Projection device with an optimized emission point distribution based on an isoline configuration

1 . A method for manufacturing an image projection device for projecting an image onto an eye, the device being defined in an orthogonal reference system (X,Y,Z) and comprising an emission surface S extending generally in the plane (X,Y) of said orthogonal reference system (X,Y,Z), the emission surface S comprising a stack of elements, said elements comprising a set of M x waveguides g p , a set of M x ×M y diffraction gratings r pq and a set of M y electrodes e q , M x and M y being positive integers whose product M x ×M y is strictly greater than 1, each diffraction grating r qp being positioned at the intersection of one of said waveguides g p and one of said electrodes e p so as to form an emission point EP pq for a light wave, said set of M x waveguides g p being arranged in a waveguide configuration, and said set of M y electrodes e q being arranged in an electrode configuration,

the method comprising a phase of designing said device and a phase of physically manufacturing said device thus designed, wherein said design phase comprises a step consisting in determining said waveguide configuration or said electrode configuration, said determined configuration being a non-rectilinear isoline configuration defined in the plane (X,Y) defined by the emission surface S and generating an aperiodic distribution of the M x ×M y emission points EP pq .

2 . The method for manufacturing an image projection device according to claim 1 , wherein the step of determining a configuration consists in determining said waveguide configuration and said electrode configuration, said determined configurations being non-rectilinear isoline configurations defined in the plane (X,Y) defined by the emission surface S and generating an aperiodic distribution of the M x ×M y emission points EP pq .

3 . The method for manufacturing an image projection device according to claim 1 , wherein said design phase comprises the step consisting in determining an initial geometric curve extending on either side of said emission surface S along an axis of extension parallel to the axis X and/or to the axis Y of said orthogonal reference system (X,Y,Z), said initial geometric curve being defined randomly while complying with at least one curve construction characteristic.

4 . The method for manufacturing an image projection device according to claim 3 , wherein said initial geometric curve consists of a succession of segments.

5 . The method for manufacturing an image projection device according to claim 3 , wherein said design phase comprises the step consisting in applying a distance function to said initial geometric curve so as to generate the isoline waveguide configuration and/or the isoline electrode configuration.

6 . The method for manufacturing an image projection device according to claim 5 , wherein said distance function is determined by a fast-marching method.

7 . The method for manufacturing an image projection device according to claim 3 , wherein said initial geometric curve comprises only ordinary points referred to as ‘regular points’ for which the partial derivatives of said curve along X and Y are not simultaneously zero.

8 . The method for manufacturing an image projection device according to claim 3 , wherein said initial geometric curve comprises, at any point of said curve, in the plane (X,Y), a radius of curvature greater than or equal to a predefined minimum radius of curvature.

9 . The method for manufacturing an image projection device according to claim 8 , wherein said minimum radius of curvature is defined on the basis of the physical properties of the waveguides g p and/or of the electrodes e q , and/or of the manufacturing constraints of said waveguides or of said electrodes.

10 . The method for manufacturing an image projection device according to claim 1 , wherein said design phase comprises the step consisting in discretizing said emission surface S into L x ×L y elementary emission zones Z ij in a continuous mesh in the plane (X,Y), each elementary emission zone Z ij comprising a subset of

m

x

i

⁢

j

×

m

y

i

⁢

j

emission points

E

⁢

P

pq

ij

,

said step consisting in determining said waveguide configuration and/or said electrode configuration being applied to each elementary emission zone Z ij so as to form a non-rectilinear isoline waveguide sub-configuration and/or a non-rectilinear isoline electrode sub-configuration.

11 . The method for manufacturing an image projection device according to claim 10 , wherein said non-rectilinear isoline waveguide sub-configuration and/or said non-rectilinear isoline electrode sub-configuration are generated by applying a fast-marching method to an initial geometric curve extending in the plane of the emission surface S on either side of the elementary emission zone Z ij along an axis of extension parallel to the axis X and/or to the axis Y.

12 . An image projection device for projecting an image onto an eye, the device being manufactured based on the method defined according to claim 1 , said device being defined in an orthogonal reference system (X,Y,Z) and comprising an emission surface S extending generally in the plane (X,Y) of said orthogonal reference system (X,Y,Z), the emission surface S comprising a stack of elements, said elements comprising a set of M x waveguides g p , a set of M x ×M y diffraction gratings r pq and a set of M y electrodes e q , the numbers M x and M y being integers strictly greater than 1, each diffraction grating r qp being positioned at the intersection of one of said waveguides g p and one of said electrodes e p so as to form an emission point EP pq for a light wave, said set of M x waveguides g p being arranged in a waveguide configuration, and said set of M y electrodes e q being arranged in an electrode configuration, said waveguide configuration or said electrode configuration being a non-rectilinear isoline configuration defined in the plane (X,Y) defined by the emission surface S and generating an aperiodic distribution of the (M x ×M y ) emission points EP pq .

13 . A transparent portable optical data display system comprising an image projection device according to claim 12 , wherein said system is a glasses system or an augmented reality headset.