阅读说明：本技术 扩散元件、照明模块和非球面透镜的加工方法 (Diffusion element, illumination module and processing method of aspheric lens ) 是由 小野健介 浜田刚 南贤一 盐谷健一 西坂拓马 于 2019-03-26 设计创作，主要内容包括：本发明涉及一种非球面透镜的加工方法,其包括：对玻璃基板实施前处理的前处理工序、以及对实施了前述前处理的前述玻璃基板实施湿式蚀刻的蚀刻工序,前述前处理工序包括：对前述玻璃基板的某个位置照射脉冲激光而使前述玻璃基板内部的部分区域发生改性,至少在照射了前述脉冲激光的位置处沿着厚度方向发生密度分布的工序；或者,利用化学方法或物理方法,在前述玻璃基板的表面形成规定的楔形凹部的工序。(The invention relates to a processing method of an aspheric lens, which comprises the following steps: a pretreatment step of pretreating a glass substrate and an etching step of wet-etching the glass substrate subjected to the pretreatment, the pretreatment step including: irradiating a position of the glass substrate with a pulse laser beam to modify a partial region inside the glass substrate, thereby generating a density distribution in a thickness direction at least at the position irradiated with the pulse laser beam; or forming a predetermined wedge-shaped recess on the surface of the glass substrate by a chemical method or a physical method.)

1. A method for processing an aspherical lens, comprising:

a pretreatment step of pretreating a glass substrate; and

an etching step of performing wet etching on the glass substrate subjected to the pretreatment,

The pretreatment process comprises the following steps: irradiating a position of the glass substrate with a pulse laser beam to modify a partial region inside the glass substrate, thereby generating a density distribution in a thickness direction at least at the position irradiated with the pulse laser beam; or forming a predetermined wedge-shaped recess on the surface of the glass substrate by a chemical method or a physical method.

2. The method of processing an aspherical lens according to claim 1, wherein the pretreatment is performed at a plurality of positions in the plane of the glass substrate.

3. The method for processing an aspherical lens according to claim 1 or 2, wherein the wet etching is performed without using a resist mask.

4. The method for processing an aspherical lens according to any one of claims 1 to 3, wherein the pulsed laser is irradiated to the glass substrate through an objective lens.

5. The method for processing an aspherical lens according to any one of claims 1 to 4, wherein a surface of the glass substrate on which the aspherical lens is to be processed is a first surface, and a surface opposite to the first surface is a second surface,

the pulsed laser is irradiated from the second surface side of the glass substrate.

6. The method for processing an aspherical lens according to any one of claims 1 to 5, wherein when a surface of the glass substrate on which the aspherical lens is to be processed is a first surface, the first surface is set to 0, and a direction of advance of the pulse laser beam is set to a + side,

the pulse laser has a focal point position in the range of-0.290- +0.075 mm.

7. The method of processing an aspherical lens according to any one of claims 1 to 6, wherein the pulse width of the pulsed laser is 10ps or less and the power is 5.0W or more.

8. The method of processing an aspherical lens according to any one of claims 1 to 7, wherein at least one parameter selected from the group consisting of a focal position, irradiation time, and power of the pulse laser is changed in accordance with a position at which the pretreatment is performed.

9. The method of processing an aspherical lens according to any one of claims 1 to 3, wherein k' represents a conic coefficient obtained when the surface shape of the concave portion is fitted by an aspherical equation in which all aspherical higher-order coefficients are set to 0, and k represents a conic coefficient of an aspherical shape of the formed aspherical lens,

K' < k is satisfied.

10. The method of processing an aspherical lens as defined in any one of claims 1 to 3 and 9, wherein the concave portion has no flat portion at the tip or the width of the flat portion at the tip is 2 μm or less.

11. The method of processing an aspherical lens as defined in any one of claims 1 to 3, 9 and 10, wherein the concave portion is formed by performing sand blasting, dicer half-cut, dry etching or drilling on the surface of the glass substrate.

12. The method of processing an aspherical lens according to claim 11, wherein the abrasive grains in the blasting have a size of 20 μm or less.

13. The method of processing an aspherical lens according to claim 11 or 12, wherein at least one parameter selected from the group consisting of a size of abrasive grains in the blasting, a blasting time, and a blasting pressure is changed according to a position at which the pretreatment is performed.

14. A diffusion element, comprising:

a glass substrate; and

a plurality of concave aspheric lenses directly processed on one surface of the glass substrate,

the aspherical lens is disposed without a gap in at least an effective region of the surface of the glass substrate,

The maximum size of the aspherical lens is 250 μm or less,

the divergence angle of the outgoing light flux when parallel light enters the effective region from the surface on which the lens is processed, that is, the divergence angle is 30 ° or more in total angle.

15. The diffusing element of claim 14 wherein the lens shape of the aspheric lens is a parabolic shape,

the aspherical lens has a surface accuracy of 0.1 μm or less.

16. The diffusing element of claim 14 or 15 wherein the maximum tilt angle of the aspheric lens is 30 ° or greater.

17. The diffusing element of any of claims 14 to 16 wherein the aspheric lenses each have a moire pattern that is concentric in a front view.

18. A lighting module is provided with:

a light source;

a mounting substrate on which the light source is mounted; and

a window member disposed above the light source and having a diffusion function,

a window component having a diffuser element according to any one of claims 14 to 17.

19. The lighting module of claim 18, wherein the window component is provided with a diffusing surface exhibiting a diffusing function, the diffusing surface facing downward,

the distance between the light source and the diffusion surface of the window member is 0.3mm or less.

20. The lighting module of claim 18 or 19, wherein the light emitted from the light source has a wavelength of 800-1000 nm.

Technical Field

The present invention relates to a method for processing an aspherical lens. Furthermore, the invention relates to a diffusing element and a lighting module using the same.

Background

Diffusion elements are used in a variety of optical devices. As an example, an illumination device and a measuring device for performing three-dimensional measurement can be cited.

Some of such optical devices use light that cannot be observed with the naked eye, such as near-infrared light or ultraviolet light. Examples of such devices include a remote sensing device used for face recognition and focusing of a camera in a smartphone or the like, a remote sensing device connected to a game machine or the like to capture a user's action, and a LIDAR (Light detection and Ranging) device used for sensing a surrounding object in a vehicle or the like. Further, there may be mentioned: and an illumination device for irradiating high-energy light such as ultraviolet light, blue-violet light, and blue light for the purpose of growing and sterilizing plants.

In recent years, it has been required for such an optical device to irradiate light at an exit angle significantly different from the traveling direction of incident light. For example, in a camera device used for focusing purposes such as a smartphone, a measuring device for sensing a peripheral object in a near infrared monitoring camera installed indoors and outdoors, an illumination device or a measuring device used for detecting a peripheral object such as an obstacle or a finger in a VR (Virtual Reality) headset, and the like, it is desirable to irradiate light in a wide-angle range in which a spread angle (total angle) is 30 ° or more and 50 ° or more, depending on a field angle of the camera device and a human visual angle.

By utilizing the refraction action of the lens, the incident light can be spread to a certain range and irradiated. Further, by using the lens array, the light intensity distribution in the incident light flux can be uniformized and emitted.

Non-patent document 1 describes an example of a diffusing element using a microlens array, which has a divergence angle of 100 ° or more with respect to a laser light source having a wavelength of 633 nm. In non-patent document 1, a photoresist (photosensitive polymer) is laminated on a glass substrate in a uniform thickness, and then the photoresist is exposed to a small focused beam for each spot while modulating the intensity of a laser beam during scanning, thereby changing the exposure level to the photoresist. As a result, a surface having a continuous uneven structure with a depth can be obtained. Patent document 1 describes an example of a laser marking system for manufacturing such a diffusion element.

Patent document 2 describes an example of a diffusing element having a microlens array in which parabolic microlenses are arranged without gaps, although the diffusion angle of the embodiment is about 10 °.

Patent document 3 describes, as an example of a diffusion plate made of an inorganic material and a method for manufacturing the same: a method in which a resist laminated on a transparent substrate is exposed to light using a gray scale mask, and then developed, and the pattern of the resist is transferred to the surface of the transparent substrate by dry etching.

Patent document 4 describes a method of combining isotropic etching and anisotropic etching as an example of a method of forming a curved lens surface of an aspherical microlens. In the method described in this document, patterning is performed on a substrate with a resist and a mask interposed therebetween to open initial holes, and thereafter, isotropic etching is performed on the mask with the resist interposed therebetween to widen an opening of the mask. Thereafter, after the resist is removed, the substrate is subjected to anisotropic etching treatment through a mask having a wide opening, thereby opening the insertion hole. Thereafter, isotropic etching is performed on the substrate provided with the insertion hole to form a recess.

Disclosure of Invention

Problems to be solved by the invention

The problem is that when it is intended to realize wide-angle (e.g., 30% or more in total angle) light irradiation with glass having high heat resistance and high-energy light resistance including ultraviolet rays (i.e., ultraviolet resistance, blue-violet resistance, and blue resistance), it is difficult to realize the light irradiation due to the difficulty in processing, or desired optical characteristics (particularly, uniformity of light intensity in an irradiation plane) cannot be obtained due to low processing accuracy.

When a wide-angle diffusing element having a diffusion angle (total angle) of 30 ° or more is manufactured using a spherical lens having a spherical lens surface, the light intensity distribution of the outgoing light beam shows a nonuniform light intensity distribution that is strong at the center and weak at the periphery (see fig. 19 (a)). On the other hand, when the same wide-angle diffusing element is manufactured using an aspherical lens having an aspherical surface such as a paraboloid in the shape of the lens surface, the light quantity distribution of the outgoing light beam can be made uniform (see fig. 19 (b)).

Note that, if a microlens array is used, the light amount in the incident light flux can be made uniform by the array structure, but if the light amount distribution of the outgoing light flux from each lens is made nonuniform, the outgoing light fluxes from each lens overlap, that is, the light amount distribution of the outgoing light flux from the element is also made nonuniform. This problem appears more remarkably in the case where the irradiation range is wide.

In this manner, in consideration of the diffusing element capable of uniform irradiation in a wide-angle range, each lens shape is preferably an aspherical surface. However, in general, as the exit angle increases, the inclination of the boundary portion (outermost peripheral portion) becomes an acute angle and the amount of concavity also increases. For example, considering an aspherical lens having a diffusion angle of 30 ° or more, a concave amount of at least 20 μm is required.

Since anisotropic etching can be achieved if dry etching is used, the surface of the base material can be processed into an aspherical shape. Examples of the processing method include: a method of forming an aspherical lens array of a photoresist by using the gray mask and then performing dry etching; a method of performing dry etching after resin imprinting using a mold.

However, in the dry etching, if the amount of lens concavity is increased (for example, 5 μm or more) and the boundary portion is sharply formed, it is difficult to perform the processing with good accuracy. For example, when a lens shape having a large concave amount is processed by dry etching, a boundary portion which must be at an acute angle is ground, and blunted angle is generated (see fig. 20). This is because: at an acute angle portion of the boundary of the lens array, the processing rate by the etching gas becomes locally large. Fig. 20 (a) shows a desired aspherical shape, and fig. 20 (b) shows the shape of the aspherical lens after processing. In this case, the material of the lens array is quartz glass. In addition, although fig. 20 (b) shows a concave lens array, in the case of a convex lens array, the processing of the etching gas does not reach the acute angle portion of the boundary of the lens array, and therefore the processing rate is locally reduced. In any case, it is difficult to process the acute boundary portion (see α in fig. 20 (b)) with good accuracy by dry etching.

On the other hand, in wet etching, etching proceeds isotropically, and therefore, only a spherical lens can be processed only when etching is performed directly.

In view of such processing difficulty, when a microlens array is produced in which the amount of concavity of each lens is 20 μm or more, a method using a mold, a method of converting a refractive microlens into an equivalent diffraction microlens, or the like is often employed (for example, see patent document 2).

In addition, according to the description of non-patent document 1, even a microlens array having an aspherical surface in which the concave amount of each lens is 20 μm or more can be manufactured with high accuracy by using a marking system using a laser. However, the laser marking system described in patent document 1 and the like can be applied only to a diffusion element made of pog (polymer on glass) in which a resin uneven structure is formed on a glass substrate, and a microlens array cannot be directly processed on the glass substrate. Patent document 2 also does not disclose a method of directly processing a glass substrate, and the like, and it is considered that the PoG structure is still the premise.

In the case of PoG, depending on the use environment, heat resistance and resistance to high-energy light including ultraviolet light become problems.

For example, with the demand for downsizing and thinning of optical devices, there are cases where the lighting module included in the optical device is required to be thinned. It can be considered that: as the thickness of the illumination module is reduced, the distance between the light source and the diffusion element for diffusing the light from the light source in the illumination module is reduced, and the ambient environment of the diffusion element is heated to a high temperature. Further, it can be considered that: regardless of the distance between the light source and the diffusion element, the ambient environment of the diffusion element becomes high in temperature as the output of the light source increases. It can also be considered that: when a module in which a diffusion element and a light source are integrated is mounted on an electronic substrate by reflow soldering or the like, the ambient environment of the diffusion element is heated to a high temperature during the mounting of the device, not limited to the ambient environment during operation.

When such an illumination module is mounted on an automobile, very severe environmental resistance is required. For example, the high temperature test may be 150 ℃ for 1000 hours, the high temperature and high humidity test may be 85 ℃ for 85% RH for 1000 hours, and the thermal cycle test may be-55 ℃ to 125 ℃ for 500 cycles. In this case, the lens is required to have not only heat resistance but also low moisture absorption and a thermal expansion coefficient approximately equal to that of the material of the lighting module.

Further, the light used is not limited to near infrared light/visible light. For example, when ultraviolet light, blue-violet light, or blue light is used, it is necessary to consider deterioration of optical characteristics due to deterioration of optical components caused by irradiation with these high-energy light.

Generally, a resin material is inferior to a glass material in heat resistance and high-energy light resistance, and has a large moisture absorption property. The heat-resistant Temperature (Maximum Temperature) of a typical diffusion element made of PoG is about 120 ℃, but if it is borosilicate glass or the like known as a material having a small thermal expansion coefficient, the heat-resistant Temperature is 200 ℃ or higher. The heat-resistant temperature in this case means a usual use temperature. Therefore, in a case where it is possible to place the element in such an ambient environment, it is preferable that the element is constituted only by a glass material having high heat resistance and high light resistance.

However, when an attempt is made to directly machine a microlens array having an aspherical surface and a deep concave portion on the surface of a glass substrate, the following problems arise. That is, the glass substrate has a problem that the dry etching rate is very slow and is not crystalline, so that the anisotropic etching cannot be performed by using the crystalline.

For example, patent document 3 describes a method of processing the surface of a glass substrate into a lens shape other than a spherical surface by using a gray scale mask, but the full width at half maximum (FWHM) corresponding to the diffusion angle (full angle) of a diffusion element is only 10 ° at the maximum. This is considered because: at an acute angle portion of the boundary of the lens array, the processing rate by the etching gas becomes locally large. Further, when a large diffusion angle is to be obtained, the depth of the lens is increased, and therefore, the processing time in the dry etching step is increased, which is not preferable from the viewpoint of productivity.

In the method described in patent document 4, although the number of steps is increased, the surface of the glass substrate can be processed into an aspherical lens shape. However, the method described in patent document 4 uses anisotropic etching, and has a problem that the material is limited to quartz or the like.

Further, in order to form the stepped shape formed by the dry etching step into a smooth aspherical shape, it is necessary to increase the amount of wet etching, which results in a problem of a small diffusion angle.

In addition, the processing rate in the wet etching step of quartz is very low compared with borosilicate glass and lead-free glass, and therefore, this is not preferable from the viewpoint of productivity.

In view of the above problems, an object of the present invention is to provide an aspherical lens processing method capable of processing an aspherical lens which can be irradiated at a wide angle (for example, a spread angle (total angle) of 30 ° or more) directly and accurately on a surface of a glass substrate. Another object of the present invention is to provide a diffusion element capable of wide-angle irradiation with high accuracy and high productivity, and an illumination module including the diffusion element, which has excellent heat resistance and ultraviolet light resistance.

Means for solving the problems

The method for processing an aspherical lens according to the present invention is characterized by comprising: a pretreatment step of pretreating a glass substrate and an etching step of wet-etching the glass substrate subjected to the pretreatment, the pretreatment step including: irradiating a position of the glass substrate with a pulse laser beam to modify a partial region inside the glass substrate, thereby generating a density distribution in a thickness direction at least at the position irradiated with the pulse laser beam; or forming a predetermined wedge-shaped recess on the surface of the glass substrate by a chemical method or a physical method.

Further, a diffusion element according to the present invention includes: a glass substrate; and a plurality of concave aspherical lenses directly processed on one surface of the glass substrate, wherein the aspherical lenses are arranged without a gap in at least an effective region of the surface of the glass substrate, the maximum size of the aspherical lenses is 250 [ mu ] m or less, and a divergence angle of an outgoing beam when parallel light is incident from the surface on which the lenses are processed with respect to the effective region, that is, a divergence angle is 30 ° or more in total angle.

Further, the lighting module according to the present invention includes: a light source; a mounting substrate on which the light source is mounted; and a window member having a diffusion function provided above the light source, the window member having the diffusion element according to the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide an aspherical lens processing method capable of directly processing an aspherical lens capable of wide-angle diffusion on the surface of a glass substrate with good accuracy. Further, according to the present invention, a diffusion element capable of wide-angle irradiation and excellent in heat resistance and ultraviolet light resistance, and an illumination module including such a diffusion element can be provided with high accuracy and high productivity.

Drawings

Fig. 1 is an explanatory diagram illustrating an example of a method of processing an aspherical lens described in the first embodiment.

Fig. 2 is a cross-sectional view and a plan view of the aspherical lens 2 obtained after the etching step.

Fig. 3 is an explanatory diagram showing process dependence in the etching process.

Fig. 4 is an explanatory diagram showing process dependence in the etching process.

Fig. 5 is a graph showing the measurement results of the light distribution characteristics in examples a-2 to a-6 of the diffusing element 10 including the plurality of aspherical lenses 2 obtained by the processing method of the first embodiment.

Fig. 6 is a graph showing the measurement results of the light distribution characteristics in examples B-1 to B-6 of the diffusing element 10 including the plurality of aspherical lenses 2 obtained by the processing method of the first embodiment.

FIG. 7 (a) shows the laser focal point position L in each example shown in Table 1_fGraph of relationship to divergence angle and central intensity. FIG. 7 (b) shows the laser focal point position L in each example shown in Table 2_fGraph of relationship to divergence angle and central intensity.

Fig. 8 is a diagram showing a cross-sectional shape of the aspherical lens 2 obtained by the processing method of the first embodiment.

Fig. 9 is a configuration diagram showing an example of an illumination module 100 using the diffusion element 10 obtained by the processing method of the first embodiment.

Fig. 10 is an explanatory view schematically illustrating a design concept of the second embodiment.

Fig. 11 is an explanatory diagram illustrating an example of a method of processing an aspherical lens according to the second embodiment.

Fig. 12 (a) is a diagram showing an example of a machining result in the wedge machining step using blast machining, and fig. 12 (b) is a diagram showing a cross-sectional shape of the aspherical lens 2 obtained by wet etching after the wedge machining step using blast machining.

Fig. 13 is a diagram showing the light intensity distribution on a certain irradiation plane of light irradiated by the diffusion element 10 obtained by wet etching after the wedge processing step by sandblasting.

FIG. 14 is a plan view of the diffusing member 10 of example 1-1.

FIG. 15 is an observation image by a laser microscope of example 1-1.

Fig. 16 is a graph showing the light intensity distribution calculated by ray tracing simulations for examples 1 to 5 and examples 1 to 23.

Fig. 17 is a diagram showing light intensity distributions calculated by ray tracing simulations for comparative examples 1 and 2.

Fig. 18 is a graph showing the calculation results of light distribution simulation when the diffusing elements 10 of examples 1 to 5 were applied to the illumination module 100.

Fig. 19 is an explanatory diagram showing an example of the light quantity distribution of the outgoing light flux of the spherical lens and the aspherical lens.

Fig. 20 is an explanatory diagram showing an example of the shape accuracy of the aspherical lens.

Detailed Description