1100D Debayer

[russellhq]

Well, I've not done any decent astrophotography since October last year due to the rubbish weather, so finally decided to scratch that itch that is debayering!

I started with a couple trial runs on some webcam sensors I had and after that, it was full steam ahead with the canon.

Well, first hurdle passed: Glass off!

Picture of the tools use and sensor. You can see the glass is in one piece.

Yes, it's a blowtorch!  I set the torch to the lowest setting, and with the sensor package held in the clamp (mole grips), I gently waved the heat over the glass for a second or 2 then took it away. I repeated this gentle heating process and slowly but surely, the glue started to melt. You could see it run round the border as it melted.

Once I could see the glue was melted all the way around, I applied gentle pressure with a stanley blade between glass and sensor package. This didn't work first time, so I applied some more heat. Second time with the blade and just a gentle push, the glass fell away in one piece

Now to being the scratching!

[Gina]

Is the image sensor still working? 

[russellhq]

Is the image sensor still working? 

Yip!

[ChrisLX200]

Blow torch and Mole grips,  precision electronics at its best

I'll be watching with interest

ChrisH

[Dave_D]

awaiting the sequel 'how to fine polish a parabola with a lump hammer'

[Gina]

Yip!

IMG_5440.jpg

Great!   Well done - now watch those fine gold wires - don't even breathe on them!   Good luck

I too shall be watching with interest

[russellhq]

Camera's away now for the night, but here's a flat field of my first pass. I wanted to test how well the scraper was working. Looks like I need to try a bit harder...

The plan was to only scrape in the horizontal direction to avoid scraping towards the wires.

[Gina]

Coming on very nicely   but be careful not to go too deep or you'll kill it.   Watch the blue border too - that contains some critical components.

[russellhq]

Coming on very nicely   but be careful not to go too deep or you'll kill it.   Watch the blue border too - that contains some critical components.

Thanks Gina. I've been using a plastic tool to try and limit the damage to the sensor, seems to be working OK so far. Also, next task will be to clean up the red area and then decide whether to try and get closer to the border...

[russellhq]

Well, tried taking some more off today and clean up the sensor a bit. Took this while taking a dark, was a complete accident but looks quite detailed.

Looks like I've killed a couple rows and I'm still struggling to get the sensor clean

[russellhq]

I've been trying to remove the traces of dyes and lenses but had no success with the scraping tools matchstick, clear CD case plastic, credit card plastic.  So I looked around the house for some inspiration and came up with 2 options: wood ash and HobBrite. I use both for cleaning glass so thought they might work.

I tried them out first on a piece of the CD case plastic. The wood ash didn't scratch but left the surface dull. I then tried the HobBrite. This worked better but still left the surface with a slight dullness but I thought I'd give it a go anyway.

Well here's the results of HobBrite on the bottom right corner of the sensor. You can see it's removed some of the left over matrix but has left scratches on the surface:

Given the promise polishes have, I did some research and came up with 2 options: cerium oxide and jewellers rouge. The rouge is softer and is slower to cut which I think will make it better suited to polishing the sensor.

I just need to come up with an applicator: I'm thinking a wooden tool for this. It'll be semi-absorbent and won't scratch the surface.

On a side note, has anyone noticed removing the lenses has made the sensor less sensitive?

[libraryman]

Try a piece of Melamine!! i tried it and it worked very well, it just needs a narrow flat edge, but do not use it directly after contact with any abrasive material i.e. sandpaper unless the edge is cleaned first;  bits of carborundum embedded in the Melamine  will scratch the sensor.

Ray  

[russellhq]

Try a piece of Melamine!! i tried it and it worked very well, it just needs a narrow flat edge, but do not use it directly after contact with any abrasive material i.e. sandpaper unless the edge is cleaned first;  bits of carborundum embedded in the Melamine  will scratch the sensor.

Ray  

Thanks ray, I was looking for some of this around the house but couldn't find any. I think a bit of abrasive got picked up when I was sharpening my plastic tool and that's what scratched and the sensor and killed the rows.

Have you got a flat of your finished sensor you could share?

[libraryman]

Hi Russ, no i haven't, i tested the Melamine on several duff sensors that were supplied to me! i tried a number of other tools prior to the Melamine; none of them were anywhere near as good, all i can tell you is that it does appear to be the best tool that i found, it does not scratch the gold layer underneath and is hard enough to remove all the matrix and not leave the mess behind.

I can only suggest that you try it and feed back your results.

Pm me with your address. i will send you a piece

Ray

[russellhq]

Thansk ray. When you were testing, what width did you make your scraper head? I found that keeping it narrow worked best: about 3-4mm.

[libraryman]

Yes 3-4 mm was just right, however the width counts for nothing if you cannot keep it flat!! that is where potential problems arise..with the Melamine it did not seem to matter.

Hope that helps

Ray 

[russellhq]

Yes 3-4 mm was just right, however the width counts for nothing if you cannot keep it flat!! that is where potential problems arise..with the Melamine it did not seem to matter.

Hope that helps

Ray 

Thanks Ray, you have pm

In your tests, did you try Acetal or Derlin? These are both relatively stiff plastics which might have promise as a scraping tool.

[libraryman]

No, just the usual suspects, CD cover hard wood stick, other unidentifiable but hard plastic type materials, soft alloys  ect.

i have your PM will post tomorrow.

hopefully you will find it better but please let us know either way.

Ray 

[russellhq]

I've never been very patient: just bought some chamois leather and polishing paste to try out on the sensor:

[russellhq]

Here's a flat showing top left corner where I use the polishing paste:

And here a photo taken outside to test the sensor:

[Gina]

That seems to be working   That paste is the same as I used.

[astromerlin]

That paste seems to be doing the job, What did you apply the paste with?

[russellhq]

I used a piece of chamois on a sensor cleaning swab.

[libraryman]

Hi Russ, can you explain a little more about how you removed the cover glass?

Did you heat one corner then chase the colour change around or did you heat the whole glass then let it cool before heating again?

Ray

[russellhq]

First I clamped the sensor in the vertical position. This would allow the glass to fall away in one go once the bond was broken. Next I slowly heated the entire glass surface by waving the flame of the blowtorch over the glass for a second or two, removing heat for about 5 or so seconds and then reapplying. This would reduce the chances of the glass cracking due to differing thermal expansion rates.

After about a minute of heating I could see the bond changing in look, I put this down to the glue melting. I could see the bonds appearance change as others have described where it runs round the frame. There were some stubborn bits that didn't change, so I just added a little more heat.

At this I had a go at popping off the glass cover by trying to get a Stanley blade between the glass and frame. It didn't work the first time, I guess this was because the glue had cooled and set, so I applied more heat and tried again. This time the blade managed to get between the glass and frame and the glass fell off in one piece. I then let out a big sigh of relief!