[Physics] Light Ray Reflection from concave mirror

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Suppose a ray of light hits a concave mirror and is parallel to the principal axis but far away from it such that it doesn't follow paraxial ray approximation. Will it pass through focus or between focus and radius of curvature or between pole and focus?

Here pole, focus and radius of curvature mean the same thing as in paraxial ray approximation .

Best Answer

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Assuming mirror to be spherical section. C is the center of sphere.

See, Using trigonometry. $$x=d \times \sin(2\theta)$$ $$x=R\times\sin\theta$$

Eliminate $\theta$ and get $d$ : distance from Center of curvature as a function of $x$.

Verify for small theta where $\sin\theta\approx\theta$

If you just want to see that which side ray bents then see. $$d=\dfrac{R\times \sec\theta}2$$ which shows that $d\ge R/2$ . So, ray bends towards the pole as looses it paraxial character.