All Questions
24
questions
0
votes
1
answer
84
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Keplerian telescope with parabolic mirrors
Is it possible to arrange two off axis parabolic mirrors (OPAs) to transform the emitted rays of a point source into a collimated beam, as in the figure below?
That is, similar to a Keplerian ...
- 117
0
votes
1
answer
299
views
Focal Length of a Rotating Liquid Mirror [closed]
I saw this video on YouTube about using rotating liquid metal as parabolic mirrors to make reflecting telescopes.
In the video apart from the standard equation of the curve the liquid makes, the focal ...
- 11
1
vote
1
answer
359
views
Optics proof: Beam expander telescope
Beam expanders are afocal optical devices that widen/narrow the diameter of an incoming laser beam $D' = D / M$.
Telescopes are afocal optical devices that multiply angle of incidence of each light-...
- 181
0
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0
answers
64
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Is a tilted, no lens telescope, can work?
I got a crazy idea to build a no-lense telescope with an optical zoom of 100,000. Please tell me where it will fail :)
Go into a dark room
Make a 0.1-millimeter hole in the ceiling
Take a 10-meter ...
- 2,127
1
vote
1
answer
377
views
Why are the lenses of a Keplerian Telescope positioned the sum of their focal points apart?
I am currently designing an extremely simple Keplerian telescope and am confused as to why many explanations say that the objective lens and eyepiece lens are positioned a distance of the sum of their ...
- 41
0
votes
1
answer
284
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Ray Diagrams: Where is the eyepiece located in a reflector telescope?
I'm in the process of building my own reflector telescope; I have an 8" primary mirror with a focal length of 1200mm.
Of course a telescope has a focuser that lets the eyepiece move up and down ...
1
vote
2
answers
836
views
Limits of zooming in (for camera/telescope)
What limits the ability of a camera/telescope to zoom in on distant objects?
The question is twofold:
What zoom really is?
Firstly, I would like to gain clear understanding of what we mean by zoom ...
- 60.3k
1
vote
1
answer
213
views
Why are the magnifying powers of microscopes & telescopes defined in terms of ratio of angles & not in terms of ratio of sizes of objects & images?
The magnifying power of microscopes and telescopes is defined as follows:
$$m=\frac{\color{red}{\text{Angle}} \text{ subtended by the final image on the eye}}{\color{red}{\text{Angle}} \text{ ...
- 5,306
1
vote
1
answer
3k
views
How does a diverging lens in a Galilean telescope form an image at infinity when its object is at its focal plane?
This is a follow up question to Farcher's answer for the question - How does a Galilean telescope form an enlarged image even though it has a diverging lens?.
Let us consider the following ray ...
- 5,306
5
votes
1
answer
3k
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Can we use a telescope as a microscope and vice versa? [duplicate]
I got this question after I leant about microscopes and telescopes from my textbook. In a simplified compound microscope, the objective has a smaller aperture and a smaller focal length compared to ...
- 5,306
2
votes
1
answer
551
views
What is prime focus of a telescope
Telescope here refers to a system of two convex lenses. In one of the problems I wanted to solve, it is given that "a Barlow lens of focal length $f_{b}$ is placed at a distance $D < f_{b}$, from ...
user183683
0
votes
1
answer
152
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How can I make a Telescope with the lenses I have
List of lenses I have
Convex - 200mm F.L - 50mm Dia
Convex - 50mm F.L - 50mm Dia
Convex - 40mm F.L - 40mm Dia
Convex - 45mm F.L - 25mm Dia
Concave - 200mm F.L - 50mm Di
I tried to make a ...
- 101
1
vote
0
answers
489
views
Problems with using Compound microscope and telescope in the place of each other [duplicate]
Compound microscope is used to see magnified image of tiny objects. Whereas telescope is used to see distant objects' magnified image. I wonder can we use telescope to see small objects placed close ...
- 571
0
votes
2
answers
1k
views
A confusion about the use of telescope
Suppose we are measuring wavelength of a light with the help of spectrometer and a grating. Spectrometer consists of three main parts: Collimator, Turntable, Telescope. Grating is placed on turn table....
- 571
3
votes
4
answers
7k
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How does a Galilean telescope form an enlarged image even though it has a diverging lens?
I have been reading about Galilean telescope and the picture in the book is something like this:
After rays pass through the converging lens, there is a real image formed which is intercepted by the ...
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