anyone good at physics


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hehe nice call.

I did physics and I have no idea what your on about, what sort of funky ass project would make you draw the light rays in the hubble telescope

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Originally posted by StimpyX

Here's a physics question: Cheerios, or Cap'n Crunch?

Or in other words: What???

Cap'n Crunch :D Crunch Berries to be exact.

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This is more astronomy than physics, anyhow... ;)

There are a couple of (expensive, heh...) software packages for designing telescopes. OSLO and ZEMAX are two (professional) ones which uses raytracing algoritms to make up the way the light beams refracts or reflects (as in the case of the Cassegrain focus) on the different surfaces. If you can get hold of either one your on your way... ;)

Anyway a Cassegrain focus is just an array of a parabolic primary mirror (ie the one that is first hit by light - the real diameter of the telescope) and a hyperbolic secondary mirror which reflects the light from the primary either out through a hole in the middle of the primary or to a "neutral" tertiary mirror which reflects the light out of the side of the telescope (mostly always on larger earthbased telescopes). Out to a detector of some kind that is, whether that consists of a CCD camera or a spectrograph or something else. Er...well hope you'll get some info from that :)

Don't have a scanner otherwise I could have scanned a few pictures and mailed them to you, sorry. Although there are litterary tons of material to be found on the internet as it's one of the primary sources for astronomy data distribuition nowadays.

Check out www.eso.org for some telescope data (including the manual for using the thing! ;)

Edit: Ah, heh..guess the url in the post above is useful as well, didn't see that one :p

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my head hurts, i can't get around what you said bluemusic :alien:, i saw some stuff on nasa's website, try searching there, can't remember the link sorry

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I'll try again...

Cassegrain focus means there are two "main" mirrors. The first one, the primary, has the shape of a parabola. This mirror is the primary light "collector" and is the large one in the array. It reflects the light onto a secondary much smaller mirror which has the shape of a hyperbola (just turn your sattelite dish around and let it reflect/collect on the outside and you get the idea). The secondary sits just in front of the primary (it's small remeber?) and reflects the light to some detector. This could be done either by drilling a hole in the center of the primary letting the light out that way. Though a much better way (on earthbased telescopes) is to have a "straight" tertiary mirror (ie no magnification) reflect the light out through a hole in the side of the telescope since a good spectrograph or a nitrogen cooled CCD are more than a few kilos and can get quite large.

Just to add: of course this is not technically astronomy, it's optics. It's just that one would hardly ever use a Cassegrain focus outside of a telescope :)

A picture says more than a thousand words. Guess I'm proof of that. :p

Go find a nice picture of a Cassegrain focus and you're much better off than with my longwinding explanation. Check out adaptive optics while you're at it. That's where the really cool things begin...being the nerd I am :p

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hehehe, taking Physics 20 and i'm stumped lol... anyways i am just learning the concepts of physics and newtons law's, meh, what can you do..and i'm just in gr.10, mwhahahah

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