The rays of my ray diagram are not lining up

[jeremy5561]

Homework Statement

I am given the object distance and height, and the focal length of the mirror and I must draw the ray diagram.
Although this was drawn by a computer program that I programmed, I thought it would be more relevant in this forum, because I believe that the rays are correctly drawn and the program is not at question.

Homework Equations

The image you see on the screen (blue arrow) is calculated using the math equations:
1/f=1/do+1/di
hi/ho=-di/do

The Attempt at a Solution

The ray diagram was drawn following the three rules

1. A ray perpendicular to the principal axis will reflect thorough the focal point.
2. A ray that passes through the focal point will reflect perpendicular to the principal axis.
3. A ray that passes through the centre of curvature will reflect back thorough the centre of curvature.

This ray diagram seems to follow all three rules perfectly, yet the rays do not line up on the object. What did I do wrong?

http://coldwartimeline.tk/raydiagram.bmp

 

[gneill]

You have just discovered the effects of spherical aberration (look it up!).

This is why high quality Newtonian reflecting telescopes, for example, will utilize a parabolic mirror rather than a spherical one.

 

[jeremy5561]

Ahh... thank you.