WO2006090646A1

WO2006090646A1 - Method for manufacturing optical glass, method for manufacturing polarization converting element and polarization converting element

Info

Publication number: WO2006090646A1
Application number: PCT/JP2006/302841
Authority: WO
Inventors: Minoru Tanaka; Hiroki Kameyama; Takashi Sekiguchi
Original assignee: Fujinon Sano Corporation
Priority date: 2005-02-22
Filing date: 2006-02-17
Publication date: 2006-08-31
Also published as: JP2006234861A; TW200643473A

Abstract

A glass laminate block is formed by laminating and bonding stepwise a plurality of optical glass boards having different optical characteristics along a reference wall, inclining the work stepwise in a front and rear direction, having both right and left side sections vertical and a length of one or a plurality of optical glass plates at a substantially middle step shorter than that of other optical glass plates, and by forming a reference groove on the vertical planes on both right and left sides. A bonded glass flat plate is formed by slicing the glass laminate block by a prescribed thickness in a direction parallel to the reference wall, the edges are removed by polishing a ridge line section and an angular corner section of the bonded glass flat plate, and both front and rear planes of the bonded glass flat plate are polished. Then, the surface polished bonded glass flat plate is cut into optical elements having prescribed sizes. At the time of cutting the bonded glass flat plate, the reference groove formed on a vertical plane is permitted to be a reference section for alignment by an aligning member of an aligning jig for cutting.

Description

Optical glass manufacturing method, polarization conversion element manufacturing method, and polarization conversion element technical field

The present invention relates to a method for manufacturing an optical element such as a polarization conversion element and a method for manufacturing a polarization conversion element in which, for example, total reflection film surfaces and polarization film surfaces are alternately formed and the polarization direction of incident light is aligned and output. Further, the present invention relates to a polarization conversion element manufactured by this method for manufacturing a polarization conversion element.

Background art

[0002] A polarization conversion element as an example of an optical element has a function of aligning and outputting the polarization direction without lowering the light utilization efficiency when light containing polarization components orthogonal to each other is incident. To demonstrate. For this reason, the optical element is formed in a flat plate shape. The total reflection surface and the polarization surface are alternately formed in multiple stages at an angle of 45 ° with respect to the incident surface. A 1Z2 wave plate is formed in a stripe shape at the part facing the polarization plane. As a result, when light containing P-polarized light component and S-polarized light component is incident, the light of S-polarized light component is reflected by the polarization surface, then reflected again by the total reflection surface, and emitted from the opposite surface as it is. Is done. On the other hand, the P-polarized component light is separated from the S-polarized component by passing through the polarization plane, and is emitted as the light of the S-polarized component by rotating the polarization direction by 90 ° with the 1Z2 wavelength plate. The configuration of this type of polarization conversion element is described in Patent Document 1, for example.

[0003] As described above, in order to arrange a plurality of total reflection surfaces and polarization planes that are inclined at an angle of 45 ° with respect to the optical path so as to be alternately arranged in the upper and lower directions, an optical glass having a total reflection film formed thereon The plates and the optical glass on which the polarizing film is formed are alternately overlapped so that their film surfaces are 45 ° with respect to the incident plane of the optical element. For this purpose, a glass wall block is formed by providing a reference wall inclined at 45 °, laminating two types of optical glass sequentially along the reference wall, and fixing each layer with an adhesive. To do. Then, this glass laminate block is sliced in a direction parallel to the reference wall with a wire saw, for example, and both the front and back surfaces are polished to form a bonded glass flat plate having a predetermined thickness. Made. If this bonded glass flat plate is placed in the vertical direction, that is, if the polished surface is placed in a direction perpendicular to the optical path, the total reflection surface and the polarization plane that are inclined at 45 ° to the optical path will be A plurality of them can be alternately arranged. The manufacture of such an optical element is disclosed in Patent Document 2. In Patent Document 2, a bonded glass flat plate obtained as described above is further divided to manufacture a beam splitter! / Speak. Patent Document 1: Japanese Patent Laid-Open No. 10-186195

Patent Document 2: JP 2000-199810 A

Disclosure of the invention

Problems to be solved by the invention

[0004] By the way, after slicing the glass laminate block to have a predetermined thickness, both the front and back surfaces are polished. Since this polishing needs to be performed with high accuracy, it is performed by lapping. It is common. In this lapping process, in order to protect the machining tool so as not to be damaged, it is necessary to remove by sharply polishing sharp edges on the corners and ridges of the workpiece in advance. When this polishing process is performed, the reference position is lost in the outer shape of the workpiece. Then, after lapping the workpiece, it becomes impossible to perform some processing by positioning the workpiece on the basis of the outer shape. Therefore, for example, at the stage of the bonded glass flat plate described above, there is no large standard, and there is no accurate standard when cutting and dividing it into a plurality of optical elements of a predetermined size. In addition, there is a problem that the dimensional accuracy of the product may vary.

[0005] The present invention has been made in view of the above points, and the object of the present invention is to reliably leave a portion serving as a reference surface until the final stage of manufacturing an optical element. Use the reference surface to make it possible to perform operations such as dividing into desired sizes very accurately.

Means for solving the problem

[0006] In order to achieve the above-described object, according to the present invention, a plurality of optical glass plates having different optical characteristics are laminated in a stepped manner along a reference wall according to a certain order and bonded to each other. The glass product is inclined stepwise in the front-rear direction and the left and right sides are vertical. A glass plate block forming step for forming a layered body block, and a flat plate forming step for slicing the glass laminate block in predetermined directions in a direction parallel to the reference wall to form a bonded glass flat plate And an edge treatment step for polishing edges and corners of the bonded glass flat plate to remove edges, and a surface polishing step for polishing both front and back surfaces of the bonded glass flat plate subjected to the edge removal treatment. A flat plate dividing step of cutting the bonded glass flat plate that has undergone surface polishing and dividing it into optical elements of a predetermined size, and among the optical glass plates that are bonded together in the glass plate blocking step The length of one or a plurality of optical glass plates stacked in an approximately middle stage is shorter than the length of the other optical glass plates, so that the left and right sides of the glass laminated body block are vertically formed. A reference groove is formed in the face, and this reference groove is used as a reference portion positioned by a positioning member provided in the cutting positioning jig when the bonded glass flat plate is divided during the flat plate dividing step. It is characterized by that.

In short, in the final stage of manufacturing an optical element, a large-sized bonded glass flat plate is divided into a necessary size as an optical element, thereby improving manufacturing efficiency. A high quality optical element can be manufactured as a product by holding the reference portion until cutting for this division.

[0008] As the optical glass plate, one or a plurality of optical glass plates positioned in the middle step between two or more kinds of alternately laminated layers can be formed of a thick raw glass plate. . In this way, by inserting the raw glass plate in the middle, it is possible to divide the raw glass plate as a boundary portion in the plane plate dividing step. Further, the cut surfaces of the raw glass plates can be polished and the polished surfaces can be bonded to each other.

[0009] When forming the glass laminate block, they are laminated in an inclined step shape having a predetermined angle, but a reference wall that is at least inclined is required, but a second reference surface is provided on the other side. It can also be formed. That is, in addition to the reference wall formed obliquely, a second reference wall in a vertical state provided in a direction perpendicular to the reference wall is provided, and in the second reference wall, the reference groove is disposed in the arrangement portion of the reference groove. A protrusion is formed. In the glass plate blocking process, an optical glass plate is laminated along the reference wall and the second reference wall. For example, ultraviolet curable resin can be used for bonding between the optical glass plates of the glass laminate block. And UV is optical glass End face direction force Set to irradiate.

Here, the first invention when used as a method for manufacturing a polarization conversion element as an optical element is the first optical element in which a total reflection film is formed along a reference wall having an inclination angle of 45 °. A glass plate and a second optical glass plate on which a polarizing film is formed are alternately arranged, and a plurality of steps are stacked and bonded together to incline stepwise in the front-rear direction and the left and right sides are suspended. A glass plate block forming step for forming a straight glass laminate block, and the glass laminate block is sliced at a predetermined thickness in a direction parallel to the reference wall to form a bonded glass plane plate A flat plate forming step, an edge processing step for removing edges by polishing the ridges and corners of the bonded glass flat plate, and a surface for polishing both front and back surfaces of the bonded glass flat plate subjected to the edge removal processing A polishing step and the joining gas A plane plate dividing step of cutting the plane plate into optical elements of a predetermined size, and a 1Z2 wavelength at a position facing the polarizing film or the total reflection film on one side of the divided plane plate Of the optical glass plates laminated in the glass plate blocking step, the length of one or a plurality of optical glass plates laminated in an approximately middle stage is set to the other optical glass plate. A reference groove is formed on the left and right vertical surfaces formed in the glass laminate block by being shorter than the length of the glass plate, and the bonded glass plane plate is divided during the plane plate dividing step. In this case, the reference portion is positioned by a positioning member provided in the cutting positioning jig.

[0011] Further, according to a second aspect of the method for manufacturing a polarization conversion element, a first optical glass plate having a total reflection film formed along a reference wall having an inclination angle of 45 ° and a polarizing film are provided. The formed second optical glass plates are arranged alternately, and a plurality of steps are stacked and bonded together, and the optical glass plates arranged in the middle steps are thicker than other optical glass plates. A glass plate block forming process comprising a glass plate, forming a glass laminate block that is inclined stepwise in the front-rear direction and the left and right sides are vertical, and the glass laminate block is defined as a reference wall. A flat plate forming step of forming a bonded glass flat plate by slicing in a parallel direction at a predetermined thickness, and an edge process for removing edges by polishing ridges and corners of the bonded glass flat plate Bonded glass plane with process and edge removal treatment Front and back surfaces and surface polishing step of polishing a cut of the bonding glass flat plate, an optical predetermined size A flat plate dividing step of dividing into two parts by cutting the raw glass plate into two parts, and facing the polarizing film or the total reflection film on one side of the flat plate thus divided 1G2 wavelength plate is laminated at a position to be laminated, and an inversion joining step of reversing one side after joining the cut surface divided into two by the raw glass plate and joining the polished surfaces. By making the length of one or more optical glass plates laminated in the middle step of the optical glass plates bonded together in the plate blocking process shorter than the length of the other optical glass plates A reference groove was formed on the left and right sides of the laminate block, and this reference groove was provided in the cutting positioning jig when dividing the bonded glass flat plate during the flat plate dividing step. For positioning member Ri is characterized in that the reference portion being determined position, Ru.

The invention's effect

[0012] Since the reference plane remains until the final stage of optical element production! /, Therefore, high-precision processing and processing are performed until the bonded glass flat plate is divided, and high quality as an optical element is obtained. There are effects such as.

Brief Description of Drawings

FIG. 1 is an explanatory diagram of a configuration of a polarization conversion element as an optical element.

FIG. 2 is an explanatory view showing a step of forming a glass laminate block in the method of the present invention.

FIG. 3 is a side view of FIG.

FIG. 4 is an explanatory view showing a flat plate forming step in the method of the present invention.

FIG. 5 is an explanatory view showing a plane plate dividing step in the method of the present invention.

FIG. 6 is an explanatory view showing an inversion joining process in the method of the present invention.

Explanation of symbols

[0014] 1A, 1B optical element

10, 11, 12 Optical glass plate

13 Glass laminate block

14 Reference groove

15 Bonded glass flat plate 16a, 16b Optical element piece

20 First reference wall

21 Second reference wall

21a ridge

22 Positioning pin

23 Cutting positioning jig

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, Fig. 1 shows the configuration of an optical element as a final product manufactured by the method of the present invention. This optical element is a polarization conversion element, and two structurally different elements are shown. FIG. 4A shows an optical element 1A having an entrance surface 2A and an exit surface 3A, and an optical film is formed at an angle of 45 ° with respect to the entrance surface 2A and the exit surface 3A. The first optical film is the total reflection film 4, and the second optical film is the polarizing film 5. The polarizing film 5 reflects S-polarized light and transmits P-polarized light. Further, a 1Z2 wavelength plate 6 is formed by a film forming means at a portion facing the polarizing film 5 on the exit surface 3A side of the optical element 1A.

[0016] The light emitted from the light source 7 includes S-polarized light and P-polarized light, and the light emitted from the light source 7 is incident on the incident surface as much as 2A while passing through the optical element 1. Of the light, S-polarized light is reflected by the polarizing film 5, and the reflected light of the parenthesis is reflected again by the total reflection film 4, and then is emitted as S-polarized light with the exit surface 3A force. On the other hand, the P-polarized light is separated into S-polarized light by the polarizing film 5, and the plane of polarization is rotated by 90 ° by the 1Z2 wavelength plate 6 to be converted into S-polarized light. Accordingly, all light is converted into S-polarized light on the exit side of the optical element 1A. In the illustrated polarization conversion element, light including S-polarized light and P-polarized light is converted into S-polarized light and emitted. However, the 1Z2 wavelength plate 6 is made to face the total reflection film 4. In this case, all the emitted light is P-polarized light.

FIG. 1 (b) shows another type of optical element IB, where the 2B side is the entrance surface and the 3B side is the exit surface. In this optical element 1B, total reflection films 4 and polarizing films 5 are alternately formed, but the tilt directions of the films are reversed on the left and right sides with the central portion C in the length direction as the center. The 1Z2 wave plate 6 is provided on the side facing the polarizing film 5. Even if configured in this way The light emitted from the light source 7 including the P-polarized light and the S-polarized light is all emitted as S-polarized light in the same manner as the optical element 1A.

[0018] Therefore, hereinafter, a method for manufacturing the optical element 1B as a polarization conversion element will be described. Here, as shown in FIGS. 2 and 3, three types of optical glass plates 10, 11, and 12 are used. The optical glass plate 10 has a total reflection film 4 formed on one surface thereof, and the optical glass plate 11 has a polarizing film 5 formed on one surface thereof. The optical glass plate 12 is a bare glass that is not formed on any surface. One or more optical glass plates 12 are used. On the other hand, the optical glass plates 10 and 11 have the same thickness and the same size. On the other hand, the optical glass plate 12 has a width dimension larger than the optical glass plates 10 and 11 (as will be described later, the direction of the force toward the second reference wall 21 in FIG. 3) smaller than those. ing.

The optical glass plates 10 and 11 are laminated alternately. An optical glass plate 12 is interposed in the middle one or two to three stages. An optical glass plate 11 having a polarizing film 5 formed thereon is provided at the upper and lower stages of the stage where the optical glass plate 12 is provided, and a total reflection film 4 is formed at the lowermost stage and the uppermost stage. An optical glass plate 10 is provided. By laminating the optical glasses 10, 11 and 12 in this order, the glass laminate block 13 is formed.

[0020] This glass laminate block 13 is laminated in a staircase shape, and as a whole, as shown in Fig. 2, the glass laminate block 13 has a staircase shape with an angle of 45 ° in the front-rear direction. As described above, the left and right sides of the glass laminate block 13 are vertical surfaces. For this, two reference walls are used. The first reference wall 20 serves as an inclined reference wall for forming the staircase of the glass laminate block 13, and the first reference wall 20 is inclined at an angle of 45 °. The second reference wall 21 is in a vertical state, and a protrusion 21a is formed in the middle. The optical glass 12 is laminated at the position of the protrusion 21a, and the length of the protruding portion of the protrusion 21a is a dimensional difference in the width direction between the optical glass plates 10 and 11 and the optical glass plate 12. The dimension is equivalent to half of the size.

[0021] The optical glass plates 10, 11 and 12 can be easily obtained by laminating the adjacent first and second reference walls 20, 21 so that two adjacent sides are brought into contact with each other. Also, the force can be accurately laminated. When a predetermined number of optical glass plates are laminated, A laminated body block 13 is formed. As shown in FIG. 2, the laminated glass block 13 has a force that is laminated in an inclined state while being shifted in an oblique direction. As is apparent from FIG. 3, in the portion of the optical glass plate 12 located in the middle stage, grooves 14 penetrating in the front-rear direction are formed on both left and right side portions. Here, all the optical glass plates 10 to 12 are strictly controlled in size, and therefore the groove 14 formed between the glasses serves as a reference groove having a highly accurate dimension.

[0022] When the optical glass plate is laminated to form the glass laminate block 13, for example, an ultraviolet curable adhesive is applied to the laminated surface, and after the lamination is completed, for example, on the vertical surface side The ultraviolet curable adhesive is cured by irradiating with ultraviolet rays. As a result, the glass laminate block 13 is fixed. The above is the glass plate blocking process.

Next, as shown in FIG. 4, the glass laminate block 13 is sliced in the tilt direction, that is, in the direction parallel to the first reference wall 20 to obtain the bonded glass flat plate 15. As will be described later, the thickness T of the bonded glass flat plate 15 is thicker by the polishing allowance on both sides than the final thickness of the optical element 1B. In order to slice this glass laminated body block 13, it can cut | disconnect easily by using a wire saw or a band saw. Of course, the glass laminate block 13 is cut after taking out the reference wall force. This process is a flat plate forming process. Here, the reference groove 14 is present in all of the predetermined number of bonded glass flat plates 15 obtained by slicing the glass laminate block 13.

[0024] Since the bonded glass flat plate 15 formed in the flat plate forming step has sharp portions at the ridgeline portions, that is, the sides constituting the six surfaces and the corners, these sharp edges are present. The part is polished and chamfered. This is the edge processing step. This edge treatment process is to prevent damage to parts of the polishing apparatus, particularly the lapping surface plate, etc. in the surface polishing process described later, and to prevent the bonded glass flat plate 15 from being cracked or chipped. However, although a sharp part remains in the part of the reference groove 14, the reference groove 14 is in a deep position and has a slight length, so that it is difficult to carry out the capping at the time of lapping. If the tool is damaged! /, There will be no other problems! / ...

[0025] The surface of the bonded glass flat plate 15 obtained as described above is polished. This surface polishing is an example For example, both front and back surfaces are processed simultaneously by lapping. This surface polishing is performed according to the amount remaining as a polishing allowance in the flat plate forming process.

Thereafter, as shown in FIG. 5, a bonded glass flat plate 15 after film formation is placed on a cutting positioning jig 23 in which two positioning pins 22 are erected, for example, diamond. The bonded glass flat plate 15 is cut along cutting lines DX1 to DX3 and DY1 to DY4 with a cutting tool such as a cutter. Then, after cutting, the width G is polished for each cutting line. The polishing for the width G is indispensable at the position of the cutting line DX2, but it is not always necessary to polish at other positions. Here, among the horizontal cutting lines DX1 to DX3, the cutting by the cutting lines DX1 and DX3 creates a flat portion at the upper and lower ends when configured as the polarization conversion element 1B, and the intermediate cutting line DX2 Is a cutting line for performing reversal bonding as will be described later.

When the bonded glass flat plate 15 is cut, the bonded glass flat plate 15 must be accurately positioned on the cutting positioning jig 23. Here, in the positioning of the bonded glass flat plate 15, it is necessary to accurately position the y direction and the 0 direction among the X, y, and Θ directions. However, in the X direction, the distance between the cutting lines DY1–DY2, DY2-DY3, and DY3–DY4 is important, but it is not a problem if these cutting lines are shifted slightly to the left or right as a whole. From the above, no special positioning accuracy is required in this direction. The positioning jig for cutting 23 is provided with two positioning pins 22 and 22, and these positioning pins 22 are in a reference glass 14 located on both the left and right sides of the bonded glass flat plate 15. In this case, the side wall portion of the reference groove 14 is the side surface portion of the optical glass plate 11 having an accurate dimensional accuracy, and this portion is not polished during the edge processing step, so that the dimensional accuracy is maintained. ing. Therefore, the bonded glass flat plate 15 can be accurately positioned in the y direction and the Θ direction by bringing the two positioning pins 22 into contact with the side surfaces of the optical glass plate 11 in the reference grooves 14 on both sides. . Even if the optical glass plate 10 is partially chipped on its side surface, the bonding glass flat plate 15 is displaced in the X direction so that the contact portion with the positioning pin 22 avoids the chipped position. In this way, positioning can be performed.

The above is the plane plate dividing step. During this flat plate splitting process, the cutting line in FIG. The part on the left side from DY1 and the right side of the cutting line DY4 force is discarded, so that the reference groove does not exist. However, since no positioning wall is required after this, there will be no problem even if the positioning reference position no longer exists!

[0029] When the optical element 1B is divided into six parts as described above, it is a surface on the side of the emission surface 3B, which faces the polarizing film 5 or faces the total reflection film 4 The 1Z2 wave plate 6 is formed only at the position where it is applied. The 1Z2 wavelength plate 6 can be formed by a film forming means, and an appropriate means such as affixing a film can also be adopted. Therefore, on the surface on the emission surface 3B side, the surface from which the glass is exposed and the surface on which the 1Z2 wavelength plate 6 is laminated are alternately striped. After this lamination, an antireflection film is formed on both the front and back surfaces.

Further, as shown in FIG. 6, one of the optical element pieces 16a and 16b that is divided into two by the cutting line DX2 and whose end face is polished, for example, the optical element piece 16b is reversed and the back surface is reversed. The face of the ground glass plate 12 is bonded and bonded with an adhesive. As a result, the optical element IB shown in FIG. 1 (b) is manufactured. Here, in the optical element 1B, when the 1Z2 wavelength plate 6 is laminated at a position facing the polarizing film 5, the emitted light becomes S-polarized light, and the 1Z2 wavelength plate 6 is positioned at the position facing the total reflection film 4. When is placed, the emitted light becomes P-polarized light.

[0031] Note that, in the case of manufacturing the optical element 1A shown in Fig. 1 (a), the optical glass plate constituting the middle stage of the glass laminate block is not a raw glass plate, although it is almost the same as described above. Laminate optical glass plates 10 and 11 alternately. Then, in order to form the reference groove, except for the lowermost and uppermost optical glass plates, one or more optical glass plates laminated in the middle are those having a narrow width dimension. Use. Also, in the flat plate dividing process, it is not necessary to cut the part corresponding to the cutting line DX2 in Fig. 6, and the subsequent reverse joining is not performed.

Claims

The scope of the claims

[1] A plurality of optical glass plates having different optical characteristics are stacked in a stepped manner along a reference wall in a certain order, and bonded together to incline in a stepwise manner in the front-rear direction. Glass plate block forming process to form a glass laminate block with both sides vertical;

A flat plate forming step of slicing the glass laminate block at a predetermined thickness in a direction parallel to the reference wall to form a bonded glass flat plate;

An edge processing step of polishing edges and corners of the bonded glass flat plate to remove edges;

A surface polishing step for polishing both the front and back surfaces of the bonded glass plane plate that has been subjected to edge removal processing;

It comprises a flat plate dividing step of cutting a bonded glass flat plate that has been subjected to surface polishing and dividing it into optical elements of a predetermined size,

Of the optical glass plates to be bonded together in the glass plate blocking step, the length of one or more optical glass plates stacked in an approximately intermediate stage is shorter than the length of the other optical glass plates. Thus, a reference groove is formed on the left and right vertical surfaces formed in the glass laminate block, and when the bonded glass flat plate is divided during the flat plate dividing step, the positioning for cutting is performed. A reference part that is positioned by a positioning member provided on the jig

A method for manufacturing an optical element.

[2] When forming the glass laminated body block, one or a plurality of optical glass plates disposed in an intermediate stage are constituted by a raw glass plate thicker than other optical glass plates, and the raw glass The reference groove is formed by shortening the width dimension of the plate, and in the plane plate dividing step, the substrate is cut at a portion of the glass plate and divided into two, and after the cut surface is polished, the other is inverted. 2. The method of manufacturing an optical element according to claim 1, wherein these polished surfaces are bonded.

[3] When forming the glass laminate block, in addition to the inclined reference wall, a second reference wall in a vertical state provided in a direction perpendicular to the reference wall is provided. The reference wall of 2 is formed with a protrusion at the reference groove placement portion, and the glass plate blocking step 2. The method of manufacturing an optical element according to claim 1, wherein the optical glass plate is laminated along the reference wall and the second reference wall.

[4] A first optical glass plate with a total reflection film and a second optical glass plate with a polarization film are alternately arranged along a reference wall having an inclination angle of 45 ° in a staircase pattern. A glass plate block forming step for forming a glass laminate block that is inclined in a stepwise manner in the front-rear direction and the left and right sides are vertical,

A flat plate dividing step of cutting the bonded glass flat plate to divide it into optical elements of a predetermined size;

A laminating step of laminating a 1Z2 wavelength plate at a position facing the polarizing film or the total reflection film on one side surface of the divided flat plate,

Of the optical glass plates to be bonded together in the glass plate blocking step, the length of one or more optical glass plates laminated in an approximately middle stage shall be shorter than the length of the other optical glass plates. Forming a reference groove on the right and left vertical surfaces formed in the glass laminate block, and when dividing the bonded glass flat plate in the flat plate dividing step, the reference groove is used as a cutting positioning jig. The reference part is positioned by the provided positioning member.

A method for manufacturing a polarization conversion element, comprising:

[5] A first optical glass plate on which a total reflection film is formed and a second optical glass plate on which a polarizing film is formed are arranged alternately along a reference wall having an inclination angle of 45 °. The optical glass plates that are stacked and bonded together and are arranged in the middle step are composed of thicker glass plates that are thicker than the other optical glass plates, and are inclined stepwise in the front-rear direction. A glass plate block forming step for forming a glass laminate block in which A flat plate forming step of slicing the glass laminate block at a predetermined thickness in a direction parallel to the reference wall to form a bonded glass flat plate;

A flat plate dividing step of cutting the bonded glass flat plate and dividing it into optical elements of a predetermined size, and then cutting into two parts by cutting at the portion of the raw glass plate;

A laminating step of laminating a 1Z2 wavelength plate at a position facing the polarizing film or the total reflection film on one side of the divided flat plate;

After polishing the cut surface divided into two parts by the raw glass plate, it comprises an inversion joining step of inverting one side and joining the polished surfaces.

A method for manufacturing a polarization conversion element, comprising:

A polarization conversion element manufactured according to claim 4 or claim 5.