Method for measuring several wavefronts incoming from different propagation directions

Patent metadata

Field	Value
Publication number	US-11609124-B2
Application number	US-202117487313-A
Country	US
Kind code	B2
Filing date	Sep 28, 2021
Priority date	Sep 29, 2020
Publication date	Mar 21, 2023
Grant date	Mar 21, 2023

Abstract

A method for determining wavefront shapes of N angular channels CL of different propagation directions PL, said propagation directions PL being determined by a mean propagation direction vector , from a single signal image acquisition I(x,y) of a multi-angular signal light beam containing said angular channels, each angular channel Ci being separated from other angular channels Cj by an angular separation Δαij defined by Δαij=arccos, where “·” stands for the inner product between and .

First claim

The invention claimed is:

1. A method for determining wavefront shapes of N angular channels C L of different propagation directions P L , said propagation directions P L being determined by a mean propagation direction vector , from a single signal image acquisition I(x,y) of a multi-angular signal light beam containing said angular channels, each angular channel Ci being separated from other angular channels Cj by an angular separation Δα ij defined by Δα ij =arccos , where “·” stands for the inner product between and , with a device comprising an optical assembly made at least of an optical mask and an imaging sensor for generating and recording intensity patterns of incident beams, by having these beams reflect on, or propagate through, the optical mask,
the optical mask having the optical properties:
i) to cause the intensity pattern to depend on the wavefront shape, so that a tilt applied to the wavefront shape, with said tilt being smaller than an angular memory effect δα of said optical mask, results in a local displacement amount of the intensity pattern, and
ii) for two incident beams M n , M m of respective propagation directions P n , P m determined by mean propagation direction vectors and , respectively, said incident beams M n , M m having a same wavefront shape and separated from each other by a separation angle defined by Δα mn =arccos larger than the angular memory effect δα, ie Δα mn >δα, to produce uncorrelated intensity patterns over a surface area A of the imaging sensor, two uncorrelated random intensity patterns being defined as statistically orthogonal relatively to a zero-mean cross-correlation product,
the angular memory effect δα being smaller than angular separations Δα ij of angular channels C L :

δα
>

Δ
⁢

α
ij

,

for
⁢

all
⁢

i

,

j
∈

[

1
,
N

]

,

with
⁢

i

≠
j

the method comprising:
a) providing several reference intensity patterns R L (x,y), wherein each reference intensity pattern R L (x,y) corresponds to a respective propagation direction P L , L varying between 1 and N, x and y being coordinates,
b) recording one single signal image I(x,y) of the intensity pattern generated by said multi-angular signal light beam which comprises the N propagation directions P L using the device, the single signal image I(x,y) being representative of light impinging on the at least one surface area (A);
c) computing intensity-weight data W L I (x,y) and deformation data T L I (x,y), for all L varying from 1 to N, the intensity-weight data W L I (x,y) and the deformation data T L I (x,y) being representative of an intensity modulation and a diffeomorphism, respectively, of each given reference intensity pattern R L (x,y), at propagation direction P L for the single signal image I(x,y),

all the N intensity-weight data W L I (x,y) and the N deformation data T L I (x,y) being computed, for L varying from 1 to N, so as to minimize, for all sampling points (x, y) of the surface area A, from the single signal image I(x,y):
a difference D A between the single signal image I(x,y) on the one hand, and the sum of reference intensity patterns R L multiplied by intensity-weight data W L I (x,y) and deformed by deformation data T L I (x,y), on the other hand:
N

D
A

=



I
⁡
(

x
,
y

)

-

∑

L
=
1

N

W
L
I

(

x
,
y

)

⁢

R
L

[

(

x
,
y

)

+

T
L
I

(

x
,
y

)

]



A

the symbol ∥.∥ A designating a norm calculated for all (x, y) sampling points in the surface area A;
for the surface A, each given reference intensity patterns R L (x,y) being orthogonal to each reference intensity pattern R K (x,y) relatively to the zero-mean cross-correlation product, when K natural number different from L and chosen between [1; N];
d) generating data for each propagation direction P L representative of:

 the shape of the wavefront by integrating the deformation data T L I (x,y),
the intensity map based on the weight W L I (x,y).

2. The method according to claim 1 , comprising at step a), recording said reference intensity patterns R L (x,y) using the device, each reference intensity pattern R L (x,y) being generated by a respective reference incident beam L with propagation direction P L , L varying from 1 to N.

3. The method according to claim 1 , the optical mask comprising a diffuser, an engineered pseudo-diffuser, a diffractive element, an optical fiber bundle, a metasurface, a freeform optical element an array of micro-optical elements, each mic

Assignees

• Univ Paris
• Centre Nat Rech Scient
• Inst Nat Sante Rech Med
• Univ Sorbonne

Inventors

• Guillon Marc
• Tessier Gilles
• Wu Tengfei
• Berto Pascal

Classifications

• H04N23/80

  Camera processing pipelines; Components thereof · CPC title

• G01J9/00 Primary

  Measuring optical phase difference (devices or arrangements for controlling the phase of light beams G02F1/01); Determining degree of coherence; Measuring optical wavelength (spectrometry G01J3/00) · CPC title

• G06T7/32

  using correlation-based methods · CPC title

• G02B5/30

  Polarising elements (light-modulating devices with active elements G02F1/00) · CPC title

• G06T7/50

  Depth or shape recovery · CPC title