Computer-based method for designing a more efficient lens

Abstract

The invention relates to a method (100) for designing a lens using computer-aided design software, the method comprising a step (102) of designing a current design, and at least one iteration of a phase (104), referred to as the improvement phase, comprising the following steps: - measuring (106-110), by simulation with the design software, on the current design, an optical transfer function, OTF, individually at least for light of a colour selected from light of the following colours: red light, green light and blue light; - determining (112) a quality indicator dependent at least on one measured OTF; and - when the quality indicator is unsatisfactory, modifying (116) the current design with a view to obtaining a design referred to as the final design, for which the quality indicator is satisfactory. The invention also relates to a computer program implementing such a method.

Description

DESCRIPTION Title: Computer design process for a more efficient optical lens

[0001] The present invention relates to a method for computer designing an optical lens with improved optical quality. It also relates to a computer program implementing such a method. It further relates to an apparatus and a vehicle equipped with an optical lens designed by such a method.

[0002] The field of the invention is generally the field of computer design of optical lenses used in particular for imaging. State of the art

[0003] The design of an optical lens used for imaging is carried out using design software, such as Zemax ® software. In summary, a digital model of the lens is designed in said design software. Then, its expected performance is estimated by measuring, with said design software, the modulation transfer function, MTF (for "Modulation Transfer Function") in white light. The measured MTF is compared to a predefined threshold MTF, to determine if the quality of the lens is deemed satisfied. The digital model of the lens is modified iteratively to improve the measured MTF, until a satisfactory measured MTF is obtained.

[0004] The MTF measured in white light is representative of all the optical aberrations of the optical lens, namely chromatic aberration, geometric aberration and third and higher order aberrations (called "3rd order aberrations"). ème order in the following for the sake of brevity).

[0005] Now, inventors have discovered that certain aberrations, such as lateral chromatic aberration and geometric aberration can be effectively corrected by calculation. Therefore, there is a need for a new way of designing an optical lens.

[0006] An aim of the present invention is to remedy at least one of the aforementioned drawbacks.

[0007] Another aim of the invention is to propose a simpler and less time-consuming solution for designing an optical lens.

[0008] Another aim of the invention is to propose a design solution for an optical lens making it possible to obtain, at equal quality, a less complex architecture compared to current solutions.

[0009] Another aim of the invention is to propose a design solution for an optical lens making it possible to obtain, with equal architectural complexity, improved performance during its use compared to current solutions.

[0010] Another aim of the invention is to propose a design solution for an optical lens which jointly allows the obtaining of a less complex optical lens and improved performance during its use. Statement of the invention

[0011] The invention proposes to achieve at least one of the aforementioned aims by a method of designing, with design software executed by computer, an optical lens comprising several optical elements, said method comprising a step of designing a design, called current design, of said lens, and at least one iteration of a phase, called improvement, comprising the following steps: - measurement, by simulation with said design software, on said current design, of an optical transfer function, OTF, individually for at least one color radiation chosen from the following color radiations: red radiation, green radiation or blue radiation; - determination of a quality indicator based on at least one measured FTO; and - when said quality indicator is not satisfactory, modification of said current design with a view to obtaining a design, called final, for which said quality indicator is satisfactory.

[0012] The inventors noticed that optical aberrations of the displacement type due to an optical lens can be corrected very effectively by calculation, i.e. by digital processing of the acquired images, whereas aberrations of the spreading type are very difficult to correct, or sometimes even impossible to correct depending on the imaged scene.

[0013] Based on this observation, the present invention proposes to design an optical lens using as a quality indicator, not an MTF measured with white light as is currently the case, but at least an FTO measured individually for at least one, and in particular for each, of the red, green and blue components. Such an indicator allows a design of the optical lens by reducing, or even minimizing, the spreading-type aberrations, knowing that the displacement-type aberrations can be corrected by digital processing. Thus, the invention proposes a solution for designing a more efficient optical lens and making it possible to obtain an optical lens whose optical quality is improved.

[0014] Furthermore, in the solutions of the state of the art, the design of an optical lens is carried out with the objective of obtaining a design minimizing all the optical aberrations due to said optical lens, namely the displacement-type aberrations and the spreading-type aberrations. However, during the design, a design choice reducing one of these aberrations can lead to an increase in the other of these aberrations: this makes the design of an optical lens complicated and time-consuming, and ultimately results in lenses with an increasingly complex architecture and comprising ever more lenses. Moreover, this solution leads to choosing an architecture corresponding to a compromise between all the optical aberrations, which limits the optical performance of the lens, in particular with regard to the spreading-type aberrations, which are very difficult to correct by calculation.

[0015] In a different way, the method according to the invention proposes a faster and less time-consuming optical lens design solution, because it does not seek to optimize all optical aberrations, but mainly spreading-type aberrations. In addition, the solution proposed by the invention makes it possible to design, for equal imaging quality, an optical objective whose complexity is reduced. In addition, the solution proposed by the invention makes it possible to design, for equal complexity, an optical objective making it possible to obtain better imaging quality since said objective will have less spreading-type aberration which is difficult, or even impossible, to correct by digital processing, while the other aberrations can be effectively corrected by digital processing when using the optical objective.

[0016] By "optical aberration" we mean the notion that the image of a point in the scene becomes a more or less large luminous spot in the place (generally plane) where the image is formed. Aberration results in different types of effects: there are aberration effects whose characteristic is to move the average position of the optical spot produced by a point in the scene, relative to a place where we would ideally have wanted it to occur. We will call them displacement-type aberrations. There are other effects which are that the optical spot has a spatially spread energy distribution, instead of being punctual, in the image location. We will call them spreading-type aberrations.

[0017] Aberrations due to an optical lens are commonly referred to as chromatic aberration, geometric aberration and 3D aberration. ème order.

[0018] By aberrations of 3 èmeorder, we mean all the aberrations introduced by an optical objective in an image acquired with said optical objective, except chromatic aberration and geometric aberration. These aberrations of the 3 ème order (and higher order) include for example spherical aberration, Coma, astigmatism, field curvature, distortion (of shape and energy distribution of the optical spot), etc. These aberrations of the 3 ème order are of the spreading type.

[0019] By "chromatic aberration", which results from the decomposition of light into several color bands, we mean an optical aberration which produces different positions in space of the focal point in function of the wavelength. For a so-called "lateral" chromatic aberration, it is a displacement of the focal point in the image location, as a function of the wavelength. We then observe an image with iridescent contours, or colored fringes around objects of uniform color, for example white. For a so-called "axial" chromatic aberration, it is a focusing outside the image location because the focal points are shifted along an axis perpendicular to the image location (or the axis corresponding to the central optical ray arriving at the image point, which may be oblique to the image location). We then observe an image in which certain colors are blurred. Lateral chromatic aberration can be corrected by digital processing of the image captured by a lens as long as it is quantified, that is to say measured during the design / manufacture of the optical lens. It joins the displacement type aberrations.Axial chromatic aberration, on the other hand, joins the spreading type aberrations, because if for example the green color is focused on the sensor of the image plane, the red color can focus before, and the red optical beam becomes widened when it meets the sensor further than the point of focus.

[0020] Geometric aberration refers to a deviation between a paraxial ray defined in the Gaussian approximation and the corresponding real ray. Geometric aberration can also be characterized by a deviation between the paraxial wave surface and the real wave surface. For example, geometric aberrations produce a distortion of the shape of the resulting image. For example, a square can become a shape equal to the outline of a barrel (turned corners), or a dressmaker's cousin (growths on the corners). Thus, the straight and vertical edges of a building can become curved, not vertical. This aberration can be corrected by digital processing of the captured image as long as it is quantified, i.e. measured during the design / manufacture of the optical lens. Geometric aberrations are of the displacement type.

[0021] By "displacement aberration" or "displacement aberration" we mean lateral chromatic aberration and geometric aberration.

[0022] By "spreading-type aberration" or "spreading aberration" is meant axial chromatic aberration and aberrations of the 3 ème order.

[0023] “Color radiation” means red color radiation, or green color radiation or blue color radiation.

[0024] According to embodiments, the optical transfer function, OTF, may be the modulation transfer function, MTF (or “Modulation Transfer Function”).

[0025] According to embodiments, for a measurement point, the MTF can be measured in the following manner, in the design software.

[0026] An image plane is considered corresponding to the plane of an image sensor with which said lens will be assembled once manufactured, to form an imaging module. According to an exemplary embodiment, the optical lens is illuminated by simulating a target placed at a certain distance, called the distance from the scene. This distance can be made infinite to obtain a distance from the scene called infinity. The simulated target comprises an alternation of: - patterns, called dark, not allowing the radiation to pass through, and - patterns, called light, corresponding to the color of the color radiation for which the MTF is measured. Dark patterns are assumed to result in radiation-free patterns in the image plane since they do not allow radiation to pass through. Light patterns are assumed to result in patterns of the same color as the color radiation on the image sensor since they allow said radiation to pass through.

[0027] In this configuration, the MTF of a point (x,y) of the image plane is calculated in the following manner. For an area centered on the point (x,y), and comprising several alternating patterns, several contrast values ​​are calculated as a function of the values ​​received by the “pixels” of the image plane, each contrast value corresponding to an alternating pattern in said area. The MTF value for the point (x,y) of the image plane is calculated as a function of said measured values, for example by an average of said values. Thus, for a color radiation, the value is obtained of the MTF, measured by simulation, for said radiation, and for a point (x,y) of the image plane.

[0028] By repeating this measurement by simulation for several points of the image sensor, we can obtain the MTF measured for said radiation, said MTF then being represented by a field of several discrete values.

[0029] Of course, MTF measurement can be done in other ways.

[0030] According to embodiments, the optical transfer function, OTF, may be the point spread function, PSF (or FEP for “Point Spread Function”).

[0031] According to embodiments, for a measurement point, the PSF can be measured in the following manner, in the design software.

[0032] We consider an image plane corresponding to the plane of an image sensor with which said lens will be assembled once manufactured, to form an imaging module. According to an exemplary embodiment, the optical lens is illuminated by simulating a target placed at a certain distance, called the distance from the scene. This distance can be made infinite to obtain a distance from the scene called infinity. The simulated target comprises a plurality of points allowing the color radiation for which the PSF is measured to pass through. The rest of the target is opaque and does not allow the radiation to pass through. Each point located at a position (x,y) forms in the image plane a more or less wide spot and of more or less different shape. When the spot is a perfect circle, then the value of the PSF of the point (x,y) corresponds to the radius of the spot captured on the sensor. When the spot has another shape, the PSF can, for example, be calculated as the average radius of the spot.The mean radius can be calculated as follows. First, the center of the spot is extracted, for example, by determining the barycenter of the positions of the points forming the spot, weighted by the intensity detected at each position. Then, the sum of the detected amplitude multiplied by the square of the distance to the barycenter is calculated. This sum is divided by the sum of the detected amplitudes. This gives a square of the mean radius of the spot. The square root is taken. This gives an effective mean radius of the spot.

[0033] By repeating this measurement by simulation for several points of the image sensor, we can obtain the PSF measured for said color radiation, said PSF then being represented by a field of several discrete values.

[0034] Of course, PSF measurement can be performed in other ways.

[0035] According to embodiments, the improvement phase can be repeated until a quality indicator is obtained whose value reaches a predetermined target value, or a predetermined range of target values, for at least one, and in particular for each, measurement point of the at least one FTO.

[0036] In this case, the iteration(s) of the improvement phase aim to improve the measured FTO of the current design to at least a predetermined threshold. Thus, the final design obtained for the optical lens has spreading aberrations below a predetermined threshold.

[0037] In these embodiments, the improvement phase comprises a step of comparing the measured FTO to at least one predetermined threshold FTO. As long as the measured FTO does not reach the threshold FTO for each measurement point, then the improvement phase is repeated. The current design for which the FTO reaches the at least one predetermined threshold FTO is stored as the final design of the optical lens according to which the actual lens will be produced.

[0038] According to embodiments, the improvement phase can be repeated until the value of the quality indicator reaches an optimal value for, at least one, and in particular each, measurement point of the FTO.

[0039] In this case, the iterations of the improvement phase aim to optimize the measured FTO, i.e. to minimize the spreading-type aberrations. Thus, the final design obtained for the optical objective is optimized with respect to spreading aberrations.

[0040] In these embodiments, the improvement phase comprises a step of comparing the measured FTO to the best FTO value. measured during previous iterations. If the measured FTO does not improve for several consecutive iterations, for example 10 consecutive iterations, then the iterations of the improvement phase are stopped because it is considered that the measured FTO of the current design is optimized and can no longer be improved. Of course, other implementation examples are possible to determine whether the optimal value of the FTO has been reached.

[0041] When the FTO is the MTF, the improvement phase can be repeated until the value of the quality indicator reaches a maximum value.

[0042] When the FTO is the PSF, the improvement phase can be repeated until the value of the quality indicator reaches a minimum value.

[0043] According to embodiments, for at least one color radiation, and in particular each color radiation, the measuring step can carry out a measurement of the value of the FTO at several measuring points, for example at the center of the lens on the edge of the lens, etc.

[0044] In this case, each measured FTO may be represented by FTO values ​​measured at several measurement points. Preferably, the measured FTO may be represented by a field of several values ​​comprising several measured FTO values, each for a position (x,y), and in particular at a pixel of position (x,y), of an image plane for carrying out said measurement. The image plane corresponds to the plane of an image sensor with which said lens will be assembled once manufactured, to form an imaging module. In this case, the measured FTO is represented by discrete values ​​each corresponding to a measurement point.

[0045] Alternatively, it is possible, from the measured values, to deduce a mathematical relationship taking as input a position (x,y) of the image sensor and giving as output a measured FTO value.

[0046] Of course, at least one measured FTO can be in other forms, such as a matrix, a vector, etc.

[0047] According to embodiments, the measuring step can perform the FTO measurement only for a single color radiation, the quality indicator being determined based on the FTO measured for said radiation.

[0048] In this case, the measurement step can be carried out more quickly. In addition, obtaining a final design will also be faster, and improving the quality indicator will be easier to achieve, since the quality indicator depends solely on the FTO for the single color radiation.

[0049] In some embodiments, the only color radiation for which the FTO is measured may be green radiation. Indeed, the inventors have discovered that the green color is more representative of the aberrations of an optical lens compared to red and blue radiation.

[0050] In the case where the FTO is measured for a single color radiation, the quality indicator can be the said measured FTO.

[0051] Optionally, the quality indicator may correspond to said measured FTO in which different weights may be given to the measured FTO value for different measurement points. For example, a greater weight may be given to at least one measurement point located in the center of the optical lens and a lesser weight may be given to at least one measurement point located at the periphery of the optical lens.

[0052] Alternatively, or in addition, the value field may be used to calculate a single quality indicator value, using a predetermined mathematical relationship, taking as input the values ​​contained in the value field. The mathematical relationship may be a sum, mean, variance, etc. of the values, or the square of each of the values, contained in the value field.

[0053] Other examples of embodiment are possible without departing from the scope of the invention.

[0054] According to embodiments, the measuring step can carry out the measurement of the FTO individually for several, in particular each, of the color radiations, the quality indicator being determined as a function of the FTOs measured for said radiations.

[0055] For example, the measurement step may perform an FTO measurement for green radiation, for red radiation, and for blue radiation. Thus, the measurement step provides a simulation-measured FTO for green radiation, a simulation-measured FTO for red radiation, and a simulation-measured FTO for blue radiation.

[0056] Each measured FTO can include multiple FTO values, each for one measurement point (x,y) in the image plane.

[0057] In the case where several FTOs are measured for several color radiations, the quality indicator can be calculated, for at least one measurement point, with a mathematical relationship taking into account the value of each FTO measured for said measurement point.

[0058] For example, for a measurement point, the quality indicator can be an average, a mean of squares, a sum, or a sum of squares, of the FTO values ​​measured for this measurement point for the different colors. Of course, these examples are in no way limiting and the quality indicator can be calculated according to other mathematical relationships.

[0059] Optionally, different weights can be used for different colors. For example, at a measurement point, the FTO value for the color green can be given a higher weight compared to the FTO measured for the color red, etc.

[0060] Optionally, different weights may be used for different measurement points. For example, a greater weight may be given to at least one measurement point located in the center of the optical lens and a lesser weight may be given to at least one measurement point located at the periphery of the optical lens.

[0061] Alternatively, or in addition, the value field may be used to calculate a single quality indicator value, using a predetermined mathematical relationship, taking as input the values ​​contained in the value field. The mathematical relationship may be a sum, mean, variance, etc. of the values, or the square of each of the values, contained in the value field.

[0062] Other examples of embodiment are possible without departing from the scope of the invention.

[0063] In some embodiments, the improvement of the current design can be achieved without taking into account lateral chromatic aberration. In this case, lateral chromatic aberration is completely relaxed in the design of the optical lens.

[0064] According to embodiments, the improvement phase may comprise a step of measuring, on the current design, a lateral chromatic aberration function, FACL.

[0065] This FACL can be compared to a limit threshold for lateral chromatic aberration that should not be exceeded during the design of the optical lens. Thus, the current design of the optical lens can be improved, while keeping a limit for lateral chromatic aberration. In this case, lateral chromatic aberration is not completely relaxed during the design of the optical lens.

[0066] In some embodiments, the improvement of the current design can be achieved without taking geometric aberration into account. In this case, geometric aberration is completely relaxed during the design of the optical lens.

[0067] According to embodiments, the improvement phase may comprise a step of measuring, on the current design, a geometric aberration function, FAG.

[0068] This FAG can be compared to a limit threshold of geometric aberration that should not be exceeded during the design of the optical lens. Thus, the current design of the optical lens can be improved, while keeping a limit for the geometric aberration. In this case, the lateral chromatic aberration is not completely relaxed during the design of the optical lens.

[0069] According to embodiments, the method according to the invention may comprise a determination of at least one correction function. - lateral chromatic aberration, and / or - geometric aberration. for the final design.

[0070] In embodiments, a lateral chromatic aberration correction function, FCACL, may be provided to individually correct lateral chromatic aberration.

[0071] According to embodiments, a geometric aberration correction function, FCAG, may be provided, to individually correct geometric aberration.

[0072] According to embodiments, a single aberration correction function, FCA, may be provided to simultaneously correct lateral chromatic aberration and geometric aberration.

[0073] At least one correction function can be deduced from the previously measured FACL and FAG.

[0074] The FACL, and / or the FAG, is known if it was measured, during the improvement phase, on the current design which was adopted as the final design.

[0075] If the improvement phase does not include a measurement of the FACL, and / or the FAG, this or these functions can be measured on the final design.

[0076] FACL measurement can be performed in different ways.

[0077] According to embodiments, an image plane is considered corresponding to the plane of an image sensor with which said lens will be assembled once manufactured, to form an imaging module. According to an exemplary embodiment, the optical lens is illuminated by simulating a target arranged at a certain distance, called the distance from the scene. This distance can be made infinite to obtain a distance from the scene called infinity. The target can be illuminated by white radiation, or successively by green, red and blue radiation. A pattern corresponding to a position (x,y) of the image plane generates on said image plane a spot for each of the colors. The position of each color spot can be detected. The detected positions of the three spots color are then used to calculate a displacement vector, relative to a reference position. The reference position may be the position of one of the three spots, for example the green spot. Alternatively, the reference position may be another position, for example the position of the optical axis of the optical lens in the image plane.

[0078] By carrying out, simultaneously or in turn, the measurement for several positions (x,y) in the image plane it is then possible to determine the FACL.

[0079] FAG measurement can be performed in different ways.

[0080] According to embodiments, an image plane is considered corresponding to the plane of an image sensor with which said lens will be assembled once manufactured, to form an imaging module. According to an exemplary embodiment, the optical lens is illuminated by simulating a target arranged at a certain distance, called the distance from the scene. This distance can be made infinite to obtain a distance from the scene called infinity. The target is illuminated by white radiation, or successively by green, red and blue radiation. A pattern located at an angle (0i,yi) relative to the axis of the optical lens, with 0i the angle of inclination relative to the axis of the optical lens and yi the angle of rotation about the axis of the optical lens, generates on said image plane a spot for each of the colors red, green and blue. The position of each color spot can be detected.The detected positions of the three spots are then used to calculate a displacement distance for each color, relative to the center of the optical lens. Optionally, the displacement distance can be divided by the focal length, so as to obtain an angular magnitude as a function of the angle (0i,yi) of the optical beam entering the optical lens relative to the axis of the optical lens.

[0081] By performing, simultaneously or in turn, the measurement for several angles (0i,yi) relative to the optical axis of the optical objective, it is possible to determine the FAG.

[0082] According to embodiments, the lateral chromatic aberration correction function, FCACL, may be in the form of a field of values ​​comprising, for each of several positions (x,y) of the image plane, at least one displacement vector to be applied to correct said lateral chromatic aberration at said position. For at least one position (x,y) of the sensor, the FCALC may comprise: - a single displacement vector for each of the colors red, green and blue; or - for at least one of said colors, a displacement vector dedicated to said color.

[0083] Alternatively, the FCACL may be a mathematical function taking as input the position (x,y) of the image sensor and providing one or more displacement vectors to be applied to correct said aberration at said position (x,y).

[0084] According to yet another alternative, the FCACL can be presented in the form of a correspondence table indicating, for each of several pixels of the image plane, a corrected position of said pixel and this individually: - for each color, or - for the red color and for the blue color in the case where the green color is taken as a reference.

[0085] According to embodiments, the geometric aberration correction function, FCAG, may be in the form of a field of values ​​comprising, for each of several angles (0i,yi), at least one distance vector to be applied to correct said geometric aberration. For at least one angle (0i,yi), the FCAG may comprise: - a single distance correction value to be applied for each of the red, green and blue colors; or - for at least one of said colors, a distance correction value dedicated to said color.

[0086] Alternatively, the FCAG can be a mathematical function taking as input an angle (0i,yi) relative to the optical lens axis and providing one or more distance correction values.

[0087] Following yet another alternative, the FCAG can be presented in the form of a correspondence table indicating, for each of several pixels of the image sensor, a corrected position of said pixel and this individually for each color.

[0088] According to embodiments, for at least one iteration, the step of modifying the current design may comprise at least one of the following steps: - replacement of at least one optical element; - addition, or removal, of at least one optical element; - modification of the geometry of at least one optical interface of at least one optical element; - modification of the refractive index of at least one optical element; - modification of the dependence of the refractive index on the wavelength for at least one optical element; - modification of a distance between at least two optical elements; - modification of the position of at least one optical element; of said current design.

[0089] Of course, these examples are given for information purposes only, without any limitation of the scope of the invention.

[0090] According to another aspect of the invention, there is provided a computer program comprising executable instructions which, when executed by a computing device, implement all the steps of the method according to the invention.

[0091] The computer program can be in any computer language, such as machine language, C, C++, JAVA, Python, etc.

[0092] The computer program can be integrated into the design software used for optical lens design.

[0093] Alternatively, the computer program may include the design software, or be independent of said design software.

[0094] According to another aspect of the invention, there is provided a camera module comprising: - an optical objective designed with the method according to the invention; and - an image sensor associated with said optical lens.

[0095] The image sensor can be any type of image sensor combined with an optical lens, such as a CMOS or CCD image sensor, but is not limited to these image sensors.

[0096] According to another aspect of the present invention, there is provided a method of manufacturing optical lenses comprising the following steps: - designing an optical lens according to the method according to the invention; and - manufacturing of at least one optical lens in accordance with the final design obtained.

[0097] According to embodiments, the manufacturing method according to the invention may comprise, for at least one manufactured objective, a measuring step: - a lateral chromatic aberration function, FACL; and - a lateral geometric aberration function, FACL; with at least one measuring device.

[0098] This or these functions measured on the manufactured objective can be used for: - verify that the manufactured optical lens conforms to the final design obtained during the design; and / or - correct lateral chromatic aberration, and / or geometric aberration, when taking an image with said optical lens.

[0099] According to embodiments, the measuring step can be carried out for each optical objective manufactured.

[0100] Alternatively, the measurement step can be performed for some of the manufactured optical lenses. For example, within the same batch of optical lenses, the measurement step can be performed for a single optical lens, or a few optical lenses. The measured aberration function(s) can be used for all lenses in the same batch.

[0101] A batch of optical lenses may correspond to lenses with the same design. Alternatively, a batch of optical lenses may correspond to lenses with the same design and assembled according to the same assembly recipe.

[0102] According to another aspect of the same invention, there is provided an installation for manufacturing optical lenses comprising: - a design apparatus configured to implement the design method according to the invention; and - a production line for optical lens(es), and

[0103] The installation according to the invention may comprise, in terms of means and / or configuration, any combination of the optional characteristics described above in relation to the manufacturing method according to the invention and which are not repeated here for the sake of brevity.

[0104] In particular, the manufacturing facility is configured to implement the manufacturing method according to the invention.

[0105] According to another aspect of the invention, there is provided an apparatus comprising at least one optical objective designed with the method according to the invention.

[0106] The apparatus according to the invention may in particular comprise at least one camera module according to the invention.

[0107] In particular, the device may be a user device such as a smartphone, tablet, etc.

[0108] The user device may optionally include a display screen, in particular a touch screen, etc.

[0109] In particular, the device may be a virtual reality headset or an augmented reality headset, intended to be worn by a user.

[0110] The helmet may optionally include a display screen, in particular a touch screen, etc. [YES] In particular, the device may be a user device such as a camera or photo camera, etc.

[0112] The user device of the camera or photo type may optionally include a display screen, in particular a touch screen, etc.

[0113] In particular, the device may be a computer-type user device.

[0114] The computer-type user device may optionally include a display screen, in particular a touch screen, etc.

[0115] The computer-type user device may optionally include a keyboard, or any other equipment integrated or associated with said device.

[0116] In particular, the device may be a television.

[0117] The television may optionally include a display screen, in particular a touch screen, etc.

[0118] In particular, the device may be a medical imaging device.

[0119] The medical imaging device can be, for example, an endoscope, an ultrasound device, etc.

[0120] Of course, the apparatus according to the invention is not limited to the examples of apparatus which have just been given.

[0121] According to another aspect of the present invention, there is provided a vehicle comprising at least one optical lens designed with the method according to the invention.

[0122] The apparatus according to the invention may in particular comprise at least one camera module according to the invention.

[0123] According to embodiments, the vehicle may be a land vehicle, such as a car, for example non-autonomous driving, semi-autonomous driving, or autonomous driving.

[0124] According to embodiments, the vehicle may be a flying vehicle, such as a drone, an airplane, a helicopter, for example with non-autonomous driving, semi-autonomous driving or autonomous driving.

[0125] According to embodiments, the vehicle may be a marine vehicle, such as a boat or a submarine, for example non-autonomously driven, semi-autonomously driven or autonomously driven.

[0126] According to another aspect of the present invention, there is provided a method of acquiring an image of a scene, said method comprising the following steps: - acquisition of an image with an optical objective designed by the method according to the invention, and - digital processing of said image for the correction of said image.

[0127] According to embodiments, the digital processing may comprise a step of correcting the chromatic aberration introduced into the image by the optical lens, for example with a correction function provided during the design of the lens, and / or during the manufacture of the optical lens.

[0128] According to embodiments, the digital processing may comprise a step of correcting the geometric aberration introduced into the image by the optical lens, for example with a correction function provided during the design of the lens, and / or during the manufacture of the optical lens.

[0129] According to embodiments, the optical lens can be used for 2D or 3D imaging.

[0130] According to embodiments, the optical lens can be used for image acquisition to image a scene at a given time, or for acquiring a stream of images, or a video, of a scene. Description of figures and embodiments

[0131] Other advantages and characteristics will appear on examining the detailed description of non-limiting embodiments, and the attached drawings in which: - FIGURES 1-3 are schematic representations of three non-limiting exemplary embodiments of a method according to the invention; - FIGURE 4 is a schematic representation of a non-limiting exemplary embodiment of a method for manufacturing optical objective(s) according to the invention; - FIGURE 5 is a schematic representation of a non-limiting exemplary embodiment of an installation for manufacturing optical lens(es) according to the invention; - FIGURE 6 is a schematic representation of a non-limiting exemplary embodiment of a camera module according to the invention; - FIGURE 7 is a schematic representation of a non-limiting exemplary embodiment of a method for acquiring an image according to the invention; - FIGURES 8a-8c are schematic representations of non-limiting exemplary embodiments of an apparatus according to the invention; and - FIGURE 9 is a schematic representation of a non-limiting exemplary embodiment of a vehicle according to the invention.

[0132] It is understood that the embodiments which will be described below are in no way limiting. In particular, it is possible to imagine variants of the invention comprising only a selection of characteristics described below isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art. This selection includes at least one preferably functional characteristic without structural details, or with only part of the structural details if it is this part which is only sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0133] In particular, all the variants and embodiments described can be combined with each other if there is no technical obstacle to this combination.

[0134] In the figures and in the rest of the description, the elements common to several figures retain the same reference.

[0135] FIGURE 1 is a schematic representation of a non-limiting exemplary embodiment of a method according to the present invention.

[0136] The method 100 of FIGURE 1 can be used for the design of an optical lens used for imaging, i.e., for acquiring an image or video. Such an optical lens can be combined with an image sensor to form an imaging module and integrated into different devices.

[0137] An optical lens is usually composed of several optical elements, such as lenses, spacers, etc. When designing an optical lens, a specification indicates the performance of the lens during image acquisition. This performance is usually quantified with the MTF (Modulation Transfer Function).

[0138] The design of an optical lens is carried out with design software that allows defining a digital model of the lens, also called a digital design or design, and simulating the propagation of waves through said design and measuring different quantities. One of the most well-known design software is, for example, ZEMAX ® software.

[0139] The method 100 of FIGURE 1 comprises a step 102 during which a design, called a current design, of the lens is produced with the design software, for example with the ZEMAX ® design software. This design is obtained by stacking several optical elements along a stacking direction, which also corresponds to the axis of the optical lens. Each optical element of the optical lens is modeled, in the form digital: in other words, each optical element is represented by digital data describing said optical element, namely the shape of each of its optical interfaces, its position, the position of its APEX if applicable, its optical index, its orientation in the XY plane perpendicular to the Z axis of the optical lens, its inclination relative to the Z axis, etc. All of this data makes it possible to simulate the propagation of an optical wave through said optical element. Thus, it is possible to simulate, by calculation, the propagation of an optical wave of a given wavelength within each optical element of the optical lens, and consequently the propagation of an optical wave through the stack of optical elements forming the optical lens.

[0140] The optical wave propagated by simulation through the numerically modeled optical lens is detected at an image plane, which simulates the plane of an image sensor. Thus, it is possible to simulate measurements on the optical wave propagated by simulation at an image sensor.

[0141] The method 100 comprises, after step 102, at least one iteration of a phase 104 of improving the current design of said optical lens.

[0142] This improvement phase 104 includes a determination of a value of a quality indicator on the current design of the optical lens.

[0143] According to the invention, the quality indicator, noted Q, is determined from an optical transfer function, FTO, measured by simulation, on the current design, for at least one color radiation chosen from the following color radiations: red radiation, green radiation, blue radiation.

[0144] In the example of FIGURE 1, the quality indicator Q is calculated based on the FTOs measured, by simulation, for each of the radiations, namely an FTO measured for the red radiation, an FTO measured for the green radiation and an FTO measured for the blue radiation.

[0145] Additionally, in the example of FIGURE 1, in a non-limiting manner, the OTF is the modulation transfer function, MTF. Alternatively, the OTF may be the modulation transfer function, MTF. Generally, the OTF may be any function representative of the optical behavior of an optical objective.

[0146] Phase 104 includes a step 106 of measurement, by simulation on the current design, of the MTF for green radiation.

[0147] For example, green radiation can be green radiation with a wavelength between 500 nm and 570 nm, and in particular equal to 535 nm.

[0148] The MTF measurement can be carried out using the technique described above. According to an example of implementation, the optical objective is illuminated by simulating a target placed at a certain distance, called the distance from the scene. This distance can be made infinite to obtain a distance from the scene called infinity. The simulated target includes an alternation: - patterns, called dark, which do not let the radiation pass through, and - patterns, called light, which correspond to the color of the radiation, the color green. Dark patterns are assumed to result in radiation-free patterns in the image plane since they do not allow radiation to pass through. Light patterns are assumed to result in patterns of the same color as the color radiation, i.e., green, in the image plane since they allow said radiation to pass through.

[0149] In this configuration, the MTF of a point (x,y) of the image plane is calculated in the following manner. For an area centered on the point (x,y), and comprising several alternations of patterns, several contrast values ​​are calculated as a function of the values ​​received by the simulated “pixels” of the image plane, each contrast value corresponding to an alternation of patterns in said area. The MTF value for the point (x,y) of the image plane is calculated as a function of said measured values, for example by an average of said values.

[0150] Step 106 performs a plurality of measurements of MTF values ​​for several points of the image plane and provides an MTF for the green radiation, represented by a field of measured MTF values, each for a position (x,y) of the image plane.

[0151] Phase 104 includes a step 108 measuring, by simulation on the current design, the MTF for red radiation, in a similar manner to what was described for green radiation in step 106, replacing the green radiation with red radiation.

[0152] For example, red radiation can be red radiation with a wavelength between 570 and 730 nm, and in particular equal to 650 nm.

[0153] The step provides an MTF for red radiation represented by a field of measured MTF values, each for an (x,y) position of the image plane.

[0154] Phase 104 includes a step 110 measuring, by simulation on the current design, the MTF for the blue radiation, in a similar manner to what was described for the green radiation in step 106, by replacing the green radiation with blue radiation.

[0155] For example, blue radiation can be blue radiation with a wavelength between 400 and 500 nm, and in particular equal to 450 nm.

[0156] Step 110 provides an MTF for red radiation represented by a field of measured MTF values, each for an (x,y) position of the image plane.

[0157] Phase 104 comprises a step 112 of determining a quality indicator Q, for iteration i of the improvement phase, as a function of the MTFs measured during steps 106-110.

[0158] The calculation of the quality indicator can be carried out in different ways.

[0159] For example, for a measurement point, the quality indicator can be an average, a mean of squares, a sum, or a sum of squares, etc. of the measured MTF values ​​for this measurement point for the different colors. Optionally, different weights can be used for different colors. For example, at a measurement point (x,y), the MTF value for the color green can be given a higher weight compared to the measured MTF for the color red and for the color blue, etc. In this example, the quality indicator is presented as a field of values, giving for each point (x,y) of the image plane a quality indicator value.

[0160] According to another exemplary embodiment, the field of values ​​previously obtained for the quality indicator can be used to calculate a single quality indicator value, using a predetermined mathematical relationship, taking as input the values ​​contained in said field of values. The mathematical relationship can be a sum, an average, a variance, etc. of the values, or the square of each of the values, contained in the value field. Optionally, different weights can be used for different measurement points. For example, a greater weight can be given to at least one measurement point located in the center of the optical lens and a lesser weight can be given to at least one measurement point located at the periphery of the optical lens. In this example, the quality indicator is in the form of a single value for the current design.

[0161] Phase 104 comprises a step 114 which tests the quality indicator obtained in step 112 to determine whether said quality indicator is satisfactory.

[0162] According to embodiments, the quality indicator can be compared to at least one threshold quality indicator, or a range of threshold quality indicators. When the quality indicator is in the form of a field of values, each for an (x,y) position of the image plane, then the or each threshold quality indicator can also be in the form of a field of values, each for an (x,y) position of the image plane. The comparison can then be carried out position by position. When the quality indicator is in the form of a single value, the or each threshold quality indicator can also be in the form of a single value.

[0163] According to embodiments, the quality indicator can be compared to at least one quality indicator previously measured during a previous iteration of the improvement phase.

[0164] Of course, other examples of implementation are possible and the examples given are in no way limiting.

[0165] If at step 114, the quality indicator is not deemed satisfactory, then the improvement phase 104 comprises a step 116 of modifying the current design. Such a modification of the current design may comprise at least one of the following operations: - replacement of at least one optical element; - addition, or removal, of at least one optical element; - modification of the geometry of at least one optical interface of at least one optical element; - modification of the optical index of at least one optical element; - modification of a distance between at least two optical elements; - modification of the position of at least one optical element; - etc. A new iteration of the optimization phase 104 can then be carried out until a satisfactory quality indicator is obtained.

[0166] If at step 114 the quality indicator is deemed satisfactory, then improvement phase 104 is ended.

[0167] The method 100 then comprises a step 118 of storing the current design as the final design of the optical lens.

[0168] The method 100 may further comprise an optional step 120, measuring a lateral chromatic aberration function, FACL, representative of the lateral chromatic aberration, ACL, of the final design.

[0169] For a given measurement point, the ACL can be measured in different ways. According to an exemplary embodiment, the optical objective is illuminated by simulating a target placed at a certain distance, called the distance from the scene. This distance can be made infinite to obtain a distance from the scene called infinity. The target can be illuminated by white radiation, or successively by green, red and blue radiation. A pattern corresponding to a position (x,y) of the image plane generates on said image plane a spot for each of the colors. The position of each color spot can be detected. The detected positions of the three color spots are then used to calculate a displacement vector, relative to a reference position, which can be the position of one of said three spots, or another position.

[0170] By performing, simultaneously or in turn, the measurement for several positions (x,y) in the image plane it is then possible to determine the FACL. In this case, the FACL is presented in the form of a field of values, each for a position (x,y) of the image plane and each comprising one or more displacement vectors.

[0171] The method 100 may further comprise an optional step 120, measuring a geometric aberration function, FAG, representative of the geometric aberration, AG, of the final design.

[0172] For a measurement point, the FAG can be measured in different ways. According to an exemplary embodiment, the optical objective is illuminated by simulating a target placed at a certain distance, called the distance from the scene. This distance can be made infinite to obtain a distance from the scene called infinity. The target is illuminated by white radiation, or successively by green, red and blue radiation. A pattern located at an angle (0i,yi) relative to the axis of the optical objective, generates on said image plane a spot for each of the colors red, green and blue. The position of each color spot can be detected. The detected positions of the three spots are then used to calculate a displacement distance for each color, relative to the center of the optical objective.Optionally, the displacement distance can be divided by the simulated focal length, so as to obtain an angular magnitude as a function of the angle (0i,yi) of the optical beam entering the optical lens relative to the axis of the optical lens.

[0173] By performing, simultaneously or in turn, the measurement for several angles (0i,yi) relative to the optical axis of the optical objective, it is possible to determine the FAG.

[0174] The method 100 may further comprise an optional step 122, determining and providing at least one lateral chromatic aberration and / or geometric aberration correction function, from the FACL measured during step 120 and / or from the FAG measured during step 122.

[0175] Method 100 of FIGURE 1 designs an optical lens without considering the lateral chromatic aberration and geometric aberration of the resulting design. In other words, these aberrations are completely relaxed during the design of the optical lens.

[0176] Alternatively, it may be desirable to keep these aberrations to an acceptable level, without optimizing the optical lens design for these aberrations.

[0177] FIGURE 2 is a schematic representation of another non-limiting exemplary embodiment of a method according to the present invention.

[0178] The method 200 of FIGURE 2 allows for designing an optical lens while maintaining an acceptable level for lateral chromatic aberration, ACL, and / or geometric aberration. In other words, the method 200 allows for designing the optical lens without completely relaxing ACL and / or GA.

[0179] The method 200 of FIGURE 2 includes all of the steps of the method 100 of FIGURE 1 except for the differences noted below.

[0180] In the method 200 of FIGURE 2, when the quality indicator is deemed satisfactory in step 114, the improvement phase 104 further comprises an optional step 202 of measuring a lateral chromatic aberration function, FACL, for the current design, for example in a similar / identical manner to what was described with reference to step 120, applied to the current design.

[0181] In a step 204, the FACL is compared to a predetermined threshold to maintain an acceptable level of lateral chromatic aberration. If the FACL does not meet the predetermined threshold, then the improvement phase continues with step 116 of modifying the current design.

[0182] If, at step 204, the FACL satisfies the predetermined threshold, then the improvement phase 104 includes an optional step 206, of measuring a geometric aberration function, FAG, for the current design, by example in a similar / identical manner to what was described with reference to step 122, applied to the current design.

[0183] In a step 208, the FAG is compared to a predetermined threshold to maintain an acceptable level of geometric aberration. If the FAG does not satisfy the predetermined threshold, then the improvement phase 104 continues with the step 116 of modifying the current design. Otherwise, the improvement phase 104 is terminated.

[0184] Method 200 continues with step 118 storing the current design as the final design.

[0185] The method 200 does not include steps 120 and 122 since the FACL and the FAG were measured during the last iteration of the improvement phase 104.

[0186] The method 200 may optionally comprise the step 124 of providing at least one aberration correction function, based on the measured FACL and FAG for the final design.

[0187] Method 100 of FIGURE 1, and method 200 of FIGURE 2, realize a design of an optical objective by taking into account the FTO, and in particular the MTF, for each of the color radiations.

[0188] Alternatively, it is possible to design an optical lens by considering the FTO only for a single color radiation, for example green radiation, or red radiation, or blue radiation.

[0189] FIGURE 3 is a schematic representation of another non-limiting exemplary embodiment of a method according to the present invention.

[0190] The method 300 of FIGURE 3 makes it possible to design an optical lens by taking into account the MTF only for a single color radiation, for example green radiation.

[0191] Method 300 includes all of the steps of method 100 except steps 108 and 110.

[0192] The quality indicator used can be the MTF measured for green radiation. In this case, step 112 is confused with step 106, or is not carried out.

[0193] Alternatively, the quality indicator may correspond to the measured MTF for green radiation, in which different weights may be given to different measurement points. For example, a greater weight may be given to at least one measurement point located in the center of the optical lens and a lesser weight may be given to at least one measurement point located at the periphery of the optical lens.

[0194] Alternatively, or in addition, the measured MTF value field for green radiation may be used to calculate a single quality indicator value, using a predetermined mathematical relationship, taking as input the values ​​contained in the measured MTF value field for green radiation. The mathematical relationship may be a sum, mean, variance, etc. of the values, or the square of each of the values, contained in the value field.

[0195] In method 300, red radiation, or blue radiation, may be used instead of green radiation.

[0196] According to other alternatives not shown, the design of the optical objective can be achieved by taking into account two color radiations chosen from green, red and blue radiations.

[0197] According to other alternatives not shown, the design of the optical objective can be carried out starting from the method 200 of FIGURE 2, but using a single color radiation, or two color radiations.

[0198] FIGURE 4 is a schematic representation of a non-limiting exemplary embodiment of a method of manufacturing an optical lens according to the present invention.

[0199] The method 400 of FIGURE 4 can be used to manufacture optical lenses used for imaging, i.e., for acquiring an image or video.

[0200] The method 400 comprises a step 402 of designing the optical lens according to the invention, and in particular according to any one of the methods 100, 200 and 300 of FIGURES 1-3. Step 402 provides a final design, and possibly at least one of the following functions: - a lateral chromatic aberration function, FACL, for the final design; - a geometric aberration function, FAG, for the final design; - a lateral chromatic aberration correction function, FCACL, for the final design; and - a geometric aberration correction function, FCAG, for the final design;

[0201] The method 400 comprises a step 404 of manufacturing an optical lens. The manufacturing of the optical lens is carried out in a conventional and known manner and will therefore not be described in detail here.

[0202] The method 400 may further comprise, optionally, a phase 406 of characterizing an optical lens 00 manufactured in step 404.

[0203] The characterization phase 406 may comprise an optional step 408 of measuring, with a measuring device, a lateral chromatic aberration function, FACL, for the optical objective 00.

[0204] The characterization phase 406 may comprise an optional step 410 of measuring, with a measuring device, a geometric aberration function, FAG, for the optical objective 00 manufactured in step 404.

[0205] The characterization phase 406 may comprise an optional step 412 of determining and providing at least one lateral chromatic aberration and / or geometric aberration correction function, for the optical lens 00 manufactured in step 404.

[0206] According to embodiments, the characterization phase 406 can be carried out for each optical objective manufactured.

[0207] Alternatively, the characterization phase 406 may be carried out for some of the manufactured optical lenses. For example, within the same batch of optical lenses, the characterization phase 406 may be carried out for a single optical lens, or a few optical lenses. The measured aberration function(s), and / or the determined correction function(s), may be used for all the lenses of the same batch.

[0208] A batch of optical lenses may correspond to lenses with the same design. Alternatively, a batch of optical lenses may correspond to lenses with the same design and assembled according to the same assembly recipe.

[0209] FIGURE 5 is a schematic representation of a non-limiting exemplary embodiment of an installation for manufacturing an optical lens according to the present invention.

[0210] The manufacturing facility 500 of FIGURE 5 may be used to manufacture optical lenses used for imaging, i.e., for acquiring an image or video.

[0211] The installation 500 can be configured to implement a manufacturing method according to the invention and in particular the manufacturing method 400 of FIGURE 4.

[0212] The installation 500 comprises an apparatus 502 for designing an optical lens by implementing a method according to the invention, and in particular any one of the methods 100, 200, 300 of FIGURES 1-3. The design apparatus 502 provides a final design for the optical lens, and possibly at least one of the following functions: - a lateral chromatic aberration function, FACL, for the final design; - a geometric aberration function, FAG, for the final design; - a lateral chromatic aberration correction function, FCACL, for the final design; and - a geometric aberration correction function, FCAG, for the final design;

[0213] The design apparatus 502 may be any type of device such as a computer. The design apparatus 502 may perform: - a computer program according to the invention, or - design software used for the design of the optical lens integrating the computer program according to the invention, or implementing a method according to the invention.

[0214] The installation 500 comprises a line 504 for manufacturing optical lens(es). The manufacturing line 504 is in the form of a conventional, known, optical lens manufacturing line and will therefore not be described in detail here.

[0215] The installation 500 may optionally comprise at least one measuring device 506 for characterizing at least one optical lens 00 manufactured in step 504. The at least one measuring device 506 is in particular configured to implement step 406 of the manufacturing method 400 of FIGURE 4.

[0216] FIGURE 6 is a schematic representation of a non-limiting exemplary embodiment of a camera module.

[0217] The camera module 600 of FIGURE 6 includes an optical lens 602 designed in accordance with the present invention, and in particular by any of the methods 100, 200 and 300 of FIGURES 1-3, or manufactured by the method 400 of FIGURE 4. The optical lens 602 may be the optical lens 00 of FIGURES 4-5.

[0218] In the non-limiting example shown in FIGURE 6, the optical lens 602 comprises four lenses 604-610, stacked in a barrel 612 in a stacking direction 614, which also corresponds to the axis 614 of the optical lens 602.

[0219] The camera module 600 further comprises an image sensor 616 associated with the optical lens 602. The image sensor 616 may be any type of image sensor such as a CCD or CMOS sensor.

[0220] Of course, the camera module 600 may include other organs / components which are not shown in FIGURE 4, such as for example a mechanism modifying the imaged viewing angle or a mechanism modifying the imaged sharpness zone.

[0221] The camera module 600 may optionally comprise a module 618 for digitally processing the data captured by the image sensor 616. Such a digital processing module 618 may for example be arranged to perform a correction of the image captured by the image sensor 616, for example to correct the lateral chromatic aberration and / or the geometric aberration. This module 618 may for example integrate one or more previously determined aberration correction functions, for example the correction function(s) determined in steps 124 and 412 described above.

[0222] The processing module 618 may be an independent module. Alternatively, the processing module 618 may be integrated into another module or another application, such as for example a photo application used for the acquisition of image(s).

[0223] The module 618 may be a hardware unit such as a processor, a microchip, a computer, a server, etc. Alternatively, the module 618 may be a software unit, such as an application or a computer program. Alternatively, the module 618 may be a combination of at least one hardware unit and at least one software unit. The module 618 may be an individual module. Alternatively, the module 618 may be integrated into an existing module within a device, such as, for example, a photo application of a device equipped with the camera module 600.

[0224] FIGURE 7 is a schematic representation of a non-limiting exemplary embodiment of a method for acquiring an image according to the invention.

[0225] The method 700 comprises a step 702 of acquiring an image with an optical objective characterized by the present invention, or with a camera module according to the invention, and in particular the camera module 600 of FIGURE 6.

[0226] The method 700 further comprises a step 704 of digitally processing the acquired image. Such digital processing may perform a correction of the acquired image for example to correct, at least in part, the lateral chromatic aberration and / or the geometric aberration, due to the optical objective in the acquired image. Such an aberration correction may for example be performed with at least one aberration correction function such as those obtained in steps 124 and 412 described above.

[0227] FIGURE 8a is a schematic representation of a non-limiting exemplary embodiment of an apparatus according to the present invention.

[0228] The apparatus 810 of FIGURE 8a comprises at least one imaging module according to the present invention, and in particular the imaging module 600 of FIGURE 6.

[0229] In the example shown in FIGURE 8a, the device 810 is a smartphone, or a tablet.

[0230] Optionally, the device 810 may further comprise a display screen 812 equipped with a touch surface 814, for example capacitive.

[0231] The imaging apparatus 810 may further comprise an imaging application 816, such as a photo and / or video application, installed on said apparatus 810 and executed by said apparatus 810. The application 816 may for example integrate the processing module 618 of the imaging module. Alternatively, the processing module 618 may be independent of the application 816.

[0232] FIGURE 8b is a schematic representation of another non-limiting exemplary embodiment of an apparatus according to the present invention.

[0233] The apparatus 820 of FIGURE 8b comprises at least one imaging module according to the present invention, and in particular the imaging module 600 of FIGURE 6.

[0234] In the example shown in FIGURE 8b, the apparatus 820 is a virtual reality, VR, headset or an augmented reality, VA, headset.

[0235] Optionally, the headset 820 may further comprise a display screen 822. Optionally, the headset 820 may further comprise a sensor (not shown) for detecting the position aimed by an eye, or eyes, of the user on said display screen 822.

[0236] The headset 820 may further comprise an imaging application (not shown), such as a photo and / or video application, installed on said device and executed by said device 820. The imaging application may for example integrate the processing module 618 of the imaging module. Alternatively, the processing module 618 may be independent of the imaging application of the headset 820.

[0237] FIGURE 8c is a schematic representation of another non-limiting exemplary embodiment of an apparatus according to the present invention.

[0238] The apparatus 830 of FIGURE 8c comprises at least one imaging module according to the present invention, and in particular the imaging module 600 of FIGURE 6.

[0239] In the example shown in FIGURE 8c, the apparatus 830 is a medical imaging apparatus, such as an endoscope, an ultrasound apparatus, etc.

[0240] Optionally, the medical imaging apparatus 830 may further comprise a display screen 832.

[0241] Optionally, the medical imaging device 830 can further be equipped with a detection surface 834, for example capacitive.

[0242] Optionally, the medical imaging device 830 may further comprise a distal objective 836 for collecting light radiation, which may or may not be part of the imaging module 600.

[0243] The imaging apparatus 830 may further comprise an imaging application (not shown), such as a photo and / or video application, installed on said apparatus 830 and executed by said apparatus 830. The imaging application may for example integrate the processing module 618 of the imaging module. Alternatively, the processing module 618 may be independent of the imaging application of the apparatus 830.

[0244] FIGURE 9 is a schematic representation of a non-limiting exemplary embodiment of a vehicle according to the present invention.

[0245] The vehicle 900 of FIGURE 9 comprises at least one imaging module according to the present invention, and in particular the imaging module 600 of FIGURE 6, for example integrated into a camera 902.

[0246] In the vehicle 900, the camera 902 may for example be arranged on the windshield of the vehicle 900 in the upper part of said windshield, or above the front windshield. Of course, this positioning is given as a non-limiting example and the camera 902 may be arranged elsewhere.

[0247] In the example shown in FIGURE 9, the vehicle 900 is a land vehicle, in particular a car. The vehicle 900 may further comprise a display screen 904 equipped with a touch surface 906, for example capacitive, arranged in the passenger compartment of the vehicle 900.

[0248] The vehicle 900 may further comprise an imaging application 908, such as a photo and / or video application. The imaging application 908 may, for example, integrate the processing module 618 of the imaging module. Alternatively, the processing module 618 may be independent of the imaging application 908.

[0249] Of course, the invention is not limited to a land vehicle. A vehicle according to the invention may be a flying vehicle, such as a flying drone, an airplane, a helicopter, etc. A vehicle according to the invention may be a maritime vehicle, such as a maritime drone, a boat, a submarine, etc.

[0250] The invention is not limited to the examples of devices and vehicles given with reference to the FIGURES. It can be implemented in any type of devices and vehicles.

[0251] Of course, the invention is not limited to the examples which have just been described.

Claims

CLAIMS 1. Method (100;200;300) for designing, with computer-executed design software, an optical lens (00;600) comprising several optical elements (604-610), said method (100;200;300) comprising a step (102) of designing a design, called current design, of said optical lens (00;600), and at least one iteration of a phase (104), called improvement, comprising the following steps: - measurement (106-110), by simulation with said design software, on said current design, of an optical transfer function, OTF, individually for at least one color radiation chosen from the following color radiations: red radiation, green radiation or blue radiation; - determination (112) of a quality indicator based on at least one measured FTO; and - when said quality indicator is not satisfactory, modification (116) of said current design with a view to obtaining a design, called final, for which said quality indicator is satisfactory.

2. Method (100; 200; 300) according to the preceding claim, characterized in that the optical transfer function is: - the modulation transfer function, MTF (for “Modulation Transfer Function” in English), or - the point spread function, PSF (for “Point Spread Function” in English).

3. Method (100; 200; 300) according to any one of the preceding claims, characterized in that the improvement phase (104) is repeated until a quality indicator is obtained whose value reaches a predetermined target value, or a predetermined range of target values, for at least one, and in particular for each, measurement point of the at least one FTO.

4. Method (100;200;300) according to claim 1, characterized in that the improvement phase (104) is repeated until the value of the indicator quality reaches an optimal value, for at least one, and in particular each, FTO measurement point.

5. Method (100;200;300) according to any one of the preceding claims, characterized in that, for at least one color radiation, the measuring step (106,108,110) carries out a measurement of the value of the FTO at several measuring points.

6. Method (300) according to any one of the preceding claims, characterized in that the measuring step (106) carries out the measurement of the FTO only for a single color radiation, the quality indicator being determined as a function of the FTO measured for said radiation.

7. Method (100; 200) according to claims 1 to 5, characterized in that the measuring step (106, 108, 110) carries out the measurement of an FTO for individually for several, in particular each, of the color radiations, the quality indicator being determined as a function of the FTOs measured for said radiations.

8. Method (100;200;300) according to the preceding claim, characterized in that the quality indicator is calculated, for at least one measurement point, with a mathematical relationship taking into account the value of each FTO measured for said measurement point.

9. Method (200) according to any one of the preceding claims, characterized in that it comprises a step (202; 206) of measuring, on the current design: - a lateral chromatic aberration function, FACL; and / or - a geometric aberration function, FAG.

10. Method (100; 200; 300) according to the preceding claim, characterized in that it comprises a step (124) determining at least one correction function: - lateral chromatic aberration, and / or - geometric aberration. for the final design.

11. Method (100; 200; 300) according to any one of the preceding claims, characterized in that the step (116) of modifying the current design comprises at least one of the following steps carried out: - replacement of at least one optical element; - addition, or removal, of at least one optical element; - modification of the geometry of at least one optical interface of at least one optical element; - modification of the refractive index of at least one optical element; - modification of the dependence of the refractive index on the wavelength for at least one optical element; - modification of a distance between at least two optical elements; - modification of the position of at least one optical element; of said current design.

12. Computer program comprising executable instructions which, when executed by a computing device, implement all the steps of the method (100;200;300) according to any one of the preceding claims.

13. Method (400) of manufacturing an optical lens (00) comprising several optical elements, said method (400) comprising the following steps: - obtaining (402) a final design for said optical objective by the method (100;200;300) according to any one of claims 1 to 11; and - manufacturing (404) of said optical lens (00) according to said final design.

14. Imaging module (600) comprising: - an optical lens (00) designed with the method (100;200;300) according to any one of claims 1 to 11; and - an image sensor (601) associated with said optical lens (00).

15. Method (700) for acquiring an image of a scene, said method (700) comprising the following steps: - acquisition (702) of an image with an optical objective (OO) designed by the method (100; 200; 300) according to any one of claims 1 to 11, and - digital processing (704) of said image for the correction of said image.

Images