Thursday, October 8, 2015

DIY USB camera for an optical microscope

I recently got a "new" microscope : a Lemardeley from the 60s featuring both mono and binocular eyepieces (x5, x8, x10) and x10, x25, x60 and x120 objectives Taking pictures using a standard camera/smartphone is possible but gives some vignetted pictures, what about making a dedicated camera?

The Lemardeley microscope
Old good guy
On this picture the microscope is mounted with the binocular eyepiece, note the monocular one securely placed on the left wall of the wood box. also the objectives and oculars have a place in a sliding rack.
Luckily objectives of my previous microscope (from 2003) are using the same screw thread so i could adapt its x4 objective! (and potentially the x10 and x40 but that is quite useless here)
So here is the magnifying range :

X Ocular Lens
5 8 10
objectives 4 20 32 40
10 50 80 100
25 125 200 250
60 300 480 600
120 600 960 1200

adding a camera
After reading a lot on the web, i found that best results were given with a lensless camera module and without any ocular.
What is needed :
  • USB webcamera (here it was taken from an old ASUS laptop)
  • Old roll of film box
  • USB cable to connect the camera (either the webcam's one or a dedicated DIY one for embedded webcams
  • Hot glue, pasting tape, anything to cut or drill holes

How to
  1. Getting webcam and disassembling it to only keep the PCB, -not removing the lens yet-
  2. Checking if the roll fits on the eyepiece tube and drilling a hole on the back of it
  3. removing the camera lens and adapting roll box to fit the camera, hot gluing it (note the dust on the sensor, this will be an issue later...)
  4. make/adapting the cable (will depend on the camera used...)
  5. Testing

looking at a random chip
Here is a sensor on an HP scanner board : click for full size, -red circle shows the region zoomed on the right -one after the other-
Pictures are taken with guvcview.

Note the black dot (circled in red) : this is the result of the dust on the camera CCD