WO2014013200A1 - Optical device and camera comprising same - Google Patents

Description

 OPTICAL DEVICE AND VIEWING DEVICE COMPRISING SAME

The present invention relates to an optical device and a camera having it. It applies, in particular, to the stereoscopic shooting for the detection of movements in a multidimensional space but can also be applied to the stereoscopic shooting for the three-dimensional ("3D") display of images or videos on an image sensor, screen, or any print media.

 Stereoscopic cameras are known comprising two cameras mounted in parallel. However, these devices are expensive and complex to implement because a slight angular offset of the sensors and a poor synchronization between the shots cause difficulties in processing and / or visual perception of the images. Video capture is also made complex by this system. In addition, stereoscopic images are visible only on 3D screens.

 The present invention aims to remedy these disadvantages.

 For this purpose, the present invention aims, in a first aspect, an optical device, which comprises:

 a first lateral mirror for displaying a first image corresponding to a first optical path

 at least one chromatic filtering means for not passing light rays of wavelengths in disjoint transmission spectral bands over at least two different optical paths, and

 at least one second lateral mirror placed on one of said optical paths.

 Thanks to these arrangements, at least two different points of view, corresponding to the different optical paths are simultaneously captured by the same image sensor associated with the device object of the invention, in different color ranges. Three-dimensional shooting is thus facilitated. It should be noted that the filtering means may consist of filters or at least one dichroic mirror.

 In embodiments, at least one of said mirrors is a dichroic mirror.

This dichroic mirror makes it possible to superimpose the optical paths upstream of an image sensor. In embodiments, at least one optical relay is placed on at least one of the optical paths to adapt the image.

 Thanks to these provisions, the image is identical between the optical paths even if they have a different length, that is to say give them the same magnification.

 In embodiments, at least one of said mirrors is formed of a prism.

 Thanks to its provisions, the mechanical implementation is facilitated.

 In embodiments, at least one side mirror is a convex mirror.

 It is noted that an image processing software straightens the image after the acquisition.

 With these provisions, the viewing angle is improved and can reduce the blind spot in front of the device.

 In embodiments, the device object of the present invention comprises a mechanical adapter to be secured to a camera, a camera or a camcorder.

 The user can thus connect the device of the invention to an image sensor, like a camera lens or camcorder or in addition to a lens.

 In embodiments, the device that is the subject of the present invention comprises an optical means adapted to make the optical paths converge, with an adjustable convergence distance.

 In embodiments, the optical means adapted to converge optical paths is formed of a plurality of optical lenses of which at least one is movable.

 Thanks to these provisions, the user can adjust the sharpness of the image on the image sensor.

 In embodiments, the optical means adapted to converge the optical paths comprises at least one mechanical wheel whose movement displaces at least one optical lens.

 The user can manually adjust the sharpness of images.

In embodiments, the optical means adapted to converge the optical paths comprises an electric motor. Thanks to these arrangements, the sharpness of the images can be made automatic and / or be controlled by an electrical control circuit of an imaging device.

 In embodiments, one of the mirrors located in the axis of the image sensor is transversely movable.

 Thanks to these provisions, the user can adjust the superimposition of the images according to the different optical paths on an image sensor. This superposition can be performed according to the distance of the object whose images are to be captured.

 In embodiments, an optical means adapted to more or less superimpose the optical paths comprises at least one mechanical wheel whose movement moves at least one mirror.

 The user can manually adjust the image overlay.

 In embodiments, an optical means adapted to more or less superimpose the optical paths comprises an electric motor.

 Thanks to these arrangements, the superposition of the images can be made automatic and / or be controlled by an electrical control circuit of an image taking apparatus.

 In embodiments, at least one said lateral mirror is rotatable.

 Thanks to these provisions, the user can adjust the superimposition of the images that follow the different optical paths. This superposition can be performed according to the distance of the object whose images are to be captured.

 In embodiments, the device which is the subject of the invention comprises means for translational displacement of at least one lateral mirror. Thanks to these arrangements, it is possible to vary the distance between the viewpoints of the images corresponding to the different colors, for example to adapt this distance to that at which one wishes to detect movements of a person.

In embodiments, two of said side mirrors are positioned symmetrically with respect to a common portion of the two optical paths, the device of the invention further comprising a convex central mirror positioned symmetrically with respect to this common part of the optical paths. In embodiments, the device of the present invention comprises a convex central mirror through which each of said optical paths passes.

 Thanks to these arrangements, the images formed by the light traveling through the different optical paths are separated laterally. An image sensor thus captures, on two distinct areas, said images.

 In embodiments, the device according to the invention comprises three filters placed on optical paths connecting the central convex mirror to three lateral mirrors, said color filters having disjoint transmission spectral bands.

 In embodiments, at least one side mirror is positioned such that its normal has an angle of about 45 degrees with respect to the optical path passing through said mirror.

 In embodiments, at least one side mirror is positioned such that its normal has an angle less than 45 degrees with respect to the optical path passing through said mirror.

 In embodiments, the device which is the subject of the invention comprises an optical lens facing each lateral mirror.

 In embodiments, at least one said lens is inclined with respect to an axis defined by a common portion of the optical paths.

 According to a second aspect, the present invention relates to a camera with an optical device object of the invention and an image sensor positioned on a common part of the optical paths of the optical device.

 Other advantages, aims and features of the present invention will emerge from the description which follows, for an explanatory and non-limiting purpose, with reference to the appended drawings, in which:

 FIG. 1 represents, in front view, a first embodiment of an optical device forming the subject of the present invention,

 FIG. 2 represents, in section and in plan view, the device illustrated in FIG. 1 associated with an image sensor,

FIG. 3 represents, in section and in plan view, a second embodiment of the optical device of the present invention associated with an image sensor, FIG. 4 represents, in section and in plan view, a third embodiment of the optical device of the present invention associated with an image sensor,

 FIG. 5 represents, in section and in plan view, a fourth embodiment of the optical device of the present invention associated with an image sensor,

 FIG. 6 represents, in front view, a fifth embodiment of the optical device object of the present invention,

 FIG. 7 represents, in section and in plan view, the device illustrated in FIG. 6,

 FIG. 8 represents, in the form of a block diagram, various modules implemented in different embodiments of the devices that are the subject of the present invention,

 FIG. 9 represents an anaglyph image and an anaglyph image display device,

 FIG. 10 represents in section and in plan view, a third embodiment of the optical device object of the present invention associated with an image sensor,

 FIG. 11 shows in section and in plan view a fourth embodiment of the optical device of the present invention associated with an image sensor;

 FIG. 12 represents in section and in plan view, a fifth embodiment of the optical device of the present invention associated with an image sensor,

 FIG. 13 represents, in front view, a sixth embodiment of the camera according to the present invention and

 FIG. 14 represents, in plan view, the device illustrated in FIG. 13.

 FIGS. 1 and 2 show a device 10 comprising a tube 21 and an objective 12. FIG. 2 also shows an image sensor 22 placed downstream, in the direction of passage of the light, of the objective 12. The image sensor 22 may be that of a camera, a webcam or a camcorder, for example. The objective 12 can be integrated into the housing comprising this image sensor 22.

The tube 21 comprises, facing the objective 12, a first central dichroic mirror 25, also called dichroic filter, having the particularity of reflecting the light rays having certain predetermined wavelengths and being allowed to pass through light rays having other wavelengths. The dichroic mirror 25 makes it possible, by reflection, to a first chromatically filtered image by the dichroic mirror and reflected by a first mirror 14 to form on the image sensor 22. Thanks to its properties, the dichroic mirror 25 is traversed by a second image reflected by a second mirror 13, and reflected by a third mirror 15, so that this image is formed on the sensor 22.

 The optical path passing through the mirror 14 is referenced 17. The optical path passing through the mirrors 13 and 15 is referenced 16. In this embodiment, the four mirrors are positioned at 45 degrees of angle with respect to the optical paths.

 Lenses 1 1 and 19, placed respectively on the optical paths 17 and 16, form, with the mirrors 13 and 14, the mirror 15, the dichroic mirror 25 and the objective 12, on the image sensor 22, images objects located in front of the device, typically at a distance of a few centimeters to three meters depending on the focal distance and the inclination of the lenses.

 The objective 12 makes it possible to focus the image, coming from the tube 21, on the sensor 22. To do this, the objective 12 has lens sets and a mechanical system, not shown, adjustable by the user, for moving the lenses relative to each other by moving them away from or closer to said sensor 22. The adjustment of the spacing of the lenses can be automated by means of a motorized device, integrated into the lens, and powered by the device 22, or manually by disengaging the motorized system of the lens.

 In a variant not shown, the device 10 does not have lenses 1 1 and 19 or lens 12, thus simplifying mechanical assemblies and reducing manufacturing costs. Preferably, in this case, the optical device 10 is provided with a mechanical means for securing to a camera, for example a thread or a bayonet.

 In this example, the dichroic mirror 25 is provided to reflect, at 45 ° to its plane, the wavelength corresponding to the red color.

The red components of a first image from the first optical path 17 are thus diffracted by the dichroic mirror 25 towards the image sensor 22. The other colors of the light spectrum of this first image pass through the dichroic mirror without being reflected and reach the bottom 23 of the tube 21, preferably dark to avoid parasitic reflections.

 In this example, the dichroic mirror 25 is provided to pass the wavelengths corresponding to the green and blue colors which, in additive synthesis, form the cyan color.

 The green and blue components, components of the cyan color, of a second image coming from the second optical path 16 pass, without being reflected by the dichroic mirror 25, towards the image sensor 22. The other colors of the light spectrum of this second image is reflected and reaches the bottom 23 of the tube 21.

 In a variant not shown, the light rays coming on the bottom 23 of the tube 21 are used by integrating a complementary image acquisition sensor.

 In a variant not shown, each optical path 16 and 17 passes through a color filter with disjoint transmission spectral bands to accentuate the contrasts between the complementary colors filtered by the dichroic mirror 25.

 In a variant, the combinations of the dichroic mirror 25 may be red and blue, green and magenta, red and green, or any other combination of colors in the visible or invisible range, such as infrared or ultraviolet, for example.

 The lateral mirrors 13 and 14 are, in this embodiment, positioned symmetrically with respect to the optical axis of the objective 12, which corresponds to the common part of the optical paths 16 and 17 but offset along this axis . The side mirrors 13 and 14 are positioned at an angle of about 45 degrees with respect to the corresponding optical path. This arrangement makes it possible to have optical paths of identical length.

 In a variant not shown, the device 10 comprises means for lateral displacement, in translation, of at least one mirror / lateral lens pair 13 and 19 or 14 and 1 1, which makes it possible to vary the distance between the parallel parts and disjointed optical paths 16 and 17.

FIG. 3 shows a device 40 comprising the same elements as the device 10, with side mirrors 43 and 44 replacing the mirrors 13 and 14 and lenses 41 and 42 replacing the lenses 19 and 11. Normals with mirrors 43 and 44 are positioned at an angle less than 45 degrees with respect to the optical paths. The lenses 41 and 42 are inclined to be substantially perpendicular to the optical paths.

 FIG. 4 shows a device 50 comprising the same optical elements as the device 10, with the difference that they are placed differently, the dichroic mirror 52 not being on the optical axis of the image sensor 22.

 The tube 58 comprises, facing the objective 12, a central mirror 54 on which are reflected images formed by mirrors 57 and 55 and by a dichroic mirror 52. Lenses 51 and 53, placed on two optical paths, form with the mirrors 55 and 57, the dichroic mirror 52, the central mirror 54 and the objective 12, on the acquisition sensor 22, images of objects situated in front of the device 50.

 FIG. 5 shows a device 60 comprising a tube 76. The tube 76 comprises, opposite the objective 12, a dichroic mirror 74 passing a first range of light wavelengths coming from the optical path passing through the lens 72, and reflecting the complementary light wavelengths at the first range and coming from the optical path passing through the lens 71 and reflected by the mirror 73. FIG. 5 also shows an image acquisition sensor 22 on which the image coming from the two optical paths is formed.

 FIG. 6 and 7 show a device 80 similar to the device 10, except that the tube 20 is replaced by a cylinder 86 to adapt it more easily to existing cameras and camcorders. Its shape recalls an interchangeable camera lens.

 FIG. 8 shows a software module 92, an optical system 90 and a hardware module 91. The software module 92 implements an algorithm 93 which decodes the chromatic channels of the digitized image, and an algorithm 94 making it possible to shift the chromatic channels with respect to each other. This feature allows the user to play on both components to enhance the 3D effect.

The software module 92 can be implemented directly on the image acquisition system, and / or on an image display medium such as a computer or a mobile phone for example. At least in the case where a convex or concave mirror is implemented, the software module 92 performs the correction of the geometric deformations of the captured images.

 FIG. 9 shows an image 203, representing an image of a scene positioned in front of the device 10 shown in FIG. 2, as formed on the sensor 22, after optical and chromatic modifications due to the tube 21 and presented in FIGS. 2. The image is voluntarily enlarged to facilitate understanding. This image 203 is the resultant of the superposition of the images coming from the two optical paths 16 and 17 after having been optically superposed, chromatically filtered by the dichroic mirror 25 and finally converged by the objective 12, on the sensor 22.

 The image 203 is thus a superposition of two spatially offset images, presenting two different points of view of the same scene and chromatically complementary. An image 201 presents the perspective of the scene viewed from the left side, with only the cyan component, and an image 202 presents the perspective of the scene viewed from the right side with only the red component. The characteristics of this image 203 thus formed make it an "anaglyph" image, that is to say that it is formed by the superposition of at least two complementary chromatic images, slightly offset with respect to the other and each representing a different point of view of a scene. A shift of six to seven centimeters, the average gap between the two human eyes, between the two shots allows, as a rule, a correct visualization in three dimensions of said scene. Complementary colors may be red and cyan for example, but color combinations may be red and blue, green and magenta, red and green, or any other combination for three-dimensional viewing. This type of color display allows three-dimensional viewing of photos or videos through special glasses with color filters.

FIG. 9 also shows chromatic glasses 400, comprising a red color filter 401 and a cyan color filter 402. The red color filter 401, associated with the right eye of the user, makes it possible to display only the red image 202 of the scene. The cyan color filter 402, associated with the right eye of the user, makes it possible to display only the cyan image 201 of the scene. The two filtered images allow the brain to recompose the image in three dimensions.

 In one variant, the chromatic images are reversed, the red color image is found on the left of the image and the cyan image is on the right of the image. The glasses filters will also be reversed, the red filter is on the left and the cyan filter is on the right.

 FIG. 10 shows a device 500 comprising the same elements as the device 10, with a central mirror 503 replacing the mirror 15. The central mirror 503 is laterally movable along the axis 504. By shifting this central mirror 503 relative to at the mirror 25, in front of the objective 22, the image is shifted from a first optical path passing through the lens 19 and the mirror 13 with respect to a second optical path passing through the lens 11 and the mirror 14.

 In embodiments, a mirror located in the optical axis of the image sensor is transversely movable.

 In embodiments, at least one mirror facing the image sensor is movable in the axis perpendicular to the optical axis of the image sensor.

 FIG. 11 shows a device 600 comprising the same optical elements as the device 50 shown in FIG. 4, with the difference that an optical system, also called an optical relay, is placed on the optical path passing through the mirror 55 and the lens 51, before being reflected by the dichroic mirror 52. The optical relay is composed of a set of lenses for optically adapting the size of the image of the optical path passing through the mirror 55 to the size of the image of the optical path passing through the mirror 52 and the lens 53. Thanks to this device, the two images coming from the two optical paths have an identical size when they are displayed on the sensor 22 even if the lengths of the paths optics are different.

FIG. 12 shows a device 700 comprising a tube 701 comprising the same optical elements as the device 60 presented in FIG. 5, with the difference that an optical system, also called an optical relay, is placed on a first optical path passing through by a first mirror 73 and a lens 71, before being reflected by the dichroic mirror 74. The optical relay is adjusted to optically adapt the size of the image from the first optical path. Thanks to this device, the two images coming from the two optical paths have a size identical when they are displayed on the sensor 22 even if the lengths of the optical paths are different.

 In embodiments, as represented by the curved arrows facing the mirrors 43 and 44 and the lenses 41 and 42, in FIG. 3, an opto-mechanical means adapted to converging the optical paths with a convergence distance is provided. adjustable. For example :

 the optical means adapted to converging the optical paths is formed of several optical lenses of which at least one is mobile,

 the optical means adapted to converging the optical paths comprises at least one mechanical wheel whose movement displaces at least one optical lens, the user being thus able to adjust the convergence and / or

 - The optical means adapted to converge the optical paths comprises an electric motor, a processor can thus adjust the convergence.

 In embodiments, at least one side mirror is rotatable.

 In embodiments, two of the side mirrors are positioned symmetrically with respect to a common portion of the two optical paths, the device further comprising a convex central mirror positioned symmetrically with respect to this common portion of the optical paths. .

 In embodiments, the device that is the subject of the present invention comprises three filters placed on optical paths connecting the convex central mirror or a combination of semi-reflecting or dichroic mirrors with three lateral mirrors, said color filters having spectral bands of disjointed transmission. Three points of view are thus represented by three ranges of colors on the same image captured by an image sensor.

 In embodiments, at least one side mirror is convex.

 In embodiments not shown, at least one mirror is a semi-transparent mirror, the color filtering being performed by optical filters of lower cost than a dichroic mirror.

 In not shown embodiments at least one of the mirrors is formed of a prism.

FIG. 13 shows a device 1 10 comprising a camera 1 16 provided with a lens 1 1 1 emerging on a tube 120. The tube 120 comprises, facing the lens 1 1 1, a convex central mirror 1 15 on which are reflected images formed by two side mirrors 1 13 and 1 19, filtered by color filters 1 14 and 1 17, respectively. Lenses 1 12 and 1 18 form, on two optical paths, with the mirrors 1 13 and 1 19, the mirror 1 15 and the objective 1 1 1 of the images on the image sensor of the camera 1 16, of objects 121 located in front of the device, typically at a distance between ten centimeters and three meters.

 The chromatic filters 1 14 and 1 17, positioned on two optical paths incident on the convex central mirror 1 15 have disjoint transmission spectral bands, for example in the respectively red and cyan color wavelengths which is the complementary color of the red, which is the additive synthesis of green and blue.

 The side mirrors 1 13 and 1 19 are, in this embodiment, positioned symmetrically with respect to the optical axis of the lens 1 1 1. The side mirrors are positioned at an angle of 45 degrees to an axis passing through the center of two side mirrors. The convex central mirror 1 is positioned symmetrically with respect to the optical axis of the lens 1 1 1. The convex central mirror 1 has a surface forming a sphere segment.

 In a variant not shown, the device 1 10 comprises means for moving at least one side mirror 1 13 or 1 19, which allows to vary the distance between the optical paths passing through the lenses 1 12 and 1 18.

 Among the advantages of the invention are:

 - a real stereoscopy with a single camera,

 - compatibility with all sensor resolutions,

 - an interchangeable lens compatible with all types of cameras or camcorders and

 - viewing 3D photos on a classic 2D screen.

Claims

1. Optical device (10), characterized in that it comprises:  a first lateral mirror (13) for displaying a first image corresponding to a first optical path,  at least one chromatic filtering means (25) for passing light rays of wavelengths in disjoint transmission spectral bands over at least two different optical paths, and  at least one second lateral mirror (14) placed on one of said optical paths, in which at least one of said optical paths passes through a convex mirror. The device of claim 1, wherein the color filtering means (25) is a dichroic mirror. 3. Device according to one of claims 1 or 2, wherein at least one optical relay (602, 702) is placed on at least one of the optical paths. 4. Device according to claim 3, wherein at least one optical relay (602, 702) for matching the optical path length offsets is placed after reflection on at least one side mirror. 5. Device according to one of claims 1 to 4, which comprises an optical means adapted to converge optical paths, with an adjustable convergence distance. 6. Device according to claim 5, wherein the optical means adapted to converge the optical paths is formed of several optical lenses of which at least one is movable. 7. Device according to one of claims 5 or 6, wherein the optical means adapted to converge optical paths comprises at least one mechanical wheel whose movement moves at least one optical lens. 8. Device according to one of claims 5 to 7, wherein the optical means adapted to converge the optical paths comprises an electric motor. 9. Device according to one of claims 1 to 8, which comprises means for translational movement of at least one side mirror. 10. Device according to one of claims 1 to 9, wherein two of said side mirrors are positioned symmetrically with respect to a common portion of the two optical paths, the device further comprising a convex central mirror positioned so symmetrical with respect to this common part of the optical paths. 1 1. Device according to one of claims 1 to 10, which comprises a convex central mirror through which each of said optical paths passes. 12. Device according to claim 1 1, which comprises three filters placed on optical paths connecting the central convex mirror to three side mirrors, said color filters having disjoint transmission spectral bands. 13. Device according to one of claims 1 to 1 2, wherein at least one side mirror is positioned in such a way that its normal has an angle less than 45 degrees with respect to the optical path passing through said mirror. 14. Device according to one of claims 1 to 13, which comprises an optical lens facing each side mirror. 15. Device according to claim 14, wherein at least one said lens is inclined relative to an axis defined by a common portion of the optical paths. 16. Device according to one of claims 1 to 1 5, wherein at least lateral is convex. 17. A camera comprising an optical device according to one of claims 1 to 16 and an image sensor positioned on a common portion of optical paths of the optical device. 18. Device according to claim 17, wherein a mirror located in the optical axis of the image sensor is movable transversely. 19. Device according to one of claims 17 or 18, wherein at least one mirror facing the image sensor is movable in the axis perpendicular to the optical axis of the image sensor.