Caveat

This modification is specific to the camera shipped with the PLAB 3 Spectrometer model JDEPC-0V05. Other cameras may have a different IR filter configuration.

Also be aware that you will be working with very small items so visual aids may be necessary.

And.. there is a possibility of accidentally scratching the lens so be patient and careful.

What I want to do

After upgrading the Spectrometer 3 as per @stoft and adding my own updates I wanted to check camera focus and also remove the IR filter.

My attempt and results

The work required the removal of the camera to check the focus using a convenient bar code. Removal of the lacquer holding the camera lens in place and removing the IR filter on the back of the lens. I used an old dental pick to remove the lacquer and was able to unscrew the lens. You should remove any debris before removing the lens completely using a blast of air from a hand squeeze bulb The series of photos shows the progress.

It is important not to get any debris into the sensor array.

Here I used the pick on the back of the lens scoring the filter around the outer edge in a circular motion and you can see bits of the filter had come off. At some point one may feel a "catch" where the pick has gone through and the filter can be levered out with the pick.

I then used an air bulb to remove any debris on the lens.

Then used a needle to apply a tiny drop of nail polish on opposite edges of the lens to make sure the lenses stayed put.

The camera was reassembled and focused

After reassembly and calibration I took a spectrum of old Sol and to my surprise the image was completely washed out. I could not find any source of light leaks! So covered the whole spectrometer in aluminum foil which solved the problem. So the removal of the IR filter had dramatically increased the camera's sensitivity A permanent fix was to laminate foil between 2 pieces of heavy black cardstock and fabricate the new cover. Subsequent testing proved all was well with a broader bandwidth response.

Questions and next steps

I'm wondering why the red channel extends into the UV range. Noise floor increase? Further band width investigation.

Why I'm interested

I need a stable instrument to do some further studies on Ag nano particles.