JPWO2008136243A1 - Optical element manufacturing method and joining jig - Google Patents

Abstract

The first jig of the joining jig has an abutting surface that abuts against two surfaces sandwiching the ridge line farthest from the joining surface of one prism, and the second jig is a joint of the other prism. It has a contact surface that contacts two surfaces sandwiching the ridge line farthest from the surface. In the contact step of S3, the first ridgelines in the direction perpendicular to the joint surfaces of the prisms are such that the ridgelines of the two prisms are parallel to each other and satisfy a predetermined positional relationship in a direction perpendicular to the ridgelines and parallel to the joint surface. The two jigs are moved relative to each other so that the two surfaces of the one prism are brought into contact with the contact surface of the first jig, and the two surfaces of the other prism are moved to the second. The joint surfaces of the two prisms are brought into close contact with the contact surface of the jig.

Description

  The present invention relates to a method for manufacturing an optical element for bonding two prisms using a bonding jig, and a bonding jig used for manufacturing the optical element.

  In recent years, with the advent of Blu-ray Discs and HD-DVDs, high external dimension accuracy is required for prisms of optical pickups (for example, cube-type junction prisms such as polarization separation elements). For example, as shown in FIG. 12, conventionally, the required outer dimension tolerance has been about the standard dimension ± 0.1 mm of the vertical width v and the horizontal width w, but recently, the reference of the vertical width v and the horizontal width w. A tolerance of about ± 0.05 mm is often required.

  Further, in the pickup prism, as shown in FIG. 13, the positional deviation accuracy (beam shift accuracy) Abs of the optical axis of the outgoing light Lo with respect to the optical axis of the incident light Li is often required within ± 0.05 mm. . This beam shift is mainly caused by misalignment of the joint surface (reflection surface) of the two prisms. That is, the shift of the position of the joint surface to the position indicated by the broken line in FIG.

  From the above, it has been demanded that the pickup prism satisfy both the above-mentioned external dimension accuracy and beam shift accuracy at the same time.

  Against this background, various methods for manufacturing a pickup prism have been proposed. For example, in the manufacturing method disclosed in Patent Document 1, as shown in FIG. 14, a plate-like glass material provided with an optical thin film for beam splitting is laminated stepwise using an optical adhesive (for example, an ultraviolet curable adhesive). After that, it is processed into a desired cube shape through each process of cutting, polishing, antireflection film coating, lamination, cutting, polishing, and cutting.

  According to this manufacturing method, in addition to being able to use a relatively inexpensive plate-like glass material, a large amount of prisms can be processed in a series of processing steps, so that prisms can be produced at low cost. . However, various processing errors are likely to be accumulated due to processing methods that repeat lamination, cutting, and polishing. As a result, as shown in FIG. 15, it is difficult to ensure the positional accuracy of the joint surface 101 that affects the beam shift accuracy, and it becomes difficult to obtain the required beam shift accuracy.

  On the other hand, a method for manufacturing a pickup prism using a long triangular prism has also been proposed. In this manufacturing method, as shown in FIG. 16, first, two long triangular prisms 201 and 202 are prepared. One prism is provided with a beam splitting optical thin film and an antireflection optical thin film, and the other prism is provided with an antireflection optical thin film. Next, the long triangular prisms 201 and 202 are joined using an optical adhesive (for example, an ultraviolet curable adhesive), and this is pressed against the V-shaped groove 203a of the joining jig 203, and an upper portion 45 of the joining surface. The tops are aligned and pressurized (arrow P in the figure) to cure the adhesive. That is, in this step, one surface other than the joining surface of the long triangular prism 201 is brought into contact with one surface of the V-shaped groove 203a, and the other surface of the groove 203a other than the joining surface of the long triangular prism 202 is contacted. One surface is brought into contact, and the long triangular prisms 201 and 202 are pressurized from above (from the direction along the bonding surface). Thereafter, the obtained long prisms 204 are individually cut and processed into cube-type prisms.

According to this manufacturing method, there is no accumulation of processing errors due to repetition of the same type of process, and the accuracy ΔH of the height dimension H of the long triangular prisms 201 and 202 is within the reference dimension ± 0.035 mm as shown in FIG. If managed, a prism satisfying the required beam shift accuracy Abs (within ± 0.05 mm) can be obtained. (In actual operation, the height dimension H of the long triangular prism is more for safety reasons. Take strict control values). At this time, when the obtained cube prism is assembled to the optical pickup, one of the two triangular prisms joined, that is, the short side 2 sandwiching 90 degrees of the prism on which the beam splitting optical thin film is formed. By positioning the cube prism by bringing the positioning pin 205 into contact with the side, the beam shift accuracy Abs can be easily suppressed within the above range.
JP 2000-143264 A (refer to claim 1, FIG. 3, etc.)

  By the way, in the long triangular prisms 201 and 202, generally, as shown in FIG. 18, each of the 45-degree ridge lines (corners) has a C0.1 to 0.2 degree to prevent chipping. Chamfered. In addition, C0.1-0.2 means cutting a corner | angular part in the position of 0.1-0.2 mm from the vertex of a corner | angular part. If this chamfering process is uneven, joining displacement occurs in the long triangular prisms 201 and 202 at the time of pressurization (arrow P in the figure), so that the vertical width v and the horizontal width w of the cube prism finally obtained are Is wide (for example, V> W in the figure), and it is difficult to ensure the accuracy of the outer dimensions.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical element manufacturing method capable of simultaneously ensuring both the external dimension accuracy and the beam shift accuracy, and the optical An object of the present invention is to provide a joining jig used for manufacturing an element.

  1. A method of manufacturing an optical element that joins two prisms using a joining jig, wherein the joining jig is in contact with two surfaces sandwiching a ridge line farthest from the joining surface of one prism. And a second jig having a contact surface that contacts two surfaces sandwiching the ridge line farthest from the joint surface of the other prism. A first jig and a second jig in a direction perpendicular to the joint surface of each prism so that the ridge lines are parallel to each other and satisfy a predetermined positional relationship in a direction perpendicular to each ridge line and parallel to the joint surface; The two surfaces of one prism are brought into contact with the contact surface of the first jig, and the two surfaces of the other prism are brought into contact with the contact surface of the second jig. An optical element characterized by having an adhesion process for bringing the joint surfaces of the two prisms into close contact with each other Production method.

  2. Adhesive dropping step of dropping an adhesive onto the joint surface of one prism before bringing the joint surfaces of the two prisms into close contact; A pressurizing step of pressurizing the two prisms by relative movement with the second jig, and a curing step of curing the adhesive after the pressurization (simultaneously or after pressurization) 2. The method for producing an optical element according to 1, wherein the optical element is produced.

  3. After the bonding surfaces of the two prisms are brought into close contact with each other, the method further includes a curing step of allowing the adhesive to permeate into the bonding surface from the end of the bonding surface and curing the adhesive. The manufacturing method of the optical element of description.

  4. An optical element manufacturing method for joining two prisms using a joining jig, wherein the joining jig is in contact with two surfaces sandwiching a ridge line farthest from the joining surface of one prism. And a second jig having an abutment surface that abuts against two surfaces sandwiching the ridge line farthest from the junction surface of the other prism, and the junction surface of one prism An adhesive dropping step of dropping an adhesive onto the prism, an adhesion step of bringing the bonding surface of the other prism into close contact with the bonding surface of the prism onto which the adhesive has been dropped, and the two surfaces of the one prism being connected to the first jig The two surfaces of the other prism are brought into contact with the contact surface of the second jig so that the ridge lines of the two prisms are parallel to each other and perpendicular to the ridge lines. In a state where a predetermined positional relationship is satisfied in a direction parallel to the surface, Method of manufacturing an optical element, characterized in that it has a pressing step of pressing the bonded surfaces of the two prisms in a direction, and a curing step of curing the adhesive after the pressurization step.

  5. The first jig and the second jig of the joining jig pass through the center of the joining surface of each prism and run in a direction parallel to the ridge line when the prisms are brought into close contact in the contact step. 5. The method of manufacturing an optical element according to any one of 1 to 4, wherein the center line is positioned so as to be positioned coaxially.

  6). Each of the two prisms is a right-angle prism, and in the contact step, the two prisms are brought into close contact with each other using a slope as a joint surface, and a ridge line facing the slope in one prism and a ridge line facing the slope in the other prism The method for manufacturing an optical element according to any one of 1 to 5, wherein the prisms are brought into close contact so that a plane including

  7. The method for producing an optical element according to any one of 1 to 6, further comprising a thin film forming step of forming an optical thin film on a joint surface of one prism before the two prisms are brought into close contact with each other. Method.

  8). The two prisms are long, and the manufacturing method further includes a cutting step of cutting the two prisms by a predetermined width on the basis of the prism on which the optical thin film is formed. The manufacturing method of the optical element of 7 to do.

  9. The two prisms are long, the adhesive is photocurable, and the joining jig includes a plurality of first jigs and second jigs in pairs. In the contact step, the first jig and the second jig of each pair are brought into contact with a plurality of locations in the longitudinal direction of each prism to bring the prisms into close contact. In the curing step, the first jig and 5. The method of manufacturing an optical element according to any one of 2 to 4, wherein the adhesive positioned between each pair of second jigs is irradiated with light to cure the adhesive.

  10. The two prisms are long, the adhesive is photocurable, and one of the first jig and the second jig of the joining jig has two The prism has a length corresponding to the length in the longitudinal direction of the prism, and the other jig has two end abutting members that can abut on one prism and both ends in the longitudinal direction, An intermediate abutting member capable of abutting against one prism is provided between the two end abutting members. In the contact step, the two end abutting members of the other jig and the intermediate abutting member are disposed. With the contact member in contact with one prism and the one jig in contact with the other prism, the one jig and the other jig are moved relatively to bring the prisms into close contact with each other. In the curing step, the intermediate contact member is separated from one prism, and the adhesive at a position corresponding to between the two end contact members Irradiating light, method of manufacturing an optical element according to any one of 2 to 4, characterized in that curing the adhesive.

  11.2 A joining jig used when joining two prisms, the first jig having a contact surface that contacts two surfaces sandwiching the ridge line farthest from the joint surface of one prism, and the other A second jig having a contact surface that contacts two surfaces sandwiching a ridge line farthest from the joint surface of the prism, and a first jig and a second jig in a direction perpendicular to the joint surface of each prism The ridge line of the two prisms is parallel to each other and satisfies a predetermined positional relationship in a direction perpendicular to each ridge line and parallel to the bonding surface. In this way, the first jig and the second jig are moved relative to each other in the direction perpendicular to the joint surface of each prism, and the two surfaces of one prism are brought into contact with the contact surface of the first jig. In contact with the two surfaces of the other prism in contact with the contact surface of the second jig, Joining jig, characterized in that adhering the bonding surface of the prism.

  12 The first jig and the second jig pass through the center of the joint surface of each prism and the center lines running in a direction parallel to the ridge line are coaxially positioned when the prisms are in close contact with each other. The bonding jig according to 11, wherein the bonding jig is positioned.

  13. Each contact surface of the first jig and the second jig is bent at a right angle, and is a surface that contacts one of the two surfaces of one prism among the contact surfaces of the first jig. Is the first contact surface, the surface that contacts the other of the two surfaces is the second contact surface, and of the contact surfaces of the second jig, one of the two surfaces of the other prism The first contact surface and the second contact surface in the first jig are defined as a third contact surface and a fourth contact surface that contacts the other of the two surfaces. And the intersection line between the third contact surface and the fourth contact surface in the second jig are such that the plane including these two intersection lines is the first jig and the second contact line. The first abutting surface and the second abutting surface, the third abutting surface and the fourth abutting surface are positioned so as to be parallel to the relative movement direction with respect to the jig. Is an angle of 45 degrees opposite to the plane. In joining jig according to 11 or 12, characterized in that each inclined.

  14 Of the first jig and the second jig, one jig has a length corresponding to the length in the longitudinal direction of the two prisms, and the other jig is one prism. And two end contact members that can contact at both ends in the longitudinal direction, and an intermediate contact member that can contact one prism between the two end contact members. The moving means, when bringing the joint surfaces of the two prisms into close contact, brings the two end contact members and the intermediate contact member of the other jig into contact with one prism, While the jig is in contact with the other prism, the one jig and the other jig are relatively moved, and the adhesive on the bonding surface of the two prisms is irradiated with light to thereby apply the adhesive. The bonding according to any one of 11 to 13, wherein the intermediate abutting member is separated from one prism when curing Ingredients.

  According to the method of manufacturing an optical element and the joining jig of the present invention, the first jig and the second jig are relatively relative to each other when the two prisms are brought into close contact with or pressurized (by the moving means or the pressing means). Since the moving direction is a direction perpendicular to the joining surface of each prism and not along the joining surface, even when the two prisms are pressurized along the moving direction (of course, when not pressurized) That is, the movement of these jigs does not cause the two prisms to be extremely displaced in the direction along the joint surface. When the two edges are parallel and in a predetermined positional relationship at the time of close contact or pressurization, the outer shape of the optical element formed by bonding the two prisms regardless of the degree of variation in the chamfering processing of the two prisms. Dimensional accuracy can be ensured.

  Further, when the two prisms are joined to obtain an optical element, the same kind of process is not repeated as in the prior art, so that there is almost no accumulation of processing errors, and the positional accuracy of the joining surface can be easily ensured. Therefore, for example, even when an optical thin film (for example, a polarization separation film) is formed on the joint surface of one prism to form an optical element and this is applied to an optical pickup, the beam shift accuracy can be easily ensured. Therefore, according to the present invention, both the external dimension accuracy and the beam shift accuracy can be ensured simultaneously.

It is a flowchart which shows the flow of each process in the manufacturing method of the optical element which concerns on one Embodiment of this invention. (A) is sectional drawing which shows the schematic structure of the joining jig used for manufacture of the said optical element, (b) is sectional drawing which shows the state holding two prisms with the said joining jig. (C) is sectional drawing which shows the state which closely_contact | adhered two prisms with the said joining jig. It is a perspective view which shows the external appearance of two prisms. It is a top view of the slope of two prisms. It is explanatory drawing which shows a mode that two prisms are closely_contact | adhered via an adhesive agent. It is explanatory drawing which shows typically a mode that each optical element is obtained by cut | disconnecting two joined prisms for every predetermined width. It is explanatory drawing which shows typically a mode that two joined prisms are cut | disconnected with a cutter. (A) is sectional drawing of an optical element when two prisms are displaced in the direction along the bonding surface, and (b) is an enlarged view of portion A in FIG. It is sectional drawing. It is a side view which shows the other structure of the said joining jig. (A) is a perspective view which shows further another structure of the said joining jig, Comprising: It is a perspective view of the said joining jig in the close_contact | adherence process of two prisms, (b) is the said joint treatment in a hardening process. It is a perspective view of a tool. It is sectional drawing which shows other structure of the said joining jig. It is explanatory drawing which shows typically the external dimension precision requested | required of the pickup prism conventionally. It is explanatory drawing which shows typically the beam shift precision requested | required of the pickup prism conventionally. It is explanatory drawing which shows each process in an example of the manufacturing method of the conventional optical element. It is explanatory drawing of the pick-up prism from which the joining surface shifted. It is explanatory drawing which shows each process in the other example of the manufacturing method of the conventional optical element. It is explanatory drawing which shows typically the mode of the positioning at the time of the assembly of the said optical element. It is explanatory drawing which shows a mode that a joining shift | offset | difference arises in two prisms at the time of pressurization resulting from the variation of the chamfering process given to the corner | angular part of a prism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Joining jig | tool 2 1st jig | tool 2a Contact surface (1st contact surface)
2b Contact surface (second contact surface)
2p intersection 3 second jig 3a contact surface (third contact surface)
3b Contact surface (fourth contact surface)
3p Intersection line 4 Moving mechanism (moving means)
11 Prism 11a surface 11b surface 11c surface (slope, joint surface)
11c ₁ center 11c ₂ center line 11p ridge line 21 prism 21a surface 21b surface 21c surface (slope, joint surface)
21c ₁ center 21c ₂ center line 21p ridge line 31 adhesive 41 optical element 61 end contact member 62 end contact member 63 intermediate contact member

  An embodiment of the present invention will be described below with reference to the drawings.

(1. About the joining jig)
FIG. 2A is a cross-sectional view showing a schematic configuration of the joining jig 1, and FIG. 2B is a cross-sectional view showing a state in which the two prisms 11 and 21 are held by the joining jig 1. FIG. 2C is a cross-sectional view showing a state in which the two prisms 11 and 21 are brought into close contact with the joining jig 1. The joining jig 1 includes a first jig 2, a second jig 3, and a moving mechanism 4.

Here, the prisms 11 and 21 are right-angle prisms having a right-angled isosceles triangle cross section, and are elongated. Then, as shown in FIG. 3, the slope (joint surface) of one prism 11 is the surface 11c, one of the two surfaces sandwiching the ridge line 11p farthest from the surface 11c is the surface 11a, and the other surface Is the surface 11b. Similarly, the slope (joint surface) of the other prism 21 is a surface 21c, one of the two surfaces sandwiching the ridge line 21p farthest from the surface 21c is a surface 21a, and the other surface is a surface 21b. Further, as shown in FIG. 4, the center of the surface 11c of the prism 11 (two diagonals of intersection in the plane 11c) as a center 11c _1, the center of the surface 21c of the prism 21 (two diagonals of intersection in the plane 21c) the center 21c _1. In the prism 11, a center line that passes through the center 11c ₁ of the surface 11c and runs in a direction parallel to the ridge line 11p in FIG. 3 is defined as a center line 11c _2, and in the prism 21, the center 21c ₁ of the surface 21c passes. and the center line 21c ₂ the center line running in a direction parallel to the ridge 21p.

  The first jig 2 holds one prism 11 and is fixed to the bottom surface portion 5 of the housing that houses the joining jig 1. The first jig 2 has a contact surface bent at a right angle so as to be able to contact the surfaces 11 a and 11 b of the prism 11. Specifically, the contact surface is composed of two contact surfaces 2a and 2b that intersect at right angles, and the intersection of the contact surfaces 2a and 2b is an intersection line 2p. The contact surface 2a is a first contact surface that contacts the surface 11a of the prism 11, and the contact surface 2b is a second contact surface that contacts the surface 11b of the prism 11.

  Here, in order to prevent the ridgeline 11p of the prism from being pierced, chipped, or the like, an escape portion may be provided so that the ridgeline 11p does not contact the intersection of the contact surface 2a and the contact surface 2b. In this case, the intersecting line 2p is defined as an intersecting line that virtually extends by extending the contact surface 2a and the contact surface 2b.

  The second jig 3 holds the other prism 21, and is connected to the moving mechanism 4 on the side opposite to the side facing the first jig 2. The second jig 3 has a contact surface that is bent at a right angle so as to be able to contact the surfaces 21 a and 21 b of the prism 21. Specifically, the abutment surface includes two abutment surfaces 3a and 3b that intersect at right angles, and the intersection of the abutment surfaces 3a and 3b is an intersection line 3p. The contact surface 3 a is a third contact surface that contacts the surface 21 a of the prism 21, and the contact surface 3 b is a fourth contact surface that contacts the surface 21 b of the prism 21.

  Here, in order to prevent the ridgeline 21p of the prism from being pierced, chipped, or the like, an escape portion may be provided so that the ridgeline 21p does not contact the intersection of the contact surface 3a and the contact surface 3b. In this case, the intersection line 3p is defined as an intersection line that virtually extends by extending the contact surface 3a and the contact surface 3b.

  In the present embodiment, the plane S including the intersection line 2p of the first jig 2 and the intersection line 3p of the second jig 3 is relative to the first jig 2 and the second jig 3. The positional relationship in the movement direction X is defined so as to be always parallel to the movement direction X. The contact surfaces 2a and 2b of the first jig 2 are inclined at an angle of 45 degrees on the opposite sides with respect to the plane S. As a result, when the prism 11 is held by the first jig 2, the surface 11c of the prism 11 is positioned above the surfaces 11a and 11b and horizontally.

  Similarly, the contact surfaces 3a and 3b of the second jig 3 are also inclined at an angle of 45 degrees on the opposite sides with respect to the plane S. In addition, the contact surfaces 3 a and 3 b are in a positional relationship parallel to the contact surfaces 2 b and 2 a of the first jig 2. As a result, when the prism 21 is held by the second jig 3, the surface 21c is positioned below the surfaces 21a and 21b and horizontally.

  The contact surfaces 3a and 3b are formed with holes (not shown) for sucking air. By sucking air through the holes, the surfaces 21 a and 21 b of the prism 21 are attracted to the contact surfaces 3 a and 3 b, and as a result, the prism 21 is held by the second jig 3.

The first jig 2 and the second tool 3, when the adhesion of each prism 11, 21, and the center line 21c ₂ of the surface 21c of the center line 11c ₂ and the prism 21 face 11c of the prism 11 is coaxial It is positioned so as to be located above (on the same straight line). In particular, the first jig 2 and the second jig 3 are both in the relative movement direction X of the first jig 2 and the second jig 3 and the direction in which the intersecting lines 2p and 3p run. It is positioned in a direction perpendicular to the plane (direction perpendicular to the plane S including the intersecting lines 2p and 3p).

Here, as the positioning method, for example, the following two methods can be considered. One is to change the positions of the first jig 2 and the second jig 3 (here, the positions in the direction perpendicular to the plane S including the intersection lines 2p and 3p (the same applies in this paragraph)). However, the second jig 3 holding the prism 21 is brought close to the first jig 2 holding the prism 11 to repeat the test work for joining the two prisms 11 and 21 to repeat the center lines 11c ₂ and 21c _2. and but it becomes coaxial or its position at the time of bonding the center 11c _1, 21c ₁ between the two that seems to match the prism 11, 21, the position of the first jig 2 and the second jig 3 It is a technique to do. The other is that an optical element in which the two prisms 11 and 21 are bonded so that the centers 11c ₁ and 21c ₁ coincide with each other or an equivalent product (for example, a template) is prepared from the beginning, and the first element is used as the first element. In this method, the position when sandwiched between the jig 2 and the second jig 3 is the position of the first jig 2 and the second jig 3.

  The moving mechanism 4 is a moving means that relatively moves the first jig 2 and the second jig 3 in a direction perpendicular to the surfaces 11c and 21c of the prisms 11 and 21. In the present embodiment, the moving mechanism 4 moves the second jig 3 in the vertical direction with respect to the first jig 2 fixed to the bottom surface portion 5, whereby the first jig 2 and the second jig 2 are moved. The jig 3 is moved relative to the above direction. The moving mechanism 4 includes a driving unit 4a and a connecting unit 4b. The drive unit 4a includes a motor, a gear, and the like, and mechanically moves the connecting unit 4b in the vertical direction. The connecting portion 4b connects the driving portion 4a and the second jig 3, and moves the second jig 3 in the vertical direction by the driving force of the driving portion 4a. That is, the connection part 4b and the drive part 4a have a relationship like a rack and pinion.

  The moving mechanism 4 may be configured to move the second jig 3 in the vertical direction by, for example, hydraulic pressure or air pressure. That is, the drive unit 4a may be configured with a hydraulic pump or a pneumatic pump, and the connecting unit 4b may be configured with a hydraulic cylinder or an air cylinder.

(2. About manufacturing method)
Next, a method of joining the two prisms 11 and 21 using the joining jig 1 having the above configuration to obtain a cube-type optical element will be described with reference to the flowchart of FIG.

  First, before the two prisms 11 and 21 are brought into close contact with each other, an optical thin film is formed on the surface 11c of one prism 11 (S1: thin film forming step). Here, the optical thin film is composed of a polarization separation film that transmits or reflects incident light according to its polarization state. The optical thin film may be formed of a thin film that selectively transmits or reflects incident light according to its wavelength, and is an optical that has a ratio of transmitted light to reflected light of 1: 1. You may be comprised with a thin film.

  Next, as shown in FIG. 5, the adhesive 31 is dropped onto the surface 11c of one prism 11 (S2: adhesive dropping step), and then the two prisms 11 and 21 are brought into close contact with each other with pressure P (S3: Adhesion process). In this contact process, as shown in FIGS. 2B and 2C, the ridgelines 11p and 21p of the two prisms 11 and 21 satisfy a predetermined positional relationship, that is, the ridgelines 11p and 21p are not twisted. The second jig 3 is moved vertically downward by the moving mechanism 4 so as to be positioned in a direction parallel to the ridgelines 11p and 21p and parallel to the contact surface. The surfaces 11c and 21c are brought into close contact with each other. At this time, the surfaces 11a and 11b of one prism 11 are brought into contact with the contact surfaces 2a and 2b of the first jig 2, and the surfaces 21a and 21b of the other prism 21 are brought into contact with the second jig 3. The surfaces 11c and 21c of the two prisms 11 and 21 are brought into close contact with each other by the movement of the second jig 3 while being in contact with the contact surfaces 3a and 3b.

  Subsequently, the two prisms 11 and 21 are pressurized by relative movement of the first jig 2 and the second jig 3 from the state of FIG. 2C (S4: pressurization step). Then, after the pressurization, that is, simultaneously with the pressurization or after the pressurization, the adhesive 31 is cured (S5: curing step). Thereafter, in one prism (for example, the prism 11), a 45 degree corner portion (for example, a corner portion that protrudes from the surface 21c of the prism 21) that protrudes from the joint portion with the other prism, that is, the surfaces 11a and 11c, The corner portion formed by the surface 11b and the surface 11c) is removed by chamfering as necessary.

  In the contact step, the prism 21 moves downward in a state where it is attracted to the jig 3 and is in close contact with the prism 11. After placing the prism 21 on the prism 11 to which the adhesive 31 has been dropped, 3, the ridgelines of the prism 11 and the prism 22 may be maintained in a predetermined positional relationship, and the pressure may be applied in a direction perpendicular to the prism joint surface.

  The adhesive 31 may be a thermosetting resin or a photocurable resin. However, in the present embodiment, the adhesive 31 is made of a photocurable resin that is cured by ultraviolet irradiation. Therefore, in the above curing step, the adhesive 11 is irradiated with ultraviolet rays from the gap between the first jig 2 and the second jig 3 in a state where the prisms 11 and 21 are in close contact with the bonding jig 1. 31 can be cured. Further, if the first jig 2 and the second jig 3 are made of a transparent material (for example, glass), the adhesive 31 is irradiated with ultraviolet rays via the first jig 2 and the second jig 3. By doing so, it is also possible to harden the adhesive 31. Further, the adhesive 31 is cured to some extent by ultraviolet irradiation in a state where the prisms 11 and 21 are in close contact with the joining jig 1, and then the prisms 11 and 21 are removed from the joining jig 1 and are separated. The adhesive 31 may be completely cured (mainly cured) by irradiating the adhesive 31 with ultraviolet rays at a place (for example, a complete curing device). The ultraviolet irradiation is performed on the adhesive 31 from the side opposite to the optical thin film forming side.

  Finally, as shown in FIG. 6, the two long prisms 11 and 21 are cut at predetermined widths (S6: cutting step). As a result, a plurality of cube-type optical elements 41 formed by bonding two transparent media can be obtained. At this time, as shown in FIG. 7, the two prisms 11 and 21 are cut by the cutter 51 so that the cut surface is perpendicular to the surface 11c of the prism 11 with reference to the prism 11 on which the optical thin film is formed. It is desirable to do. In this case, it is possible to maintain good accuracy of the perpendicularity between the surface 11c and the cut surface. In addition, it is also possible to maintain good accuracy of the perpendicularity between the cut surface and the surfaces other than the surface 11c (for example, the surfaces 11a and 11b) in the prism 11 on which the optical thin film is formed.

  The dimensions of the cube-shaped optical element 41 manufactured as described above, that is, the vertical width v (mm) and the horizontal width w (mm) shown in FIG. ), If the height dimension of the prism 11 is b (mm), both can be obtained by the following equation (1). In addition, said height dimension refers to the maximum value of the length of a perpendicular | vertical direction with respect to a slope (joint surface), ie, the distance of the ridgeline furthest away from the joint surface, and the joint surface.

  Here, when the dimensional tolerances required for the vertical width v and the horizontal width w are 4 ± 0.05 mm, and the height dimensions a and b are managed at 2.828 ± 0.02 mm, the vertical length relative to the combination of the prisms 11 and 21 is determined. The width v and the lateral width w are values as shown in Table 1 below by the calculation of the above equation (1).

  Therefore, it can be seen from Table 1 that the two prisms 11 and 21 can be joined with a margin with respect to the required external dimension accuracy (4 ± 0.05 mm). That is, if the height dimensions a and b are managed within the range of 2.828 ± 0.02 mm, for example, the optical element 41 that satisfies the external dimension accuracy can be obtained by a simple method. Further, since the joining error becomes substantially zero, the tolerance of the height dimensions a and b of the two prisms 11 and 21 can be relaxed.

  In the present embodiment, the first jig 2 is fixed and only the second jig 3 is moved by the moving mechanism 4 in the bonding jig 1. The third jig 3 may be moved relatively by the moving mechanism 4. Therefore, for example, the second jig 3 may be fixed and only the first jig 2 may be moved by the moving mechanism 4, and the first jig 3 and the third jig 4 may be Both may be moved by the moving mechanism 4.

  Note that the relative movement direction of the first jig 2 and the second jig 3 is not limited to the vertical direction as in this embodiment, and may be the horizontal direction. In this case, means for adsorbing the prisms 11 and 21 to both the first jig 2 and the second jig 3 is required. In addition, when the relative moving direction of the first jig 2 and the second jig 3 is the horizontal direction, the adhesive 31 applied to the bonding surface of one prism may hang down, In this respect, it is desirable that the moving direction is the vertical direction as in this embodiment.

  The prisms 11 and 21 described above are not long and may have a size corresponding to one optical element 41. In this case, of course, the cutting process of S6 becomes unnecessary.

(3. Effect)
As described above, in the present embodiment, the surfaces of the prisms 11 and 21 are moved by the moving mechanism 4 so that the ridge lines 11p and 21p of the two prisms 11 and 21 satisfy a predetermined positional relationship in the close contact process of S3. The first jig 2 and the second jig 3 are relatively moved in the direction perpendicular to 11c and 21c, and the surfaces 11a and 11b of one prism 11 are brought into contact with the first jig 2 The surfaces 11c and 21c of the two prisms 11 and 21 are brought into contact with 2a and 2b and the surfaces 21a and 21b of the other prism 21 are brought into contact with the contact surfaces 3a and 3b of the second jig 3. Are in close contact.

  Thus, the movement directions of the first jig 2 and the second jig 3 when the prisms 11 and 21 are brought into close contact with each other are directions perpendicular to the surfaces 11c and 21c of the prisms 11 and 21, respectively. Since the direction is not along 11c and 21c, the two prisms 11 and 21 are extremely displaced in the direction along the surfaces 11c and 21c even when the jig is moved in the moving direction after that. There is no. Therefore, the outer dimension accuracy of the optical element 41 finally obtained can be ensured as described above, regardless of the degree of variation in the chamfering processing of the two prisms 11 and 21. Further, when the two prisms 11 and 21 are joined to obtain the optical element 41, the same type of process is not repeated as in the prior art, so there is almost no accumulation of processing errors and the positional accuracy of the joining surface is easily secured. Can do. Therefore, even when the optical element 41 of this embodiment is applied to an optical pickup, the beam shift accuracy can be easily ensured.

In the present embodiment, in particular, the first jig 2 and the second jig 3 have the centerlines 11c ₂ and 21c ₂ of the surfaces 11c and 21c of the prisms 11 and 21 when the prisms 11 and 21 are in close contact with each other. Is positioned coaxially. Therefore, when the prisms 11 and 21 are in close contact with each other, the positions of the surfaces 11c and 21c of the prisms 11 and 21 are displaced, more specifically, the directions within the surfaces 11c and 21c and perpendicular to the center lines 11c ₂ and 21c _2. There is no misalignment. Therefore, it is possible to reliably ensure the external dimension accuracy of the optical element 41 (the one after cutting when the prisms 11 and 21 are long) formed by bonding the two prisms 11 and 21 together.

When the prisms 11 and 21 are in close contact with each other, the center lines 11c ₂ and 21c ₂ of the surfaces 11c and 21c of the prisms 11 and 21 need only be positioned on the same axis, and the surfaces 11c of the prisms 11 and 21 may be located. Although it is more preferable that the centers 11c ₁ and 21c ₁ of 21c coincide, for example, they may be slightly shifted in the direction in which the ridgelines 11p and 21p extend. This is because when the prisms 11 and 21 are long, the optical element 41 is bonded to the prism 11 and 21 in the direction in which the ridge lines 11p and 21p extend by cutting in the cutting step S6. Because there will be no.

Further, in each prism 11, 21, the surface accuracy near the ends of the surfaces 11c, 21c may be slightly reduced due to sagging or jumping, but the surface accuracy is relatively good near the center of the surfaces 11c, 21c. is there. Therefore, when the prisms 11 and 21 are in close contact with each other, the center lines 11c ₂ and 21c ₂ of the surfaces 11c and 21c of the prisms 11 and 21 are located on the same axis. Using the vicinity of the center of 21c, it is possible to suppress the disturbance of the wavefront of the light obtained through the optical thin film formed on the bonding surface (increase the wavefront accuracy).

Further, in FIG. 8A, the prisms 11 and 21 are joined while being shifted in a direction perpendicular to the center lines 11c ₂ and 21c ₂ in the surfaces 11c and 21c (a direction perpendicular to a plane including the ridge lines 11p and 21p). 8B is a cross-sectional view of the optical element 41, and FIG. 8B is an enlarged cross-sectional view showing a portion A in FIG. If the center lines 11c ₂ and 21c ₂ are displaced in the above direction when the prisms 11 and 21 are in close contact with each other, a region of the surface 11c of one prism 11 that is not opposed to the surface 21c of the other prism 21 (exposed). There is a concern that the region 11c _3, which is a part of the region) enters the optical effective region Ae when the optical element 41 is used, and the optical performance deteriorates. However, in the present embodiment, since the center lines 11c ₂ and 21c _{2 of the} prisms 11 and 21 are coaxially positioned when the prisms 11 and 21 are in close contact with each other, the above-described region 11c ₃ enters the effective range Ae in use. There is almost no fear, and a decrease in the optical performance of the optical element 41 can be avoided.

  In the present embodiment, as shown in FIGS. 2A and 2B, the contact surfaces of the first jig 2 and the second jig 3 are bent at right angles, and the first jig 2 is bent. The intersecting line 2p of the tool 2 and the intersecting line 3p of the second jig 3 are such that the plane S including these intersecting lines 2p and 3p moves relative to the first jig 2 and the second jig 3. It is located so as to be parallel to the direction X. The contact surfaces 2a and 2b of the first jig 2 are inclined at an angle of 45 degrees on the opposite sides with respect to the plane S. Similarly, the contact surfaces 3a and 3b of the second jig 3 are also inclined at an angle of 45 degrees on the opposite sides with respect to the plane S.

Thus, even when a right-angle prism is used as the two prisms 11 and 21 as in the present embodiment, the surface of one prism 11 is moved by the relative movement of the first jig 2 and the second jig 3. 11a and 11b are brought into contact with the contact surfaces (contact surfaces 2a and 2b) of the first jig 2, and the surfaces 21a and 21b of the other prism 21 are contacted with the contact surfaces (contact surfaces of the second jig). 3a and 3b), the center lines 11c ₂ and 21c ₂ of the surfaces 11c and 21c of the prisms 11 and 21 can be positioned coaxially so that the prisms 11 and 21 can be brought into close contact with each other. As a result, it is possible to obtain the above-described effects such as ensuring the accuracy of the outer dimensions, suppressing the disturbance of the wavefront, and avoiding the deterioration of the optical performance even when the right prisms are used as the two prisms 11 and 21. Can do.

In addition, when the joining jig 1 having the above-mentioned relationship between the positions of the intersecting lines 2p and 3p is used, in the close contact process of S3, the two prisms 11 and 21 are brought into close contact with each other as the joint surfaces. It can be said that the prisms 11 and 21 are in close contact so that the plane including the ridge line 11p of the prism 11 and the ridge line 21p of the other prism 21 is orthogonal to the surfaces 11c and 21c. Therefore, even with such a joining method, the center lines 11c ₂ and 21c ₂ of the surfaces 11c and 21c of the prisms 11 and 21 can be positioned coaxially so that the prisms 11 and 21 can be brought into close contact with each other. Similar effects can be obtained.

  Moreover, in this embodiment, in addition to the contact | adherence process of S3, the adhesive agent dripping process of S2, the pressurization process of S4, and the hardening process of S5 are performed. By sequentially performing such a series of steps, the two prisms 11 and 21 can be joined.

  In the present embodiment, the thin film forming step of S1 is performed before the adhesion step of S3. Thereby, finally, the optical element 41 having the optical performance (for example, polarization separation function) of the optical thin film can be obtained.

(4. Other manufacturing methods and joining jigs)
By the way, without performing the adhesive dropping step of S2 and the pressurizing step of S4 described above, in the curing step of S5, the adhesive 31 is permeated into the surfaces 11c and 21c from the end portion thereof by capillary action, It may be cured. Thus, S2 and S4 are not performed, and the two prisms 11 and 21 are bonded together by infiltrating the adhesive 31 into the bonding surface and curing in S5 after the two prisms 11 and 21 are closely bonded in S3. can do.

  Further, as in the present embodiment, the two prisms 11 and 21 to be used are long, and the adhesive 31 used for joining the two prisms 11 and 21 is photocurable (for example, cured by irradiation with ultraviolet rays). The first jig 2 and the third jig 3 of the joining jig 1 do not need to be configured to be long in accordance with the two long prisms 11 and 21. .

  For example, FIG. 9 is a side view showing another configuration of the joining jig 1. As shown in the figure, the joining jig 1 has a plurality of first jigs 2 and second jigs 3 in pairs. When such a joining jig 1 is used, the first jig 2 and the second jig 3 of each pair are brought into contact with a plurality of locations in the longitudinal direction of the prisms 11 and 21 in the adhesion step of S3. The prisms 11 and 21 are brought into close contact with each other, and light (for example, ultraviolet rays UV) is applied to the adhesive 31 positioned between each pair of the first jig 2 and the second jig 3 in the curing step of S5. Then, the adhesive 31 may be cured.

  In addition, after the adhesive 31 located between each pair of the first jig 2 and the second jig 3 is cured, the adhesive 31 in the remaining positions is also cured by light irradiation. For example, each of the second jigs 3 may be performed in a state of being separated from the prisms 21 (while holding the two prisms 11 and 21 in the joined state with the first jigs 2), or the joining jig 1 Alternatively, the two prisms 11 and 21 may be completely removed from another position.

  In this way, the adhesive 31 is cured in a state where the long prisms 11 and 21 are pressed at a plurality of positions with the plurality of pairs of the first jig 2 and the second jig 3, so There is almost no displacement of the prisms 11 and 21 (particularly due to bending). Therefore, even when the two prisms 11 and 21 to be used are long, when the individual optical elements 41 are finally cut, it is possible to reliably ensure the external dimension accuracy for each optical element 41. Can do. Further, it is not necessary to use long jigs corresponding to the prisms 11 and 21 as the first jig 2 and the second jig 3, and the first jig 2 and the second jig 3 are There is also an advantage that it can be configured simply.

  When the two prisms 11 and 21 to be used are long and the adhesive 31 is photocurable, the joining jig 1 may be configured as follows. FIGS. 10A and 10B are perspective views showing still another configuration of the joining jig 1.

  In this joining jig 1, one of the first jig 2 and the second jig 3 (here, the first jig 2) is arranged in the longitudinal direction of the two prisms 11 and 21. It has a length corresponding to the length. The other jig (here, the second jig 3) includes two end abutting members 61 and 62 and an intermediate abutting member 63. The end contact members 61 and 62 can contact with one prism (here, the prism 21) and both ends in the longitudinal direction. The intermediate contact member 63 has a length equal to the distance between the two end contact members 61 and 62 in the longitudinal direction, and the prism 21 is interposed between the two end contact members 61 and 62. Can be contacted.

  When the joining jig 1 having the above-described configuration is used, the moving mechanism 4 (see FIG. 2C) has two end portions of the second jig 3 as shown in FIG. The first jig 2 and the second jig in a state where the abutting members 61 and 62 and the intermediate abutting member 63 are in contact with the prism 21 and the first jig 2 is in contact with the prism 11. 3 are moved relatively to bring the prisms 11 and 21 into close contact with each other. In the curing step of S5, as shown in FIG. 10 (b), the moving mechanism 4 keeps the two end contact members 61 and 62 of the second jig 3 in contact with the prism 21 while maintaining the intermediate position. Only the contact member 63 is separated from the prism 21 upward. Accordingly, it is possible to cure the adhesive 31 by irradiating light (for example, ultraviolet rays) to the adhesive 31 at a position corresponding to the position between the two end contact members 61 and 62 on the joint surface.

  10A and 10B, the first jig 2 and the second jig 3 have a length corresponding to the longitudinal direction of the prisms 11 and 21. Therefore, there is no joining deviation due to the bending of the prisms 11 and 21, and the outer dimensional accuracy can be reliably ensured for each final individual optical element 41. Further, in the contact step of S3, the prisms 11 and 21 can be uniformly attached to both end portions and the center portion in the longitudinal direction, so that the prism 11 is dropped after the adhesive 31 is dropped on the joint surface of the prism 11 in particular. When pressurizing 21, it is preferable because the adhesive 31 can be uniformly extended in the longitudinal direction and the prisms 11 and 21 can be adhered uniformly in the longitudinal direction. In addition, since only the intermediate contact member 63 is separated from the prism 21 and the adhesive 31 is cured by light irradiation in the curing step of S5, the operation is simple.

  By the way, although the case where a right-angle prism is used as the two prisms 11 and 21 has been described above, even when a prism other than the right-angle prism is used, the configuration of the joining jig 1 is slightly changed according to the shape of the prism to be used. Thus, it is possible to employ the joining method of the present embodiment.

For example, FIG. 11 is a cross-sectional view showing still another configuration of the joining jig 1. The joining jig 1 is capable of joining the prisms 11 and 21 when the prisms 11 and 21 are triangular prisms having a triangular cross section and an obtuse angle of one of the prisms. In the first jig 2 of the joining jig 1, the contact surfaces 2 a and 2 b that contact the surfaces 11 a and 11 b of the prism 11 intersect at an obtuse angle, and in the second jig 3, the surface of the prism 21. The contact surfaces 3a and 3b that contact 21a and 21b intersect at an obtuse angle. Further, in this joining jig 1, a plane including the intersection line 2 p of the first jig 2 and the intersection line 3 p of the second jig 3 is formed between the first jig 2 and the second jig 3. The center of the surface 11c of the prism 11 is not parallel to the relative movement direction X (here, the vertical direction), but when the prisms 11 and 21 are brought into close contact due to the relative movement of the prisms 11 and 21. The first jig 2 and the second jig 3 are positioned so that the line 11c ₂ and the center line 21c ₂ of the surface 21c of the prism 21 are coaxially positioned.

  Even in this configuration, the ridgelines 11p and 21p of the two prisms 11 and 21 satisfy the predetermined positional relationship, that is, the ridgelines 11p and 21p are parallel to each other without being twisted. If the first jig 2 and the second jig 3 are relatively moved in the direction perpendicular to the surfaces 11c and 21c of the prisms 11 and 21, the surfaces 11a and 11b of one prism 11 are moved to the first The two prisms 11 are brought into contact with the contact surfaces 2 a and 2 b of the jig 2 and the surfaces 21 a and 21 b of the other prism 21 are in contact with the contact surfaces 2 a and 2 b of the second jig 3. -The surfaces 11c and 21c of 21 can be stuck. Moreover, since the moving direction X of the first jig 2 and the second jig 3 when the prisms 11 and 21 are brought into close contact with each other is the direction perpendicular to the surfaces 11c and 21c of the prisms 11 and 21, these The two prisms 11 and 21 are not extremely displaced in the direction along the surfaces 11c and 21c by the movement of the jig.

Therefore, even when the prisms 11 and 21 constituted by prisms other than the right-angle prism are used, the outer dimensional accuracy of the optical element 41 finally obtained can be ensured by using the joining jig 1 shown in FIG. Can do. Particularly, in the first jig 2 and the second jig 3, the center lines 11c ₂ and 21c ₂ of the surfaces 11c and 21c of the prisms 11 and 21 are coaxially positioned when the prisms 11 and 21 are in close contact with each other. Therefore, the outer dimensional accuracy of the optical element 41 can be reliably ensured. In addition, since there is almost no accumulation of processing errors as in the prior art, the positional accuracy of the joint surface can be easily ensured, and the beam shift accuracy can be easily ensured also in the optical pickup.

  The optical element manufacturing method and the joining jig of the present invention can be used for manufacturing a polarization separation element used for an optical pickup, for example.

Claims (14)

An optical element manufacturing method for joining two prisms using a joining jig,
The joining jig is
A first jig having a contact surface that contacts two surfaces sandwiching the ridge line farthest from the joint surface of one prism;
A second jig having a contact surface that contacts two surfaces sandwiching a ridge line farthest from the joint surface of the other prism;
The ridge lines of the two prisms are parallel to each other, and the first jig is perpendicular to the joint surface of the prisms so as to satisfy a predetermined positional relationship in a direction perpendicular to the ridge lines and parallel to the joint surface. The second jig is moved relatively to bring the two surfaces of one prism into contact with the contact surface of the first jig, and the two surfaces of the other prism are brought into contact with the second jig. A method for manufacturing an optical element, comprising: an adhesion step of bringing a joint surface of two prisms into close contact with each other in a state of contact with the contact surface. An adhesive dropping step in which an adhesive is dropped on the bonding surface of one prism before the bonding surfaces of the two prisms are brought into close contact;
A pressurizing step of pressurizing the two prisms by relative movement of the first jig and the second jig after the bonding surfaces of the two prisms are brought into close contact with each other;
The method for manufacturing an optical element according to claim 1, further comprising a curing step of curing the adhesive after the pressurization.   The method further comprises a curing step in which an adhesive is infiltrated into the joint surface from the end of the joint surface after the joint surfaces of the two prisms are brought into close contact with each other, and the adhesive is cured. 2. A method for producing an optical element according to item 1. An optical element manufacturing method for joining two prisms using a joining jig,
The joining jig is
A first jig having a contact surface that contacts two surfaces sandwiching the ridge line farthest from the joint surface of one prism;
A second jig having a contact surface that contacts two surfaces sandwiching a ridge line farthest from the joint surface of the other prism;
An adhesive dropping step of dropping an adhesive on the joint surface of one prism;
An adhesion step of bringing the bonding surface of the other prism into close contact with the bonding surface of the prism to which the adhesive has been dropped;
The two surfaces of one prism are brought into contact with the contact surface of the first jig, and the two surfaces of the other prism are brought into contact with the contact surface of the second jig. In a state where each ridge line is parallel to each other and satisfies a predetermined positional relationship in a direction perpendicular to each ridge line and parallel to the joint surface, the joint surface of the two prisms is pressurized in a direction perpendicular to the joint surface of each prism. Pressure process,
And a curing step for curing the adhesive after the pressing step.   The first jig and the second jig of the joining jig pass through the center of the joining surface of each prism and run in a direction parallel to the ridge line when the prisms are brought into close contact in the contact step. The method of manufacturing an optical element according to any one of claims 1 to 4, wherein the center line is positioned so as to be positioned coaxially. Each of the two prisms is a right angle prism,
In the contact step, the two prisms are brought into close contact with each other using the slope as a joint surface, and a plane including the ridge line facing the slope in one prism and the ridge line facing the slope in the other prism is orthogonal to each slope. The method for manufacturing an optical element according to any one of claims 1 to 5, wherein the prisms are brought into close contact with each other.   7. The method according to claim 1, further comprising a thin film forming step of forming an optical thin film on the joint surface of one prism before the two prisms are brought into close contact with each other. Of manufacturing the optical element. The two prisms are long,
8. The optical element according to claim 7, further comprising a cutting step of cutting the two prisms by a predetermined width on the basis of the prism on which the optical thin film is formed. Manufacturing method. The two prisms are long,
The adhesive is photocurable,
The joining jig has a plurality of first jigs and second jigs in pairs,
In the contact step, the first jig and the second jig of each pair are brought into contact with a plurality of locations in the longitudinal direction of each prism so that each prism is brought into close contact,
In the curing step, the adhesive is cured by irradiating light to an adhesive positioned between each pair of the first jig and the second jig. 5. A method for producing an optical element according to any one of items 4 to 4. The two prisms are long,
The adhesive is photocurable,
Of the first jig and the second jig of the joining jig,
One jig has a length corresponding to the length in the longitudinal direction of the two prisms,
The other jig is composed of one prism and two end contact members that can contact at both ends in the longitudinal direction, and an intermediate that can contact one prism between the two end contact members. A contact member,
In the contact step, the two end contact members and the intermediate contact member of the other jig are in contact with one prism, and the one jig is in contact with the other prism, Move one jig and the other jig relatively to bring each prism into close contact,
In the curing step, the intermediate abutting member is separated from one prism, and the adhesive is cured by irradiating the adhesive at a corresponding position between the two end abutting members. A method for manufacturing an optical element according to any one of claims 2 to 4. A joining jig used for joining two prisms,
A first jig having a contact surface that contacts two surfaces sandwiching the ridge line farthest from the joint surface of one prism;
A second jig having a contact surface that contacts two surfaces sandwiching a ridge line farthest from the joint surface of the other prism;
A moving means for relatively moving the first jig and the second jig in a direction perpendicular to the bonding surface of each prism;
The moving means is configured so that the ridge lines of the two prisms are parallel to each other and satisfy a predetermined positional relationship in a direction perpendicular to the ridge lines and parallel to the bonding surface. The first jig and the second jig are relatively moved so that the two surfaces of one prism are in contact with the contact surface of the first jig, and the two surfaces of the other prism are A bonding jig, wherein the bonding surfaces of the two prisms are brought into close contact with each other in contact with the contact surface of the two jigs.   The first jig and the second jig pass through the center of the joint surface of each prism and the center lines running in a direction parallel to the ridge line are coaxially positioned when the prisms are in close contact with each other. The bonding jig according to claim 11, wherein the bonding jig is positioned. Each contact surface of the first jig and the second jig is bent at a right angle,
Of the contact surfaces of the first jig, a surface that contacts one of the two surfaces of one prism is a first contact surface, and a surface that contacts the other of the two surfaces is a second contact. Face and
Of the contact surfaces of the second jig, a surface that contacts one of the two surfaces of the other prism is a third contact surface, and a surface that contacts the other of the two surfaces is a fourth contact surface. As a surface,
The line of intersection between the first contact surface and the second contact surface in the first jig and the line of intersection between the third contact surface and the fourth contact surface in the second jig The plane including these two intersecting lines is positioned so as to be parallel to the relative movement direction of the first jig and the second jig,
The first contact surface and the second contact surface, and the third contact surface and the fourth contact surface are inclined at an angle of 45 degrees on the opposite sides with respect to the plane. The joining jig according to claim 11 or 12, characterized in that: Of the first jig and the second jig,
One jig has a length corresponding to the length in the longitudinal direction of the two prisms,
The other jig is composed of one prism and two end contact members that can contact at both ends in the longitudinal direction, and an intermediate that can contact one prism between the two end contact members. A contact member,
The moving means is
When the bonding surfaces of the two prisms are brought into close contact with each other, the two end contact members and the intermediate contact member of the other jig are brought into contact with one prism, and the one jig is brought into contact with the other prism. In a state where it is in contact with, one jig and the other jig are relatively moved,
The intermediate contact member is separated from one prism when the adhesive on the joint surface of two prisms is irradiated with light to cure the adhesive. 14. The joining jig according to any one of items 13.