Public Lab Research note


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Camera Focus IR Filter Removal

by stef |

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.

IMGP1570.JPG

IMGP1571.JPG

It is important not to get any debris into the sensor array. IMGP1578.JPG

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.

IMGP1580.JPG

I then used an air bulb to remove any debris on the lens. IMGP1582.JPG

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.

IMGP1583.JPG

IMGP1584.JPG

The camera was reassembled and focused

IMGP1595.JPG

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.


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7 Comments

Wow, this is so great! I wonder if it'd be helpful to people seeking to do this process too, if you were to rename it "Removing the infrared filter from a spectrometer webcam" or something like that -- I'd love to feature it as an upgrade to point other people at. Thanks!!!!


It probably would help to identify the camera better e.g. JDEPC-0V05 as shipped with the PLAB 3 spectrometer IR filter removal and Focusing. I think there was a question raised by someone previously on this. I don't believe that I can change the header would that not be a mod function?

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Oh - you can edit using the little ^ menu next to the "LIKE" button. I agree the camera model is helpful, but i think it could be added under "What I want to do", as not everyone seeing this post may know what a JDEPC-0V05 is. Or you could do "Removing the infrared filter from a spectrometer's JDEPC-0V05 webcam"?

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Sorry, next to the "follow" button:

Screen_Shot_2016-10-19_at_4.17.29_PM.png


Thanks for that tidbit. It is re-edited.


Also -- just reading this through carefully, and was wondering if the line:

I used the pick on the back of the lens

...could be clarified -- you shattered the filter with the pick, right? (this is what I've done, so I'm assuming.) Did you use a small hammer or something to hit the filter?

Thanks! I love the detailed photos!

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Done!


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