Question

At this point, it is natural to wonder if that flat mirror in the middle of the telescope is a problem. After all, it's preventing the telescope from seeing an object directly in the middle of its field of vision, right? Investigate this in the simulation. First, use Blockers (available under tools) to encase your telescope so that rays can only enter from the left and exit the eyepiece. To not forget to surround the eyepiece with blockers as well. Next, remove the Beam, and turn the Ray Density up to 3. Zoom out so that the distance between the ideal curved mirror and the slanted segment mirror is no more than 1/4 of the simulation. Now, put a Point Source directly to the left of the segment mirror and move it to the left. Describe what happens as the point source moves farther and farther to the left. What does this imply about the "blind spot" of this Newtonian telescope? Physically, explain why this happens.

Answer 1

The result will be that there is no blind spot in a Newtonian telescope. At any position of the object, the image will be visible.

This is because the reflecing mirror of the telescope is a concave mirror. There is no one ne to one correspondence to each point in the object and the image.

The light coming from the object falls on all the points in the concave mirror and is reflected to the plane mirror.

So, even of we block the light from one side, the light from other side will fall on the plane mirror, and the image can be seen from any point.

In short there is no blind spot on the Newton's telescope.