Patent ID: 8253092
Filing Date: 2012-08-28
Classification: G02B,H01L

Abstract:
1. Apparatus comprising: an optical module for placement in front of a semiconductor optical image sensor, the optical module comprising a transparent optical die having front and rear parallel surfaces and having a rectangular optically useful zone centered on an optical axis of the semiconductor optical image sensor and a central circular zone within the optically useful zone and also centered on the optical axis, the transparent optical die having a substantially constant refractive index in a first region of the transparent optical die located between the optical axis and an outer edge of the central circular zone, and having a continuously variable refractive index corrective of negative distortion at least in a second region of the transparent optical die located between the outer edge of the central circular zone and an extent of the optically useful zone; wherein the variable refractive index, in an annular peripheral zone lying between a radius Ru enveloping the rectangular optically useful zone and a smaller radius Ro defining the central circular zone, lies between a maximum profile Pmax and a minimum profile Pmin; (a) the maximum profile Pmax being such that between the radius Ro and a radius R and then that between this radius R (b) the minimum profile Pmin being such that between the radius Ro and a radius R (c) and in which: