JP2007163551A - Optical element and method of manufacturing optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element which has a stray light suppressing region without applying black paint or the like onto an outer peripheral part of the optical element and to provide its manufacturing method. <P>SOLUTION: The optical element 6 having the stray light suppressing region outside an optical effective diameter of the optical element is constituted so that the stray light suppressing region is formed inside the optical element and outside the optical effective diameter and light absorption intensity differs from that inside the optical effective diameter. At that time, the stray light suppressing region can be constituted so that light absorption intensity within a wavelength range between 350nm and 800nm differs from that inside the optical effective diameter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical element having a stray light suppression region and a method for manufacturing the optical element.

In recent years, further improvement in performance of optical elements has been promoted.
For this reason, stray light (light other than the light flux involved in image formation) due to irregular reflection and scattering can cause ghosts and flares in the image, which is one of the causes of image quality degradation. Yes.
In particular, in an optical system configured with a combination of optical elements, stray light due to irregular reflection or scattering on the periphery, edges, and edges of lenses and prisms, which are the main components of the optical elements incorporated in the optical system. It is easy to produce.

As such a countermeasure, conventionally, for example, when centering the outer peripheral portion of a lens or prism, a method of applying black paint or the like that absorbs stray light to the rough surface generated in the outer peripheral portion, etc. Has been adopted.
For example, in Patent Document 1, Patent Document 2, Patent Document 3, etc., stray light such as black paint for black or glass is absorbed on the rough surface such as the periphery, edge, and ridge of a lens or prism to reflect the inner surface. There has been a proposal for avoiding stray light by applying a paint for preventing the above.
On the other hand, in recent years, a method for forming an optical element by press molding has been developed in order to omit the above-described centering process and to manufacture a lens easily and inexpensively. For example, as in Patent Document 4, a molding method of an optical element in which a glass material is press-molded using a mold structure has been developed.
According to this, as shown in FIG. 6, the glass material 113 is filled so as to be in contact with the upper die 111, the lower die 112, and the circumferential barrel die 119, and the optical element is molded in the die by press molding. Is done.
JP-A-3-12602 JP-A-5-181005 JP-A-9-258005 JP 7-247128 A

By the way, in the case of applying the black paint of the above-mentioned conventional example, it is possible to prevent stray light by applying the black paint to the rough surface of the outer peripheral portion of the lens or the like. A paint that can be used to prevent stray light is required.
In order to obtain the inner surface antireflection performance with such a coating material, a coating material that takes into consideration the adhesiveness, mechanical strength, heat resistance, durability, refractive index, etc. of the coating film is required.
Furthermore, in the above-mentioned conventional example in which the molded product is brought into contact with the upper die, the lower die, and the body die on the circumference, and the side portion does not become a rough surface, the black paint is applied. Inconvenience arises.
That is, since a rough surface is not formed on the outer peripheral side surface portion of the optical element, the black paint is not easily applied to the side surface portion, so that the inner surface antireflection performance can be obtained even after repeated coating. It becomes difficult.

  In view of the above problems, an object of the present invention is to provide an optical element having a stray light suppression region and a method for manufacturing the optical element without applying a black paint or the like to the outer peripheral portion of the optical element.

In order to solve the above-mentioned problems, the present invention provides an optical element having a stray light suppression region configured as follows and a method for manufacturing the optical element.
The present invention is characterized in that an optical element having a stray light suppression region outside the optical effective diameter of the optical element is configured as follows.
In the present invention, the stray light suppression region is formed inside the optical element outside the optical effective diameter, and the light absorption intensity is different from that within the optical effective diameter.
In the present invention, the stray light suppression region is characterized in that the light absorption intensity is stronger than the effective optical diameter.
In the present invention, the stray light suppression region is characterized in that the light absorption intensity in the wavelength range of 350 nm to 800 nm is different from that within the optical effective diameter.
In addition, the method for manufacturing an optical element having a stray light suppression region outside the effective optical diameter of the optical element of the present invention is characterized by having the following steps (1) and (2).
(1) A first step of manufacturing an optical element by molding.
(2) Irradiating ultraviolet rays outside the optical effective diameter of the optical element manufactured in the first step, and as the stray light suppression area, a region where the light absorption intensity is different from the optical effective diameter is outside the optical effective diameter 2nd process formed in the optical element in.
Moreover, in this invention, it molds using a glass material in the said 1st process, It is characterized by the above-mentioned.
In the present invention, a single glass material is used as the glass material.
In the present invention, in the second step, a UV laser device is used when irradiating ultraviolet rays.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical element which has a stray light suppression area | region, and an optical element is realizable, without apply | coating black paint etc. to the outer peripheral part of an optical element.

  The best mode for carrying out the present invention will be described by the following examples.

[Example 1]
In Example 1, a method of manufacturing an optical element subjected to the stray light suppression process to which the present invention is applied will be described.
In the present embodiment, a glass material is molded using a press die in the same manner as the press molding of Patent Document 4 of the conventional example described above, and outside the optical effective diameter of the optical element in which the rough surface is not formed on the outer peripheral side surface portion. Then, UV laser light was irradiated to suppress stray light.

Next, a method for manufacturing an optical element by press molding in the present embodiment will be described first.
FIG. 1 shows a configuration of a press mold used for manufacturing an optical element in this embodiment. In FIG. 1, 1 is a lower mold for molding, 2 is an upper mold for molding, 3 is a barrel mold, and 4 is a glass material as a molding material to be molded.
The body mold 3 regulates and supports the positions of the lower mold 1 for molding and the upper mold 2 for molding, and has a heater for heating the lower mold 1 for molding and the upper mold 2 for molding inside. I have.
In addition, the inner surface 5 of the body mold 3 is polished to Ra = 0.1 so that the upper mold 2 for molding can be moved smoothly in the vertical direction, and the side surface of the lens is molded into a product shape. Is configured to do.

Next, a method for manufacturing an optical element using the manufacturing apparatus as described above will be described.
First, the body mold 3, the lower mold 1 for molding, the upper mold 2 for molding, and the glass material 4 are heated to a temperature necessary for molding by a heater provided in the trunk mold 3.
Next, a load is applied from a press shaft (not shown) to the upper mold 2 for molding, and the glass material 4 is press-molded.
The glass material transfers the upper mold 2 for molding, the lower mold 1 for molding, and the inner surface 5 of the barrel mold 3, and cools to room temperature to complete the molding.
FIG. 2 shows the molded optical element.
In FIG. 2, 6 is a molded optical element, and 13 is a side surface.
The inner surface 5 of the body mold 3 is transferred to the surface of the side surface portion 13 of the molded optical element 6, and is transferred with Ra = 0.1 as the inner surface 5 of the body mold 3. A rough surface is not formed on the side surface.

Next, a process of creating an optical element capable of suppressing stray light in the optical element 6 molded as described above will be described.
FIG. 3 shows a configuration example of an apparatus for suppressing stray light by irradiating UV laser light with a UV laser apparatus outside the optical effective diameter of the optical element in the present embodiment.
In FIG. 3, 6 is an optical element molded product, 7 is a bell clamp holder, 8 is a bell clamp holder, 9 is a rotating shaft, 10 is a drive motor, and 11 is a drive motor.
In the present embodiment, the pair of bell clamp holders 7 and 8 that hold the lens 6 from both sides are arranged so as to be coaxially positioned with high accuracy with respect to the rotation shaft 9 and are free to rotate around the rotation shaft 9. It is configured to be able to rotate.
Furthermore, the outer diameters of the bell clamp holders 7 and 8 are configured to be larger than the optical effective diameter of the lens to be held.
The bell clamp holder 7 on one side is fixed at a fixed position with respect to the rotating shaft 9, but the other bell clamp holder 8 is configured to be freely movable in the axial direction of the rotating shaft 9.
The pair of bell clamp holders 7 and 8 are rotationally driven by a driving means.
The drive means rotates the pair of bell clamp holders 7 and 8 by the drive motors 10 and 11.
The bell clamp holder 8 is configured to move on the rotating shaft 9 by driving means (not shown).

Next, the operation of the apparatus for suppressing stray light by irradiating the UV laser light of the present embodiment will be described.
First, the optical element 6 is held between the opposing bell clamp holders 7 and 8 in a constant pressure state. For such holding, generally known means is used in which the optical axis of the optical element 6 is forced to coincide with the rotational axes of the bell clamp holders 7 and 8.
After holding and fixing the optical element 6 in this way, rotation of the output shafts of the drive motors 10 and 11 is started.
Since the optical element 6 is held by the bell clamp holders 7 and 8 at a constant pressure, the optical element 6 rotates without shifting in the rotation direction.
Next, UV laser light is oscillated from the laser irradiation device 12 and irradiated to the optical element 6.
Since the bell clamp holders 7 and 8 shield the optical effective diameter of the optical element 6, the UV laser light is irradiated outside the optical effective diameter of the optical element 6.
The irradiation conditions of the UV laser were a wavelength of 355 nm and an average laser output of 5 W.
After irradiating with UV laser light for 1 minute, the optical element 6 was taken out.

FIG. 4 shows a configuration of an optical element formed by an apparatus in which stray light is suppressed by irradiating UV laser light with a UV laser apparatus outside the optical effective diameter of the optical element in the present embodiment.
In FIG. 4, reference numeral 15 denotes an area irradiated with UV laser light.
The region 15 irradiated with the laser light in the optical element 6 is colored in gray, whereby the light absorption intensity changes so as to increase more than the uniform light absorption intensity within the optical effective diameter. Yes.
When this optical element was incorporated in a lens unit and its performance was evaluated in a wavelength range of 350 nm to 800 nm, it was confirmed that the product was a non-defective product free from defects such as ghosts and flares.

[Example 2]
In Example 2, an optical element on which stray light suppression processing was performed using an ultraviolet irradiation device was manufactured.
In this embodiment, instead of the UV laser device of the first embodiment, only an ultraviolet irradiation device is used, and the other portions are basically the same as those of the first embodiment. Is omitted.
FIG. 5 shows a configuration example of an apparatus in which stray light is suppressed by irradiating ultraviolet light by an ultraviolet irradiation apparatus outside the optical effective diameter of the optical element in this embodiment.
In FIG. 5, 14 is an ultraviolet irradiation device.
In this embodiment, the ultraviolet irradiation device 14 is arranged on both sides of the holding portion of the optical element constituted by a pair of bell clamp holders, and the ultraviolet irradiation device irradiates the ultraviolet light outside the optical effective diameter of the optical element. Configured.
This ultraviolet irradiation device 14 irradiated 6 kW of light for 5 minutes to form a region for suppressing stray light outside the optical effective diameter of the optical element.
Even when an ultraviolet irradiation device was used instead of the UV laser device of Example 1 as in this example, an optical element having the same effect as in Example 1 could be obtained.

The figure which shows the structure of the press-molding die used for manufacture of the optical element in Example 1 of this invention. Sectional drawing of the optical element molded product produced with the press die of Example 1 of this invention. The figure which shows the structural example of the apparatus which irradiated the UV laser beam with the UV laser apparatus outside the optical effective diameter of the optical element in Example 1 of this invention, and suppressed stray light. The figure which shows the structure of the optical element formed by the apparatus which irradiated the UV laser beam in Example 1 of this invention, and suppressed the stray light. The figure which shows the structural example of the apparatus which irradiated the ultraviolet light by the ultraviolet irradiation device outside the optical effective diameter of the optical element in Example 2 of this invention, and suppressed stray light. The figure which shows the structure of the press die used for manufacture of the optical element by press molding in patent document 4 which is a prior art example.

Explanation of symbols

1: Lower mold for molding 2: Upper mold for molding 3: Body mold 4: Molding material 5: Inner surface 6 of the body mold: Optical element 7: Bell clamp holder 8: Bell clamp holder 9: Rotating shaft 10: Drive Motor 11: Drive motor 12: Laser irradiation device 13: Optical element side surface portion 14: Ultraviolet irradiation device 15: Area irradiated with UV laser light

Claims (8)

An optical element having a stray light suppression region outside the optical effective diameter of the optical element,
The stray light suppressing region is formed inside the optical element outside the optical effective diameter, and the optical absorption intensity is different from that within the optical effective diameter.   2. The optical element according to claim 1, wherein the stray light suppression region has an intensity of absorption of the light that is stronger than that within the optical effective diameter.   3. The optical element according to claim 1, wherein the stray light suppression region has a light absorption intensity in a wavelength range of 350 nm or more and 800 nm or less that is different from that within the optical effective diameter. A method of manufacturing an optical element having a stray light suppression region outside the optical effective diameter of the optical element,
A first step of producing an optical element by molding;
The optical element manufactured in the first step is irradiated with ultraviolet rays outside the optical effective diameter, and the stray light suppression area is an optical element outside the optical effective diameter that has a light absorption intensity different from the optical effective diameter. A second step of forming inside;
A method for producing an optical element, comprising:   5. The method of manufacturing an optical element according to claim 4, wherein in the first step, molding is performed using a glass material.   The method for manufacturing an optical element according to claim 5, wherein a single glass material is used as the glass material.   The method for manufacturing an optical element according to claim 4, wherein a UV laser device is used when irradiating ultraviolet rays in the second step.   The method of manufacturing an optical element according to any one of claims 4 to 7, wherein an ultraviolet irradiation device is used when irradiating ultraviolet rays in the second step.

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