My Friend is Building a Telescope

[psyche101]

Hi Everyone.

I have been discussing my love of skywatching, and a person I converse with in another forum has told me he is building his own scope. Very decent gear, so far the list comprises of:

I am using the KAF-16801 color sensor (link) with the following specs:

16M Pixel Area CCD
4096H x 4096V (9 μm) Pixels
36.88 mm H x 36.88 mm V Photosensitive Area
2-Phase Register Clocking
100% Fill Factor
High Output Sensitivity (13 V/e-)
Low Dark Current (<10pA/cm2 at 25° C)

Looking for some lenses. Any suggestions?

Thanks all.

[Blue Skies (Jacquie)]

Aah, that doesn't sound like a telescope, that just sounds like a CCD camera. The camera would then go on a telescope.

Lenses are used in several places in telescopes - in the finderscope, in the eyepieces and in the objective lens if you have a refracting telescope, or in a focal reducer, for example.

Could you rephrase your question to be more specific? Lenses for what purpose where on a telescope?

(sorry, this is a bugbear of mine. The word 'lenses' gets tossed around too casually and can be confusing.)

[psyche101]

Originally Posted by Blue Skies

Aah, that doesn't sound like a telescope, that just sounds like a CCD camera. The camera would then go on a telescope.

Lenses are used in several places in telescopes - in the finderscope, in the eyepieces and in the objective lens if you have a refracting telescope, or in a focal reducer, for example.

Could you rephrase your question to be more specific? Lenses for what purpose where on a telescope?

(sorry, this is a bugbear of mine. The word 'lenses' gets tossed around too casually and can be confusing.)

Hi Blue Skies

Thank you very much for the reply, good question, but yes that component is indeed the camera, I was a little reluctant to say too much untill I had the fellows approval, however, he is happy for me to discuss his plans here, so as follows:

I am actually building my own telescope, so the idea is to use it for that. I will use a two lens setup for the CCD. The problem I have is that I need to make the housing for the CCD and associated analog electronics airtight so I can cool it and have either vacuum or nitrogen there. I have managed to get my hands on some optics grade lenses from our lab that I can use for that, but I still need some additional lenses and any inputs you may have could be very helpful.

The plan is to have the CCD, the ADC (AD9816) and the clocking and an emitter coupler in the CCD housing and outside an FPGA board for real time processing. I am thinking of using the Spartan-6 for that, with additional DDR memory attached and a USB interface for data transfers.

I am currently having an aluminum housing custom built for it right now and the idea is to start with to cool it with Peltier elements that should be able to cool the housing down to -50C. At least I am going to start there, although I am looking into liquid nitrogen as well The idea being to cool it as much as possible to minimize noise (thermal noise). To avoid condensation I will either have to use a vacuum tube or fill it with nitrogen, haven't decided on which yet, but I think that will be a trial and error decision It all has to be done with any fans or the like to avoid vibrations.

I hope this clears things up a little, I will send this fellow a link, no doubt he will wish to ask some questions directly.