# Parabolic Mirror Equation

I was wondering whether the curved surface mirror formula (that is usually used to solve convex or concave spherical mirror problems) remains unaltered in case of parabolic mirrors.What might be invalid is the equation 1/f= 2/R...

After all,the equation 1/v + 1/u= 1/f pertains to convex/concave surfaced mirrors...However, I am not sure of it...Can anyone suggest anything?

Neel

## Answers and Replies

the equation 1/v + 1/u= 1/f pertains to convex/concave surfaced mirrors.
I assume you mean spherical mirrors.
That formula is an approximation - it holds only for rays close to the axis (i.e. not good for very strong lenses/mirrors)
It's equally good for parabolic mirrors with the same proviso.

Thank you very much; yes,the mirror equation is a result of paraxial approximation.Although I forgot, probably there was nothing in the proof of the mirror equation that used the sphericity of the surface. It is good that it can also be used for convex or concave paraboloid mirrors (though concave paraboloid mirrors are in more use)...

Any body know how to align parabolic mirror?