阅读说明：本技术 深红色、近红外和可见光范围中的反射减少的光学装置 (Optical device with reduced reflection in the deep red, near infrared and visible range ) 是由 F·德艾加维斯 于 2019-09-16 设计创作，主要内容包括：此光学装置包括眼科镜片和在深红色与近红外区域中发射的光源。所述眼科镜片的前面和后面均涂覆有干涉涂层。对于范围从700nm至小于或等于2500nm的预定最大波长的波长,在入射角小于或等于45°时,后干涉涂层的平均反射率小于或等于2.5％。对于范围从700nm至预定最大波长的波长,在入射角小于或等于45°时,如果所述源指向所述眼科镜片的前面,则所述前干涉涂层的平均反射率小于或等于2.5％,或者如果所述源指向所述眼科镜片的后面,则所述前干涉涂层的平均反射率大于或等于25％。(The optical device includes an ophthalmic lens and a light source emitting in the deep red and near infrared regions. Both the anterior and posterior faces of the ophthalmic lens are coated with an interference coating. The average reflectivity of the rear interference coating is less than or equal to 2.5% at an angle of incidence of less than or equal to 45 ° for wavelengths ranging from 700nm to a predetermined maximum wavelength of less than or equal to 2500 nm. For wavelengths ranging from 700nm to a predetermined maximum wavelength, at an angle of incidence less than or equal to 45 °, the average reflectivity of the front interference coating is less than or equal to 2.5% if the source is directed towards the front of the ophthalmic lens, or greater than or equal to 25% if the source is directed towards the back of the ophthalmic lens.)

1. An optical device comprising an ophthalmic lens and a light source emitting in the deep red and near infrared region, the ophthalmic lens having an anterior face coated with a front interference coating and a posterior face coated with a rear interference coating, the optical device characterized by:

an average reflectance of the rear interference coating is less than or equal to 2.5% at an angle of incidence less than or equal to 45 ° for wavelengths ranging from 700nm to a predetermined maximum wavelength less than or equal to 2500 nm; and is

Average reflectance of the front interference coating:

if said source is directed towards said front face of said ophthalmic lens, said average reflectivity is less than or equal to 2.5% at an angle of incidence less than or equal to 45 °, for wavelengths ranging from 700nm to said predetermined maximum wavelength, or

If the source is directed towards the rear face of the ophthalmic lens, the average reflectivity is greater than or equal to 25% at an angle of incidence less than or equal to 45 ° for wavelengths ranging from 700nm to the predetermined maximum wavelength.

2. The optical device according to claim 1, wherein the predetermined maximum wavelength is 2500 nm.

3. The optical device of claim 1, wherein the predetermined maximum wavelength is 1400 nm.

4. The optical device of claim 1, wherein the predetermined maximum wavelength is 980 nm.

5. The optical device of claim 1, wherein the predetermined maximum wavelength is 900 nm.

6. Optical device according to any one of the preceding claims, characterized in that the light reflectance Rv of the front and rear interference coatings is less than 2.5%, preferably less than 1%, more preferably less than 0.75%, in the visible light range, at an angle of incidence less than or equal to 45 °, for wavelengths ranging from 380nm to 780 nm.

7. The optical device according to any one of the preceding claims, characterized in that (i) the rear interference coating or (ii) the front interference coating comprises at least four layers, each layer having a refractive index either lower than that of all adjacent layers or higher than that of all adjacent layers, if the source is directed towards the front face of the ophthalmic lens.

8. The optical device according to claim 7, characterized in that said lens comprises a substrate and in that, if said source is directed towards said front face of said ophthalmic lens, (i) said rear interference coating or (ii) said front interference coating comprises at least, in a direction moving away from said substrate:

a layer having a refractive index ranging from 1.6 to 2.4;

a layer having a refractive index of less than 1.6;

a layer having a refractive index ranging from 1.6 to 2.4;

a layer having a refractive index of less than 1.6.

9. The optical device according to claim 7 or 8, characterized in that said lens comprises a substrate and in that, if said source is directed towards said front face of said ophthalmic lens, (i) said rear interference coating or (ii) said front interference coating comprises at least, in the direction of movement away from said substrate:

a layer having a physical thickness ranging from 10nm to 25 nm;

a layer having a physical thickness ranging from 20nm to 35 nm;

a layer having a physical thickness ranging from 140nm to 180 nm;

a layer having a physical thickness ranging from 90nm to 120 nm.

10. Optical device according to any one of the preceding claims, characterized in that the physical thickness of (i) the rear interference coating or (ii) the front interference coating is less than or equal to 500nm, preferably less than or equal to 320nm, and generally ranges from 260nm to 320nm, if the source is directed towards the front face of the ophthalmic lens.

11. Optical device according to claim 8, characterized in that said layer having a refractive index ranging from 1.6 to 2.4 is made of zirconium oxide (ZrO) ZrO₂) Said layer made of silicon dioxide (SiO) and having a refractive index of less than 1.6₂) And (4) preparing.

12. Optical device according to any one of the preceding claims, characterized in that said ophthalmic lens is a corrective lens.

13. An augmented reality device comprising an optical device according to any one of claims 1 to 11.

14. A virtual reality device, characterized in that it comprises an optical device according to any one of claims 1 to 11.

15. An eye tracking device, characterized in that it comprises an optical device according to any one of claims 1 to 11.

Technical Field

The present invention relates to an optical device comprising an ophthalmic lens and a light source emitting in the deep red and Near Infrared (NIR) region, i.e. at wavelengths ranging from 700nm to 2500nm, and with a significant reduction in reflection in the deep red, NIR and visible ranges. The optical device may for example be comprised in an augmented reality device, a virtual reality device or an eye tracking device.

Background

The NIR range is typically used for illuminating the eye for eye tracking purposes, since the user cannot see the NIR light, and at the same time the NIR light allows a very sharp contrast to be formed on the pupil, which makes it possible to obtain eye gaze direction or eye movement measurements, or any other measurements (such as measurements related to pupil size and position, eye reflection on corneal surfaces, ocular lens surfaces, eyelids, etc.), with high accuracy and high reliability.

Such measurements may be made by specific glasses that include, in addition to ophthalmic lenses, deep red and NIR light sources, and cameras.

However, when deep red and NIR light sources transmit light towards the eye of a user wearing such a device, multiple reflections occur on the face of the ophthalmic lens. Such multiple reflections can cause noise to the camera's detector, which can prevent the pupil from being properly positioned.

Therefore, it is necessary to limit the deep red and NIR light reflection on ophthalmic lenses.

Document US-A-2015138451 discloses an eye tracking device using NIR light, wherein the NIR reflectance of certain optical surfaces is reduced for incidence angles of 35 ° and 75 °.

However, the performance at lower angles of incidence is unknown and does not disclose the properties of the optical surface with reduced NIR reflectance, such as the number of layers, the materials used, its refractive index or its thickness.

Furthermore, the reflectivity of the front optical surface of interest should be different depending on the orientation of the NIR light source relative to the optical surface, i.e. depending on whether the NIR light source is directed to the front optical surface or to the back optical surface. The documents cited above also do not address this problem.

Disclosure of Invention

The object of the present invention is to overcome the above mentioned drawbacks of the prior art.

To this end, the invention provides an optical device comprising an ophthalmic lens having an anterior face coated with an anterior interference coating and a posterior face coated with a posterior interference coating, and a light source emitting in the deep red and near infrared regions, said optical device being notable in that:

an average reflectance of the rear interference coating is less than or equal to 2.5% at an angle of incidence less than or equal to 45 ° for wavelengths ranging from 700nm to a predetermined maximum wavelength less than or equal to 2500 nm; and is

Average reflectance of the front interference coating:

if the source is directed in front of the ophthalmic lens, the average reflectivity is less than or equal to 2.5% at an angle of incidence less than or equal to 45 ° for wavelengths ranging from 700nm to the predetermined maximum wavelength,

or if the light source is directed towards the rear of the ophthalmic lens, the average reflectivity is greater than or equal to 25% at an angle of incidence less than or equal to 45 ° for wavelengths ranging from 700nm to the predetermined maximum wavelength.

Thus, if the deep red and NIR light sources are directed towards the front of the ophthalmic lens, the optical device according to the invention comprises on the rear of the ophthalmic lens on the one hand and on the front of the ophthalmic lens an antireflection coating which is efficient in the deep red and NIR range at an angle of incidence less than or equal to 45 °, whereas if the deep red and NIR light sources are directed towards the rear of the ophthalmic lens, the optical device comprises a strongly reflecting coating on the front of the ophthalmic lens.

The invention also provides an augmented reality device, a virtual reality device and an eye tracking device, each of which comprises such an optical device.

Drawings

For a more complete understanding of the description provided herein and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts.

Fig. 1 is a schematic diagram of an augmented reality device or a virtual reality device including an optical device according to the present invention in a particular embodiment.

Fig. 2 is a schematic view of an eye tracking device comprising an optical device according to the invention in a specific embodiment.

Fig. 3 is a set of graphs showing the back reflectance (R%) of the lenses prepared in example 1 of the present application as a function of the wavelength λ of light ranging between 380nm and 900nm at incident angles of 15 ° and 35 °.

Fig. 4 is a set of graphs showing the reflectance (R%) of the front face of the lens prepared in example 2 of the present application at incident angles of 15 ° and 35 ° as a function of the wavelength λ of light ranging between 380nm and 900 nm.

Detailed Description

In the following description, the drawings are not necessarily to scale, and certain features may be shown in generalized or schematic form for the purpose of clarity and conciseness or for informational purposes. Additionally, while making and using various embodiments are discussed in detail below, it should be appreciated that numerous inventive concepts are provided as described herein that may be embodied in a wide variety of environments. The examples discussed herein are merely representative and do not limit the scope of the invention. It is also obvious to a person skilled in the art that all technical features defined with respect to the method can be transposed to the device alone or in combination, whereas all technical features defined with respect to the device can be transposed to the method alone or in combination.

The terms "comprising" (and any grammatical variations thereof, such as "comprises" and "comprising)", "having" (and any grammatical variations thereof, such as "has" and "has)", "containing" (and any grammatical variations thereof, such as "contains" and "containing)", and "including" (and any grammatical variations thereof, such as "includes" and "including)" are open-ended verbs. They are used to specify the presence of stated features, integers, steps or components or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps or components or groups thereof. Thus, a method or a step in a method that "comprises," "has," "contains," or "includes" one or more steps or elements possesses those one or more steps or elements, but is not limited to possessing only those one or more steps or elements.

Unless otherwise indicated, all numbers or expressions referring to amounts of ingredients, ranges, reaction conditions, and the like used herein are to be understood as modified in all instances by the term "about.

Furthermore, unless otherwise indicated, according to the present invention, indications of an interval of values "from X to Y" or "between X and Y" mean values including X and Y.

In the present application, when the optical device comprises one or more coatings on its surface, the expression "depositing a layer or coating onto the device" is intended to mean depositing the layer or coating onto the outer (exposed) surface of the outer coating of the device, i.e. the coating which is furthest from the substrate.

A coating said to be "on" or deposited onto a substrate is defined as the following coating: the coating (i) is positioned over a substrate; (ii) not necessarily in contact with the substrate, i.e. one or more intermediate coating layers may be arranged between the substrate in question and the coating layer; and (iii) does not necessarily completely cover the substrate.

In a preferred embodiment, the coating on or deposited onto the substrate is in direct contact with the substrate.

As used herein, the back (or inner) face of the substrate is intended to mean the face closest to the wearer's eye when the device is in use. The face is generally concave. In contrast, the front face of the substrate is the face furthest from the wearer's eye when the device is in use. The face is typically convex.

In addition, the "incident angle (symbol θ)" is an angle formed by a light ray incident on the surface of the ophthalmic lens and a normal line of the surface at the incident point. Light is, for example, a light source emitting light, such as standard light source D65 as defined in international colorimetric CIE L a b. Generally, the angle of incidence varies from 0 ° (normal incidence) to 90 ° (grazing incidence). A common range of incident angles is 0 ° to 75 °.

The colorimetric coefficients of the optical device of the invention in the international colorimetric system CIE L a b were calculated between 380nm and 780nm taking into account the standard illuminant D65 and the observer (angle of 10 °). The observer is a "standard observer" as defined in the international colorimetric system CIE L a b.

In summary, the interference coating (which will be referred to as "anti-reflective coating" or "reflective coating" depending on the configuration described) of the optical device according to the invention can be deposited onto any substrate, and preferably onto an organic lens substrate (e.g. a thermoplastic or thermosetting plastic material). The thermoplastic may be selected, for example, from: a polyamide; a polyimide; polysulfones; polycarbonates and copolymers thereof; poly (ethylene terephthalate) and polymethyl methacrylate (PMMA).

The thermosetting material may be selected, for example, from: cyclic olefin copolymers such as ethylene/norbornene or ethylene/cyclopentadiene copolymers; homopolymers and copolymers of allyl carbonates of linear or branched aliphatic or aromatic polyols, such as homopolymers (CR) of diethylene glycol bis (allyl carbonate)) (ii) a Homopolymers and copolymers of (meth) acrylic acid and its esters, which may be derived from bisphenol a; polymers and copolymers of thio (meth) acrylic acid and esters thereof, polymers and copolymers of allyl esters which may be derived from bisphenol a or phthalic acid and allyl aromatics such as styrene, polymers and copolymers of urethanes and thiourethanes, polymers and copolymers of epoxy resins, and polymers and copolymers of sulfides, disulfides and episulfides, and combinations thereof.

As used herein, (co) polymer is intended to mean a copolymer or a polymer. As used herein, (meth) acrylate is intended to mean acrylate or methacrylate. As used herein, Polycarbonate (PC) is intended to mean homopolycarbonates or copolycarbonates and block copolycarbonates.

Homopolymers (CR) of diethylene glycol bis (allyl carbonate) are preferred) Allyl and (meth) acrylic copolymers (having a refractive index between 1.54 and 1.58), polymers and copolymers of thiourethanes, polycarbonates.

The substrate may be coated with one or more functional coatings prior to deposition of the antireflective or reflective coating of the invention. These functional coatings conventionally used in optical devices may be, without limitation, impact-resistant primer coatings, abrasion-resistant and/or scratch-resistant coatings, polarizing coatings, photochromic coatings, or tinted coatings. In the following, substrate refers to a bare substrate or such a coated substrate.

Prior to deposition of the antireflective or reflective coating, the surface of the substrate is typically subjected to a physical or chemical surface activation treatment in order to enhance the adhesion of the antireflective or reflective coating. This pretreatment is usually carried out under vacuum. It may be bombardment with energetic and/or reactive components, for example with ion beams ("ion pre-cleaning" or "IPC") or with electron beams, corona discharge treatment, ion spallation treatment, ultraviolet radiation treatment or plasma-mediated treatment under vacuum (usually using oxygen or argon plasma). It may also be an acidic or alkaline treatment and/or a solvent-based treatment (water, hydrogen peroxide or any organic solvent).

The optical device according to the invention comprises an ophthalmic lens and a light source emitting in the deep red and near infrared region, i.e. at a wavelength ranging from 700nm to 2500 nm.

The light source may for example be a Light Emitting Diode (LED).

For detecting the light emitted from the source, a video camera sensitive to NIR wavelengths may be used, for example a camera of the CCD (charge coupled device) type or CMOS (complementary metal oxide semiconductor) type, without any deep red and NIR filters. As a variant, instead of a camera, a single deep red and NIR sensor array or PSD (position sensitive detector) sensor or any other suitable sensor may be used.

Fig. 1 shows a non-limiting example of an arrangement in an augmented reality device or a virtual reality device comprising an optical device according to the present invention.

The optical device comprises an ophthalmic lens 10 placed between on the one hand the eye 14 of the user and on the other hand a light-optical element 12. The light optical element 12 may be, for example, a waveguide with coupling means for coupling light into the eye 14 of the user and output coupling means for coupling light out towards the eye of the user, so that the user may perceive a virtual image.

Horizontal arrows 11 through the light optics 12 and through the ophthalmic lens 10 represent light from the environment.

Deep red and NIR eye trackers are also included in the augmented reality device or virtual reality device. The deep red and NIR eye tracker comprises a deep red and NIR camera 16 and at least one deep red and NIR light source 18, which source 18 is comprised in the optical arrangement according to the invention.

In the particular embodiment shown in fig. 1, the source 18 is placed between the light optic 12 and the ophthalmic lens 10, while the camera 16 is placed in front of the light optic 12.

As a variant, the camera 16 and the source 18 may be placed in front of the light-optics 12.

As another variation, the light optic 12 may be used both to provide a virtual image and to provide light illumination. The light reflected by the eye 14 may then be returned to the light optic 12 and redirected to the deep red and NIR light sensors.

The ophthalmic lens 10 may provide optical functionality to a user.

For example, the ophthalmic lens may be a corrective lens, i.e. a spherical, cylindrical and/or add-down type of powered lens (power lens) for ametropic users for the treatment of myopia, hyperopia, astigmatism and/or presbyopia. The lens 10 may have a constant power such that it can provide the power that a single vision lens can provide, or the lens may be a progressive lens with variable power.

The lens may also include an optical filter, which may be integrated on the substrate, coating, or film. For example, the filter may be designed to cut off some of the polarization and retain the polarization corresponding to the virtual image polarization. In this way, the contrast of the virtual image may be increased, as veiling glare from the environment is reduced while the intensity of the virtual image is maintained. The lens may, for example, comprise a polarizing film, such as a TAC-PVA-TAC (triacetyl cellulose-poly (vinyl alcohol) -triacetyl cellulose) film, placed on the casting mold. The polarizing film may be a specific filter, for example, having a transmittance that decreases for wavelengths different from the virtual image wavelength, while maintaining a high transmittance for wavelengths corresponding to the optical element 12.

The lens 10 includes a deep red and NIR antireflection coating on at least one of its faces, preferably both its front and back.

The antireflective coating will be designed to reduce reflections in the deep red and NIR ranges so that the camera 16 receives little light from the reflection on the lens 10.

Fig. 2 shows a non-limiting example of an arrangement in an eye tracking device comprising an optical device according to the invention.

In this embodiment, the optical device may be implemented as an eye-worn device with a frame 20 and may be used for eye tracking without virtual image display.

For example, the optical device may be used for detecting fatigue while driving by blink detection, or for eye health monitoring.

In this embodiment, the deep red and NIR light sources 18 are directed towards the rear of the lens 10, as compared to the embodiment of fig. 1, so that the lens 10 may have an antireflection coating on its rear face only, while the front of the lens 10 has a deep red and NIR light reflecting coating. As a variant, the reflective coating can be replaced by a reflective element embedded within the lens 10, for example a MOF (multilayer optical filter).

As shown in fig. 2, the eye-worn device has a specific deep red and NIR light source 18 that can be placed on the user's temple or frame 20. The eye-worn device also has a camera 16 located near the source 18.

Light emitted by source 18 is at least partially reflected by the anterior surface of eye 14 to illuminate the anterior surface.

The deep red and NIR light is diffused and reflected by the eye 14 and travels back towards the reflective front of the lens 10 and then towards the camera 16.

Similar to the embodiment of fig. 1, the rear face of the optic 10 has a deep red and NIR light antireflection coating so that no or little reflection toward the camera 16 occurs as the light travels back from the eye 14 toward the optic 10. In addition, reflections from deep red and NIR external sources (such as the sun or the environment) will have reduced impact.

According to the invention, in the two embodiments illustrated in fig. 1 and 2 respectively, the ophthalmic lens 10 has an anterior face coated with an anterior interference coating and a posterior face coated with a posterior interference coating.

The average reflectivity of the rear interference coating is less than or equal to 2.5% at an angle of incidence of less than or equal to 45 ° for wavelengths ranging from 700nm to a predetermined maximum wavelength of less than or equal to 2500 nm.

In a particular embodiment, when the angle of incidence of the deep red and NIR light is low, i.e. not much different from normal incidence, the average reflectance of the rear interference coating is less than or equal to 2.5% at an angle of incidence of less than or equal to 35 ° for wavelengths ranging from 700nm to a predetermined maximum wavelength of less than or equal to 2500nm, typically when the light source is directed at the front of the ophthalmic lens. This allows to minimize the reflection of deep red and NIR light for the angle of incidence defined by the geometry of the ophthalmic lens and the light source.

In another particular embodiment, when the incidence angle of deep red and NIR light is high, typically when the light source is directed towards the rear of the ophthalmic lens, the average reflectance of the rear interference coating is less than or equal to 2.5% at incidence angles comprised between 35 ° (inclusive) and 45 ° (inclusive), for wavelengths ranging from 700nm to a predetermined maximum wavelength less than or equal to 2500 nm. This allows to minimize the reflection of deep red and NIR light for the angle of incidence defined by the geometry of the ophthalmic lens and the light source located at the head side of the wearer.

This is therefore an antireflective coating, significantly reducing reflections in the deep red and NIR ranges so that the camera 16 will receive little light from the reflection on the lens 10.

This will ensure a high quality measurement of the characteristics of the eye 14 since there will be limited noise light. This allows for accurate and reliable eye position and iris or pupil size measurements to be obtained, for example. In the embodiment of fig. 1, the eye positions may then be used, for example, to modify the content of the virtual image according to its position. The eye position can also be used as part of an MMI interface (multimedia interface) to drive an electronic system.

The above-mentioned predetermined maximum wavelength is 2500nm, preferably 1400nm, more preferably 980nm, even more preferably 900 nm. By way of non-limiting example, eye tracking is focused from 780nm to 900 nm.

The average reflectance of the rear interference coating in the deep red and NIR region, i.e. at wavelengths ranging from 700nm to 2500nm, is noted R_m ^NIR2500, defined by the following equation:

where R (λ) represents the reflectance at a given wavelength λ.

In a more general manner, the average reflectivity, denoted R, of the rear interference coating in the deep red and NIR region, i.e. at wavelengths ranging from 700nm to a predetermined wavelength a nm_m ^NIRA, defined by the formula:

according to the invention, it depends on deep redThe color and NIR light source being directed to the front or back of the ophthalmic lens, the average reflectance R of the front interference coating_m ^NIRIs different.

That is, for example in the configuration of an augmented reality device or a virtual reality device as shown in fig. 1, the deep red and NIR light sources are directed towards the front of the ophthalmic lens, whereas for example in the configuration of an eye tracking device as shown in fig. 2, the deep red and NIR light sources are directed towards the back of the ophthalmic lens.

If the source is directed towards the front of the ophthalmic lens, R of the front interference coating is less than or equal to 45 DEG at an angle of incidence for wavelengths ranging from 700nm to the above-mentioned predetermined maximum wavelength_m ^NIRLess than or equal to 2.5 percent.

If the source is directed towards the rear of the ophthalmic lens, R of the front interference coating is less than or equal to 45 DEG at an angle of incidence for wavelengths ranging from 700nm to the above-mentioned predetermined maximum wavelength_m ^NIRGreater than or equal to 25%.

Further, in a particular embodiment, the light reflectance Rv of the front and rear interference coatings is less than 2.5%, preferably less than 1%, more preferably less than 0.75%, in the visible range, i.e. for wavelengths ranging from 380nm to 780nm, at an angle of incidence less than or equal to 45 °.

The light reflectance Rv is defined as in the ISO 13666:1998 standard, i.e. the ratio of the luminous flux reflected by a material to the incident luminous flux in the entire visible spectrum (i.e. between 380nm and 780 nm).

Thus, visible light reflection is limited for light coming from behind the wearer of the lens and for light reflected on the front and back of the lens.

This is particularly advantageous because visual comfort is increased by limiting reflections from behind the lens, and aesthetics are improved by reducing reflections perceived by the viewer.

In a particular embodiment, the rear interference coating includes at least four layers, each layer having a refractive index that is either lower than or higher than the refractive index of all adjacent layers. In other words, layers of low refractive index material and layers of high refractive index material are alternately stacked.

In this embodiment, if the deep red and NIR light sources are directed towards the front of the ophthalmic lens, the front interference coating also comprises at least four layers, each layer having a refractive index either lower than or higher than that of all adjacent layers.

In this embodiment, as a non-limiting example, the lens includes a substrate that may be transparent or partially absorbing for visible light and transparent or partially absorbing for deep red and NIR light. In the direction of movement away from the substrate, the interference coating comprises at least:

one layer having a refractive index ranging from 1.6 to 2.4;

one layer having a refractive index of less than 1.6;

one layer having a refractive index ranging from 1.6 to 2.4;

one layer with a refractive index of less than 1.6.

In this embodiment, the layer having a refractive index ranging from 1.6 to 2.4 may be made of, for example, zirconium oxide (ZrO)₂) The layer made of and having a refractive index of less than 1.6 may, for example, be made of silicon dioxide (SiO)₂) And (4) preparing.

In this embodiment, by way of non-limiting example, the lens comprises, in the direction moving away from the substrate, at least:

one layer having a physical thickness ranging from 10nm to 25 nm;

one layer having a physical thickness ranging from 20nm to 35 nm;

one layer having a physical thickness ranging from 140nm to 180 nm;

one layer with a physical thickness ranging from 90nm to 120 nm.

In this embodiment, as a non-limiting example, the physical thickness of the rear interference coating or the physical thickness of the front interference coating (always directing the deep red and NIR light sources towards the front of the ophthalmic lens) is less than or equal to 500nm, preferably less than or equal to 320nm, and typically ranges from 260nm to 320 nm.

In a particular embodiment, the front interference coating comprises at least six layers if the deep red and NIR light sources are directed towards the rear of the ophthalmic lens. In the direction moving away from the substrate, the front interference coating comprises at least:

one layer having a refractive index ranging from 1.6 to 2.2;

one layer having a refractive index greater than or equal to 2.2;

one layer having a refractive index less than or equal to 1.6;

one layer having a refractive index greater than or equal to 2.2;

one optical layer having a refractive index ranging from 1.6 to 2.2; and

one layer having a refractive index of less than or equal to 1.6.

In this embodiment, the layer having a refractive index ranging from 1.6 to 2.2 may be made of, for example, zirconium oxide (ZrO)₂) The layer with a refractive index of less than 1.6 may be made of, for example, silicon dioxide (SiO)₂) The layer made of and having a refractive index greater than 2.2 may, for example, be made of titanium dioxide (TiO)₂) And (4) preparing.

In this embodiment, by way of non-limiting example, the lens comprises, in the direction moving away from the substrate, at least:

one layer having a physical thickness ranging from 31nm to 54 nm;

one layer having a physical thickness ranging from 74nm to 98 nm;

one layer having a physical thickness ranging from 165nm to 190 nm;

one layer having a physical thickness ranging from 87nm to 98 nm;

one optical layer having a physical thickness ranging from 0nm to 10 nm; and

one layer with a physical thickness ranging from 64nm to 85 nm.

The refractive indices mentioned in this application are expressed at a wavelength of 550nm at 25 ℃ unless otherwise specified.

In certain embodiments, the ophthalmic lens 10 may include a hard coating to increase its wear resistance. In such embodiments, the refractive index of the substrate will advantageously be similar to that of the hard coating in order to reduce striations due to mismatch between refractive indices. Indeed, fringes may also degrade the image quality for eye feature measurement, as these fringes may provide intensity variations, especially when high coherence light is used (which is the case when using NIR light with a narrow wavelength bandwidth).

The following examples illustrate the invention in a non-limiting manner.

Examples of the invention

1. General procedure

The ophthalmic lens used in the examples included an index of refraction of 1.60 (MR from Mitsui)A lens), a lens substrate coated with a 3 μm thick hard coating having a refractive index of 1.59.

An antireflective coating according to the invention is deposited on the back of the lens.

In addition, for use with deep red and NIR light sources directed towards the front of the lens, an antireflective coating according to the invention is also deposited on the front of the lens.

On the other hand, for use with deep red and NIR light sources directed towards the back of the lens, a reflective coating according to the invention is deposited on the front of the lens.

The layers of the antireflective coating and of the reflective coating are deposited by evaporation under vacuum (evaporation source: electron gun) without heating the substrate.

The deposition frame was a Leybold 1104 machine equipped with an electron gun for evaporation of oxides (ESV14(8kV)), and provided with an ion gun for preliminary stage (commonweal Mark II) to prepare the substrate surface with argon Ions (IPC).

The thickness of these layers was controlled by a quartz microbalance. Spectroscopic measurements were performed on a variable incidence spectrophotometer Perkin-Elmer Lambda 850 with URA fittings (Universal reflection fittings).

2. Test program

The method for manufacturing an ophthalmic lens comprised in an optical device according to the invention comprises a step of introducing a substrate (possibly coated with a conventional abrasion-and scratch-resistant coating on its back or front face) into a vacuum deposition chamber, a step of pumping until a high vacuum is obtained, a step of activating the substrate surface by means of an argon ion beam, turning off the ion radiation, then a step of subsequently forming different layers of an antireflection coating and of a reflective coating by successive evaporation, and a final ventilation step.

3. Results

The structural characteristics and optical properties of an ophthalmic lens obtained with the interference coating of example 1 on the back face of the lens are described in detail below.

Fig. 3 shows the reflection curves between 380nm and 900nm for incident angles of 15 ° and 35 °.

The optical value is the latter optical value.

Chromaticity of reflected light (C)^*) And hue angle (h)^*) Are provided for 15 deg. and 35 deg. incident angles, a standard light source D65 and a standard observer (angle 10 deg.).

Rv is the light reflectance calculated from 380nm to 780 nm.

In an implementation of the embodiment of fig. 1, the same interference coating as in example 1 has been deposited on the front face of the ophthalmic lens. In example 1, the average reflectance on both the front and back faces of the lens is less than or equal to 2.5%, or even less than 1%, for wavelengths ranging from 700nm to 900 nm. By such properties, noise reflections are avoided.

In an implementation of the embodiment of fig. 2, another interference coating, described in detail below in example 2, has been deposited on the anterior face of the ophthalmic lens, where the hard coating is different from the hard coating on the posterior face, the hard coating having a refractive index of 1.479 and a thickness of 3 μm.

In example 2, the average reflectance on the rear face of the lens is less than or equal to 2.5%, or even less than 1%, for wavelengths ranging from 700nm to 900 nm; and an average reflectance on the front face of the lens is greater than 25% for wavelengths ranging from 700nm to 900 nm. By such properties, light towards the back of the lens is only reflected by the front of the lens, and low reflection on the back avoids noise reflections.

Although representative processes and articles have been described in detail herein, those skilled in the art will recognize that various substitutions and modifications may be made without departing from the scope as described and defined by the appended claims.