define thin lens? how is it made?

Asked by pr_prashant | 27th Nov, 2010, 09:36: AM

Expert Answer:

In optics, a thin lens is a lens with a thickness (distance along the optical axis between the two surfaces of the lens) that is negligible compared to the focal length of the lens. Lenses whose thickness is not negligible are sometimes called thick lenses.

The thin lens approximation ignores optical effects due to the thickness of lenses and simplifies ray tracing calculations. It is often combined with the paraxial approximation in techniques such as ray transfer matrix analysis.

The focal length, f, of a thin lens is given by the Lensmaker's equation: 

where n is the index of refraction of the lens material, and R1 and R2 are the radii of curvature of the two surfaces
 
 
A lens can be considered a thin lens if d << f.

Answered by  | 27th Nov, 2010, 11:51: AM

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