identify the necessary signals, and solder some wires to the test points. The digital signal processor will be bypassed, and the error signals from the OPU can be used.

(Also I found out that the SW pin is responsible for switching the RW and ROM functions, and with this changing the laser output. I will try out is there any differences between the 2 mode )