Internal Reflections on CMOS Mono Sensors

[glend]

Thread was high-jacked. Original discussion removed.

[billdan]

Must be a similar issue with the QHY168, as QHY has asked the debayer company to return the camera with an anti-reflection cover glass installed.

This company is Chipmod in China who are selling the QHY168 Mono on special at the moment for $US 1850.00 ($350 more than the colour version)

https://www.facebook.com/chipmod.astrocn.org/

[luka]

I can confirm what Glen said that the original glass causes reflections on debayered cameras.

I have debayered Nikon D70 sensor for my self-made Cam86 camera and initially I put back the original glass. The reflections were quite obvious. Eventually I removed the glass and am using the sensor without anything in front of it. I may order the anti-reflection coated MC-clear glass from Astronomik for protection, but it works quite well without any glass.

Few other people who debayered the D70 sensor for the same camera build also commented about the reflections caused by the original glass.

[ErwinL]

That's interesting to hear. How long did you use the sensor in unprotected state? And did you ever operate an unprotected sensor while it was fogged, maybe due to cooling?

[luka]

I only started using it. About 4-5 nights only and it was all in the last few weeks. I think on the second night out it got fogged up before I realised what was going on. No problems after it warmed up and on the following nights. Few other guys have been using it for a few months longer, didn't hear about any issues.

I can see two potential issues when using the sensor without cover glass:
1. protection, the thin gold wires on sides are exposed and can be damaged VERY, VERY easily. Even looking at them the wrong way can break them ;)
Having said that I accidentally cut one on my sensor and then repaired it by soldering across. I would say that the success of the repair was based on 99% luck.
Also compressed gas from a can is OK for cleaning dust, it won't break the wires.
2. Moisture from condensation creating an electrical connection between the gold wires. Can't really comment on this.

And if you are considering removing the protective glass, as Glen said it involves high heat and chances are you will kill the sensor and/or electronics. My sensors are from Nikon D70 which can be bought from ebay for <$50. ASI1600 on the other hand costs much, much more.

[ErwinL]

Sounds good. I'm thinking about using an open sensor together with a photo lens as a kind of basic protection.

I apply a resin shield as already suggested by famous Gina. To avoid the thermal stress Gina reported, I use Pattex repair gel which remains flexible but still protects sufficiently.

Congratulations!

I'm modding 1100Ds which are said to be very difficult to open - what I can confirm. But I found a way to remove the protective glass with quite little risk by use of a soldering iron. The trick is to regulate the temperature to at least 450°C and - very important - to bring yourself to apply plenty of tin to the front glass to improve the thermal contact. This way one can introduce sufficient heat locally without endangering the CMOS.

[glend]

Thanks for high-jacking this thread guys. :shrug:

My original post removed. Its all yours.

[ErwinL]

Oh, I'm sorry, please accept my apologies.
Erwin

[multiweb]

:sadeyes: