How Does a Reverse Galilean Telescope Minify Images?

[reverse]

This is not a homework question but I am posting it here because I think it may be too basic for the other forums. I am looking for a ray diagram for a reverse galilean telescope (ie. + eyepiece, - objective, so image is minified). Can anyone describe what the ray diagram would look like or direct me to a textbook or webpage which might have a good explanation/diagram? I know the ray diagram for a regular galilean (- eyepiece, + objective) but can't seem to draw it for the lenses being reversed. THank you!

 

[arcnets]

Hi reverse,
I don't see what's so difficult about this. Can't you just use the same drawing, with light direction reversed?

 

[M98Ranger]

A reverse Galilean telescope is a type of telescope where the eyepiece is placed before the objective lens. This causes the image to be minified, meaning it appears smaller than the original object. In order to understand the ray diagram for this type of telescope, it is important to understand the basic principles of optics and how lenses work.

First, let's start with the objective lens. This is the lens that is closest to the object being observed. Its purpose is to collect and focus light rays from the object. The objective lens is a concave lens, meaning it curves inward and causes light rays to spread out. This is important to keep in mind when drawing the ray diagram.

Next, we have the eyepiece lens. This lens is responsible for magnifying the image formed by the objective lens. It is a convex lens, meaning it curves outward and causes light rays to converge.

To draw the ray diagram for a reverse Galilean telescope, we will use the same principles as we would for a regular Galilean telescope, but in reverse. Here are the steps to follow:

1. Draw a horizontal line to represent the optical axis of the telescope.

2. Place the objective lens on the left side of the optical axis. Draw two parallel rays from the top and bottom of the object, passing through the center of the lens. These rays will be refracted by the concave lens and will spread out.

3. Place the eyepiece lens on the right side of the optical axis. Draw two more parallel rays from the top and bottom of the objective lens, passing through the center of the eyepiece lens. These rays will be refracted by the convex lens and will converge.

4. The two rays from the objective lens will intersect at a point on the right side of the optical axis. This is the virtual image formed by the objective lens.

5. The two rays from the eyepiece lens will also intersect at a point on the right side of the optical axis, but this point will be closer to the eyepiece lens. This is the final image that is viewed through the eyepiece.

Overall, the ray diagram for a reverse Galilean telescope will look similar to a regular Galilean telescope, but with the positions of the lenses and the direction of the light rays reversed. It may take some practice to draw it accurately, but understanding the principles of optics and the properties of lenses will help you to visualize the