US 11,754,449 B2
System for inspecting surfaces of an optical wave using a graduated density filter
François Henault, Grenoble (FR); and Alain Spang, Vence (FR)
Assigned to CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE, Paris (FR); OBSERVATOIRE DE LA COTE D'AZUR, Nice (FR); UNIVERSITE COTE D'AZUR, Nice (FR); and UNIVERSITE GRENOBLE APLES, Saint-Martin-d'Heres (FR)
Appl. No. 17/310,393
Filed by CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE, Paris (FR); Observatoire De La Cote D'Azur, Nice (FR); UNIVERSITE COTE D'AZUR, Nice (FR); and Université Grenoble Alpes, Saint-Martin-d'Heres (FR)
PCT Filed Jan. 21, 2020, PCT No. PCT/EP2020/051326
§ 371(c)(1), (2) Date Jul. 30, 2021,
PCT Pub. No. WO2020/156867, PCT Pub. Date Aug. 6, 2020.
Claims priority of application No. 1900896 (FR), filed on Jan. 31, 2019.
Prior Publication US 2022/0099497 A1, Mar. 31, 2022
Int. Cl. G01J 9/00 (2006.01); G02B 9/64 (2006.01)
CPC G01J 9/00 (2013.01) [G02B 9/64 (2013.01)] 5 Claims
OG exemplary drawing
 
1. A system for inspecting a surface of an optical wave originating from an optical device, said optical device comprising an exit pupil, said inspection system comprising an optical measuring head and a computer for processing the images from said optical measuring head, wherein:
the optical measuring head comprises:
a density gradient filter, in a plane referenced (x′, y′) perpendicular to the optical axis of the optical measuring head, the transmission T(x′, y′) of said filter being governed by the equation:

OG Complex Work Unit Math
px and py representing the periods of the two sinusoidal functions dependent respectively on (x′−y′) and (x′+y′);
a matrix frame of identical lenses of square shape and of the same focal length, said matrix frame comprising at least four lenses, each center of one of the four lenses being arranged on an axis passing through the center of the exit pupil and a point O′M′(i, j) of the density gradient filter such that, in the plane referenced (x′, y′),

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i and j being able to adopt the values −1 and +1, m and n being positive integers; and
a photodetector array, each of the four lenses forming an image of the pupil in the plane of this array, these images being referenced I″k(x, y), k varying from 1 to 4; and
the image processing computer comprises computing means for computing the partial derivatives

OG Complex Work Unit Math
of the wave surface Δ(x, y) in the plane (x, y) of the exit pupil, these partial derivatives being equal to

OG Complex Work Unit Math
A, B and C being constants dependent on the geometric parameters of the optical measuring head.