Method for heating an optical element

Abstract

The method for heating an optical element (10) uses a laser beam (B') and a beam shaping device (2). The beam shaping device is adapted with respect to the geometric parameters of the optical element to provide the laser beam with a transverse power distribution (P(r)), so that irradiation of the surface (S) of the optical element raises the temperature of the surface to a maximum temperature distribution that is substantially uniform across the entire surface. Such a heating method provides improved temperature uniformity and allows for a reduction in processing time. It can be used to tint eyeglasses, relieve stress in preformed film structures, or crosslink varnish layers intended to form hard coats on eyeglasses.

Description

[Technical Field]

[0001] The present invention relates to a method for heating optical elements, a system for carrying out such a method, and colored, polarized and / or varnished optical elements produced using this method. [Background technology]

[0002] Some processes involved in the manufacture of optical elements such as eyeglasses require the optical element to be heated, meeting requirements including processing time, temperature uniformity across a portion of the element, control of maximum temperature, etc. For example, tinting eyeglasses can be achieved by first depositing a dye on the surface of the eyeglasses and then heating it to fix the dye on or in the eyeglass surface.

[0003] The use of an oven to heat such glasses would heat not only the surface of the glasses, but the entire glasses as well, which may not be compatible with the composite structure of the glasses, for example, when incorporating polarizing films, which are damaged by temperature values ​​such as those required for dye fixation. In addition, heating the entire glasses requires a sufficiently long processing time.

[0004] EP 2532781 A1 teaches heating the surface of eyeglasses by scanning the surface with a laser beam along a scanning path that navigates across this surface. However, such a heating method has the following drawbacks: the scanning time involved in each eyeglass processed increases the unit processing time required to heat each eyeglass to the desired surface temperature, thus reducing the throughput of the heating section that performs this heating; - Because the laser beam is applied to each point on the heated surface at different times, the temperature of the entire surface cannot be adequately controlled at once, which can result in uneven color density across the glasses. Since the laser beam has a finite diameter at the surface of the eyeglasses, the extent of overlap between adjacent scan path sections becomes an issue. In other words, the uniformity of the heat deposition on the irradiated surface strongly depends on the lateral offset between adjacent scan path sections. The color density can then exhibit a maximum or minimum value between pairs of adjacent scan path sections.

[0005] For these reasons, heating by laser scanning requires adjustment of process parameters, which is difficult and time consuming. Summary of the Invention [Problem to be solved by the invention]

[0006] Starting from this situation, one object of the present invention is to provide a novel method for heating optical elements that alleviates the above-mentioned problems.

[0007] Another object of the present invention is to provide uniform coloring of optical elements in a manner that is easier and more reliable than known methods.

[0008] It is yet another object of the present invention to heat an optical element in a reduced unit processing time. [Means for solving the problem]

[0009] According to a first aspect of the invention, a method for heating an optical element, when the optical element has a surface to be heated, which is limited by a periphery of the optical element, comprises: / 1 / collecting geometric parameters of an optical element; / 2 / Irradiating the surface of the optical element with a laser beam fixed relative to and directed onto the surface through a beam shaping device adapted with respect to the geometric parameters of the optical element so as to provide the laser beam with a transverse power distribution, whereby the irradiation of the surface increases the temperature of the surface up to a maximum temperature distribution that is substantially uniform over the entire surface limited by the periphery of the optical element; Includes.

[0010] By using laser irradiation through a beam shaping device, the entire surface of the optical element can be heated simultaneously, thereby reducing the processing time, and in addition, this avoids adjusting parameters such as the scanning speed and the pitch of the scanning path, while directly resulting in a sufficient uniformity of the temperature rise over the entire surface of the optical element.

[0011] The method of the present invention is particularly suitable when it is not necessary to increase the temperature within the bulk of the optical element body, but rather it is sufficient to increase the temperature of the optical element adjacent to its surface. By transferring heat through this surface as involved in the method of the present invention, it is then possible to increase the temperature of this surface without heating the entire optical element. A reduction in processing time also results from such a limitation of the temperature increase to the part of the optical element adjacent to its surface.

[0012] Preferred embodiments of the present invention may advantageously embody one or more of the following additional features. The geometric parameters of the optical element may include a diameter related to the surface of this optical element. In such a case, the beam shaping device may be adapted during step / 2 / to impart a flat-top profile to the transverse power distribution of the laser beam at the surface of the optical element, and the diameter of the flat-top profile may be selected to coincide with the diameter of the surface of the optical element. The irradiation parameters carried out in step / 2 / can be chosen so that an elevated temperature is combined with keeping the shape of the surface of the optical element unchanged during this step / 2 / . - The beam shaping device may be such that the transverse power distribution of the laser beam results in an absolute temperature difference existing between any two positions across the surface of the optical element at the highest temperature distribution and / or at any point during step / 2 / of less than 5°C (degrees Celsius), preferably less than 3°C, more preferably less than 2°C. The laser beam may be generated by an infrared laser source, preferably a near-infrared source or a UV laser source, which may be of the pulsed laser source type, but preferably of the continuous laser source type, such as a CO2 laser or fiber laser source type. In such a case, the laser source may be adapted so that the laser beam has a time-average power value of more than 100 W, preferably between 200 W and 2000 W, more preferably between 400 W and 1000 W. In particular, 500 W may be the most preferred time-average power value for the laser beam used in step / 2 / . The beam shaping device may include a diffractive optical element or a spatial light modulator. The laser beam may be directed onto the surface of the optical element during step / 2 / substantially parallel to the optical axis of this optical element. The optical element may consist of glasses. The optical element may be made of a resin-type material at least on the surface to be illuminated. the temperature of the surface of the optical element may be less than 200°C, preferably less than 190°C, more preferably less than 140°C, even more preferably less than 125°C, at the maximum temperature distribution at any point over this surface limited by the periphery of the optical element. The optical element may include at least one base optical element part and a polarizing film structure bonded to the at least one base optical element part and extending substantially parallel to a surface of the optical element, and the surface irradiated in step / 2 / may then belong to the at least one base optical element part such that this surface is away from the polarizing film structure within the optical element.

[0013] An improvement of the present invention can address an optical element having an irradiated surface with a convex cross-sectional shape in cross section. In such a configuration, the beam shaping device can be such that the transverse power distribution of the laser beam exhibits two maxima separated by an intermediate minimum in the cross section of the surface of the optical element. The power density value difference of the transverse power density distribution of the laser beam between either of the maxima in the cross-sectional plane and the intermediate minimum can then be determined to vary as an increasing function of the absolute curvature value of the surface in the cross-sectional plane, for example.

[0014] Alternative refinements of the present invention may address optical elements of other configurations in which the irradiated surface has a concave cross-sectional shape in the cross-sectional plane. In such other configurations, the beam shaping device may be such that the transverse power distribution of the laser beam exhibits one maximum value in the cross-sectional plane of the surface of the optical element. The absolute value of the second radial derivative of the transverse power distribution of the laser beam in the cross-sectional plane may then be determined to vary as another increasing function of the absolute curvature value of the surface in the cross-sectional plane.

[0015] A first application of the present invention relates to the coloring of optical elements. Such an application may involve depositing a dye on the surface of the optical element before step / 2 / . In that case, irradiating the surface in step / 2 / is suitable for causing fixation of the dye on or within the optical element. If the optical element is made of an organic material on its surface, the wavelength of the laser beam can advantageously be selected within the transmission band of the dye and also within the absorption band of the organic material. In this way, irradiating the surface in step / 2 / increases the temperature of the organic material through absorption of the laser beam and also increases the temperature of the dye through contact with the organic material. This activates the absorption of the dye from the surface of the optical element into the organic material, thereby permanently fixing the dye on or within the optical element. Alternatively, the wavelength of the laser beam can be selected to be within the respective absorption bands of both the dye and the organic material, such that irradiating the surface in step / 2 / increases the temperature of both the dye and the organic material through absorption of the laser beam, thereby again activating the absorption of the dye from the surface of the optical element into the organic material. Generally, the wavelength can be selected so that the total absorption of the laser beam by both the dye and the organic material in the optical element is greater than 20%, preferably greater than 30%, of the total power of the laser beam impinging on the surface of the optical element. In that case, step / 2 / can be performed for a shorter heating time, resulting in lower power loss due to transmission of the laser beam through the optical element. In particular, the wavelength of the laser beam can be in the near-infrared range, for example, substantially equal to 1908 nm or 1064 nm.

[0016] In a second application of the present invention, the optical element may be composed of a film structure, possibly a laminated film structure, in particular a polarizing film structure, and step / 2 / is carried out to reduce or suppress internal stresses present in the film structure. Therefore, the method of the present invention can be used to carry out stress-relief curing, in particular curing carried out on a film structure after it has been preformed. In fact, film preformation may generate stresses in the preformed film structure, which are high enough to prevent further use of the film structure.

[0017] In a third application of the present invention, the optical element may include a base optical element provided with a varnish layer, in particular a varnish layer intended to obtain hard coat efficiency. In that case, the varnish layer may constitute the surface of the optical element that is irradiated in step / 2 / , and step / 2 / may be carried out to crosslink the varnish layer or complete its crosslinking. Such a third application of the present invention may be advantageous when the optical element is a pair of eyeglasses made of organic materials or when it incorporates a surface layer, such as a UV filter or photochromic layer. In fact, the hard coat efficiency protects the eyeglasses or the organic material of the surface layer from wear and scratches.

[0018] A second aspect of the invention proposes a system for heating an optical element, the system comprising: a laser source; a beam shaping device arranged such that a laser beam generated by the laser source passes through the beam shaping device and thereafter strikes a surface of the optical element; Includes.

[0019] The system of the present invention is configured such that, during use of the system, a laser beam is directed onto the surface of the optical element in a fixed manner relative to this surface. In addition, the beam shaping device is adapted, selected, or adjustable with respect to the geometric parameters of the optical element to provide a transverse power distribution to the laser beam, whereby irradiation of the surface by this laser beam increases the temperature of the surface to a maximum temperature distribution that is substantially uniform across the entire surface limited by the periphery of the optical element. Such a system enables one-piece processing with short processing times per optical element unit.

[0020] Optionally, the system of the present invention may include a plurality of diffractive optical elements each suitable for forming a beam shaping device when selected based on the geometric parameters of the optical element to be heated. Alternatively, the beam shaping device may include a spatial light modulator and a controller configured to control the spatial light modulator based on the geometric parameters of the optical element.

[0021] The system of the second aspect of the present invention may be adapted to carry out the method according to the first aspect of the present invention. In particular, the system of the second aspect of the present invention may further comprise means for receiving geometric parameters of at least one optical element to be heated, and system sections spatially arranged according to the following listed order: an entrance section, an optional dye-deposition section, an optional pre-curing section, a heating section, and an output section. The system of the second aspect of the present invention also comprises a transport system arranged to transport the at least one optical element through the system sections according to the previous listed order, the heating section being adapted to irradiate the at least one optical element with a laser beam through a beam shaping device according to the received geometric parameters for the at least one optical element after the at least one optical element has been introduced into the heating section by the transport system.

[0022] A third aspect of the present invention provides a tinted optical element comprising at least one base optical element portion and a polarizing film structure bonded to the base optical element portion and extending substantially parallel to a surface of the optical element, wherein the base optical element portion and the polarizing film structure are arranged such that the surface of the optical element is remote from the polarizing film structure, and the optical element further comprises a dye fixed on or adjacent to the surface and incorporated within the optical element remote from the polarizing film structure.

[0023] Such a tinted optical element according to the third aspect of the invention may be tinted eyeglasses.

[0024] These and other features of the present invention will now be described with reference to the accompanying drawings, which relate to preferred, but non-limiting implementations of the present invention. [Brief explanation of the drawings]

[0025] [Figure 1] 1a-1b show a first implementation of the inventive method for heating spectacles. [Figure 2] FIG. 2 is a cross-sectional view of eyeglasses that can be used in the first implementation of FIGS. 1a and 1b. [Figure 3] 3a-3b show a second implementation of the method of the present invention for relieving stresses present in a preformed film. [Figure 4] FIG. 4 is a cross-sectional view of a pre-formed film that may be used in the second implementation of FIGS. 3a and 3b. [Figure 5] FIG. 5 shows a third implementation of the method of the invention for crosslinking a varnish layer deposited on spectacles. [Figure 6] FIG. 6 shows a system configuration for heating an optical element according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] For clarity, the element sizes shown in these figures do not correspond to actual dimensions or to dimensional ratios. The same reference numbers shown in different ones of these figures also indicate identical elements of elements having the same function.

[0027] An optical article according to the present disclosure comprises at least one ophthalmic lens, or optical filter, or optical glass, or optical material suitable for human vision, e.g., at least one ophthalmic lens, or optical filter, or optical film, comprising a substrate or a patch intended to be fixed on the substrate or optical glass, respectively, or the optical material is intended for use in, for example, an ophthalmic instrument for determining the visual acuity and / or refraction of a subject, or any kind of safety device including safety glass or safety barriers intended to face the eyes of an individual, e.g., a safety lens or protective device such as a mask or shield.

[0028] The optical article may be implemented as an eyewear article having a frame at least partially surrounding one or more ophthalmic lenses. By way of non-limiting example, the optical article may be eyeglasses, sunglasses, safety goggles, sports goggles, contact lenses, intraocular implants, active lenses with amplitude modulation capabilities such as polarized lenses or with phase modulation capabilities such as autofocus lenses, etc.

[0029] As used herein, the term "lens" refers to an organic or inorganic glass lens comprising a lens substrate that may be coated with one or more coatings of various natures.

[0030] The term "ophthalmic lens" is used to mean a lens fitted to a spectacle frame, for example, to protect the eyes and / or correct vision. Said lens may be selected from afocal lenses, unifocal lenses, bifocal lenses, trifocal lenses, progressive lenses. Although ophthalmic optical systems are the preferred field of the invention, it will be understood that the invention may be applied to other types of optical articles, such as, for example, lenses for optical instruments in photography or astronomy, optical aiming lenses, eye visors, optical systems for lighting systems, safety lenses, etc.

[0031] At least one ophthalmic lens or optical glass or optical material adapted to human vision can provide an optical function to the user, i.e. the wearer of the lens.

[0032] It may be, for example, a corrective lens for treating myopia, hyperopia, astigmatism and / or presbyopia, i.e. a spherical, cylindrical and / or add type refractive power lens for users with refractive errors. The lens may have a constant refractive power, thus providing a refractive power similar to that provided by a single vision lens, or may be a progressive lens with a variable refractive power.

[0033] The heating system according to the invention comprises a laser source 1 and a beam shaping device 2. The heating system according to the invention is designed to irradiate the entire surface S of an optical article or element 10, such as a pair of glasses. For example, the surface S limited by the periphery E of the optical element 10 may be less than 100 mm (millimeters) in diameter, more preferably comprised between 55 mm and 80 mm, and usually close to 70 mm, if the optical element 10 is an ophthalmic lens, or more than 100 mm, such as for example 150 mm or 200 mm, if the optical element 10 is a safety mask, for example a one-piece safety mask intended to cover both eyes of a subject.

[0034] The laser beam leaving the laser source 1, designated B, may have a collimated configuration, e.g., a beam diameter of 5 mm. The function of the beam shaping device 2 is then to expand the cross-sectional diameter of the laser beam so that the laser radiation emitted from the laser source 1 hits the entire surface S. Preferably, the laser beam B' as output from the laser beam B by the beam shaping device 2 may have a diverging configuration downstream of the beam shaping device 2, and the optical element 10 is positioned at a distance from the exit of the beam shaping device 2 suitable for the diverging laser beam B' that encompasses the entire surface S of the optical element 10. To avoid energy losses, the system is preferably adjusted so that the peripheral limit of the diverging laser beam B' at the optical element 10 is located outside the periphery E of the optical element 10 by a reduced margin.

[0035] The beam shaping device 2 can be of any type, including a diffractive optical element, a spatial light modulator, a microscope objective, etc. The spatial light modulator makes it possible to adapt the transverse power distribution across the laser beam B' so as to obtain a uniform heating of the surface S of the optical element 10. An absolute temperature difference of less than 5°C between any two positions within the surface S of the optical element 10, resulting from irradiating this surface S with the laser beam B' for a determined period of time, may be appropriate for some applications. Other applications may require absolute temperature difference values ​​of less than 3°C, or even less than 2°C, between any positions within the surface S limited by the periphery E.

[0036] Preferably, the central propagation direction of the laser beam B′ can be superimposed on the optical axis of the optical element 10 .

[0037] In some applications, it may be sufficient to provide a uniform power distribution value to the laser beam B′ to meet the requirement of temperature uniformity across the surface S of the optical element 10. The beam shaping device 2 may then impart a flat-top profile to the transverse power distribution of the laser beam B′ at a distance from the exit of the beam shaping device 2 to the optical element 10.

[0038] In applications where temperature uniformity across the surface S is more demanding, it may be necessary to adapt the transverse power distribution of the laser beam B' across this surface S. General rules for such adaptation may be the following, listed for a spherical surface as a non-limiting example: If the surface S is concave, the transverse power distribution P(r) as a function of the radial distance r from the central propagation direction of the laser beam B' should exhibit a maximum value located in this central propagation direction and decrease radially as the value of r increases. According to a possible refinement, the smaller the absolute value of the radius of curvature of the concave surface S, the higher the absolute value of the second derivative of the power distribution P(r) with respect to the radial distance r can be. This first variation law is illustrated by the profile P(r) superimposed by a dashed line in Figures 1a and 1b. If the surface S is convex, the transverse power distribution P(r) as a function of the radial distance r from the central propagation direction of the laser beam B' should exhibit two maxima in each meridian plane, located on either side of the central propagation direction of the laser beam B', and a minimum in the central propagation direction of the laser beam B'. According to another possible refinement, the smaller the absolute value of the radius of curvature of the convex surface S, the greater the difference between each maximum of the transverse power distribution P(r) and its minimum in the central propagation direction. This second variation rule is shown by the profile P(r) superimposed by a dashed line in Figures 3a and 3b.

[0039] Such an adaptation of the transverse power distribution profile can be easily implemented by using a single spatial light modulator to form the beam shaping device 2. However, it is also possible to select an appropriate model of the beam shaping device based on its fixed transverse refractive power distribution profile relative to the curvature of the surface S of the optical element 10 to be heated.

[0040] However, it may be advantageous to use a flat-top profile for the transverse power distribution P(r) for compatibility with a wide variety of possible shapes of the surface S. Thus, a single beam shaping device 2 can be used for multiple optical elements 10 without having to select an appropriate beam shaping device model for each optical element.

[0041] In most applications described below, the diameter of the surface S is less than about 120 mm, more preferably less than 80 mm, and the maximum temperature obtained on the surface S is less than 200° C., so the power of the laser source 1 can be 500 W. Preferably, it can be a continuous or pulsed source; in the latter case, 500 W should be interpreted as a time-averaged power value calculated over time, including not only the pulse duration but also the pulse separation duration. In general, it can be a matter of the maximum temperature induced on the surface S by the irradiation of the laser beam remaining lower than the glass temperature at that surface S of the constituent material of the optical element 10. This ensures that the shape of the surface S does not change during heating, thereby maintaining the optical efficiency of the element 10.

[0042] Preferably, the wavelength value of the laser source 1 may be selected for heating efficiency within the absorption band of the material of the optical element 10. Since eyeglass materials are transparent in the visible range, such wavelength value may be in the UV range or in the infrared range.

[0043] A first application of the heating method of the present invention may be the impregnation or absorption of dyes into eyeglasses. Such a first application is illustrated in FIGS. 1a and 1b. The eyeglasses may include a substrate or support layer made of any organic material commonly used in the ophthalmic field, forming an optical element 10. The substrate or support layer 10 may in particular be an optically transparent material having the shape of an optical article, e.g., an ophthalmic lens, to be attached to the eyeglasses. In this context, the term "substrate" is understood to mean the base component material of an optical lens (more specifically, an ophthalmic lens). This material serves as a support for a stack of one or more coatings or layers. For example, the substrate may be made from thermoplastic materials such as polycarbonates and thermoplastic polyurethanes, or thermosetting (crosslinked) materials such as diethylene glycol bis(allyl carbonate) polymers and copolymers (particularly CR-39® from PPG Industries), thermosetting polyurethanes, polythiourethanes, preferably polythiourethane resins having a refractive index of 1.60 or 1.67, polyepoxides, polyepisulfides such as those having a refractive index of 1.74, materials based on poly(meth)acrylates (such as PMMA) and copolymers, including (meth)acrylic polymers and copolymers derived from bisphenol-A, polythio(meth)acrylates, and copolymers and blends thereof. Specific examples of eyeglass materials suitable for the absorption applications of the present invention are those derived from thermosetting polythiourethane resins sold by Mitsui Toatsu Chemicals as the MR series, particularly MR6®, MR7®, and MR8® resins. These materials and the monomers used in their preparation are described, inter alia, in U.S. Pat. Nos. 4,689,387, 4,775,733, 5,059,673, 5,087,758 and 5,191,055.

[0044] Before heating the substrate 10, dye particles are deposited on the surface S of the eyeglasses, preferably on one of their optical surfaces, which is concave as shown in Figures 1a and 1b. The dye particles can be deposited on this surface S of the "nude" substrate, i.e., on the substrate material itself, using one of the following methods known from the prior art: dye sublimation and condensation, spin coating, deposition using an inkjet printer, etc. The thickness of the dye layer thus deposited can be several micrometers. A heating step is then required to fix the dye particles to the surface S of the eyeglasses 10 by diffusing them into the organic material of the eyeglasses 10. The heating loosens the lattice of the organic material of the eyeglasses, thereby facilitating the diffusion of the dye particles from the surface S into the eyeglass material, thereby permanently fixing the dye particles in the eyeglasses 10 next to the surface S.

[0045] Preferably, the wavelength value of the laser source 1 can be selected within the absorption band of the organic material of the eyeglasses 10, but outside the main absorption band of the dye, to avoid direct absorption of the laser radiation by the dye particles, which could damage their molecular structure and coloring efficiency.

[0046] The illumination parameters may depend on the material of the eyeglasses 10, and the values ​​shown in Table 1 below should be interpreted as starting values ​​for an optimization test series.

[0047] [Table 1]

[0048] Alternatively, the wavelength value of the laser source 1 can be selected within the absorption band of the organic material of the eyeglasses 10 and at the same time within the absorption band of the dye. This allows for a higher overall absorption value of the eyeglasses 10 with pre-deposited dye. Therefore, the heating time for the surface S to reach the same maximum temperature can be shortened and / or the power of the laser beam B' can be reduced. For example, values ​​of 1908 nm (nanometers) and 1064 nm are alternatively possible for the emission wavelength of the laser source 1. Commercially available laser sources based on thulium (Tm)-doped silica fibers emit at 1908 nm, and Nd-YAG (neodymium-doped yttrium and aluminum garnet) lasers emit at 1064 nm. The following heating characteristics were obtained using eyeglasses based on diethylene glycol bis(allyl carbonate) polymers and copolymers (CR-39® or ORMA®):

[0049] [Table 2]

[0050] In this Table 2, the total absorption is expressed as a percentage of the power of the laser beam B' incident on the surface S supporting the dye layer. The exposure time is expressed in seconds.

[0051] Various types of dyes can be used, including dyes in a liquid phase. Three disperse dye inks, red, blue, and yellow, were used as sublimable dyes, which can include dissolved or finely dispersed sublimable dyes. Each of these is a commercially available water-based ink. For inkjet printers, these inks were separately packaged in commercially available ink cartridges. The cartridges were installed in an inkjet printer, which in this implementation was a commercially available printer. Table 3 below compares the absorption values ​​of the eyeglasses 10 without dye deposition and the eyeglasses 10 with dye deposition for two different types of eyeglasses.

[0052] [Table 3]

[0053] A particular advantage of the heating method of the present invention relates to heated substrates incorporating a film structure, where the film structure may be damaged by excessive temperatures. In such a case, as shown in FIG. 2, a pair of eyeglasses may be provided having a laminated configuration incorporating a polarizing film structure. The eyeglasses 10 include a polarizing film structure 101, a first base optical element portion 102, and a second base optical element portion 103. The polarizing film structure 101 is laminated between and permanently bonded to both base optical element portions 102 and 103. The base optical element portion 102 forms a surface S that is heated, for example, to absorb a dye therein. Both base optical element portions 102 and 103 may be made of any one of the materials listed above. In this configuration, the irradiated and thus heated surface S is spaced from the polarizing film structure 101, thereby allowing the temperature of the polarizing film structure 101 to remain lower than the temperature of the irradiated surface S. In this manner, any material in the polarizing film structure 101 that may be damaged by temperatures equal to the maximum temperature of surface S is preserved. Most polarizing film structures include two protective films, for example a polyvinyl acetate (PVA) film laminated between two triacetate cellulose (TAC) protective films, and the PVA film is subject to extreme temperatures.

[0054] An interference coating (anti-reflective or reflective coating) can be deposited directly on the dyed substrate. Prior to depositing the interference coating of the present invention, it is usually preferred to coat the main surface of the substrate with one or more functional coatings that improve its optical and / or mechanical properties. These functional coatings, conventionally used in optics, can be, but are not limited to, impact-resistant primer layers, abrasion- and / or scratch-resistant coatings (hard coats), deflection coatings, antistatic coatings, photochromic coatings, pigmented coatings, or stacks made of two or more such coatings.

[0055] The impact-resistant primer coating that can be used in the present invention can be any coating that is typically used to improve the impact resistance of a finished optical article. By definition, an impact-resistant primer coating is a coating that improves the impact resistance of a finished optical article compared to the same optical article but without the impact-resistant primer coating.

[0056] Typical impact-resistant primer coatings are (meth)acrylic and polyurethane-based coatings. Specifically, the impact-resistant primer coating according to the present invention can be made from a latex composition such as a poly(meth)acrylic latex, a polyurethane latex, or a polyester latex.

[0057] Preferred primer compositions include thermoplastic polyurethane-based compositions such as those described in Japanese Patent Application Laid-Open Nos. 63-141001 and 63-87223; poly(meth)acrylic primer compositions such as those described in U.S. Pat. Nos. 5,015,523 and 6,503,631; thermosetting polyurethane-based compositions such as those described in European Patent No. 0404111; and poly(meth)acrylic or polyurethane latex-based compositions such as those described in U.S. Pat. Nos. 5,316,791 and 0680492. Preferred primer compositions are polyurethane-based and latex-based compositions, particularly compositions based on polyurethane latex, poly(meth)acrylic latex, and polyester latex, as well as combinations thereof. In one embodiment, the impact-resistant primer contains a colloidal filler.

[0058] Poly(meth)acrylic latexes are latexes based on copolymers made essentially from (meth)acrylates, such as ethyl (meth)acrylate, butyl (meth)acrylate, methoxyethyl (meth)acrylate, or ethoxyethyl (meth)acrylate, typically with a small amount of at least one other comonomer, such as styrene.

[0059] Commercially available primer compositions suitable for use in the present invention include Witcobond® 232, Witcobond® 234, Witcobond® 240, Witcobond® 242 compositions (marketed by BAXNDEN CHEMICALS), Neorez® R-962, Neorez® R-972, Neorez® R-986 and Neorez® R-9603 (marketed by ZENECA RESINS), and Neocryl® A-639 (marketed by DSM coating resins).

[0060] The thickness of the impact resistant primer coating after curing is typically in the range of 0.05 to 30 μm, preferably 0.2 to 20 μm, more specifically 0.5 to 10 μm, even 0.6 to 5 μm or 0.6 to 3 μm, and most preferably 0.8 to 1.5 μm.

[0061] The impact resistant primer coating is preferably in direct contact with the abrasion and / or scratch resistant coating.

[0062] The abrasion- and / or scratch-resistant coating may be any layer conventionally used as an abrasion- and / or scratch-resistant coating in the field of ophthalmic lenses.

[0063] The abrasion-resistant and / or scratch-resistant coating is preferably a hard coating based on poly(meth)acrylates or silanes, and usually contains one or more inorganic fillers intended to increase the hardness and / or refractive index of the coating after curing.

[0064] The abrasion-resistant and / or scratch-resistant coating is preferably made from a composition containing at least one alkoxysilane and / or its hydrolysate, for example obtained by hydrolysis using a hydrochloric acid solution and optionally a condensation and / or curing catalyst.

[0065] Suitable coatings recommended for the present invention include coatings based on epoxy silanes and / or epoxy silane hydrolysates, such as those described in EP 0614957, U.S. Pat. No. 4,211,823 and U.S. Pat. No. 5,015,523.

[0066] A preferred abrasion- and / or scratch-resistant coating composition is that disclosed in EP 0 614 957 in the name of the present applicant. It comprises a hydrolysate of an epoxytrialkoxysilane and a dialkyldialkoxysilane, colloidal silica, and a catalytic amount of an aluminum-based curing catalyst, such as aluminum acetylacetonate, with the remainder consisting essentially of a solvent conventionally used to formulate such compositions. Preferably, the hydrolysate used is a hydrolysate of g-glycidoxypropyltrimethoxysilane (GLYMO) and dimethyldiethoxysilane (DMDES).

[0067] The abrasion- and / or scratch-resistant coating composition can be deposited by known methods and then cured, preferably using heat or ultraviolet radiation. The thickness of the (cured) abrasion- and / or scratch-resistant coating typically varies from 2 to 10 μm, preferably from 3 to 5 μm.

[0068] Prior to depositing an interference coating or other functional coating, the surface of the article is typically subjected to a physical or chemical surface activation and cleaning pretreatment, such as that disclosed in WO 2013 / 013929, to improve adhesion of the deposited layer. This pretreatment is typically performed on the surface of an abrasion- and / or scratch-resistant coating (hard coat).

[0069] This pretreatment is generally carried out under vacuum. It can be bombardment with energetic species, such as ion beam methods ("ion precleaning" or "IPC") or electron beam methods, corona treatment, ion spallation treatment, ultraviolet treatment or plasma treatment under vacuum, typically using oxygen or argon plasma. It can be acid or base surface treatment with or without ultrasound treatment and / or solvent surface treatment (using water or organic solvents). Many treatment methods can be combined. These cleaning treatments optimize the cleanliness of the substrate surface.

[0070] Energy species are those with an energy range of 1 to 300 eV (electron voltage, 1 eV = 1.6 10 -19 "energy" refers to a species having an energy in the range of (Joules), preferably 10 to 150 eV, most preferably 40 to 150 eV. Energetic species can be chemical species such as ions, radicals, or species such as photons or electrons.

[0071] A preferred pretreatment is ion bombardment, for example by using an argon ion beam emitted from an ion gun.

[0072] The interference coating may be any interference coating conventionally used in the field of optical systems, particularly ophthalmic optical systems. The interference coating may be, but is not limited to, an anti-reflective coating or a reflective (mirror) coating.

[0073] The optical article according to the present invention may also comprise a coating formed on the reflective coating, capable of modifying its surface properties, such as a hydrophobic and / or oleophobic coating (antifouling topcoat). These coatings are preferably deposited on the outer layer of the reflective coating. Their thickness is usually 10 nm or less, preferably in the range of 1 to 10 nm, more preferably 1 to 5 nm. Antifouling topcoats are generally fluorosilane or fluorosilazane type coatings, preferably containing fluoropolyether moieties, more preferably perfluoropolyether moieties. More detailed information on these coatings is disclosed in WO 2012 / 076714.

[0074] Instead of a hydrophobic coating, a hydrophilic coating (anti-fog coating) can be used that imparts anti-fog properties or an anti-fog coating precursor that imparts anti-fog properties when combined with a surfactant. Examples of such anti-fog precursor coatings are described in patent application WO 2011 / 080472.

[0075] Additional coatings, such as primers, hard coats, and antifouling top coats, can be deposited on the major surface of the substrate using methods known in the art, including spin coating, dip coating, spray coating, evaporation, sputtering, chemical vapor deposition, and lamination.

[0076] Typically, an optical article according to the present invention comprises a substrate onto which a dye has been deposited and fixed by laser surface heating, said dyed substrate being subsequently coated successively with an impact resistant primer layer, an abrasion and / or scratch resistant layer, an interference coating according to the present invention and a hydrophobic and / or oleophobic coating or a hydrophilic coating or antifog precursor coating providing antifog properties.

[0077] A second application of the heating method of the present invention can be stress relaxation within a film structure. Such a second application is illustrated in FIGS. 3a and 3b. The film structure forming the optical element 10 here can be preformed, particularly with a convex surface, with or without a dye incorporated therein, for subsequent bonding to the curved surface of eyeglasses, such as the substrate defined in connection with the first application. When intended for assembly with eyeglasses in this manner, the film structure 10 is generally referred to in the art as a patch. The process performed to preform the film structure 10 is not the subject of the present invention, and any such process known in the art can be used. However, preforming generates residual stresses within the film structure 10, which can cause deformation of the eyeglasses during further processing steps. Therefore, it is necessary to relieve the internal stresses present within the film structure 10 after it has been preformed. FIG. 4 shows an example of such a preformed film structure 10. For example, it is a laminated polarizing film structure including a PVA film 10a intermediate two TAC protective films 10b and 10c. The PVA film 10a is adhered to both the TAC protective films 10b and 10c, and the film structure 10 may further include an adhesive material layer 10d on its concave surface S'. This adhesive material may be a pressure-sensitive material, although other types are possible. It is exposed so that it can capture any dust particles it comes into contact with, and such dust particles cannot be subsequently removed. To avoid this dust problem, the peripheral margin of the concave surface S' of the film structure 10 may be sealed to the flat screen layer 20 so that the adhesive material layer 10d is no longer exposed. Thus, the convex surface S of the film structure 10 remains exposed.

[0078] The combination of film structure 10 and screen layer 20 is then subjected to laser beam B', with the convex surface S of film structure 10 directed towards the beam-shaping device 2, as shown in Figures 3a and 3b. Suitable parameters for achieving sufficient stress relaxation are an irradiation time of one minute or several tens of minutes and a maximum temperature of surface S of about 120°C at the end of the irradiation time. These values ​​should again be interpreted as starting values ​​for an optimization test series. The maximum temperature difference within surface S at the end of such heating may be less than 5°C.

[0079] A third application of the heating method of the present invention can be the curing of a varnish layer supported by eyeglasses. Such a third application is shown in FIG. 5. Here, the optical element 10 is composed of a base eyeglass 10', such as a substrate or support film, and a varnish layer 10'' coating its convex surface. The base eyeglass 10' can be any of the substrate materials already described in connection with the first application, but can further include an impact-resistant primer coating, a UV filter varnish, and / or a photochromic varnish layer, at least on its convex surface, as disclosed in connection with the first application. The base eyeglass 10' can have a layered structure as shown in FIG. 2. The varnish is intended to form a surface layer that is abrasion-resistant and / or scratch-resistant after curing. For this reason, the cured varnish layer is usually called a hard coat. Such a hard coat can be a poly(meth)acrylate- or silane-based hard coating, as already disclosed in connection with the first application, and usually contains one or more inorganic fillers intended to increase the hardness and / or refractive index of the cured coating. The varnish used to form such hard coats can be prepared from a composition containing at least one alkoxysilane and / or its hydrolyzate, for example, obtained by hydrolysis using a hydrochloric acid solution and, optionally, a condensation and / or curing catalyst. Particularly suitable varnishes are based on epoxysilanes and / or epoxysilane hydrolyzates, such as those described in EP 0614957, U.S. Pat. No. 4,211,823, and U.S. Pat. No. 5,015,523. A preferred hard coat composition is disclosed in EP 0614957, which comprises hydrolyzates of epoxytrialkoxysilanes and dialkyldialkoxysilanes, colloidal silica, and a catalytic amount of an aluminum-based curing catalyst, such as aluminum acetylacetonate, with the remainder consisting essentially of a solvent commonly used to formulate such compositions. Preferably, the hydrolyzate used is a hydrolyzate of γ-glycidoxypropyltrimethoxysilane (GLYMO) and dimethyldiethoxysilane (DMDES).A varnish composition intended to form a hard coat after curing can be deposited on the base eyeglass 10' to form a layer with a final thickness of 2 μm (micrometers) to 10 μm, preferably 3 μm to 5 μm, after curing. Curing results in crosslinking within the varnish layer, thereby providing abrasion and / or scratch resistance. Heating limited to the surface portion of the optical element 10 containing the varnish layer 10'' is advantageous because it reduces processing time and avoids damage to temperature-sensitive materials that may be incorporated into the base eyeglass 10'. As shown in FIG. 5, when heating the varnish layer 10'' using a laser source 1 and a beam shaping device 2, the surface of the optical element 10 formed by the varnish layer 10'' is oriented toward the beam shaping device 2. Suitable parameters for achieving adequate crosslinking are an irradiation time of one minute or several tens of minutes and a maximum temperature of approximately 110°C at the end of the irradiation time. These values ​​should again be interpreted as starting values ​​for an optimization test series. The maximum temperature difference within the surface S at the end of such heating can be less than 5°C.

[0080] The varnish layer cured according to the third application can then be subjected to a physical or chemical surface activation and cleaning pretreatment and / or can be coated with other functional coatings, such as interference coatings, polarizing coatings, antistatic coatings, photochromic coatings, pigmented coatings or laminates made of two or more of such coatings and / or coatings formed on interference coatings and capable of modifying their surface properties, such as hydrophobic and / or oleophobic coatings (antifouling topcoats) as disclosed in connection with the first application.

[0081] 6 shows a possible configuration 100 of the heating system of the present invention, which may be suitable for mass production but is of particular interest for prescription or Rx production of optical elements, such as eyeglasses, since the optical elements are individually produced to order and benefit from a one-piece flow process. This configuration 100 includes several system compartments 101-105 combined with a transport system 110. The transport system 110, e.g., a belt transport system, is configured to continuously transport the optical elements 10 from one compartment to the next according to a chain process flow. This process flow can be a one-piece flow, where a single optical element 10 is processed in each system compartment at a time, or a batch flow, where a successive set of multiple optical elements 10 is processed in each system compartment at a time. For example, each system compartment can be dedicated to the following process steps: Compartment 101: for example, an inlet compartment provided with an air flow to prevent dust particles from entering the subsequent system compartments; Sections 102 and 103: different processing sections depending on the application; Section 104: a heating section dedicated to the implementation of the heating method of the invention and equipped with a laser source 1 and a beam shaping device 2; Compartment 105: Exit compartment, also provided with airflow to avoid eg dust particles from entering the system compartment.

[0082] In the first application of the invention mentioned above, i.e. dye inhalation, at least one of the compartments 102 and 103 may be dedicated to the deposition of dye particles onto the optical element 10, for example using a sublimation deposition process.

[0083] In the second application of the present invention, namely, stress relaxation in film structures, compartments 102-104 may each be provided with suitable means for carrying out the heating method of the present invention, so that configuration 100 has sufficient manufacturing throughput.

[0084] In the case of the third application of the invention, i.e., for varnish crosslinking, compartments 102-103 may be dedicated to pre-curing of the varnish, for example using an oven compartment or a compartment equipped with irradiating infrared lamps. Indeed, the varnish layer may first need to be heated to an intermediate temperature lower than the temperature of the crosslinking step. This intermediate temperature is so low that pre-curing using standard heating systems such as ovens or infrared lamps remains compatible with a sufficient throughput of the system configuration 100.

[0085] The system configuration 100 further includes a controller 111 configured to receive geometric parameters of the optical elements 10 loaded in the system configuration and to transmit operating parameters and control commands to the laser source 1, possibly the beam shaping device 2 if it is of the spatial light modulator type, the transport system 110 and possibly at least one of the compartments 101-103 and 105.

[0086] Obviously, additional system sections may be added to configuration 100 depending on the application in which the heating method of the present invention is implemented. Those skilled in the art of industrial processes know how to design and configure such system configurations to meet the targeted characteristics of the optical elements being manufactured while maximizing their throughput.

[0087] It is reiterated that all numerical values ​​cited herein are provided for illustrative purposes only and may be adapted depending on the particular application of the invention and the optical element being heated, however these values ​​may be used as a starting point for adjustment trials.

[0088] Clearly, the heating method of the present invention may be implemented in applications other than those specifically described, and the advantages of the present invention, or others, noted herein would still apply.

Claims

1. A method for heating an optical element (10), said optical element having a surface (S) to be heated, said surface (S) being limited by a periphery (E) of said optical element, said method comprising: / 1 / A step of collecting geometric parameters of the optical element (10); / 2 / irradiating the surface (S) of the optical element (10) with a laser beam (B'); In step / 2 / , the laser beam (B') is directed onto the surface (S) of the optical element (10) through a beam shaping device (2) adapted with respect to the geometric parameters of the optical element so as to provide the laser beam with a transverse power distribution (P(r)), whereby the irradiation of the surface in step / 2 / increases the temperature of the surface up to a maximum temperature distribution that is substantially uniform over the entire surface limited by the periphery (E) of the optical element.

2. The method of claim 1 , wherein the geometric parameters of the optical element (10) include a diameter for the surface (S) of the optical element.

3. 3. The method of claim 2, wherein during step / 2 / , the beam shaping device (2) is adapted to impart a flat-top profile to the transverse power distribution (P(r)) of the laser beam (B') at the surface (S) of the optical element (10), and the diameter of the flat-top profile is selected to match the diameter of the surface (S) of the optical element.

4. 4. The method according to claim 1, wherein the irradiation parameters carried out in step / 2 / are selected such that the elevated temperature is combined with maintaining the shape of the surface (S) of the optical element (10) unchanged during step / 2 / .

5. Method according to any one of claims 1 to 4, wherein said laser beam (B') is generated by a laser source (1) which is an infrared or UV laser source, preferably of the continuous laser source type.

6. 6. The method of claim 5, wherein the laser source (1) is adapted so that the laser beam (B') has a time-average power value of more than 100 W, preferably between 200 W and 2000 W, more preferably between 400 W and 1000 W.

7. The method according to any one of claims 1 to 6, wherein the optical element (10) comprises a pair of glasses.

8. 8. The method according to any one of claims 1 to 7, wherein the temperature of the surface (S) of the optical element (10) is less than 200°C, preferably less than 190°C, more preferably less than 140°C, even more preferably less than 125°C, at the maximum temperature distribution at any location over the surface limited by the periphery (E) of the optical element.

9. The optical element (10) comprises at least one base optical element portion (10 ２ , 10 ３ ) and a polarizing film structure (10) adhered to the at least one base optical element portion and extending substantially parallel to the surface (S) of the optical element. １ 9. The method according to claim 1, wherein the surface (S) irradiated in step / 2 / belongs to the at least one base optical element part such that the surface is away from the polarizing film structure within the optical element.

10. 10. The method according to any one of claims 1 to 9, wherein a dye is deposited on the surface (S) of the optical element (10) before step / 2 / , and wherein the irradiation of the surface in step / 2 / is suitable to cause fixation of the dye on or in the optical element.

11. 11. The method according to claim 10, wherein the optical element (10) is made of an organic material at the surface (S) of the optical element, and the wavelength of the laser beam (B') is selected to be within the transmission band of the dye and also within the absorption band of the organic material, whereby irradiating the surface in step / 2 / increases the temperature of the organic material through absorption of the laser beam and increases the temperature of the dye through contact with the organic material, thereby activating absorption of the dye from the surface of the optical element into the organic material.

12. 11. The method of claim 10, wherein the optical element (10) is made of an organic material at the surface (S) of the optical element, and the wavelength of the laser beam (B') is selected to be within the respective absorption bands of both the dye and the organic material, whereby irradiating the surface in step / 2 / increases the temperature of both the dye and the organic material through the respective absorption of the laser beam, thereby activating absorption of the dye from the surface of the optical element into the organic material.

13. 13. The method according to claim 11 or 12, wherein the wavelength of the laser beam (B') is selected such that the total absorption of the laser beam by both dyes and organic materials in the optical element (10) is more than 20%, preferably 30% or more, of the total power of the laser beam impinging on the surface (S) of the optical element.

14. 14. The method according to claim 13, wherein the wavelength of the laser beam (B') is substantially equal to 1908 nm or 1064 nm.

15. 9. The method according to any one of claims 1 to 8, wherein the optical element (10) is made of a film structure, possibly a laminated film structure, in particular a polarizing film structure, and wherein step / 2 / is carried out so as to reduce or suppress internal stresses present in the film structure.

16. 10. The method according to any one of claims 1 to 9, wherein the optical element (10) comprises a base optical element (10') provided with a varnish layer (10"), in particular a varnish layer intended to obtain hard coat efficiency, the varnish layer constituting the surface (S) of the optical element that is irradiated in step / 2 / , and step / 2 / being carried out to crosslink the varnish layer or to complete the crosslinking of the varnish layer.

17. A system for heating an optical element (10), comprising: a laser source (1), a beam shaping device (2) arranged so that the laser beam (B') generated by said laser source (1) passes through said beam shaping device and then impinges on the surface (S) of said optical element (10); wherein, during use of the system, the laser beam (B') is arranged to be directed onto the surface (S) of the optical element (10) fixed relative to said surface, and the beam shaping device (2) is adapted, selected or adjustable with respect to the geometric parameters of the optical element to provide the laser beam with a transverse power distribution (P(r)), whereby irradiation of the surface by the laser beam increases the temperature of the surface up to a maximum temperature distribution that is substantially uniform over the entire surface limited by a periphery (E) of the optical element.

18. 18. The system according to claim 17, further comprising: system sections (101-105) comprising means for receiving the geometric parameters of at least one optical element (10) to be heated, and spatially arranged according to the following enumerated order: an entrance section, an optional dye deposition section, an optional pre-curing section, a heating section, and an output section, and further comprising a transport system (110) arranged to transport the at least one optical element (10) through the system sections according to the enumerated order, wherein the heating section is adapted to irradiate the at least one optical element according to the received geometric parameters for the at least one optical element with the laser beam (B') through the beam shaping device (2) after the at least one optical element has been introduced into the heating section by the transport system.

19. A tinted optical element (10) comprising at least one base optical element portion (10 ２ , 10 ３ ) and a polarizing film structure (10) bonded to the base optical element portion and extending substantially parallel to the surface (S) of the optical element. １ ), wherein the base optical element portion and the polarizing film structure are positioned such that the surface of the optical element is remote from the polarizing film structure, and the optical element further comprises a dye affixed to or proximate to the surface and incorporated within the optical element remote from the polarizing film structure.

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