VIRTUAL REALITY OR AUGMENTED REALITY VISION SYSTEM WITH EYE IMAGE SENSOR

Description

Technical field

[0001] Virtual reality refers to a technology that places a user in an artificially generated environment in which the user can interact using software.

[0002] Augmented reality refers to a technology that superimposes reality and software-generated display elements.

[0003] The invention relates to the field of vision systems in virtual reality or augmented reality. State of the prior art

[0004] A virtual or augmented reality vision system is known in the prior art, as described in patent application FR3086399. In such a system, an image is generated at a matrix of light-emitting elements and projected towards the user's eye via an optical projection system. The system further comprises a matrix of photodetectors, with the matrix of light-emitting elements and the matrix of photodetectors at least partially interlaced together. An image of the eye, in particular an image of the retina, can thus be easily acquired.

[0005] US10698204 discloses a head-mounted display system having LED light sources that emit red, green, blue, and infrared light, a plurality of pivoting DMD image source mirrors that reflect light toward a user's eye. The light reflected from the eye is reflected toward a camera by a semi-reflective plate.

[0006] Patent application US10698204 discloses a head-mounted display system, a light source that emits infrared light, a solid substrate having a plurality of stationary, curved mirrors, which reflect the infrared light emitted by the source toward a user's eye, and collect the light reflected by this eye to reflect it toward a camera. This substrate is positioned in front of display electronics.

[0007] One idea behind the invention is to improve such a system. STATEMENT OF THE INVENTION

[0008] This objective is achieved with a virtual reality or augmented reality vision system according to the claims.

[0009] By "substantially parallel to the axis of interest" is meant "inclined at an angle less than or equal to 10° relative to the axis of interest".

[0010] In use, the axis of interest is advantageously coincident with the line of sight of a user's eye looking straight ahead. Alternatively, a light-deflecting element such as a planar waveguide makes it possible to deflect light propagating parallel to the axis of interest, to align it with the line of sight (and vice versa).

[0011] Each micro-mirror of the micro-mirror array is therefore configured to, in its first position, receive light from the first emission module and deflect at least part of this light towards the eye (directly or via a light-deflecting element as mentioned above). Similarly, each micro-mirror of the micro-mirror array is configured to, in its second position, receive light from the second emission module and deflect at least part of this light towards the eye, and receive light returned by the eye and deflect this light towards the photo-detection module (directly or via a light-deflecting element as mentioned above).

[0012] The first and second positions of each micro-mirror are each distinguished from a rest position, taken by the micro-mirror in the absence of any external stress, in particular by an electrical signal.

[0013] The first emission module, with the micro-mirror array, generates pixelated images to be projected toward the user's eye. The second emission module illuminates the eye sufficiently to acquire a good image of the eye, and at a wavelength that does not bother the user. The photo-detection module acquires an image of the eye. The micro-mirror array participates in the formation of pixelated images. It also deflects the infrared light emitted by the second emission module toward the eye, and deflects the infrared light returned by the eye toward the photo-detection module.

[0014] As in the first prior art document described in the introduction, the invention makes it possible both to project a virtual image generated using an emissive type device towards the eye, and to acquire an image of the eye. The invention, however, differs from this prior art in that the virtual image projected towards the eye is formed using a matrix of micro-mirrors. One of the ideas underlying the invention consists of using a matrix of micro-mirrors in which each micro-mirror can take two positions distinct from a rest position, and to exploit each of these two positions. Thus, each micro-mirror of the matrix of micro-mirrors can alternate between a position in which it sends visible light towards the eye, for the projection towards the eye of a virtual image, and a position in which it sends infrared light towards the eye and then deflects the infrared light returned by the eye towards a photo-detection module.It is thus possible to use only commercially available components, whereas the prior art described in the introduction involved developing a specific device with photo-detectors and light-emitting diodes interlaced together.

[0015] It may be noted that it was not at all obvious, for the person skilled in the art, to have the idea of ​​exploiting the two positions of the micro-mirrors. Conventionally, a matrix of micro-mirrors is used to generate a pixelated image, with for each micro-mirror a so-called lighting position which corresponds to a lit pixel on the image, and a so-called extinction position which corresponds to a lit pixel on the image. In the lighting position, the micro-mirror deflects the light towards the eye. In the extinction position, the micro-mirror deflects the light in a non-useful direction, where a light absorber may be located. The most obvious solution, to add an image acquisition function, consists of adding one or more photodiodes in front of the eye, between the micro-mirrors. The second emission module, for infrared illumination, can also be positioned in front of the eye.Alternatively, the second emission module can be positioned close to the first emission module. In the illumination position, a micro-mirror then deflects visible light or infrared light towards the eye, depending on whether the first or second emission device is switched on. To avoid dazzling the photodiodes, it is understood that it is important to position the latter "in the shade", that is to say in locations where they cannot receive the light coming directly from the second emission module. In a simple case, the system comprises a matrix of photodiodes, and the eye is illuminated in the infrared uniformly, with all the micro-mirrors in the illumination position. It is then sufficient for the photodiodes to be in the shade when all the micro-mirrors are in the illumination position. In a particular case, the system comprises a single photodiode, of large extent.In this case, an image of the eye can be recomposed by illuminating it with structured lighting. This structured lighting is defined using the micro-mirror matrix in which a part of the micro-mirrors is in the illumination position and a part of the micro-mirrors is in the extinction position. In this case, each region of the single photodiode must be in the shade, for the two possible positions of each of the micro-mirrors. A trick to place the photodiodes (or the regions of the single photodiode) in the shade, is to position them at the bottom of a narrow hole dug in a substrate, with the walls of the hole absorbing infrared light.

[0016] Another obvious solution for adding an image acquisition function to a virtual or augmented reality vision optical system based on the use of a micro-mirror array is to place the infrared source and the photo-detection module in alignment with the first emission module. However, this requires the use of dichroic mirrors, which cause significant optical losses, in order to emit the infrared light in alignment with the visible light and to direct the reflected infrared light towards the photo-detection module.

[0017] Preferably, for each of the micro-mirrors of the micro-mirror array, the first position and the second position are symmetrical to each other relative to an elementary plane of symmetry, with the elementary planes of symmetry associated with each of the micro-mirrors all being parallel to each other.

[0018] Advantageously, the system according to the invention further comprises an optical projection system, located downstream of the micro-mirror matrix in a direction of propagation of the visible light beam in the virtual reality or augmented reality vision system, and capable of achieving optical conjugation between the micro-mirror matrix and a predetermined focusing surface.

[0019] The projection optical system is preferably a variable focal length optical system, connected to a first control device for controlling the focal length of said projection optical system.

[0020] Preferably, the system according to the invention further comprises an optical adjustment system, arranged between the micro-mirror matrix and the photo-detection module, and configured to participate in an optical conjugation between a surface intended to receive the eye of a user and a detection surface of the photo-detection module.

[0021] Preferably, a depth of field of the optical adjustment system is adapted to allow the formation, on the detection surface of the photo-detection module, of a clear image of a surface passing into use by the user's eye, for any value of the focal length of the optical projection system belonging to a determined interval of focal lengths, with said interval of focal lengths having an extent of between three millimeters and five centimeters.

[0022] An optical axis of the photodetection device and the second emission axis may be substantially parallel, to within plus or minus 10°.

[0023] The system according to the invention may comprise at least one partially reflecting mirror, configured to deflect an optical axis of the photo-detection device or the second emission axis, so as to superimpose the latter together.

[0024] The system according to the invention may further comprise a computer, configured to receive as input at least one infrared image acquired by the photo-detection module, and to implement processing of this at least one infrared image so as to deduce therefrom one or more parameter(s) relating to the user.

[0025] Advantageously, the first light emission module is capable of emitting a beam of visible light, with a spectrum centered alternately on a first, a second and a third wavelength.

[0026] The first light emission module may comprise at least three elementary sources, respectively adapted to emit a red, blue and green light beam.

[0027] The invention also covers a first method of using a system according to the invention in which the first light emission module is capable of emitting a beam of visible light, with a spectrum centered alternately on a first, a second and a third wavelength. This method comprises the following steps: a) driving the first emission module, for the emission of a beam of visible light with a spectrum centered on the first wavelength, and driving the mirrors of the micro-mirror matrix so as to form a first component of a color image; b) driving the first emission module, for the emission of a beam of visible light with a spectrum centered on the second wavelength, and driving the mirrors of the micro-mirror matrix so as to form a second component of the color image; c) driving the first emission module, for the emission of a beam of visible light with a spectrum centered on the third wavelength, and driving the mirrors of the micro-mirror matrix so as to form a third component of the color image;and d) driving the first light emission module to stop the emission of the visible light beam, driving the second emission module to emit an infrared light beam, driving the micro-mirror array so that at least one of the micro-mirrors is in the second position, and acquisition by the photo-detection module of an infrared image of a region of an eye of the user.;

[0028] Advantageously, in step d), all the micro-mirrors of the micro-mirror array are positioned in their second position.

[0029] Alternatively, the photodetection module comprises a single photodiode, and in step d), only some of the micromirrors of the micromirror array are positioned in their second position.

[0030] The invention finally covers a second method of using a system according to the invention in which the first light emission module is capable of emitting a beam of visible light, with a spectrum centered alternately on a first, a second and a third wavelength. This method comprises the following steps: a) driving the first emission module, for the emission of a beam of visible light with a spectrum centered on the first wavelength, and driving the mirrors of the micro-mirror matrix so as to form a first component of a color image; b) driving the first emission module, for the emission of a beam of visible light with a spectrum centered on the second wavelength, and driving the mirrors of the micro-mirror matrix so as to form a second component of the color image; and c) driving the first emission module, for the emission of a beam of visible light with a spectrum centered on the third wavelength, and driving the mirrors of the micro-mirror matrix so as to form a third component of the color image; where, during at least the entire duration of steps a) to c), the second emission module emits light and the photo-detection module receives light and integrates a signal. Brief description of the figures

[0031] The present invention will be better understood by reading the description of exemplary embodiments given purely for informational purposes and in no way limiting, with reference to the appended drawings in which: there figure 1 schematically illustrates a view in use of a system according to a first embodiment of the invention; the Figures 2A to 2C schematically illustrate a second embodiment of the system according to the invention, in a sectional view; the Figures 3A and 3B schematically illustrate a micro-mirror array in a system according to the invention, respectively in a top view and in a sectional view; Figures 4A and 4B schematically illustrate the micro-mirror matrix of the Figures 3A and 3B , in two respective configurations of the latter; the Figure 5 schematically illustrates a third embodiment of the system according to the invention, in a sectional view; the Figures 6A and 6B schematically illustrate two variants of a fourth embodiment of the system according to the invention, in a sectional view; Figures 7A to 7D schematically illustrate different variants of the embodiment of the Figure 2A . Description of the embodiments

[0032] For clarity, the figures show the axes (Ox), (Oy) and / or (Oz) of an orthonormal reference frame.

[0033] To facilitate understanding of the invention, certain figures show an eye 10 of a user, as it is positioned relative to the system according to the invention, in use. The eye does not belong to the system according to the invention.

[0034] There figure 1schematically illustrates a view in use of a virtual reality vision system according to the invention. The system is not visible, because it is housed inside a support 110 intended to be mounted on the head of a user. In the example of the figure 1 , this support 110 takes the form of a mask. In use, the mask 110 is held against the user's face, covering his eyes, using a strap 120 mounted integral with the mask 110 and passing behind the user's head. Alternatively, the system according to the invention can be integrated into a support of the glasses, helmet, or any other type of support intended to be mounted on a user's head.

[0035] There Figure 2A schematically illustrates, and in a sectional view in a plane (yOz), a system 200 according to a second embodiment of the invention.

[0036] The 200 system includes: a first emission module, 230, capable of emitting light at wavelengths belonging to the visible spectrum; a second emission module, 240, capable of emitting light at wavelengths belonging to the infrared spectrum; a photo-detection module 250, sensitive in the infrared, to wavelengths belonging to the spectrum of the light emitted by the second emission module 240; and a matrix of micro-mirrors 260.

[0037] The first emission module 230 is configured to emit at least one collimated light beam, along a first emission axis 231. Here, it comprises a plurality of elementary sources, not shown, each adapted to emit a monochromatic beam centered on a different wavelength value. Each elementary source may be constituted by a respective light-emitting diode. The first emission module 230 advantageously comprises three elementary sources, adapted to emit respectively in the red, blue and green, in order to form the three components of a color image visible to the user. The visible spectrum designates a wavelength range from 400 nm to 700 nm. An emission in the blue designates an emission of light with a wavelength spectrum which has a single peak in the visible, centered on a length belonging to the wavelength range from 400 nm to 480 nm.Similarly, green emission is associated with the wavelength range 500 nm to 560 nm. Similarly, red emission is associated with the wavelength range 600 nm to 700 nm.

[0038] The second emission module 240 is configured to emit at least one collimated light beam, along a second emission axis 241. It preferably comprises a single light source, in particular a light-emitting diode, not shown. The second emission module 240 is intended to emit light at wavelengths located outside the visible spectrum, to illuminate the eye without disturbing the user. In practice, these wavelengths extend into the infrared, preferably into the near infrared. The infrared spectrum designates a range of wavelengths from 700 nm to 50 µm. The near infrared designates a range of wavelengths from 700 nm to 3 µm. The second emission module may comprise a frequency filter, to block wavelengths emitted by the light-emitting diode and belonging to the visible spectrum.The frequency filter can be mounted removable, so that it can be removed, for example, during a preliminary system adjustment phase.

[0039] The photo-detection module 250 comprises at least one photo-detector sensitive in the infrared, for example of the photodiode type. The at least one photo-detector is sensitive, more particularly, to wavelengths belonging to the emission spectrum of the second emission module 240. The at least one photo-detector may consist of a single photo-detector, of large extent. More preferably, it may consist of a matrix of photo-detectors arranged for example in rows and columns. The photo-detection module has an optical axis 251, which extends orthogonal to the plane of the single photo-detector, respectively orthogonal to the plane of the matrix of photo-detectors.

[0040] The 260 micromirror array is illustrated in more detail in Figures 3A and 3B . There Figure 3Aschematically represents the micro-mirror matrix 260, according to a top view in a plane (xOy). The Figure 3B is a sectional view of the micro-mirror array 260, in a plane (yOz). The micro-mirror array 260 comprises a plurality of micro-mirrors 261, arranged for example in rows and columns.

[0041] Each micro-mirror 261 is mounted on a rotating movable support, not shown, and each of said movable supports can be controlled individually. In the absence of any external stress on the movable supports, the micro-mirrors are in a so-called rest position, and all extend in the same rest plane 265, for example parallel to the plane (xOy). Here, to simplify the figures, each micro-mirror 261 is mounted movable in rotation about an axis parallel to the axis (Ox). The invention is however not limited to this particular case, and covers in particular embodiments in which the axis of rotation of the micro-mirrors is not parallel to the plane of their rest position.

[0042] Each micro-mirror 261 can take two positions. The first position here corresponds to a rotation of an angle R1 around its axis of rotation (here an axis parallel to the axis (Ox)), from the rest position (and in the clockwise direction). The second position corresponds to a rotation of an angle R2 around its axis of rotation (here an axis parallel to the axis (Ox)), from the rest position (and in the clockwise direction). In the example shown, the axis of rotation of a micro-mirror 261 passes through the center of the latter. Alternatively, the axis of rotation of a micro-mirror 261 can be offset under the latter.

[0043] Thus the first and second positions are distinct from each other.

[0044] To the Figure 3B, three micro-mirrors 261 take the first position, and one micro-mirror 261 takes the second position. In any event, the micro-mirrors 261 of the micro-mirror array are all parallel to each other when they are all in their first position, respectively when they are all in their second position. Here, but in a non-limiting manner, the two positions of each micro-mirror 261 are symmetrical to each other relative to an elementary plane of symmetry 262 associated with said micro-mirror 261. In other words, the (oriented) angle R1 takes a value +α while the (oriented) angle R2 takes a value -α. For each micro-mirror 261, the corresponding elementary plane of symmetry 262 is orthogonal to the rest plane 265. The elementary planes of symmetry 262 associated with each of the micro-mirrors 261 of the micro-mirror matrix are all parallel to each other, and parallel to the same median plane 264 passing through the center of the micro-mirror matrix 260.Here, the median plane 264 and the elementary symmetry planes 262 are parallel to the plane (xOz). The median plane 264 designates a plane passing through the center of the micro-mirror matrix 260, and orthogonal to the rest plane 265.

[0045] On the Figure 3A , a micro-mirror array with 16 micro-mirrors has been shown. In practice, the micro-mirror array 260 generally comprises more than ten thousand micro-mirrors, for example 2 million. Each micro-mirror 261 has a diameter of the order of a few microns, for example between 3 µm and 10 µm, and may have any shape (preferably optimized to maximize the cumulative surface area occupied by the micro-mirrors in the micro-mirror array).

[0046] For readability reasons, the Figures 2A to 2C show only one micro-mirror 261 of the micro-mirror array 260. At the Figure 2A, this micro-mirror 261 is represented in the so-called rest position, in a plane parallel to the plane (xOy).

[0047] The median plane 264 defines two half-spaces 264A and 264B. In the example shown here, the first emission module 230 extends into the first of these two half-spaces, 264A, while the second emission module 250 and the photo-detection module 240 extend into the second of these two half-spaces, 264B.

[0048] The first emission axis 231, associated with the first emission module 230, extends in the first half-space 264A. The first emission axis 231 is inclined at an angle β relative to the median plane 264.

[0049] The optical axis 251 of the photo-detection module 250 extends in the second half-space 264B. The optical axis 251 is inclined at an angle γ relative to the median plane 264.

[0050] Here, due to the symmetry of the first and second positions of each of the micro-mirrors, the angles β and γ verify: β = − γ

[0051] In other words, the optical axis 251 of the photodetection module and the first emission axis 231 are symmetrical to each other relative to the median plane 264.

[0052] The second emission axis 241, associated with the second emission module 240, extends in the second half-space 264B. The second emission axis 241 is inclined at an angle θ relative to the median plane 264.

[0053] Here, but in a non-limiting manner, the angles θ and γ verify: θ = γ

[0054] There Figure 2Billustrates the system 200, for the first position of the micro-mirror 261. In this first position, the micro-mirror 261 is rotated here by an angle R1=α around its axis of rotation, from its rest position. For example, we have α=17°, or α=15°, or α=12°. In this first position, the micro-mirror 261 receives the light emitted by the first emission module 230, and reflects this light to cause it to propagate along an axis parallel to the axis of interest 201. The axis of interest 201 here extends parallel to the axis (Oz). In use, the axis of interest 201 coincides with the line of sight of the eye when the user looks straight ahead. In variants not shown, the axis of interest is not confused with the line of sight of the eye, and a light offset element such as a planar waveguide makes it possible to bring along the line of sight the light propagating along the axis of interest, and vice versa.

[0055] By construction, the angles α and β verify: β = 2 ∗ α

[0056] There Figure 2C illustrates the system 200, for the second position of the micro-mirror 261. In this second position, the micro-mirror 261 is rotated by an angle R2 around its axis of rotation, from its rest position. Here we have R2=-α. In this second position, the micro-mirror 261 receives the infrared light emitted by the second emission module 240, and reflects this infrared light to cause it to propagate parallel to the axis of interest 201. In this second position, the micro-mirror 261 does not return towards the user's eye, along the axis 201, the light emitted by the first emission module 230. γ = 2 ∗ α

[0057] At least part of the infrared light incident on the eye 10 is reflected on a surface belonging to the eye, for example the retina. This light is returned to the micro-mirror 261, on which it is reflected in the direction of the photo-detection module 250. The infrared light reflected in the direction of the photo-detection module 250 thus arrives at the photo-detection module, allowing the latter to acquire an image of a region of the eye 10, for example an image of at least part of the retina. The infrared light returned by the eye propagates parallel to the axis of interest 201. It is therefore reflected, on the micro-mirror 261, in a direction separated by an angle equal to 2*α relative to this axis. Thus, the infrared light returned by the eye and reflected on the micro-mirror 261 propagates parallel to the optical axis 251 of the photo-detection module 250.

[0058] An ideal situation has been described here, with perfect alignments. In practice, it is possible to tolerate angle deviations of a few degrees in equations (1) and (2). An angular deviation between the first emission axis 231, and the symmetrical of the optical axis 251 of the photo-detection module relative to the median plane 264, is preferably less than or equal to 10°, or even 5°, or even 2° in absolute value. Similarly, an angular deviation between the optical axis 251 of the photo-detection module and the second emission axis 241 is preferably less than or equal to 10°, or even 5°, or even 2° in absolute value.

[0059] A simplified situation has been described here, with symmetry between the two positions of the micro-mirrors. Those skilled in the art will easily be able to adapt the above teaching to the case in which these two positions are not symmetrical to each other.

[0060] A simple case has been described here, in which the first emission module on the one hand, and the second emission module and the photo-detection module on the other hand, extend on either side of the median plane 264. As a variant, one or other of these elements can be offset, but the conditions mentioned in equations (1) and (2) can be retained using at least one offset optical fiber.

[0061] To Figures 2A to 2C , only one micromirror 261 of the micromirror array 260 was shown. The Figures 4A and 4B show the 260 micromirror array, in two distinct configurations thereof, in operation.

[0062] In operation, each of the micromirrors 261 of the micromirror array assumes one or the other of the two positions illustrated in Figures 2B and 2C .

[0063] To the Figure 4A, the first emission module sends light towards the micro-mirror array 260. Each of the micro-mirrors 261 takes the first position, illustrated in Figure 2B , or the second position, illustrated in the Figure 2C. At the micro-mirrors 261 taking the first position, the light coming from the first emission module is deflected along an axis parallel to the axis of interest (toward the eye). At the micro-mirrors 261 taking the second position, the light coming from the first emission module is deflected in a direction significantly away from the axis of interest (see radius 433). The positioning of the micro-mirrors 261, each in one or the other of the first and second positions, defines a pixelated image. A micro-mirror 261 in the first position defines an illuminated pixel of this image, while a micro-mirror 261 in the second position defines an unlit pixel of this image (in the color emitted at that time by the first emission module). An absorber (not shown) may be placed to absorb the light coming from the first emission module and deflected by the micro-mirrors when they take the second position.

[0064] To the Figure 4B, the second emission module sends light towards the micro-mirror array 260. At least one of the micro-mirrors 261 takes the second position. At the micro-mirrors 261 taking the second position, the light coming from the second emission module is deflected along an axis parallel to the axis of interest (towards the eye), and the light coming from the eye (propagating substantially parallel to the axis of interest) is deflected towards the photo-detection module. At any micro-mirrors 261 which would take the first position, the light coming from the second emission module is deflected in a direction well away from the axis of interest, where an absorber (not shown) may be located. At the Figure 4B, all the micro-mirrors 261 of the micro-mirror array take the second position, which corresponds to uniform illumination in the infrared. In a variant not shown, some of the micro-mirrors 261 take the first position and others the second position.

[0065] There Figure 5 schematically illustrates a third embodiment of system 500 according to the invention, in a sectional view. The system 500 of the Figure 5 will only be described for its differences relative to the system of Figures 2A to 2C .

[0066] The system 500 comprises an optical projection system 590, consisting of one or more lenses. In use, the optical projection system 590 extends between the eye 10 and the micro-mirror array 560. In other words, the optical projection system 590 extends downstream of the micro-mirror array 560, in the direction of propagation of the light coming from the first emission module 530 when the micro-mirrors are in their first position. Advantageously, the vergence of the optical projection system 590 is approximately 20 δ. The optical projection system 590 is capable of performing optical conjugation between a focusing surface 591, located in use at a distance from the eye, and the micro-mirror array 560.

[0067] In use, and when the eye 10 is at rest (not accommodating), the focusing surface 591 is optically conjugated with a surface passing through the retina of the eye 10, in particular a surface passing through the fovea. In other words, the eye 10 at rest sees objects located on the focusing surface 591 clearly. The optical conjugation between the focusing surface 591 and the surface passing through the retina is achieved by an optical system formed by the elements of the eye between the retina and the cornea, and where appropriate a vision correction optic such as a contact lens. For an emmetropic eye, the focusing surface 591 extends to infinity. In any event, the focusing surface 591 extends on the side of the micro-mirror array 560 opposite the projection optical system 590, generally several meters from the latter along the axis (Oz).

[0068] By means of the optical projection system 590, the focusing surface 591 is optically conjugated with the micro-mirror matrix 560. The optical projection system 590 thus participates in the optical conjugation between a surface passing through the retina of the eye and the micro-mirror matrix 560. Thus, the image formed at the micro-mirror matrix, by the tilting of each micro-mirror into the first or second position, is seen clearly by the user. In other words, the optical projection system 590 participates in the projection, onto the user's eye, of an image formed at the micro-mirror matrix 560. On the Figure 5 , thick line arrows symbolize the optical conjugation between a surface passing through the retina of the eye and the focusing surface 591, and the optical conjugation between the focusing surface 591 and the micro-mirror array 560.

[0069] The projection optical system 590 is advantageously a variable focal length optical system, so that it can be adjusted to the user's eye. The focal length adjustment can be manual, based on the user's feeling, who is looking for the focal length for which he sees the sharpest possible image. Alternatively, the focal length adjustment can be automatic. The automatic adjustment is based on an image obtained with the photo-detection module 550, to obtain the sharpest possible projected image.

[0070] There Figure 6A illustrates a system 600 according to a fourth embodiment of the invention, which will only be described for its differences relative to the embodiment of the Figure 5 . The system 600 is distinguished from the embodiment of the Figure 5in that it further comprises an optical adjustment system 695, which extends between the micro-mirror matrix 660 and the photo-detection module. The optical adjustment system 695 consists of one or more lenses. It is configured to be able to participate, together with the projection optical system 690, the optical system formed by the elements of the eye between the retina and the cornea, and where appropriate a vision correction optic such as a contact lens, and via the micro-mirror matrix 660, in the optical conjugation between a surface passing through the retina of the eye and a detection surface of the photo-detection module 650. The optical adjustment system 695 can advantageously be a variable focal length optical system.

[0071] As in the previous embodiment, the projection system 690 is here a variable focal length optical system, manually adjustable to project an image towards the user's eye that will be seen clearly by the latter. The optical adjustment system 695 is adjusted to obtain a clear image of the retina of the eye, which can be achieved with an autofocus system controlling one or more lenses of the optical adjustment system 695, without affecting the adjustment of the projection system 690.

[0072] A surface passing through the retina of the eye 10 is optically conjugated with the focusing surface 691. Thanks to the projection optical system 690, the focusing surface 691 is optically conjugated with the micro-mirror array 660. Consequently, when said surface passing through the eye designates a surface passing through the retina, the optical adjustment system 695 is configured to carry out the optical conjugation between the micro-mirror array 660 and the detection surface of the photo-detection module 650. The detection surface of the photo-detection module designates a surface orthogonal to the optical axis 651 of the latter, along which the at least one photo-detector of the photo-detection module extends.Here again, thick line arrows symbolize the optical conjugation between a surface passing through the retina of the eye and the focusing surface 691, and the optical conjugation between the surface passing through the retina of the eye and the detection surface of the photo-detection module.

[0073] As in the previous embodiment, the focusing surface 691 is optically conjugated with the micro-mirror array 660, so that the images formed using the first emission module and the micro-mirror array are seen sharply by the user. In addition, a surface passing through the retina of the eye is optically conjugated with the detection surface of the photo-detection module 650. Thus, the photo-detection module 650 can acquire a sharp image of the retina of the eye, without changing the settings of the system 600 when switching from a configuration for acquiring an image of the retina to a configuration for projecting an image toward the user's eye (and vice versa).

[0074] There Figure 6Billustrates a system 600' according to a variant of this fourth embodiment of the invention. This variant makes it possible to replace the manual adjustment of the projection optical system 690 with an automatic adjustment. This is particularly useful when changing users, requiring an adjustment of the focal length of the projection optical system 690 for example because the eye of the second user is not morphologically located exactly in the same place relative to the vision system.Automatic adjustment is also of great interest for redoing the adjustment, during use by a given user, for example because the vision system has moved or because the focal length of the optical system formed by the elements of the eye between the retina and the cornea changes slightly when the user's eye rotates (because the eye is not perfectly spherical or the user forces accommodation which causes a situation of optical discomfort).

[0075] In the variant of the Figure 6B, the adjustment optics 695, once initially adjusted, is designed to obtain a clear image of the user's retina even if the focal length of the projection system 690 is modified by a reasonable length, less than five centimeters (for example over a few millimeters or two centimeters, or even five centimeters). For this, the adjustment optics 695 has a large depth of field. In this way, the optical conjugation between the surface passing through the retina of the eye and the detection surface of the photo-detection module 650 is maintained, even in the event of a slight modification of the focal length of the projection system 690. Thus, when the image is clear for the user, the image of the retina obtained on the photo-detection module 650 is also clear, and vice versa.

[0076] In the variant of the Figure 6B, the projection optical system 690 is a variable focal length optical system, connected to a first control device 693. The variable focal length optical system may be a liquid lens, the curvature of which may be modified by applying an electrical voltage. Alternatively, the variable focal length optical system may consist of several lenses, and its focal length may be modified via an adjustment of the relative positions of said lenses. The first control device 693 may comprise electronic means and computer and / or software means. It is typically a digital or analog electronic circuit, preferably dedicated, associated with a microprocessor and / or a computer. It is connected to the projection optical system 690, and capable of adjusting its focal length to a set value.

[0077] In the example shown in Figure 6B, the system further comprises a calculator 656, configured to receive as input at least one image acquired by the photo-detection module 650, and to implement a processing of this image so as to determine a sharpness index of the latter. From the sharpness index, the calculator 656 is configured to determine a focal length adjustment command and transmit the latter to the first control device 693. The focal length adjustment command is determined so as to increase the sharpness of the image acquired by the photo-detection module 650. It is thus possible to implement an autofocus method, or automatic adjustment of the focal length of the optical projection system 690. The adjustment can be determined from images of specific areas of the retina, for example images of the fovea, by identifying the latter using the calculator 656.Alternatively, the adjustment can be determined from a large image of the retina, and by averaging over various areas of that image.

[0078] The adjustment of the optical adjustment system 695 can be initially carried out in the factory, without a human eye, by replacing the retina of the eye with a projection medium such as a white screen. The focal length of the projection system 690 is then adjusted to obtain a projected image that is sharp on the projection medium. The projected image is for example the image of a test pattern. The projection medium is advantageously observed by a camera, to search for the maximum sharpness of the projected image. This same test pattern is then used to adjust the optical adjustment system 695, so that the image of the latter, projected onto the projection medium and captured by the photo-detection module 650, is sharp. In this way, we simultaneously have the projected image of the test pattern that is sharp on the projection medium, and the image acquired by the photo-detection module 650 that is sharp.

[0079] In a variant not shown, the optical adjustment system 695 is a variable focal length optical system, connected to a second control device. The second control device is connected to the optical adjustment system to adjust its focal length to a set value. The second control device can be connected to a computer, configured to receive an image acquired by the photo-detection module, calculate a sharpness index of this image and deduce therefrom a focal length adjustment command to be transmitted to the second control device. The focal length adjustment command is determined so as to maximize the sharpness index. It is thus possible to automatically adjust the focal length of the optical adjustment system 695, so that the latter participates in an optical conjugation between a surface passing through the eye and the detection surface of the photo-detection module 650.The second control device is advantageously used after manual adjustment of the sharpness of the image seen by a user.

[0080] According to a variant not shown, the second control device is capable of adjusting the focal length of the optical adjustment system 695, so that the latter participates in the optical conjugation between a surface passing through the iris of the eye and the detection surface of the photo-detection module 650. The image of the iris can be transmitted by a computer, and analyzed so as to determine an identifier of the user. Advantageously, the second control device is capable of alternating between a position in which it acquires an image of the iris, for the identification of the user, and a position in which it acquires an image of the retina.

[0081] THE Figures 7A to 7Cillustrate different variants of the invention, which can be combined together and / or combined with one or other of the embodiments described above.

[0082] In the 700 variant of the Figure 7A , a partially reflecting mirror 755 is positioned on the optical axis of the photo-detection module 750, between the photo-detection module 750 and the micro-mirror array 760. The partially reflecting mirror 755 is configured here to deflect the second emission axis associated with the second emission module 740, so as to superimpose this second emission axis 741 with the optical axis of the photo-detection module 750. A portion of the emitted light is lost, which can be easily compensated for by a higher light intensity at emission, at the level of the second emission module 740. In a variant not shown, the positions of the photo-detection module and the second emission module are exchanged.

[0083] In the 700' variant of the Figure 7B , the optical axis 751 of the photo-detection module 750 and the second emission axis 741 of the second emission module are inclined relative to each other, at a small angle ε of between 2° and 10°.

[0084] In the 700" variant of the Figure 7C , the photo-detection module 750 is connected to a computer 756, or processor, in a wired or wireless manner. The computer 756 is configured to receive as input at least one image acquired by the photo-detection module, and to implement a processing of this image so as to deduce therefrom one or more parameters relating to the user, for example an identifier of the user or data relating to the direction of gaze or data relating to a movement of the user's eye (variation in the direction of gaze).

[0085] Finally, the Figure 7Dillustrates a variant 700‴ including a control device 770, for controlling the first transmission module 730, the second transmission module 740, the photo-detection module 750, and the micro-mirror matrix 760. The control device 770 may be called “third control device”, to distinguish it from the first and second control devices mentioned above. The control device 770 may comprise electronic means and computer and / or software means. It is typically a digital or analog electronic circuit, preferably dedicated, associated with a microprocessor and / or a computer. The control device 770 is connected to the first transmission module 730, by wired or wireless connection, and capable of sending the latter switching on and off instructions.The control device 770 is further connected to the second transmission module 740, by wired or wireless connection, and capable of sending to the latter switching on and switching off instructions. The control device 770 is further connected to the micro-lens matrix 760, by wired or wireless connection, and capable of sending to the latter instructions for positioning the micro-mirrors, each in one or the other of the first or second position. Here, but in a non-limiting manner, the control device 770 is finally connected to the photo-detection module 750, by wired or wireless connection, and capable of sending to the latter instructions relating to start and stop times of a light signal integration by the at least one photo-detector of the photo-detection module.

[0086] The control device 770 is connected here to a processor 780, which provides in particular virtual image data to be projected to the user. The control device 770 is capable of transforming this virtual image data into control instructions for the first emission module and the micro-lens matrix. If necessary, the external processor 780 can also provide requests for images of the eye. The control device 770 is then capable of transforming these requests for images of the eye into control instructions for the second emission module, the micro-lens matrix and the photo-detection module. It is thus possible to define instants of acquisition of images of the eye, for example in the context of tracking eye movements.

[0087] According to another variant not shown, the system according to the invention further comprises a calculator as described with reference to the Figure 7C, configured to receive as input at least one image acquired by the photo-detection module, and to implement a processing of this image so as to deduce therefrom data relating to a direction of gaze or to a movement of the user's eye. This data can be transmitted to the control device 770, to adapt a virtual image display command according to the direction of gaze or the movement of the eye. It is thus possible to optimize a rendering of virtual reality. In addition or as a variant, data relating to the movement of the eye constitute a password, which is analyzed at the level of the control device 770 to release or not access to additional data.

[0088] A complete system may comprise two systems according to the invention as described above, each dedicated to a respective eye of the user. Alternatively, a complete system comprises a single system according to the invention as described above, dedicated to one of the two eyes, while the projection of images towards the second eye is not coupled with the possibility of imaging this second eye (the possibility of having an autofocus on this eye is then lost, which reduces the comfort of use since the autofocus is replaced by a manual adjustment of the focal length of the optical projection system associated with the second eye).

[0089] The examples describe various embodiments of a virtual reality vision system according to the invention. According to other embodiments, not shown, the vision system according to the invention forms an augmented reality vision system. Those skilled in the art will easily be able to adapt the examples described to the case of an augmented reality vision system, for example by adding a planar waveguide to move the micro-mirror array out of the eye's field of vision and allow light from an external scene to pass through.

[0090] According to still other variants, the optical system according to the invention does not include a second emission module, and the photo-detection module is sensitive in the visible range. An image of the eye can be acquired by the photo-detection module, simultaneously with the sending of light by the first emission module. If necessary, the pixelated image projected towards the eye can be subtracted from the acquired image.

[0091] According to still other variants, the first emission module comprises a single, polychromatic light source, associated with a coloring wheel to emit a light beam whose spectrum is centered in turn on different values ​​of the wavelength.

[0092] The following describes various methods of using a system according to the invention, in which the first emission module comprises three elementary sources emitting respectively in red, blue and green. Such methods are advantageously implemented by a control device as illustrated in Figure 7D .

[0093] A first process involves the following steps: a) switching on a first of said elementary sources, and driving the mirrors of the micro-mirror matrix so as to form a first component of a color image; b) switching off the first of said elementary sources, switching on a second of said elementary sources, and driving the mirrors of the micro-mirror matrix so as to form a second component of the color image; c) switching off the second of said elementary sources, switching on a third of said elementary sources, and driving the mirrors of the micro-mirror matrix so as to form a third component of the color image;and d) switching off the third of said elementary sources, switching on the second emission module, controlling the micro-mirror matrix so that at least one of the micro-mirrors is in the second position, and acquisition by the photo-detection module of an infrared image of a region of an eye of the user.;

[0094] Preferably, in step d), all the micro-mirrors of the micro-mirror array are positioned in their second position, so as to achieve uniform illumination of the eye, in the infrared.

[0095] Alternatively, the photo-detection module comprises only a single photo-detector. In this case, it is possible, in a known manner, to acquire an image of the eye by illuminating the eye successively with different predetermined lighting patterns. Those skilled in the art will nevertheless have to adapt the known methods to take into account the fact that the illumination of the eye in the infrared is carried out using the micro-mirrors in their second position, where this second position corresponds to pixels that are switched off in the images intended to be seen by the user.

[0096] In a variant of the above method, the second light-emitting module is permanently switched on. Each time the micro-mirror matrix deflects visible light towards the eye, in the form of a first pixelated image, it thus also deflects infrared light towards the eye, in the form of a second pixelated image complementary to the first pixelated image. On average, over a sufficiently long period, the sum of the different second pixelated images projected towards the eye produces substantially uniform illumination. In this method, the acquisition of an image of the eye using the photo-detection module is therefore carried out over a long period, simultaneously with the projection of visible images towards the eye. In particular, the integration of the light signal, by the at least one photo-detector of the photo-detection module, lasts for the entire duration of at least one cycle consisting of steps a) to c) mentioned above.Alternatively, this signal integration lasts for the entire duration of several cycles, where each cycle consists of the steps a) to c) mentioned above and relates to a separate color image. The integration over a long time makes it possible to carry out the infrared illumination with a reduced light intensity. It is not necessary, moreover, to adjust the control rules of the first emission module and the micro-mirror matrix, in comparison with the prior art.

[0097] The methods described above are easily adaptable to the case in which the first emission module comprises a single polychromatic light source associated with a coloring wheel.

Claims

1. A virtual reality or augmented reality vision system (200; 500; 600; 600'; 700; 700'; 700"; 700‴) including: - a first emission module (230; 730), capable of emitting a visible light beam oriented along a first emission axis (231); - a second emission module (240; 740), capable of emitting an infrared light beam oriented along a second emission axis (241); and - an infrared-sensitive photo-detection module (250; 650; 750); characterised in that it further includes an array of micro-mirrors (260; 560; 660; 760), wherein each micro-mirror (261) is capable of taking a first position and a second position distinct from each other, with the micro-mirrors parallel to each other when they are all in the first position, respectively when they are all in the second position, and in that: - each micro-mirror (261) of the array of micro-mirrors (260; 560; 660; 760) is configured to, in its first position, receive light from the first emission module (230; 730) and reflect it along an axis parallel to an axis of interest (201); and - each micro-mirror (261) of the array of micro-mirrors (260; 560; 660; 760) is configured to, in its second position, receive light from the second emission module (240; 740) and reflect it along an axis substantially parallel to the axis of interest (201), and receive light propagating along an axis parallel to the axis of interest (201) and reflect it toward the photo-detection module (250; 650; 750).

2. The system (500; 600; 600'; 700; 700'; 700"; 700‴) according to claim 1, characterised in that for each of the micro-mirrors (261) of the array of micro-mirrors (260; 560; 660; 760), the first position and the second position are symmetrical to each other relative to an elementary plane of symmetry (262), with the elementary planes of symmetry associated with each of the micro-mirrors being all parallel to each other.

3. The system (500; 600; 600') according to claim 1 or 2, characterised in that it further includes an optical projection system (590; 690; 790), located downstream of the array of micro-mirrors (560; 660; 760) along a direction of propagation of the visible light beam in the virtual reality or augmented reality vision system, and capable of performing optical conjugation between the array of micro-mirrors and a predetermined focusing surface (591; 691).

4. The system (600') according to claim 3, characterised in that the optical projection system (690) is a variable focus optical system, connected to a first control device (693) for controlling the focal length of said optical projection system.

5. The system (600; 600') according to claim 3 or 4, characterised in that it further includes an optical adjustment system (695), disposed between the array of micro-mirrors (660) and the photo-detection module (650), and configured to participate in optical conjugation between a surface for receiving a user's eye and a detection surface of the photo-detection module (650).

6. The system (600; 600') according to claim 5, characterised in that a depth of field of the optical adjustment system (695) is adapted to allow forming, on the detection surface of the photo-detection module (650), a sharp image of a surface passing through the user's eye in use, for any value of the focal length of the optical projection system (690) belonging to a determined interval of focal lengths, with said interval of focal lengths having a range of between three millimetres and five centimetres.

7. The system (700') according to any of claims 1 to 6, characterised in that an optical axis (751) of the photo-detection device (750) and the second emission axis (741) are substantially parallel, to within 10°.

8. The system (700) according to any of claims 1 to 6, characterised in that it includes at least one partially reflective mirror (755), configured to deflect an optical axis of the photo-detection device (750) or the second emission axis (741), so as to superimpose the same together.

9. The system (700") according to any of claims 1 to 8, characterised in that it further comprises a calculator (756), configured to receive at least one infrared image acquired by the photodetection module (750) as an input, and to implement processing of this at least one infrared image so as to deduce one or more parameter(s) relating to the user.

10. The system (200; 500; 600; 600'; 700; 700'; 700"; 700‴) according to any of claims 1 to 9, characterised in that the first light emission module (230) is capable of emitting a visible light beam, having a spectrum alternately centred on a first, second and third wavelength.

11. The system (200; 500; 600; 600'; 700; 700'; 700"; 700‴) according to claim 10, characterised in that the first light emission module (230) includes at least three elementary sources, adapted to emit a red, blue and green light beam respectively.

12. A method for using a system (200; 500; 600; 600'; 700; 700'; 700"; 700‴) according to claim 10, the method including the following steps: a) controlling the first emission module (230), for emitting a visible light beam with a spectrum centred on the first wavelength, and controlling the mirrors of the array of micro-mirrors (260; 560; 660; 760) so as to form a first component of a colour image; b) controlling the first emission module (230), for emitting a visible light beam with a spectrum centred on the second wavelength, and controlling the mirrors of the array of micro-mirrors (260; 560; 660; 760) so as to form a second component of the colour image; c) controlling the first emission module (230), for emitting a visible light beam with a spectrum centred on the third wavelength, and controlling the mirrors of the array of micro-mirrors (260; 560; 660; 760) so as to form a third component of the colour image; and d) controlling the first light emission module (230) to stop emitting the visible light beam, controlling the second emission module (240; 740) for emitting an infrared light beam, controlling the array of micro-mirrors (260; 560; 660; 760) so that at least one of the micro-mirrors is in the second position, and acquiring by the photo-detection module (250; 650; 750) an infrared image of a region of an eye of the user.

13. The method according to claim 12, characterised in that in step d), all the micro-mirrors of the array of micro-mirrors (260; 560; 660; 760) are positioned in their second position.

14. The method according to claim 12, characterised in that the photo-detection module (250; 650; 750) comprises a single photodiode, and in that in step d), only some of the micro-mirrors of the array of micro-mirrors (260; 560; 660; 760) are positioned in their second position.

15. A method for using a system according to claim 10, the method including the following steps: a) controlling the first emission module (230), for emitting a visible light beam with a spectrum centred on the first wavelength, and controlling the mirrors of the array of micro-mirrors (260; 560; 660; 760) so as to form a first component of a colour image; b) controlling the first emission module (230), for emitting a visible light beam with a spectrum centred on the second wavelength, and controlling the mirrors of the array of micro-mirrors (260; 560; 660; 760) so as to form a second component of the colour image; and c) controlling the first emission module (230), for emitting a visible light beam with a spectrum centred on the third wavelength, and controlling the mirrors of the array of micro-mirrors (260; 560; 660; 760) so as to form a third component of the colour image; wherein, at least for the entire duration of steps a) to c), the second emission module (240; 740) emits light and the photodetection module receives light and integrates a signal.