Method for coating lenses with lenticules having improved control of power shift

Abstract

A method for coating a plurality of optical lenses, at least one major surface of which is at least partially covered with lenticules, the method comprising: - dipping (DIP) at least one first optical lens of the plurality of optical lenses into a coating fluid, - withdrawing (WDW) the at least one first optical lens from the coating fluid at a controlled withdrawal speed, - measuring (MEAS) a thickness of a coating layer deposited on the at least one first optical lens, - determining (ADJ) an adjusted withdrawal speed based on the measured thickness, and - repeating the steps of dipping (DIP), withdrawing (WDW), measuring (MEAS) and determining (ADJ) on at least one other optical lens of the plurality of optical lenses during the withdrawing (WDW) step using the adjusted withdrawal speed.

Description

Technical Field

[0001] This disclosure pertains to the field of ophthalmic optics. It generally relates to the coating of optical lenses.

[0002] Specifically, a method for coating an optical lens, along with corresponding components, computer programs, and storage media, is disclosed, wherein the main surface of the optical lens is at least partially covered with microlenses. Background Technology

[0003] In the ophthalmology industry, people have known for decades about surface treatment of optical lenses.

[0004] For example, optical articles such as ophthalmic lenses typically include a base lens substrate shaped to provide a desired optical power, and an anti-abrasion coating covering at least one surface of the base lens substrate to prevent the base lens substrate from being scratched or damaged.

[0005] The most common methods for applying hard coatings to optical lenses are dip coating and spin coating.

[0006] A known problem with dip coating is controlling the thickness of the resulting hard coating.

[0007] For many applications, it has been found desirable to incorporate multiple microlenses (such as microlenses) on a base lens substrate to provide localized variations in the power of the optical article. For example, a lens is known from US 2017 / 0131567 that includes multiple microlenses formed on the surface of the lens, the localized variations in power provided by the microlenses being able to suppress or slow the progression of myopia.

[0008] In this respect, the substrate coated on at least one surface, including a microlens, affects the resulting optical power at the microlens. This effect can be compensated for by pre-adjusting the optical power of the microlens during substrate manufacturing. However, such adjustment may only be suitable for compensating for the effect of a specific expected thickness of the hard coating.

[0009] Therefore, it is necessary to improve the control of the thickness of the coating fluid or solid layer deposited on the optical lens during the impregnation process in order to better control the focal length shift of the microlens caused by the coating layer. Summary of the Invention

[0010] The present invention aims to improve these aspects by providing a method for better control of the thickness of coated fluid or solid layers.

[0011] Therefore, the present invention relates to a method for coating a plurality of optical lenses (preferably ophthalmic lenses), at least one main surface of which is at least partially covered with a small lens, the method comprising:

[0012] - Immerse at least one of the first optical lenses among a plurality of optical lenses in the coating fluid.

[0013] - At least one first optical lens is extracted from the coating fluid at a controlled extraction speed.

[0014] -Measure the thickness of the coating deposited on at least one first optical lens.

[0015] -The adjusted extraction speed is determined based on the measured thickness, and

[0016] - During the extraction step, using an adjusted extraction speed, repeat the steps of immersion, extraction, measurement, and determination on at least one of the multiple optical lenses.

[0017] This method allows for better control over the thickness of the coating fluid or solid layer. This, in turn, improves the control over the focal length shift of the microlens caused by the coating layer. This method enhances the optical power distribution of the microlens, resulting in better reliability and efficiency for all end products.

[0018] The method may include the step of drying the coating layer deposited on the first optical lens, with the measurement step performed between the extraction step and the drying step.

[0019] This feature allows for faster adjustment of the extraction speed by measuring the thickness as early as possible, and improves the responsiveness of that adjustment.

[0020] The method may include the steps of drying a coating deposited on a first optical lens and curing the coating deposited on the first optical lens, with a measurement step performed between the drying and curing steps.

[0021] This feature allows the measured thickness of the coated fluid layer to be close to the final thickness of the layer in the finished product, enabling more precise control of the final thickness while keeping the waiting time before adjusting the extraction speed low.

[0022] The method may include a step of curing a coating deposited on a first optical lens, with a measurement step performed after the curing step.

[0023] This feature allows for the most precise control over the final thickness of the coating, at the expense of responsiveness in adjusting the extraction speed.

[0024] The measurement steps can be performed using non-contact optical methods.

[0025] This feature allows for rapid and accurate measurements without affecting the coated layer during drying and / or curing.

[0026] The method may include continuously adjusting the viscosity of the coating fluid in the impregnation assembly where the impregnation step is performed.

[0027] This feature allows for a consistent relationship between the extraction rate and the thickness of the coating fluid layer deposited on the lens.

[0028] The adjusted extraction rate can be determined based on an empirical function of the difference between the measured thickness of the coating and the desired nominal thickness.

[0029] This feature allows for precise adjustment of the extraction speed for specific fluids and known types of lenses.

[0030] The empirical function can further depend on the fluid properties of the coating fluid and the surface mechanical and physical properties of the main surface and the minor surface of the optical lens.

[0031] During the extraction step, the extraction speed can be kept constant.

[0032] During the extraction step, the extraction speed can be gradually reduced.

[0033] The present invention also relates to a coating assembly for coating an optical lens, wherein at least one main surface of the optical lens is at least partially covered with a small lens, the assembly comprising:

[0034] - An immersion assembly comprising a tank for receiving a coating fluid and at least one movable member for immersing at least one lens in the coating fluid and for withdrawing the lens at a controlled extraction speed.

[0035] - A measurement system for measuring the thickness of a coating deposited on at least one lens, and

[0036] - A control system, including a processing unit and a memory, configured to control the measurement system and moving components.

[0037] The control system is configured to determine the adjusted extraction speed based on the measured thickness.

[0038] The present invention also relies on a computer program comprising one or more stored sequences of instructions that are accessible by a processing unit and, when executed by the processing unit, cause the processing unit to perform at least a portion of the method described above.

[0039] The present invention also relates to a non-transitory storage medium that stores one or more stored instruction sequences of a computer program as described above. Attached Figure Description

[0040] - Figure 1 This is a side view of the lens obtained by the method according to the present invention.

[0041] - Figure 2This is a schematic representation of the steps of the method according to the present invention, and

[0042] - Figure 3 This is a schematic diagram of a coating assembly for implementing the method according to the invention.

[0043] - Figure 4 and Figure 5 This is a graph showing the coating thickness versus the focal length shift of the microlens, obtained when implementing existing manufacturing methods.

[0044] - Figure 6 and Figure 7 This is a graph showing the coating thickness versus the focal length shift of the microlens, obtained when implementing the manufacturing method according to the invention. Detailed Implementation

[0045] Figure 1 An optical lens 10 obtained by the method according to the present invention is shown.

[0046] The optical lens 10 is preferably an ophthalmic lens, comprising a body 12 made of organic or mineral material, defining two main surfaces, including a convex side 14 (also called the anterior side or object side) and a concave side 16 (also called the dorsal side or eyeball side).

[0047] The optical lens 10 includes a small lens 18 disposed on the convex side, and a coating layer 20 extending at least to the small lens 18 and preferably to both main surfaces.

[0048] Alternatively, the small lens 18 may be arranged on the concave side 16 of the optical lens 10, or simultaneously on the convex side 14 and the concave side 16.

[0049] More specifically, in the following text, a small lens is a discrete optical element that causes localized changes in the optical power of an optical device (such as optical lens 10).

[0050] The small lenses 18 may form protrusions and / or depressions on the main surface on which they are arranged. The outline of the small lenses 18 may be circular or polygonal, such as hexagonal.

[0051] According to an embodiment, the small lens 18 is a microlens. A microlens can be spherical, toric, or have an aspherical shape. A microlens can have a single focal point, or cylindrical power, or be nonfocal.

[0052] In a preferred embodiment, a small lens or microlens can be used to prevent the progression of myopia or hyperopia. In this case, the optical lens 10 includes a body 12 that provides optical power for correcting myopia or hyperopia, and respectively, if the wearer is myopic, the small lens or microlens can provide optical power greater than that of the body 12, or if the wearer is hyperopic, the small lens or microlens can provide optical power less than that of the body 12.

[0053] In other embodiments, the small lens 18 or microlens may be a Fresnel structure, a diffraction structure defining each Fresnel structure, a permanent technical protrusion, or a phase-shifting element. The small lens or microlens may also be a refractive optical element such as a microprism, or a light-diffusing optical element such as a small protrusion or cavity, or any type of element that produces roughness on the main surface of the optical lens 10.

[0054] In an embodiment, the microlens 18 or small lens may be a π-Fresnel microlens as described in US2021109379 A1, i.e., a Fresnel microlens with a π phase jump in the phase function at the nominal wavelength, as opposed to a single-focus Fresnel lens with multiple values ​​of 2π for the phase jump. Such a microlens includes a structure with a discontinuous shape. In other words, the shape of this structure can be described by a height function, exhibiting discontinuity in distance from the reference plane of the principal surface of the optical lens to which the microlens belongs, or a discontinuity in its derivative.

[0055] The small lens 18 of the present invention can have an external shape that can be inscribed within a circle with a diameter greater than or equal to 0.5 micrometers (μm) and less than or equal to 1.5 millimeters (mm).

[0056] The small lenses 18 of the present invention have a height measured in a direction perpendicular to the main surface on which they are arranged, which is greater than or equal to 0.1 μm and less than or equal to 50 μm.

[0057] The master surface can be defined as the surface including the center point of each microstructure, and can be a plane, a sphere, a spherical surface, or even a composite surface. When the microstructure is embedded in the lens, this master surface can be a virtual surface, or when the microstructure is not embedded, it can be close to or the same as the physical outer surface 14, 16 of the ophthalmic lens.

[0058] The height of the microstructure can then be determined relative to a local axis perpendicular to the main surface, and the difference between the maximum positive deviation along that axis and the minimum negative deviation from the main surface can be calculated for each point of the microstructure.

[0059] The microlenses 18 can have a periodic or pseudo-periodic layout, or they can be in random positions. Examples of microlens layouts can be grids with a constant grid step size, honeycomb layouts, multiple concentric rings, or continuous layouts, such as those with no space between microstructures.

[0060] These small lenses 18 can provide light wavefront modification in terms of intensity, curvature, or optical deviation. The modification of the wavefront in terms of intensity allows the structure to be absorptive and to locally absorb the wavefront intensity, ranging from 0% to 100%. The modification of the curvature allows the structure to locally modify the wavefront curvature, ranging from + / -20 diopters. The modification of the optical deviation allows the structure to locally scatter light, with an angle ranging from + / -1° to + / -30°.

[0061] The distance between the microlenses 18 can range from 0 (continuous) to 3 times the size of the structure (separated microstructures).

[0062] The coating layer 20 is preferably of a type known as a hard coating. Hard coatings are typically single-layer coatings, but can also have a two-layer structure. Hard coatings are made, for example, of acrylic compounds, epoxy compounds, epoxy acrylic compounds, silane compounds, epoxy silane compounds, polyurethane acrylic compounds, siloxane compounds, and any mixtures of the foregoing compounds. Hard coatings are robust; their edges are less prone to degradation than those of softer coatings when exposed to moisture and under typical use, and their wavelength transmission remains constant over time and during use.

[0063] The coating layer 20 is applied by the method according to the invention, as described below. Figure 2 The above is based on dip coating technology.

[0064] This method is implemented using coating component 100. Figure 3 An example of this coated component is shown in the image.

[0065] The coating assembly 100 includes an immersion assembly comprising a tank 110 containing coating fluid 112 and a moving member 120 for immersing the optical lens 10 into the coating fluid 112. The coating assembly also includes a control system CTRL and a measurement system MSYS.

[0066] The coating fluid 112 is, for example, a solution of the material used to form the coating layer 20 dissolved in a volatile solvent. Such a coating fluid 112 is, for example, a varnish.

[0067] The movable member 120 includes a rod 122 movable along a substantially vertical immersion axis, a drive assembly 124 for driving the rod 122 along the immersion axis, and at least one lens holder 126 placed on the rod 122, which is capable of holding at least one optical lens 10 during the method.

[0068] The control system includes a processing unit PROC configured to execute programs and a memory MEM for storing instructions and data.

[0069] The control system is configured to control the measurement system and moving components.

[0070] The memory stores one or more stored instruction sequences that are accessible by the processing unit and, when executed by the processing unit, cause the control system to perform the described method.

[0071] The measurement system is configured to measure the thickness of the coating layer 20 deposited on the optical lens 10.

[0072] The measurement system is advantageously suited for measuring the thickness by a non-contact method (preferably an optical method).

[0073] Examples of this method include spectral reflectance or elliptic polarization.

[0074] Measurement systems include, for example, the F10-AR spectrometer from FILMETRICS with UPG-F10-AR-HC software upgrade, the F10-HC spectrometer from FILMETRICS, or the Arcspectro Thinfilm NIR spectrometer from ARCOPTICS.

[0075] The measurement system may include a measurement probe mounted on a hinged arm for bringing the probe close to, but not in contact with, the optical lens 10, and then removing the probe after the measurement is completed.

[0076] The coating assembly 100 may further include a viscosity measuring tool 128 immersed in the coating fluid 112, which is connected to a viscosity control system VCT. The viscosity control system VCT is also connected to at least one pump 130, which is fluidly connected to at least one side tank 132 containing the viscosity agent and further connected to the tank 110.

[0077] The viscosity control system VCT is configured to monitor the viscosity of the coating fluid 112 during the method by periodically measuring the viscosity with a viscosity measuring instrument 128 and comparing the measured viscosity values ​​with a predetermined desired value. The viscosity control system is also configured to actuate at least one pump 130 to inject one or more viscosity agents into the tank 110 containing the coating fluid 112 to adjust its viscosity to be closer to the predetermined desired value.

[0078] The method includes a preparation step PREP, during which at least one optical lens 10 is prepared and loaded into a coating assembly 100 and onto one of the lens holders 126.

[0079] Each optical lens 10 loaded into the coating assembly 100 includes a body 12 and at least one small lens 18 on the main surface, as described above.

[0080] If the coating fluid 112 is applied only to one of the main surfaces of the optical lens 10 or a portion of such a surface, the preparation step includes covering the remainder of the optical lens 10 with a film that will subsequently be peeled off.

[0081] The method then includes an immersion step (DIP) during which the optical lens 10 is immersed in a coating fluid 112 contained in a can 110.

[0082] Under the control of the control system, the rod 122 is driven downward by the drive assembly 124 until the optical lens 10 is partially or completely submerged as needed.

[0083] The method then includes an extraction step WDW, during which the optical lens 10 is extracted from the coating fluid at a controlled extraction rate, thereby leaving a coating fluid deposit layer on at least a portion of the optical lens 10.

[0084] The thickness of the deposited layer depends on the extraction rate, the fluid properties of the coating fluid 112, and the physical and mechanical properties of the main surfaces 14 and 16 of the optical lens 10 and the small lens 18.

[0085] The extraction speed is controlled by the control system and can be kept constant during the extraction step or decreased during the extraction step. The extraction speed can also be increased during the extraction step.

[0086] This reduction or increase in the extraction speed can be implemented from a reference initial extraction speed according to any type of time-decreasing or increasing function.

[0087] The method then includes a drying step (DRY), during which at least a portion of the solvent contained in the coating fluid is evaporated, leaving behind the coating material that forms the coating layer 20.

[0088] Through the evaporation of the solvent, the coating material forms a hard layer covering the optical lens 10. This evaporation can be accelerated by using airflow and by controlling ambient pressure and temperature.

[0089] The method then includes a hardening step HRD, during which the coating material forming the coating layer 20 is cured.

[0090] The curing step may include the polymerization of organic compounds contained in the coating material, for example by photopolymerization.

[0091] The method includes a final step RDY, during which the finished optical lens 10 is removed from the coating assembly 100.

[0092] The method also includes a measurement step MEAS, during which the thickness of the coating layer 20 is measured.

[0093] The thickness of the coating layer 20 is measured by a measurement system, for example by one of the methods described above, along the optical axis X of the optical lens 10.

[0094] The measurement takes a few seconds and therefore does not significantly slow down the coating process.

[0095] The measurement step can be performed after the drying step and before the curing step. This allows for measurements close to the thickness of the coating layer 20 of the finished optical lens 10, where the volume of solvent has been removed, but waiting for the curing step is not required, thus allowing for faster measurements.

[0096] Alternatively, the measurement step can be performed after the extraction step and before the drying step to obtain the earliest possible measurement, at the cost of accuracy relative to the final thickness.

[0097] Alternatively, the measurement step can be performed after the curing step to obtain the most accurate measurement of the thickness of the coating 20 relative to the final product, at the cost of speed.

[0098] The method further includes an adjustment step ADJ, during which the extraction speed used by the future optical lens 10 during the extraction step is adjusted based on the measured thickness of the coating layer 20.

[0099] The measured thickness is compared with the expected nominal thickness of the coating layer 20 during the measurement step, and the extraction speed is adjusted based on the difference.

[0100] More specifically, if the difference between the measured thickness of the coating and the expected nominal thickness is greater than or equal to 1.5%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60% or more, the extraction speed should be adjusted.

[0101] The extraction speed can be adjusted using an empirical function of the difference between the measured thickness and the desired nominal thickness.

[0102] The empirical function may also depend on the fluid properties of the coating fluid 112 and / or on the physical and mechanical properties of the main surfaces 14, 16 and the small lens 18 of the optical lens 10.

[0103] Alternatively, the adjustment is determined using a control loop function that is generally known.

[0104] The adjusted extraction speed is used during the extraction step to coat any other optical lenses 10 mounted in assembly 100 until the extraction speed is further adjusted.

[0105] Measuring the thickness earlier allows for faster adjustments to the extraction speed, thereby reducing the number of lenses coated with incorrect coating material thickness.

[0106] Therefore, the method according to the invention allows for better control of the coating thickness applied to an optical lens including a small lens.

[0107] This significantly reduces the variability of the focal length shift of the small lenses in the final product.

[0108] Figures 4 to 7 By comparing the method described above with the existing method of manually controlling the extraction speed, this improvement in the variability of coating thickness and microlens focal length shift is shown.

[0109] Figure 4 It is a graph of the coating thickness over time when implementing a manufacturing method in the prior art to coat multiple lenses, including small lenses. Figure 4 The relationship between extraction speed and time is also shown, wherein the extraction speed is manually adjusted twice based on thickness measurements.

[0110] Figure 5 It is a graph showing the measured focal length shift of the microlens of the coated lens on the same time scale.

[0111] Figure 4 and Figure 5 The fluid properties of the coating fluid, particularly its thickness, are shown to change over time due to solvent evaporation. This results in a coating thickness change of 0.4 micrometers and a corresponding diopter shift of 0.2 diopters.

[0112] To limit this variation, the solvent viscosity and extraction rate were manually adjusted based on the measured thickness of the coating, with a 50-minute interval between two adjustments to the extraction rate.

[0113] Figure 6 Is with Figure 4 The corresponding charts are used to automatically adjust the extraction speed as described above. The thickness of the coating is continuously measured, and the extraction speed is adjusted accordingly.

[0114] Figure 7 The lens power shift obtained using this method is shown, and the variability of the power shift is shown to be 0.05 diopters, which is a significant improvement compared to the previous value.

[0115] Therefore, the variability of thickness can be reduced by about 85%, with the variability of focal length shift decreasing from 0.2 diopters (d) to 0.05d.

Claims

1. A method for coating a plurality of optical lenses, at least one main surface of the optical lenses being at least partially covered by microlenses, the method being carried out by a coating assembly, the method comprising: - Immerse at least one of the plurality of optical lenses, the first optical lens, in the coating fluid. - The at least one first optical lens is extracted from the coating fluid at a controlled extraction speed. - Measure the thickness of the coating layer deposited on the at least one first optical lens. - The adjusted extraction speed is determined based on the measured thickness, and - During the extraction step for at least one of the plurality of optical lenses, the adjusted extraction speed is used to repeat the steps of immersion, extraction, measurement, and determination on the at least one other optical lens.

2. The method according to claim 1, wherein, The method includes the step of drying the coating deposited on the first optical lens, and the measurement step is performed between the extraction step and the drying step.

3. The method according to claim 1, wherein, The method includes the steps of drying the coating deposited on the first optical lens and hardening the coating deposited on the first optical lens, wherein the measurement step is performed between the drying step and the hardening step.

4. The method according to claim 1, wherein, The method includes the step of hardening the coating deposited on the first optical lens, and the measurement step is performed after the hardening step.

5. The method according to claim 1, wherein, The measurement steps are performed using a non-contact optical method.

6. The method according to claim 1, wherein, The method includes continuously adjusting the viscosity of the coating fluid in the impregnation assembly where the impregnation step is performed.

7. The method according to claim 1, wherein, The adjusted extraction rate is determined based on an empirical function of the difference between the measured thickness of the coating and the desired nominal thickness.

8. The method according to claim 7, wherein, The empirical function further depends on the fluid properties of the coating fluid and the surface mechanical and physical properties of the main surface and the small lens.

9. The method according to claim 1, wherein, During the extraction step, the extraction speed remains constant.

10. The method according to claim 1, wherein, During the extraction step, the extraction speed gradually decreases.

11. A coating assembly for coating an optical lens, wherein at least one main surface of the optical lens is at least partially covered with a small lens, the coating assembly comprising: - An immersion assembly comprising a tank for receiving a coating fluid and at least one moving member for immersing at least one optical lens in the coating fluid and for withdrawing the optical lens at a controlled extraction rate. - A measurement system for measuring the thickness of a coating deposited on the at least one optical lens, and - A control system, comprising a processing unit and a memory, configured to control the measuring system and the moving component. The control system is configured to implement the method according to any one of claims 1 to 10.

12. A computer program comprising one or more stored sequences of instructions, the sequences of instructions being accessible by a processing unit of a coating assembly according to claim 11 and, when executed by the processing unit, causing the processing unit to perform the method according to any one of claims 1 to 10.

13. A non-transitory storage medium storing one or more stored instruction sequences of a computer program according to claim 12.

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