Eyepiece - Back to the camera.

This afternoon I reached the point of being able to test the Raspberry Pi camera module against one of the eyepieces from the microscope.

In order to do this, I kludged together an illuminator (using four white LEDs) and a printed image that sits in the graticule tray - an object that is in focus at the same time as the image from the microscope objective.

By holding the objective to the camera, I was able to estimate the separation between camera lens and eyepiece required for the best possible image - as well as to determine whether any intermediate lenses would be required.

The test was unexpectedly an immediate success. With the camera sat against the built in eye-cup on the eyepiece (a Vickers x10 Complan), the (circular) test image almost filled the height of the rectangular image - meaning that with a little tweaking and with the creation of a suitable adaptor, the camera is essentially able to be used as-is.

The graticule image - this was scaled down to a 19.5mm diameter.

In the graticule image above, the edge of the graticule mount covers the edge of the image - the fine, black line representing the expected limit of the vignette.

First Test - captured image through the eyepiece

As you can see, the test image is rather grainy - this is because the image is of a tiny picture printed out using an ink jet printer. There is also some distortion, but this is mainly due to the graticule being somewhat misshapen.

A blurred artifact (from the 3 o'clock to the 6 o'clock position) is the visual effect of some de-lamination in this eyepiece's optics.

The image is not properly centred because the test system was simply being held together in my hand. The pale mark in the lower left of the image is a reflection off of the inside of the eye-cup.

Conclusion:
This test was more successful than anticipated, and will warrant a proper adaptor being made in the near future.

Next steps:
A paper and card prototype adaptor will be used to perform more sophisticated testing and adjustment of the optical system. An acrylic design will follow, which will be capable of supporting the camera and associated computer while attached to the eyepiece.