Method for determining the position of cosmetic defects of a transparent optical device

Abstract

Method for determining the position of cosmetic defects of a transparent optical device, the transparent optical device comprising a front surface and a rear surface, the method comprises: - acquiring a first image of cosmetic defects of the optical device using a background pattern transmissive imaging method with an acquisition device configured to acquire images from one of the surface of the optical element, with a depth of field smaller than or equal to the transparent optical device total height and focusing at a first predetermined distance D1 along a Z-axis perpendicular to one of the surface of the transparent optical device at a reference point of the said surface. - determining the position of each cosmetic defect along the Z-axis in the whole volume of the transparent optical device by evaluating the sharpness of the cosmetic defects in the first image of cosmetic defects.

Description

[0001] Method for determining the position of cosmetic defects of a transparent optical device

[0002] FIELD OF THE DISCLOSURE

[0003] The disclosure relates to a method for determining the position of cosmetic defects of a transparent optical device, the transparent optical device comprising a front surface and a rear surface.

[0004] The disclosure further relates to a method for sorting a transparent optical device, a method for manufacturing an optical lens, and a machine for managing cosmetic defects on an optical device.

[0005] The disclosure also relates to a computer program product comprising one or more stored sequences of instructions that are accessible to a processor and which, when executed by the processor, causes the processor to carry out the steps of the method according to the disclosure and the computer readable medium carrying one or more sequences of instructions of the computer program product according to the disclosure.

[0006] BACKGROUND OF THE DISCLOSURE

[0007] Usually, the quality of an optical device is controlled either with a human’s eye or with an automatic vision system.

[0008] However, the control of the quality of an optical device with a human’s eye is expensive, takes time and needs significant human resources.

[0009] Further, the usual automatic vision systems are not able to consider only relevant cosmetic defects during cosmetic inspection of the optical device with good accuracy and repeatability like the eye of a trained operator.

[0010] A method for evaluating cosmetic defects of an optical device is disclosed in WO20 19 / 077166. Such method does not provide a fully accurate and automatic estimate of the position of the cosmetic along a Z-axis perpendicular to one of the surface of the optical lens at a reference point. The Z-axis position of the cosmetic defect may be important since such position may have an impact on the final optical device, and may thus have an impact on a cosmetic verdict of the optical device. For example, when the optical device is a semi-finished optical lens, cosmetic defects on the unfinished optical surface may not have the same impact on the final optical lens as cosmetic defects present on the finished surface. Indeed, the unfinished surface is still to be machined. The cosmetic defect is therefore to be removed during the machining step.

[0011] Thus, there is a need for a method which allows determining the position of cosmetics defects of a transparent optical device and in particular the Z-axis positions of such cosmetic defects.

[0012] One object of the disclosure is to provide such method.

[0013] SUMMARY OF THE DISCLOSURE

[0014] To this end, the disclosure proposes a method for determining the position of cosmetic defects of a transparent optical device, the transparent optical device comprising a front surface and a rear surface, the method comprises:

[0015] - acquiring a first image of cosmetic defects of the optical device using a background pattern transmissive imaging method with an acquisition device configured to acquire images from one of the surface of the optical element, with a depth of field smaller than or equal to the transparent optical device total height and focusing at a first predetermined distance DI along a Z-axis perpendicular to one of the surface of the transparent optical device at a reference point of the said surface.

[0016] - determining the position of each cosmetic defect along the Z-axis in the whole volume of the transparent optical device by evaluating the sharpness of the cosmetic defects in the first image of cosmetic defects.

[0017] Advantageously, acquiring an image with a depth of field smaller than or equal to the transparent optical device total height and focusing at a first predetermined distance DI along a Z-axis perpendicular to one of the surfaces of the transparent optical device at a reference point of the said surface allows obtaining efficiently and accurately the position of each cosmetic defect along the Z-axis.

[0018] Therefore, when using the method of the disclosure, one may easily and accurately determine if a defect is on one of the surfaces of the transparent optical device and in particular if the cosmetic defect is on one of the surfaces of the transparent optical lens to be manufactured.

[0019] According to embodiments, the method according to the disclosure may further comprise one or several of the following features according to any possible combination:

[0020] - the method further comprises acquiring a second image of said cosmetic defects of the transparent optical device using said background pattern transmissive imaging method with the said acquisition device configured to acquire images from the said one of surface of the optical element, with a depth of field smaller than or equal to the transparent optical device total height and focusing at a second predetermined distance D2 along said Z-axis, wherein the position of each cosmetic defect in the whole volume of the transparent optical device is determined by comparing the sharpness of the cosmetic defects in the images of cosmetic defects; and / or

[0021] - the acquisition device is arranged to acquire spatial contrast such that the background pattern lies outside the depth of field, allowing cosmetic defects to be evaluated based on their relative sharpness or blurriness with respect to the focal plane; and / or

[0022] - the acquisition device and the transparent optical device are held in a fixed spatial configuration during the image acquisition; and / or

[0023] - the sharpness evaluation is performed on at least one cosmetic defect that appears blurred or with low sharpness in the image, and the Z-axis position is determined by comparing the degree of sharpness or blurriness of the defect relative to other image elements and to the focal plane. ; and / or

[0024] - the depth of field is configured optically, for example while maintaining a fixed mechanical displacement, for example a fixed spatial configuration, between the acquisition device and the transparent optical device, wherein the optical configuration is done by adjusting optical characteristics of the system, for example at least one of focal length, aperture, size of the detector, sensor distance ; and / or

[0025] - at least one additional image is acquired at a second predetermined distance D2, and the position of each cosmetic defect is determined by comparing the sharpness of the cosmetic defects in the first and second images; and / or

[0026] - the method further comprises prior to determining the position of each cosmetic defect, acquiring a third image of cosmetic defects of the transparent optical device using said background pattern transmissive imaging method with the said acquisition device configured to acquire images from the first surface of the optical element, with a depth of field smaller than or equal to 4mm, preferably smaller than or equal to 2 mm, and focusing at a distance corresponding to the smallest distance between the sensor of the acquisition device and the first surface of the optical device to which is added half the central thickness of the transparent optical device; and / or

[0027] - the method further comprises prior to determining the position of each cosmetic defect, receiving geometrical data relating to the shape and relative position of the front and rear surfaces of the transparent optical device and wherein said geometrical data are used to determine the position of the cosmetic defects within the transparent optical device; and / or

[0028] - the transparent optical device has an optical center and a main optical axis; and / or

[0029] - the method further comprises prior to the acquisition steps configuring the acquisition device and placing the transparent optical device so as to have the main optical axis of the acquisition device and the main optical axis of the transparent optical device aligned; and / or

[0030] - the position of each cosmetic defect comprises at least the altitude of the cosmetic defect along the main optical axis of the transparent optical device; and / or

[0031] - the images of cosmetic defect have a common spatial reference between them or each image of cosmetic defect is provided with a geometrical transformation so as to shift to a common spatial reference; and / or

[0032] - the transparent optical device is a semi-finished ophthalmic lens; and / or - the transparent optical device is a transparent mold and / or inserts for molds; and / or

[0033] - the method further comprises:

[0034] • acquiring an initial image of cosmetic defects of the transparent optical device using a background pattern transmissive imaging method with an acquisition device configured to acquire images from the rear surface of the optical element, with a depth of field greater than or equal to 8 mm, and

[0035] • determining the presence of cosmetic defects to monitor on or within the transparent optical device and the position of said cosmetic defects to monitor in a (X,Y)-plane perpendicular to the Z-axis,

[0036] • determining the first predetermined distance DI based on the geometrical data so as to correspond to the first surface at the position of the cosmetic defects in the (X,Y)-plane, and

[0037] • evaluating the sharpness of each cosmetic defects in the first image so as to identify if said defects is near the front surface; and / or

[0038] - the method may further comprise determining the distance of the cosmetic defect to a reference point of the transparent optical device, for example the optical center or geometrical center of the transparent optical device and the geometry of the transparent optical device.

[0039] Furthermore, the disclosure proposes a method for sorting a transparent optical device, the method comprising:

[0040] - providing a transparent optical device,

[0041] - determining the presence of cosmetic defects on or within the transparent optical device,

[0042] - determining the position of cosmetic defects according to the method for determining the position of cosmetic defects of the disclosure,

[0043] - sorting the transparent optical device based on the presence of cosmetic defects and the position of said cosmetic defects. Advantageously, the method for sorting an optical device of the disclosure allows sorting optical devices based on the cosmetic quality of the optical devices prior to the manufacturing or the machining the optical devices, for example into ophthalmic lenses.

[0044] The method for sorting a transparent optical device may further comprise deciding if the transparent optical device is accepted or rejected based at least on the position of the cosmetic defects. It may further comprise deciding that the optical device needs to be reevaluated by another evaluation method or needs human intervention.

[0045] According to an embodiment, the transparent optical device has a finished surface and the method for sorting a transparent optical device further comprises scoring the cosmetic defect based on the type of cosmetic defect and the position of the cosmetic defect relative to the finished surface of the transparent optical device along the Z-axis, the transparent optical device being sorted based on the scoring of the cosmetic defects.

[0046] According to embodiments, the method for sorting a transparent optical device according to the disclosure may further comprise a decision step, during which a decision is stated if the transparent optical device is accepted or rejected. During the decision step, the decision if the optical device is accepted or rejected may be manually stated.

[0047] The disclosure also relates to a method for manufacturing an optical lens, the method comprising:

[0048] - providing a semi-finished optical lens,

[0049] - sorting the semi-finished optical lens based at least on the method for sorting a transparent optical device according to the disclosure,

[0050] - positioning the semi-finished optical lens on a blocking device for machining and / or surfacing,

[0051] - machining and / or surfacing the unfinished surface of the semi-finished optical lens.

[0052] The disclosure also relates to a machine for managing cosmetic defects on an optical device comprising: - an optical device cosmetic defect acquisition module configured to acquire image of cosmetic defects of the transparent optical device using fringe deflectometry method,

[0053] - an analytical module configured to apply a method for determining the position of cosmetic defects according to the disclosure, for example based on geometry data representative of the geometry of the semi-finished optical lens.

[0054] It is to be noted that the steps needed, and their order of application may be adapted to the specific needs of the user or operator using the process of the disclosure. On specific cases, a human operator may also accomplish some of the steps, for example a final control or determining if the optical devices passes or fails. Further, for a given industry, for example in the manufacturing of spectacle lenses, the predetermined quality factor threshold may also be adapted depending on different customer needs. Indeed, depending on the cosmetic quality required by each customer, some lenses which do not satisfy the needs for a first customer may be allowed for a second customer.

[0055] Some combination of steps of the method for determining the position of cosmetic defect(s) of a transparent optical device according to the disclosure, in a specific order, allow advantageously having a precise and quick evaluation of the position of the cosmetic defects of the optical device. Of course, other combination of the steps of the method for determining the position of cosmetic defect(s) of an optical device according to the disclosure, in another order, may be carried out.

[0056] The disclosure further relates to a computer program product comprising one or more stored sequences of instructions that are stored, for instance, on a non- transitory computer memory, and that are accessible to a processor and which, when executed by the processor, causes the processor to carry out the steps of the method for determining the position of cosmetic defect(s) of an optical device according to the disclosure.

[0057] The disclosure further relates to a computer readable storage medium having a program recorded thereon, where the program makes the computer execute the steps of the method for determining the position of cosmetic defects of a transparent optical device according to the disclosure.

[0058] The disclosure further relates to a computer readable medium comprising one or more stored sequences of instruction of a computer program product, wherein the one or more sequences of instructions are accessible to a processor and which, when executed by the processor, causes the processor to carry out the steps of the method for determining the position of cosmetic defect(s) of a transparent optical device according to the disclosure.

[0059] The disclosure further relates to a computer program product comprising one or more stored sequences of instructions that are stored, for instance, on a non- transitory computer memory, and that are accessible to a processor and which, when executed by the processor, causes the processor to carry out the steps of the method for sorting a transparent optical device according to the disclosure.

[0060] The disclosure further relates to a computer readable storage medium having a program recorded thereon, where the program makes the computer execute the steps of the method for sorting a transparent optical device according to the disclosure.

[0061] The disclosure further relates to a computer readable medium comprising one or more stored sequences of instruction of a computer program product, wherein the one or more sequences of instructions are accessible to a processor and which, when executed by the processor, causes the processor to carry out the steps of the method for sorting a transparent optical device according to the disclosure.

[0062] Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions utilizing terms such as "computing", "calculating", “processing” or the like, refer to the action and / or processes of a computer or computing system, or similar electronic computing device, that manipulate and / or transform data represented as physical, such as electronic, quantities within the computing system's registers and / or memories into other data similarly represented as physical quantities within the computing system's memories, registers or other such information storage, transmission or display devices.

[0063] Embodiments of the present disclosure may include apparatuses for performing the operations herein. This apparatus may be specially constructed for the desired purposes, or it may comprise a general purpose computer or Digital Signal Processor ("DSP") selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a computer readable storage medium, such as, but is not limited to, any type of disk including an application specific integrated circuit (ASIC), floppy disks, optical disks, CD-ROMs, magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs) electrically programmable read-only memories (EPROMs), electrically erasable and programmable read only memories (EEPROMs), magnetic or optical cards, or any other type of media suitable for storing electronic instructions, and capable of being coupled to a computer system bus.

[0064] The processes presented herein are not inherently related to any particular computer or other apparatus. Various general purpose systems may be used with programs in accordance with the teachings herein, or it may prove convenient to construct a more specialized apparatus to perform the desired method. The desired structure for a variety of these systems will appear from the description below.

[0065] In addition, embodiments of the present disclosure are not described with reference to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the disclosures as described herein.

[0066] BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Other characteristics and advantages of the disclosure will become more apparent from the claims and from the following description of some embodiments given by way of example without limitation with reference to the drawings, in which:

[0068] Figure 1 is a flowchart of the different steps of a method for determining the position of cosmetics defects of a transparent optical device according to the disclosure,

[0069] Figure 2 represents an example of a transparent optical device,

[0070] Figure 3 is a flowchart of a method for sorting transparent optical devices, Figure 4 is a flowchart of a method for manufacturing an optical lens, and Figure 5 is a schematic representation for managing cosmetic defects on an optical device.

[0071] Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help improve the understanding of the embodiments of the present disclosure.

[0072] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0073] The disclosure relates to a method for determining the position of cosmetic defects of a transparent optical device, the transparent optical device comprising a front surface and a rear surface. The method may be implemented by computer means. A flowchart of the different steps of the method for determining the position of cosmetic defects of a transparent optical device according to the disclosure is represented in figure 1.

[0074] The present disclosure can be used for all kinds of transparent optical devices. A transparent optical device may be such as optical lenses and optical blocks, and in particular ophthalmic elements and devices and transparent molds used to obtain optical devices or inserts for molds. Non-limiting examples of ophthalmic elements include corrective and non-corrective lenses, including single vision or multi-vision lenses, which may be either segmented or non- segmented, as well as other elements used to correct, protect, or enhance vision, including without limitation contact lenses, intra-ocular lenses, magnifying lenses and protective lenses or visors such as found in spectacles, glasses, goggles and helmets. The transparent optical device of the present disclosure is preferably a semi-finished optical lens and more preferably a corrective or non-corrective semi-finished optical lens designed to have a surface to be machined so as to be used in spectacles, glasses, goggles and helmets.

[0075] The transparent optical device may be a tinted optical device, a polarized optical device, or an uncoated optical device.

[0076] As illustrated on figure 2, the optical device 10 may comprise a first surface 11, for instance a front surface, a second surface 12, for instance a rear surface, and a peripheral surface joining the front and rear surface.

[0077] According to an embodiment of the disclosure, the transparent optical device has a reference point 14, such as an optical center or geometrical center and a main optical axis.

[0078] A cosmetic defect is a defect having an impact on a visual aspect of the optical device.

[0079] A cosmetic defect may be an extended defect such as a scratch, a spread defect, a varnish drop, a varnish wave, an internal defect, a polarized mark, or a concentric streak, punctual defects, pits, bumps, blisters.

[0080] A cosmetic defect is a defect formed during a previous processing or handling step, and may be a point defect such as a fiber, a dirty insert, a handling scratch, a water mark, a crater, a black point, a dust...

[0081] Some cosmetic defect are removable cosmetic defects, namely cleanable cosmetic defects, may relate to a fiber on the optical device, a dust on the optical device, a water mark on the optical device, a varnish wave on the optical device, a varnish drop on the optical device, or a spread defect on the optical device. For instance, if all the cosmetic defects are removable cosmetic defects, the optical device may be accepted.

[0082] Cosmetic defects of the optical device which are irremovable cosmetic defects, namely cosmetic defects that cannot be cleaned, may relate to a scratch on a surface of the optical device, an internal defect of the optical device, a dirty insert on the optical device, a handling scratch on the optical device, a crater on the optical device, a black point on the optical device, a concentric streak on the optical device, a polarized mark on the optical device, or a spread defect on the optical device. For instance, if the front surface of the optical device comprises irremovable cosmetic defects, the optical device may be refused.

[0083] The position of the cosmetic defect on the transparent optical device is of great importance. Indeed, depending on the position of the cosmetic defect the transparent optical device may be used or not.

[0084] For example, the transparent optical device may be an un-edged transparent optical device and cosmetic defect that are positioned in the part of the transparent optical device that is to be removed during the edging process do not have the same impact on the quality of the transparent optical device than the cosmetic defects that are to be present on the edged transparent optical device.

[0085] Furthermore, at least one surface of the transparent optical device may be machined, polished or coated. Therefore, determining the Z-axis position of a cosmetic defect is important. Indeed, a cosmetic defect that is on a surface that is to be machined does not have the same impact as a cosmetic defect present on a finished surface of the transparent optical device.

[0086] Therefore, there is a clear need for a method for determining the position, in particular the Z-axis position, of a cosmetic defect of a transparent optical device.

[0087] As represented on figure 1, the method for determining the position of cosmetics defects of a transparent optical device comprises:

[0088] - a first image acquisition step S5, and

[0089] - a position determining step S9.

[0090] During the first image acquisition step S5, a first image of cosmetic defect(s) of the optical device is acquired. For acquiring the first image a background pattern transmissive imaging method is used. Such background pattern transmissive imaging method is carried out with an acquisition device configured to acquire images from one of the surface of the optical element, with a depth of field smaller than or equal to the transparent optical device total height and focusing at a first predetermined distance DI along a Z-axis perpendicular to one of the surface of the transparent optical device at a reference point of the said surface.

[0091] In particular, the background pattern transmissive imaging method used according to the disclosure is configured such that the acquisition device is focused on the transparent optical device and not on the background pattern. The background pattern is not intended to be imaged sharply. It is used to generate an image with spatial variation that allows visualization of cosmetic defects. Such configuration is commonly used in known imaging methods including deflectometry, wherein the focus is not on the pattern but on the object. The method of the disclosure therefore remains in line with existing optical configurations and uses the background pattern exclusively to facilitate defect detection without requiring the pattern to be in focus in the image acquired with the acquisition device.

[0092] According to an embodiment of the disclosure, the background pattern transmissive imaging method is implemented with a reduced depth of field and a fixed imaging configuration. According to an embodiment of the disclosure, one or more image is acquired at predetermined distances with a fixed acquisition setup, and the sharpness or blurriness of cosmetic defects is evaluated to determine their position along the Z-axis. This implementation differs from known methods, which either do not address depth localization or determine depth only for sharply imaged features, and do not describe the use of a reduced depth of field over a large observation area suitable for evaluating cosmetic defects across the full extent of a transparent optical device. In an embodiment, “the sharpness (or blurriness) of cosmetic defects is evaluated to determine their position along the Z-axis” means in the specification that the sharpness level, ei: blurriness or blurriness level of a cosmetic defect is used to evaluate a depth of said cosmetic defect even (or especially) when the cosmetic defect isn’t sharp enough on the image. It can be done by comparing the blurriness to a known position of the sharp field with regard to the observed device, it can also be done by knowing further the dimension of the depth of field, and / or by comparing further to a sharpness level of a sharper feature, and / or to a sharpness level or blurriness level of the same cosmetic level seen in another image, build with another position of the depth of field, or using tables or abacuses.

[0093] In particular, the predetermined distance DI is chosen so as to correspond to a position between the rear and front surface of the transparent optical device. Short depth of field is a well-known optical effect often used in photography to make sharper the obj ect in the focus, the obj ect on which one wants to concentrate the attention of the viewer and blur the other objects on the photo which are physically situated either behind or in front of the object in the focus. The distance on which the foreign object becomes not-in-focus, i.e. blurred, depends on the optical characteristics of the system, for example focal length of the objective, size of the detector and the aperture used during the acquisition.

[0094] The inventors have the idea that by adjusting the system allowing to carry out a background pattern transmissive imaging method certain, one may use the described principle of short depth of field focusing the attention only on one analyzed side of the transparent optical device and blurring all the rest on the image.

[0095] An adaptation of the background pattern transmissive imaging method with a reduced depth of field allows to detect cosmetic defects on one side, for example the unfinished surface, of a transparent optical device such as a semi-finished optical or ophthalmic lens.

[0096] The use of a reduced depth of field, for example smaller than the total height of the transparent optical device, enables the selection of a region of interest within the transparent optical device, for example the front surface, the rear surface, or an intermediate layer. In contrast with methods using a depth of field greater than the height of the transparent optical device, which make visible all the cosmetic defects within the optical volume at once, the reduced depth of field of the disclosure allows focusing on one portion of the optical volume. This configuration allows limiting the detection of cosmetic defects to selected depth zones.

[0097] The depth of field may be adapted by changing the camera sensor size, focus, for example objective lens, aperture and distance sample-sensor we can reduce the depth of field.

[0098] During the position determining step S9, the position of each cosmetic defect along the Z-axis in the whole volume of the transparent optical device by evaluating the sharpness of the cosmetic defects in the first image of cosmetic defects.

[0099] An example of a transparent optical device is represented on figure 2.

[0100] The transparent optical device 10 has a front surface 11 and a rear surface 12. The front and rear surfaces are connected by an external periphery surface 14. In use of the resulting finished optical lens, the front face 11 is disposed nearest the object being viewed.

[0101] The front surface 11 may typically comprises a surface design associated with a first reference system.

[0102] The rear surface 12 is to be modified by a machining method so as to provide, for example the rear surface 13 of a finished optical lens, represented by the dotted line. Rear surface 12 is to be machined by a machining tool so that the rear surface 13 is orientated with respect to the first reference system.

[0103] The transparent optical device 10 may be obtained by molding or machining or additive manufacturing.

[0104] According to an embodiment of the disclosure, the transparent optical device has an optical center 14 and a main optical axis 16.

[0105] As illustrated on figure 1, the method according to the disclosure may comprise prior to the first image acquisition step configuring the acquisition device and placing the transparent optical device 10 so as to have the main optical axis of the acquisition device and the main optical axis 16 of the transparent optical device aligned.

[0106] Such alignment helps determining the Z-axis position of the cosmetic defect. In such configuration the Z-axis corresponds to the same direction as the main optical axis 16, for example is the main optical axis.

[0107] Typically, the method of the disclosure allows determining at least the altitude of a cosmetic defect along the main optical axis of the transparent optical device.

[0108] As illustrated on figure 1, according to an embodiment of the disclosure, the method for determining the position of the cosmetic defects may comprise: an initial image acquisition step SI, a cosmetic defect presence determining step S2, a first predetermined distance DI determining step S3, a sharpness evaluation step S4.

[0109] During the initial image acquisition step SI, an initial image of cosmetic defects of the transparent optical device is acquired. The acquisition of the initial image of cosmetic defects is done using a background pattern transmissive imaging method with an acquisition device configured to acquire images from the rear surface of the optical element, with a depth of field greater than or equal to 8 mm, and for example smaller than or equal to 20 mm.

[0110] During the cosmetic defect presence determining step S2, the presence of cosmetic defects to monitor is determined on or within the transparent optical device. The position of said cosmetic defects to monitor in a (X,Y)-plane perpendicular to the Z-axis is determined.

[0111] Based on the geometrical data of the transparent optical device, in particular the front and rear surfaces and the distance and orientation of both surface, one may determine a best adapted predetermined distance DI during the first predetermined distance DI determining step S3.

[0112] During the sharpness evaluation step S4, the sharpness of each cosmetic defect(s) in the first image is evaluated so as to identify if said cosmetic defects is near a surface, for example to determine if a cosmetic defect is closer to the front surface or the rear surface of the transparent optical device. In the whole of the specification, unless mentioned otherwise “the sharpness” means a sharpness level, which can be on a scale between “sharp” and “totally blurry”. For the specification, “sharpness” can often be replaced by “sharpness or blurriness” ; indeed it can mean alternatively a “blurriness level”. Accordingly, a sharpness evaluation step means evaluating the sharpness level of a cosmetic defect or feature on the image.

[0113] The method of the disclosure may typically comprise using a reduced field image acquisition method to determine the Z-axis position of the cosmetic defect.

[0114] As illustrated on figure 1, the method for determining the position of cosmetic defect(s) of a transparent optical device may comprise a second image acquisition step S6.

[0115] During the second image acquisition step S6, a second image of said cosmetic defect(s) of the transparent optical device is acquired using said background pattern transmissive imaging method with the said acquisition device configured to acquire images from the said one of surface of the optical element with a depth of field smaller than or equal to the transparent optical device total height and focusing at a second predetermined distance D2 along said Z-axis. The second predetermined distance D2 is different from the first predetermined distance DI. For example, the difference between DI and D2 is greater than or equal to 1mm, for example greater than or equal to 2 mm, for example greater than or equal to 3 mm, for example greater than or equal to 5 mm.

[0116] The position of each cosmetic defect in the whole volume of the transparent optical device may be determined by comparing the sharpness of the cosmetic defect(s) in the first and second images of cosmetic defect(s).

[0117] During the sharpness evaluation step, the method of the disclosure may evaluate the relative sharpness / blurriness of the cosmetic defects in at least one image acquired with a short depth of field and determine the position of the cosmetic defect along the Z-axis based on such relative sharpness / blurriness. The method of the disclosure may be used to determine the relative positions of at least two cosmetic defects along the Z-axis at least one having a low sharpness value.

[0118] According to an embodiment, the cosmetic defect does not necessarily appear as a sharp and well-resolved object in the at least one image (nor in any of the images). Nevertheless, by comparing the level of sharpness / of blurriness of the cosmetic defect in multiple images acquired at different predetermined distances or by comparing the level of sharpness / blurriness with a cosmetic defect of a different sharpness / blurriness, or even with a cosmetic defect being sharp / well resolved in at least one image, the position of the cosmetic defect along the Z-axis can be determined. The evaluation may be carried out even for blurred defects, based on the determined relationship between defocus blur and object depth.

[0119] The Z-axis position of each cosmetic defect in the whole volume of the transparent optical device is determined by comparing the sharpness of each cosmetic defect(s) in the images of cosmetic defect(s). For example, a cosmetic defect that appears sharper in the second image may be considered at a distance D2 along the Z-axis whereas a cosmetic defect sharper in the first image may be considered at a distance DI along the Z-axis.

[0120] According to an embodiment, the method for determining the position of cosmetic defects is based on a static acquisition setup and the comparative sharpness of the cosmetic defects in at least two images acquired with a short depth of field. The method does not require ray tracing, surface reconstruction, or mechanical displacement of the optical components. The sharpness evaluation is performed across images acquired at different focal distances, and allows determining the Z-position of cosmetic defects within the transparent optical device. Such method is not disclosed in known systems relying on deflectometry, stereovision, or microscope observation.

[0121] According to an embodiment of the disclosure, the distance DI corresponds to the front surface of the transparent optical device and the distance D2 corresponds to the rear surface of the transparent optical device.

[0122] As illustrated on figure 1, the method according to the disclosure may comprise prior to determining the position of each cosmetic defect, a third image acquisition step S7.

[0123] During the third image acquisition step S7, a third image of cosmetic defect(s) of the transparent optical device is acquired using the background pattern transmissive imaging method with the same acquisition device configured to acquire images from the first surface of the optical element, with a depth of field smaller than or equal to 4mm, preferably smaller than or equal to 2 mm, and focusing at a distance corresponding to the smallest distance between the sensor of the acquisition device and the first surface of the optical device to which is added half the central thickness of the transparent optical device.

[0124] Preferably, the image acquisition device and the transparent optical device are in the same position between each image acquisition step. Alternatively, one may compensate for the change of position between the image acquisition device and the transparent optical device if the relative positions between each image acquisition step is know accurately.

[0125] To make the Z-axis position determination easier and more accurate, the method according to the disclosure may comprise prior to the position determining step S9, a data receiving step S8.

[0126] During the data providing step S8, geometrical data relating to the shape and relative position of the front and rear surfaces of the transparent optical device are provided. The provided geometrical data are used to determine the position of the cosmetic defects within the transparent optical device. The geometrical data may be received form a distant entity or retrieve from a data base or obtain by a measuring step of the transparent optical device.

[0127] Advantageously, the method of the disclosure using a reduced depth image acquisition method allows determining easily and accurately the Z-axis position of cosmetic defect and therefore helps distinguish the cosmetic defect that may be removed upon machining form the cosmetic defect that are on a un-finished surface.

[0128] The disclosure further relates to a method for sorting a transparent optical device. The method may be implemented by computer means. A flowchart of the different steps of the method for sorting a transparent optical device according to the disclosure is represented in figure 3.

[0129] As illustrated on figure 3, the method for sorting a transparent optical device comprises at least : a transparent optical device providing step SI 00, a cosmetic defect presence determining step SI 02, a cosmetic defect position determining step SI 03, a sorting step SI 04.

[0130] During the transparent optical device providing step SI 00, a transparent optical device to be sorted is provided. The transparent optical device may be of any of the kind describe previously in relation with the method for determining the position of a cosmetic defect.

[0131] During the cosmetic defects presence determining step SI 02, the presence of at least one cosmetic defect on or within the transparent optical device is determined.

[0132] The presence of cosmetic defect(s) may be determined using any known method, for example visual inspection or using a background pattern transmissive imaging method with an acquisition device configured to acquire images from one of the surface of the optical element.

[0133] During the cosmetic defects position determining step SI 03, the position of the at least one cosmetic defect identified during the cosmetic defect presence determining step SI 02 is determined. The position of the at least one cosmetic defect may be determined using the method of the disclosure described in detail in relation with figure 1.

[0134] During the sorting step SI 04, the transparent optical device is sorted based on the presence of cosmetic defects and the position of said cosmetic defects.

[0135] The sorting of the transparent optical device may be done applying a quality score as disclosed in WO2019077166. The quality score being calculated taking into account the Z-axis position of the cosmetic defect, in particular the Z-axis position relative to an unfinished surface of the transparent optical device or a surface that has not optical impact for a transparent mold.

[0136] Based on the sorting step SI 04 on may decide if the transparent optical device is accepted or rejected based on the quality score, for example based at least on the position of the cosmetic defects.

[0137] According to an embodiment, the transparent optical device has a finished surface and the method further comprises scoring the cosmetic defect based on the type of cosmetic defect and the position of the cosmetic defect relative to the finished surface of the transparent optical device along the Z-axis, the transparent optical device being sorted based on the scoring of the cosmetic defects.

[0138] Advantageously, the method according to the disclosure allows distinguishing whether a cosmetic defect is located near the finished surface, within the volume, or near the surface to be surfaced of a semi-finished optical lens. The determined position of the cosmetic defect is then used for sorting the transparent optical device based on its cosmetic quality. For example, a cosmetic defect located near the front surface of the lens may have an impact on the cosmetic verdict, while a defect located on the unfinished surface may be removed during a subsequent surfacing step. The method of the disclosure therefore provides functional information for surfacing decisions.

[0139] Advantageously, the method according to the disclosure enables determining the position of cosmetic defects in a transparent optical device without requiring that each defect be individually brought into focus or imaged in a separate focal plane. The transparent optical device may then be sorted based on the position of the cosmetic defects and the expected impact of said defects after machining. By using a background pattern transmissive imaging method with a depth of field smaller than the total height of the optical device, and analyzing the sharpness or blurriness of the defects across multiple acquisitions, the method provides functional data enabling cosmetic classification. This approach improves manufacturing yield by avoiding the rejection of devices with non-relevant defects.

[0140] As illustrated on figure 4, the disclosure also relates to a method for manufacturing an optical lens, the method comprising:

[0141] - a semi-finished optical lens providing step S200,

[0142] - a sorting step S201,

[0143] - a positioning step S202, and

[0144] - a machining step S203.

[0145] During the semi-finished optical lens providing step S200, a semi-finished optical lens is provided. The semi-finished optical lens as a finished surface, for example the front surface, and an un-finished surface to be machined so as to be adapted to the wearer, for example the rear surface.

[0146] During the sorting step S201, the semi-finished optical lens is sorted based on the method for sorting a transparent optical device according to the disclosure.

[0147] If the semi-finished optical lens is considered acceptable, based on the type and position of the cosmetic defect, the un-finished surface of the semi-finished optical lens is to be machined.

[0148] During the positioning step S202, the semi-finished optical lens is blocked on a blocking device for machining and / or surfacing.

[0149] The blocking position may be adapted to the identified cosmetic defect(s), in particular to the position of the identified cosmetic defect(s).

[0150] During the machining step, the un-finished surface of the semi-finished optical lens is machined so as to provide a finished optical lens adapted to the wearer.

[0151] As illustrated on figure 5, the disclosure also relates to a machine 300 for managing cosmetic defects on an optical device comprising: - an optical device cosmetic defect acquisition module 310 configured to acquire image of cosmetic defects of the transparent optical device using fringe deflectometry method,

[0152] - an analytical module 312 configured to apply a method for determining the position of cosmetic defects.

[0153] The disclosure has been described above with the aid of embodiments without limitation of the general inventive concept. Moreover, the embodiments of the disclosure may be combined without any restriction.

[0154] Many further modifications and variations will suggest themselves to those skilled in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the disclosure, that being determined solely by the appended claims.

[0155] In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that different features are recited in mutually different dependent claims does not indicate that a combination of these features cannot be advantageously used. Any reference signs in the claims should not be construed as limiting the scope of the disclosure.

Claims

CLAIMS1. Method for determining the position of cosmetic defects of a transparent optical device, the transparent optical device comprising a front surface and a rear surface, the method comprises:- acquiring a first image of cosmetic defects of the optical device using a background pattern transmissive imaging method with an acquisition device configured to acquire images from one of the surface of the optical element, with a depth of field smaller than or equal to the transparent optical device total height and focusing at a first predetermined distance DI along a Z-axis perpendicular to one of the surface of the transparent optical device at a reference point of the said surface- determining the position of each cosmetic defect along the Z-axis in the whole volume of the transparent optical device by evaluating the sharpness of the cosmetic defects in the first image of cosmetic defects.

2. The method according to claim 1, wherein the method further comprises:- acquiring a second image of said cosmetic defects of the transparent optical device using said background pattern transmissive imaging method with the said acquisition device configured to acquire images from the said one of surface of the optical element, with a depth of field smaller than or equal to the transparent optical device total height and focusing at a second predetermined distance D2 along said Z-axis, wherein the position of each cosmetic defect in the whole volume of the transparent optical device is determined by comparing the sharpness of the cosmetic defects in the images of cosmetic defects.

3. The method according to claim 2, further comprising prior to determining the position of each cosmetic defect, acquiring a third image of cosmetic defects of the transparent optical device using said background pattern transmissive imaging method with the said acquisition device configured to acquire images from the first surface of the optical element, with a depth of field smaller than or equal to 4 mmand focusing at a distance corresponding to the smallest distance between the sensor of the acquisition device and the first surface of the optical device to which is added half the central thickness of the transparent optical device.

4. The method according to any of the preceding claims, further comprising prior to determining the position of each cosmetic defect, receiving geometrical data relating to the shape and relative position of the front and rear surfaces of the transparent optical device and wherein said geometrical data are used to determine the position of the cosmetic defects within the transparent optical device.

5. The method according to any of the preceding claims, wherein the images of cosmetic defect have a common spatial reference between them, or each image of cosmetic defect is provided with a geometrical transformation so as to shift to a common spatial reference.

6. The method according to any of the preceding claims, wherein the transparent optical device is a semi-finished ophthalmic lens.

7. The method according to any of the preceding claims, wherein the transparent optical device is a transparent mold and / or inserts for molds.

8. The method according to any of the preceding claims, further comprising- acquiring an initial image of cosmetic defects of the transparent optical device using a background pattern transmissive imaging method with an acquisition device configured to acquire images from the rear surface of the optical element, with a depth of field greater than or equal to 8 mm, and- determining the presence of cosmetic defects to monitor on or within the transparent optical device and the position of said cosmetic defects to monitor in a (X,Y)-plane perpendicular to the Z-axis,- determining the first predetermined distance DI based on the geometrical data so as to correspond to the first surface at the position of the cosmetic defects in the (X,Y)-plane, and-evaluating the sharpness of each cosmetic defects in the first image so as to identify if said defects is near the first surface.

9. A method for sorting a transparent optical device, the method comprising: providing a transparent optical device, determining the presence of cosmetic defects on or within the transparent optical device, determining the position of cosmetic defects according to the method for determining the position of cosmetic defects according to any of the preceding claims, sorting the transparent optical device based on the presence of cosmetic defects and the position of said cosmetic defects.

10. The method according to the preceding claim, the method further comprises deciding if the transparent optical device is accepted or rejected based at least on the position of the cosmetic defects.

11. The method according to claim 10, wherein the transparent optical device has a finished surface and the method further comprises scoring the cosmetic defect based on the type of cosmetic defect and the position of the cosmetic defect relative to the finished surface of the transparent optical device along the Z-axis, the transparent optical device being sorted based on the scoring of the cosmetic defects.

12. A method for manufacturing an optical lens, the method comprising: providing a semi-finished optical lens, sorting the semi-finished optical lens based at least on the method according to claim 13, positioning the semi-finished optical lens on a blocking device for machining and / or surfacing, a machining and / or surfacing the unfinished surface of the semi-finished optical lens.

13. A computer program product comprising one or more stored sequences of instructions that are accessible to a processor and which, when executed by the processor, causes the processor to carry out the steps of the method according to any of claims 1 to 10.

14. A computer readable medium carrying one or more sequences of instructions of the computer program product according to claim 13.

15. A machine for managing cosmetic defects on an optical device comprising: - an optical device cosmetic defect acquisition module configured to acquire image of cosmetic defects of the transparent optical device using fringe deflectometry method, an analytical module configured to apply a method according to any of claims 1 to 11.

Images