JP2016151645A - Manufacturing method of optical unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which in assembling an optical unit capable of an optical modulation in an optical system, it takes much man-hour for adjusting alignment of a polarization direction of the optical system with an optical modulation direction of an optical element cassette owned by the optical unit.SOLUTION: A manufacturing method of an optical unit 1 includes: a housing 4 attachable/detachable in a prescribe direction with respect to a prescribed optical system; and an optical element cassette 30 implementing an optical modulation with respect to polarization of the optical system. The manufacturing method thereof comprises: an optical element cassette preparation process of preparing a plurality of optical element cassettes 30 mutually different in an optical modulation direction (an arrow mark C) upon implementing the optical modulation; an optical element cassette selection process of selecting the optical element cassette 30 having the optical modulation direction corresponding to a polarization direction of the optical system; and an optical element cassette attachment process of attaching the optical element cassette 30 selected by the optical element cassette selection process to the housing 4.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an optical unit provided in an optical device of an optical system such as a microscope, and relates to a method of manufacturing an optical unit having an optical element cassette made of a liquid crystal element capable of controlling the phase of transmitted light.

  Conventionally, an optical device such as a laser microscope, an optical pickup device, a laser processing machine, or the like that detects information such as the shape of an object by irradiating the object with light or causes some change in the object. It's being used. In such an optical system, for example, an optical unit having an optical element cassette made of a liquid crystal element is incorporated, and a light modulation technique for enabling super-resolution or correcting wavefront aberration has been proposed.

  In order to obtain the above characteristics, the alignment direction of the liquid crystal element of the optical element cassette, that is, the light modulation direction of the optical element cassette is matched with the polarization direction of the linearly polarized light of the laser light source of the optical system. For this reason, there has been proposed an optical unit having a mechanism capable of rotating the optical modulation direction of the optical element cassette around the optical axis of the optical system (for example, see Patent Document 1).

International Publication No. 2012/124634 (Page 9-11, Figure 2-3)

  However, in the prior art shown in Patent Document 1, the polarization direction of the laser light source and the light modulation direction of the optical element cassette are different when the optical unit is first incorporated into the optical system or when the optical unit is incorporated into another optical system. In order to adjust the alignment, the optical unit must be rotated each time, which has a problem of man-hours.

  Therefore, the present invention has been made to solve these problems, and it is easy to select and incorporate in advance an optical element cassette having a light modulation direction that matches the polarization direction of the laser light source of the optical device. Another object of the present invention is to provide a method for manufacturing an optical unit capable of reliably modulating light.

  In order to achieve the above object, the optical unit of the present invention employs the following manufacturing method.

  An optical unit manufacturing method according to the present invention is a manufacturing method of an optical unit comprising: a housing that can be attached to and detached from a predetermined optical system in a predetermined direction; and an optical element cassette that performs optical modulation on the polarization of the optical system. An optical element cassette preparing step of preparing a plurality of optical element cassettes having different light modulation directions when performing light modulation, and selecting an optical element cassette having a light modulation direction corresponding to the polarization direction of the optical system And an optical element cassette attaching step for attaching the optical element cassette selected in the optical element cassette selecting step to the housing.

  By using such a manufacturing method, an optical element cassette whose optical polarization direction and optical modulation direction coincide with each other is selected and installed, so ultra-high resolution and wavefront aberration correction can be performed easily and reliably. An optical unit can be manufactured.

  In the optical element cassette preparation step, the optical modulation direction of the optical element cassette is the first direction perpendicular to the optical axis of the optical system and the second direction perpendicular to the optical axis and the first direction, respectively. You may prepare things.

  If such a manufacturing method is used, even if the polarization direction of the optical device is unknown, it is possible to easily and reliably ensure the polarization direction by preparing the light modulation direction of these two directions and selecting the appropriate one. And the optical modulation direction can be matched, and an optical unit that enables optical modulation in the optical system can be manufactured.

  In the optical element cassette attaching step, the direction in which the optical element cassette is attached to the housing may be the first direction.

  By using such a manufacturing method, the polarization direction and the light modulation direction can be more easily and reliably matched, and an optical unit that enables light modulation in the optical system can be manufactured.

  As described above, according to the manufacturing method of the optical unit of the present invention, the polarization direction of the light of the optical system and the light modulation direction of the optical element cassette can be easily and surely matched. Resolution, wavefront aberration correction, and the like are possible. In addition, when changing the characteristics of the light modulation or incorporating it in another optical system, an optical unit that can easily and reliably modulate the light is provided by selecting and mounting the light modulation direction of the optical element cassette. Is possible.

It is a perspective view for demonstrating the optical system in which the Example of the optical unit of this invention was integrated. It is a disassembled perspective view for demonstrating the Example and optical system of the optical unit of this invention. It is a disassembled perspective view for demonstrating the Example of the optical unit of this invention. It is a process flow figure for demonstrating the manufacturing process of the Example of the optical unit of this invention. It is a perspective view for demonstrating the manufacturing process of the Example of the optical unit of this invention. It is a top view for demonstrating the light modulation direction of an optical element cassette in the manufacturing process of the Example of the optical unit of this invention. It is a perspective view for demonstrating the process of incorporating an optical element cassette in the manufacturing process of the Example of the optical unit of this invention.

  The optical element cassette incorporated in the optical unit of the present invention is detachable in a predetermined direction with respect to the optical system body, and a plurality of types of optical element cassettes having different light modulation directions are prepared, and the polarization direction of the laser light of the optical system On the other hand, it is a characteristic part that an optical element cassette having the same light modulation direction is selected from the optical element cassette and incorporated in the optical unit.

Hereinafter, the optical unit will be described in detail with reference to the drawings, and a manufacturing method of the optical unit incorporated in the optical system will be described in detail.
An embodiment of an optical unit incorporated in the optical system will be described with reference to FIGS. Next, a method for manufacturing an optical unit incorporated in the optical system will be described with reference to FIGS.

[Description of Optical Unit Configuration: FIGS. 1 to 3]
First, the configuration of the optical unit will be described with reference to FIGS.
FIG. 1 is a partial perspective view of an optical system in which an optical unit according to an embodiment of the present invention is incorporated in an optical system having an objective lens. FIG. 2 is an exploded perspective view for explaining the configuration of the optical unit and the optical system, and FIG. 3 is an exploded perspective view for explaining the configuration of the optical unit. In addition, in each figure, the same number is attached | subjected to the same structural member, and the overlapping description is abbreviate | omitted.

  1 and 2 are perspective views for explaining an optical system 100 in which an optical unit is mounted between an optical system main body and an objective lens. Here, the optical system main body 2 is an optical system in which optical elements such as a light source and a lens are incorporated, and generally has a complicated and large structure. is there.

As shown in FIGS. 1 and 2, the optical unit 1 includes a housing 4 including an upper lid 20 and a lower lid 40, a front lid 60 having a front lid opening 61, an arigata 24, and a connecting member 25. The attachment / detachment mechanism 23 is used. The optical unit 1 can be easily attached and removed accurately by inserting and positioning the optical unit 1 in a predetermined direction, for example, the direction of the arrow A, by means of the attaching / detaching mechanism 23 and the arimizo 26 formed on the optical system body 2. Placement is possible. The objective lens 3 is configured such that the male screw portion 311 of the objective lens 3 is screwed and attached to a female screw portion, which will be described later, formed in the lower lid 40 from the lower arrow B direction.
Note that the order in which the objective unit 3 is attached to the optical unit 1 and then the optical unit 1 is attached to the optical system body 2 may be used.

  As a result of examining various products of the optical system 100 including the optical system main body 2 having the arimizo 26, the polarization direction of the linearly polarized light of the laser light of the optical system 100 is determined in advance by the optical system 100. That is, it was clarified that the film was formed in a direction parallel to or perpendicular to the Arimiso direction.

Next, the overall configuration of the optical unit 1 will be described in detail with reference to FIG.
Here, in the three-dimensional XYZ axes, the Z-axis direction is the optical axis 80 direction through which the laser beam is transmitted to the optical unit 1, and the Y-axis direction perpendicular to the optical axis is the optical element cassette 30. The X-axis direction is a direction perpendicular to the Y-axis.

  As shown in FIG. 3, the upper lid 20 has a rectangular plate-like upper surface formed with a cylindrical portion 21 projecting in the Z-axis direction and a concentric upper lid opening 211, and the connecting member 25 is fixed to the upper portion of the upper lid 20. A plurality of connecting portions 201 for fixing the lower lid 40 to the lower portion of the upper lid 20 and a plurality of connecting portions 202 for fixing the lower lid 40 are formed. The upper lid opening 211 is coaxial with the optical axis 80 and forms an optical path through which laser light passes. Further, an arigata 24 and a connecting member 25 that form an attaching / detaching mechanism 23 that can be attached to and detached from the optical system main body 2 are formed on the upper lid 20.

  The connecting member 25 has a cylindrical shape, and the connecting member opening 252 which is a hollow portion thereof is positioned by fitting with the cylindrical portion 21 of the upper lid 20, forms an optical path passing through the optical axis 80, and a plurality of connecting members The connection portion 201 between the portion 251 and the upper lid 20 is fixed by, for example, screwing or a connection method in which a convex portion is formed on one side and a concave portion is formed on the other side and press-fitted. Note that the shape of the connecting member 25 is not limited to a cylindrical shape, and may be a prismatic shape as long as a hollow portion capable of transmitting laser light is formed.

The arigata 24 that constitutes the attachment / detachment mechanism 23 has a shape that fits into the antimizo 26 formed in the optical system main body 2, and is formed with a through hole 242 through which laser light is transmitted and a plurality of connection portions 241. The connecting portion of the connecting member 25 is attached so that the attaching / detaching direction with the optical system body 2 and the attaching / detaching direction of the optical element cassette 30 to / from the housing 4 of the optical unit 1 are perpendicular to the optical axis and coincide with the Y-axis direction. 251 and the arigata 24 are screwed together at the connecting portion 241. In the embodiment of the optical unit of the present invention, the direction in which the attachment / detachment direction of the optical system body 2 and the attachment / detachment direction of the optical element cassette 30 coincide with each other is described in the Y-axis direction. The attachment / detachment direction may be in the X-axis direction orthogonal to each other.

The optical element cassette 30 includes a light modulation element 31, a light modulation element holder 32, and a connector 33.
As the light modulation element 31, for example, a liquid crystal element that optically modulates incident light by a drive signal can be used. The light modulation element 31 is preferably electrically connected to the connector 33 with a cable such as an FPC in order to obtain a drive signal from the outside via the connector 33. Further, a single or a plurality of light modulation elements 31 may be used in accordance with the desired light modulation. The light modulation element holder 32 holds the light modulation element 31 and has an opening at a portion corresponding to the light modulation region of the light modulation element 31.

  The optical element cassette 30 is formed of the light modulation element 31 whose light modulation direction is indicated by an arrow C (Y-axis direction). For example, the X-axis direction orthogonal to the Y-axis direction of the arrow C is the light modulation direction. It is preferable to prepare at least two types of optical element cassettes 30, such as the light modulation element 31.

  The connector 33 is fixed to one end of the light modulation element holder 32 and is connected to the external cable 70 to receive a drive signal from a control device (not shown). This makes it possible to electrically control light modulation such as wavefront aberration correction and super-resolution of the light modulation element 31.

  The lower lid 40 is formed with a left side wall 42, a right side wall 43, a rear side wall 44, which are U-shaped side walls, and a recess that allows the optical element cassette 30 to be built in at the bottom 41, and the front lid on the open end side. A U-shaped opening in the mounting portion 45 forms an entrance that allows the optical element cassette 30 to be taken in and out freely. This entrance forms a housing opening of the housing 4 that forms the upper lid 20. The screw member 52 formed on the right side wall 43 fixes the optical element cassette 30 in contact with the convex portions provided on the left side wall 42 and the back side wall 44, and positions the optical axis center. Note that an elastic member such as a spring having a predetermined elastic force may be provided in place of the above-described convex portion so that the optical element cassette is returned when it is pushed too much.

  The cylindrical lower lid opening 46 formed downward from the bottom 41 has a female screw portion 411 formed on the inner side, and its central axis is coaxial with the optical axis 80 penetrating the upper lid 20, and the objective lens 3. Is formed to be screwable. The lower lid opening 46 described above may have a hollow portion in a prismatic shape protruding downward.

  Here, when the lower cover 40 and the objective lens 3 are screwed together, the length of the female screw portion 411 is set so that the male screw portion of the objective lens 3 does not interfere with the optical element cassette 30. Or a partition may be provided between the bottom 41 and the lower lid opening 46.

  In addition, the lower lid 40 corresponds to a position where the plurality of connection portions 401 are coupled to the connection portion 202 of the upper lid 20, and the plurality of connection portions 402 correspond to a position where the plurality of connection portions 402 are coupled to the connection portion 601 of the front lid 61. Is formed. The connection method with these connection parts 401, 202, 402, 601 is a method such as screwing as described above, and the optical element cassette 30 can be incorporated by fixing the upper lid 20 to the lower lid 40. A housing 4 is formed.

  After the optical element cassette 30 is inserted and housed in the housing 4, the front lid 60 is fixed to the housing 4 by screwing the plurality of connecting portions 402 of the front lid attaching portion 45 and the connecting portion 601 of the front lid 60 described above. Then, the optical element cassette 30 is fixed.

  As a result, the optical unit 1 composed of the housing 4 and the attachment / detachment mechanism 23 formed by the upper lid 20 and the lower lid 40 is fitted and connected by the arimizo 26 and the arigata 24 at the upper portion, and the female screw portion 411 and the male screw portion at the lower portion. By screwing 311, the optical system main body 2 and the objective lens 3 are arranged and incorporated as shown in FIG. 1. The linearly polarized light of the laser beam of the optical system coincides with the light modulation direction of the light modulation element 31 of the built-in optical element cassette 30 by the opening and the through hole formed along the optical axis 80. It is formed to be transmissive.

The external cable 70 passes through the front lid opening 61 of the front lid 60 and is connected to the connector 33 of the optical element cassette 30 so that the optical element cassette 30 can be electrically controlled.
This makes it possible to electrically control light modulation such as wavefront aberration correction and super-resolution by the optical unit 1.

  In the above description, the attachment / detachment mechanism has been described as the alligator 24 that fits into the arbor 26, but is not limited to this configuration, and can be attached / detached in one direction with respect to the optical system body 2. Various configurations can be adopted. For example, if the optical system main body 2 has an alligator, it is only necessary to form an arbor on the attaching / detaching mechanism, and it may have a mechanism for attaching with a magnet, a chuck, or the like. In addition, when the optical system main body 2 includes only a mechanism that can be attached and detached by screwing, an intermediate member that can be attached to and detached from the attaching / detaching mechanism by screwing with the optical system main body 2 may be provided.

  In the above description, the case 4 has been described as including the upper lid 20 and the lower lid 40. However, the present invention is not limited to this, and any structure that can hold the optical element cassette 30 may be used. For example, you may provide the opening part which can hold | maintain the optical element cassette 30 in the above-mentioned connection member 25. FIG. In this case, the attaching / detaching mechanism is the arigata 26, and the connecting member 25 can be regarded as the housing 4.

  Although the optical element cassette 30 has been described as being detachable in the Y direction, the direction is not limited to this, as long as the optical element cassette 30 can be held in a unique direction with respect to the optical axis. For example, the X-axis direction may be used as described above, or the Z-axis direction may be used. Further, the housing 4 may be attached to and detached from the optical axis in a unique direction.

[Description of Manufacturing Method of Optical Unit: FIGS. 4 to 7]
Here, the manufacturing method of the optical unit which concerns on this invention is demonstrated using FIGS.
FIG. 4 is a process flow diagram illustrating a method for manufacturing an optical unit. 5 to 7 are diagrams for explaining the manufacturing method. That is, FIG. 5 is a perspective view for explaining a process of attaching the optical unit to the optical system. FIG. 6 is a plan view for explaining optical element cassettes having different light modulation directions. In the XY coordinates, the insertion direction of the optical element cassette into the optical unit is the Y-axis direction, and the orthogonal direction is the X-axis direction. FIG. 7 is a perspective view for explaining a process of mounting the optical element cassette on the optical unit.

As shown in FIG. 4, the manufacturing process of the manufacturing method of an optical unit is mainly three steps, and prepares a plurality of optical element cassettes having different light modulation directions in at least two directions. Step ST01), an optical element cassette selection step (step ST02) for selecting one of the optical element cassettes prepared by determining the polarization direction of the optical system and preparing at least two directions, and an optical for attaching the selected optical element cassette to the housing It is comprised by the element cassette attachment process (step ST03).
Further, after step ST03, if necessary, an optical modulation inspection step (step ST04) for confirming whether optical modulation is possible by connecting an external cable to the connector of the optical element cassette may be added. In the following description, description will be given in order as an example in which ST04 is performed in addition to steps ST01 to ST03. In addition, in each figure, the same number is attached | subjected to the same structural member, and the overlapping description is abbreviate | omitted.

Further, the optical unit 1 may be incorporated into the optical system main body 2 and the objective lens 3 at an arbitrary timing between before step ST01 and after step ST03. This will be described as an example of performing steps.
As shown in FIG. 5, the optical unit 1 is incorporated in the optical system in a predetermined direction between the optical system body 2 and the objective lens 3. However, since the optical element cassette 30 is mounted in the process of step ST03 described later, the front lid 60 is removed, and the housing opening 47 and the front lid mounting portion 45 of the housing 4 are exposed.

[Description of optical element cassette preparation process: FIGS. 4 and 6]
First, the optical element cassette preparation step (step ST01) shown in FIG. 4 will be described.
In this step, light modulation elements having different light modulation directions are prepared in at least two directions according to the type of light modulation. For example, the optical element cassette 30 shown in the plan views of FIGS. 6A and 6B is formed of the light modulation element 31, the light modulation element holder 32, and the connector 33 as described in FIG. The difference between the two is the light modulation direction of the light modulation element 31, and the light modulation direction of the light modulation element 31a in FIG. 6A, which is the first direction, is the direction of the arrow C in the Y-axis direction. The light modulation direction of the optical modulation element 31b in FIG. 6B, which is two directions, is an arrow D direction in the X-axis direction. As described above, it is not always necessary to use a combination of the same direction and the orthogonal direction as the direction of the arrowhead. The light modulation element with respect to a predetermined direction and the light modulation element with a direction rotated from the predetermined direction to an arbitrary angle are respectively provided. Although it is sufficient to prepare a plurality of each, the polarization direction of the laser beam of the optical system is usually parallel or orthogonal to the direction of the arimizo 26. Therefore, it is desirable to prepare at least two directions of the XY axes mainly as the light modulation direction of the optical element cassette 30.

[Description of optical element cassette selection process: FIGS. 4 and 6]
Next, the optical element cassette selection process (step ST02) shown in FIG. 4 will be described.
In this process, the optical element cassette 30 to be used is selected from the optical element cassettes 30 prepared in step ST01. As for the selection method, when the polarization direction of the optical system main body 2 is known, the light modulation element in which the polarization direction and the light modulation direction match or are close to each other from the plurality of optical element cassettes 30 prepared in step ST01. Select. If it is not known, an arbitrary one is selected from the plurality of optical element cassettes 30 prepared in step ST01. For example, the optical element cassette 30 shown in FIG. 6A whose light modulation direction is the C direction is selected.

[Description of optical element cassette mounting process: FIGS. 4 and 7]
Next, the optical element cassette attaching step (step ST03) shown in FIG. 4 will be described.
In this step, the optical element cassette 30 selected in step ST02 is attached to the housing 4. As shown in FIG. 7, the optical element cassette 30a whose light modulation direction is selected in step ST02 is inserted into the housing opening 47 of the housing 4 of the optical unit 1 from the direction of arrow E. The direction of arrow E is the same as the direction in which the optical system body 2 and the optical unit 1 are attached and detached (the direction of arrow A in FIG. 2).

  Then, after the optical element cassette 30 is built in the casing 4, the optical element cassette 30 is clamped by the screw member 52, covered with the front lid 60, and fixedly arranged in the casing 4. The connecting portion 601 of the front lid 60 and the connecting portion 401 of the lower lid 40 are fixed by a method such as screwing as described above. The built-in optical element cassette 30 can be electrically connected by inserting an external cable from the front lid opening 61 of the front lid 60 into the connector 33 of the optical element cassette 30.

[Description of Light Modulation Inspection Process: FIGS. 4 and 1]
Next, the light modulation inspection process (step ST04) shown in FIG. 4 will be described.
In this step, it is determined whether or not the optical element cassette 30 selected in step ST02 is appropriate. Here, when the polarization direction of the optical system is known and it is clear that the optical modulation direction of the selected optical element cassette 30 matches, this step is omitted and the manufacturing process is terminated. . Hereinafter, a case where the polarization direction of the optical system is not known will be described as an example.

As shown in FIG. 1, the optical unit 1 to which the optical element cassette 30 is attached can be electrically connected by an external cable 70 to inspect whether light modulation can be controlled.
If the light modulation can be controlled, it indicates that the polarization direction of the laser beam of the optical system and the light modulation direction of the optical unit 1 coincide with each other. If light modulation does not occur or sufficient light modulation effect does not occur, the light modulation direction of the optical unit 1 is inconsistent, so it is determined as NG, the process returns to step ST02, and the light modulation direction is in the D direction. The optical element cassette 30 is selected and reassembled.

That is, it is easy to feed back from the optical modulation inspection process of step ST04 and repeat the optical element cassette selection process, optical element cassette mounting process (step ST03), optical modulation inspection process (step ST04) and manufacturing process of step ST02. It is possible to make the polarization direction coincide with each other. And the manufacturing process which incorporates an optical unit in an optical system is completed by the above manufacturing process.
When exchanging with another type of light modulation element that performs light modulation, the polarization direction of the laser light is already known by the above-described process, and therefore the same light as the light modulation direction of the light modulation element before replacement A light modulation element having a modulation direction may be selected, and the step ST04 can be omitted.

  By the manufacturing process as described above, the optical unit 1 of the present invention can be easily and easily obtained by preparing optical element cassettes 30 having different light modulation directions, selecting the light modulation direction from the cassettes, and incorporating them in the optical unit 1. In addition, the optical modulation direction can be matched with the polarization direction of the optical system, and it is possible to correct the wavefront aberration and to give the optical system characteristics that enable super-resolution.

  Furthermore, even when the optical unit is incorporated in another optical system, the optical system 1 having at least two light modulation directions is prepared, selected, and incorporated, so that the optical system can be easily and reliably installed. Thus, the optical modulation direction of the optical element cassette 30 can be matched with the polarization direction of the optical element, and an optical system having optical modulation characteristics can be formed. In the present embodiment, an optical unit having two light modulation directions of the X-axis direction and the Y-axis direction is prepared. However, the polarization direction of the optical system body to be incorporated is not the X-axis direction or the Y-axis direction, for example, X If the light modulation direction is known in advance, such as tilted several times with respect to the axial direction, a light modulation element having a light modulation direction different from the previous two directions may be prepared and prepared. .

  As described above, the optical apparatus according to a preferred embodiment of the present invention has been described with reference to an optical apparatus for a microscope with a strict optical axis adjustment, but in addition, an optical apparatus having an optical system such as an optical pickup, a fundus examination apparatus (OCT), or a projector. It is applicable to.

  The present invention is not limited to the above-described embodiments of the optical device, and it is not necessary to perform all of them, and various modifications and omissions may be made within the scope of the contents described in the claims. Needless to say, you can.

DESCRIPTION OF SYMBOLS 1 Optical unit 2 Optical system main body 3 Objective lens 4 Case 20 Upper lid 21 Cylindrical part 23 Detachment mechanism 24 Arigata 25 Connection member 26 Arimiso 30 Optical element cassette 31 Light modulation element 32 Light modulation element holder 33 Connector 40 Lower cover 41 Bottom part 42 Left side Wall 43 Right side wall 44 Back side wall 45 Front lid mounting portion 46 Lower lid opening portion 47 Housing opening portion 52 Screw member 60 Front lid 61 Front lid opening portion 70 External cable 80 Optical axis 100 Optical system 201, 202, 241, 251 401, 402, 601 Connection part 211 Upper lid opening part 242 Through hole 252 Connecting member opening part 311 Male thread part 411 Female thread part

Claims (3)

A housing removable in a predetermined direction with respect to a predetermined optical system;
An optical element cassette that performs light modulation on the polarization of the optical system;
An optical unit manufacturing method comprising:
An optical element cassette preparation step of preparing a plurality of optical element cassettes having different light modulation directions when performing light modulation;
An optical element cassette selecting step of selecting the optical element cassette having the light modulation direction according to the polarization direction of the optical system;
An optical element cassette attaching step of attaching the optical element cassette selected in the optical element cassette selecting step to the housing. In the optical element cassette preparing step, the optical modulation direction of the optical element cassette is the first direction perpendicular to the optical axis of the optical system, and perpendicular to the optical axis and the first direction, respectively. A method for manufacturing an optical unit according to claim 1, wherein a second one is prepared. The method of manufacturing an optical unit according to claim 2, wherein in the optical element cassette attaching step, the direction in which the optical element cassette is attached to the housing is the first direction.

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