JP2001266398A - Composite optical member and its inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite optical member and its inspection method by which diffraction gratings possessed by the composite optical member can be independently inspected. SOLUTION: The member is integrally formed by molding, having an incident plane 105a and an outgoing plane 105b of light respectively at both end faces in the direction of the optical axis N; in the area including the optical axis N of the incident plane 105a and the outgoing plane 105b, a three-beam diffraction grating 105h and a first diffraction grating 105f are formed; and the area other than each diffraction grating of the incident plane 105a and the outgoing plane 105b is used as a reference plane for mirror finish.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite optical member having a diffraction grating on both end surfaces, and more particularly to a composite optical member suitable for evaluating characteristics of the diffraction grating and a method of inspecting the composite optical member.

[0002]

2. Description of the Related Art First, a CD provided with a conventional composite optical member
An optical unit for a (compact disc) will be described.

FIG. 14 is a partial sectional view of a conventional optical unit 50, and FIG. 15 is a perspective view of a composite optical member 49 of the conventional optical unit 50.

An optical unit 50 includes a light source 46 for emitting laser light (wavelength 780 nm band) for CD and a light receiving member 47 for receiving laser light reflected by a CD (not shown).
A substrate portion 48a having a light source 46 and a light receiving member 47;
The substrate portion 48a includes the light source 46 and the light receiving member 47.
, A light-transmitting composite optical member 49 joined so as to cover the light-emitting portion 48d.

The light source 46 is fixed on the substrate 48a so as to face the composite optical member 49, and the light receiving member 47 is formed on the surface of the substrate 48a close to the light source 46. The return light emitted from the light source 46 and reflected by the CD is diffracted by the diffraction grating 49 a formed on the upper end surface (emission surface) of the composite optical member 49 and guided to a predetermined position of the light receiving member 47. Further, in order to perform tracking control by the three-beam method, a beam forming portion 49b which is a diffraction grating is provided on the lower end surface (incident surface) of the composite optical member 49. It should be noted that the composite optical member 49 uses a predetermined reference optical system to transmit the light diffracted by the diffraction grating 49a to the light receiving member 47.
After the composite optical member 49 is adjusted so as to be guided to a predetermined position, the composite optical member 49 is bonded to the emission section 48d with an adhesive.

The beam forming sections 4 are respectively provided on the entrance surface and the exit surface.
The composite optical member 49 having the diffraction grating 49a and the composite optical member 9b is generally formed integrally by molding. After the molding, it is necessary to evaluate the characteristics of the beam forming portion 49b and the diffraction grating 49a.

For example, when evaluating the characteristics of the diffraction grating 49a, the laser beam enters the inside of the composite optical member 49 from the beam forming part 49b on the incident surface (lower end surface) along the optical axis N of the composite optical member 49 shown in FIG. The laser beam is applied to the diffraction grating 49a on the emission surface (upper surface) by transmitting the light, and the diffraction characteristic of the diffraction grating 49a is inspected by referring to the zero-order light and the diffraction light of the laser light transmitted through the diffraction grating 49a. Was.

[0008]

However, in the above-described conventional method for inspecting a composite optical member, the beam forming section 49 is used.
Since a large number of light beams incident and diffracted and branched from b are further branched at the diffraction grating 49a, even if the further branched laser beam is measured, the diffraction grating 49a is not independently inspected. The diffraction grating 49a could not be accurately evaluated. This means that the beam forming unit 49b
The same applies to the case of evaluating.

The beam forming portion 49b and the diffraction grating 49a on the entrance surface and the exit surface of the composite optical member 49, respectively.
The other region has no optical function and therefore has a low surface accuracy, and no consideration has been given to using this region for inspection of each diffraction grating.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide a composite optical member capable of independently inspecting a diffraction grating of the composite optical member and a method of inspecting the composite optical member. is there.

[0011]

Means for Solving the Problems As a first means for solving the above problems, they are integrally formed by molding,
A light incident surface and a light outgoing surface are provided on both end surfaces in the optical axis direction, respectively. A diffraction grating is formed in a region including the optical axis of the light incident surface and the light outgoing surface. Has a mirror-finished reference surface separately from each of the diffraction gratings.

Further, as a second solution, light is transmitted from one of the reference planes to the inside of the composite optical member, and the other diffraction grating is irradiated with the light. The diffraction characteristic of the diffraction grating is inspected by referring to the zero-order light and the diffracted light.

Further, as a third solution, an optical plate having a reference surface is provided so as to face one of the reference surfaces or the other of the reference surfaces. By irradiating the optical plate with inspection light from the opposite side to generate transmitted light transmitted through the optical plate and reflected light reflected on the reference surface, the transmitted light is transmitted to the one reference surface or the other reference surface. And the transmitted light reflected by the one reference surface or the other reference surface is transmitted through the optical plate through a reverse path, and the incident light is referred to by referring to interference light between the transmitted light and the reflected light. The surface accuracy of the surface or the emission surface is inspected.

Further, as a fourth solution, a light incident surface and a light exit surface which are integrally formed by molding and are provided at both end surfaces in the direction of the optical axis with light orthogonal to the optical axis are provided, respectively. A diffraction grating is formed in a region including the optical axis, and the composite optical member has the entrance surface and the exit surface having mirror-finished reference surfaces separately from the respective diffraction gratings so as to face each other. The inspection method, wherein an optical plate having a reference surface is disposed so as to face one of the reference surfaces, and a reference plane reflecting plate is disposed so as to face the other reference surface; Irradiating the optical plate with an inspection laser beam from the opposite side of the plate from the composite optical member to generate transmitted light transmitted through the optical plate and reflected light reflected on the reference surface, and the transmitted light is The composite optical part is incident on one of the reference surfaces. Is transmitted to the reference plane reflector from the other reference plane, and the transmitted light reflected by the reference plane reflector is transmitted through the optical plate in a reverse path, and the transmitted laser light and the reflected light The parallelism between the incident surface and the exit surface and the transmitted wavefront aberration are inspected with reference to the interference light.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A composite optical member 105 according to an embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is an explanatory view showing an optical pickup device 100 according to an embodiment of the present invention, FIG. 2 is a partially sectional perspective view of a two-wavelength laser diode 102, and FIG. 4 is a left side view of FIG. 3, FIG. 5 is a right side view of FIG. 3, FIG. 6 is a view from the direction 6 of FIG. 3, FIG. 7 is a plan view of the housing 106, and FIG. 9 is a left side view of FIG. 8, FIG. 10 is a right side view of FIG. 8, FIG.
FIG. 12 is a view from the direction 11 in FIG. 8, and FIG.
13 is an explanatory view for explaining the function of the composite optical member 105, and FIGS. 14 to 16 are schematic views for explaining an inspection method of the composite optical member 105.

As shown in FIG. 1, an optical pickup device 1
00 is a pickup body, that is, a carriage 500
And a composite optical unit 101, a flat reflecting mirror 300, a collimating lens 400, and an objective lens 200 disposed in the carriage 500. The composite optical unit 101 includes the composite optical member 105 according to the embodiment of the present invention.

The optical pickup device 100 is disposed so as to face an optical disk, that is, a CD 61 or a DVD (digital versatile disk or digital video disk) 62, and the CD 61 (DV).
D62) Focusing (F) in a direction orthogonal to the plane
The objective lens 200 is movably supported in the tracking direction (T), which is the radial direction of the CD 61 (DVD 62). The objective lens 200 is a CD61 and a DVD.
62.

The composite optical unit 101 is an integrated optical element that receives and emits light, and irradiates a laser beam to the optical disk and receives reflected light (return light) from the optical disk to reproduce information recorded on the optical disk. Or to record information on an optical disc.

As shown in FIG. 1, the composite optical unit 101 mainly includes a light emitting member, that is, a two-wavelength laser diode 102, and a light receiving member 1 having a light receiving element 104a built therein.
04, the composite optical member 105, and the printed circuit board 107
And a housing 106 to which these members are attached and fixed.

As shown in FIG. 2, the two-wavelength laser diode 102 has a disc-shaped substrate portion 102a and a substrate portion 102a.
a, a rectangular parallelepiped base 102b protruding from one flat portion 102a ', a laser chip 103 positioned and fixed on the side wall surface of the base 102b, and a flat portion 102a' including the base 102b. A cylindrical body 1 that is attached and fixed
The cap 102e includes a top plate 102d having an opening 102d and an opening 102d ', and a transparent disk-shaped glass plate 102f fixed so as to cover the opening 102d' from the inside of the cap 102e. ing. In this manner, the laser chip 103 is arranged in a sealed space in one package including the substrate portion 102a, the cap portion 102e, and the glass plate 102f.

The laser chip 103 has a light source 103a for emitting a short-wavelength (wavelength 650 nm band) laser beam 103a 'for DVD, and a long-wavelength (wavelength 780) for CD.
light source 103b that emits laser light 103b '
Are formed so as to be close to each other so as to have an interval D. In the present embodiment, D is set to 120 μm. In addition, the 650 nm band for DVD is, specifically, 6 band.
35 nm or 650 nm has been adopted as the DVD standard.

The laser beams 103a 'and 103b' respectively emitted from the light sources 103a and 103b are emitted through the openings 102d 'so as to be parallel to each other in a direction orthogonal to one flat portion 102a' of the substrate portion 102a. It is supposed to be. Note that the laser beams 103a ', 1
The emission position of 03b 'is located at the tip surface 10 of the laser chip 103.
3 '(arranged so as to be parallel to the plane portion 102a'). Further, a plurality of external connection terminals 102g are provided from the other flat portion of the substrate portion 102a opposite to the one flat portion 102a '.
(See FIG. 1), and the external connection terminal 102 is provided.
The drive current is supplied to the laser chip 103 via g.

In the process of manufacturing the two-wavelength laser diode 102, the laser chip 103 having the two light sources 103a and 103b is processed on a predetermined substrate surface by a process similar to a semiconductor process.
The distance D between a and 103b can be easily and uniformly formed to a predetermined value with high accuracy. In addition, since mass production of discrete components is possible, the cost of the two-wavelength laser diode 102 can be reduced.

As shown in FIG. 1, the light receiving member 104 includes a package 104b having a light receiving window 104b 'and incorporating a light receiving element 104a, and external connection terminals 104c protruding from both sides of the package 104b. I have.
A power supply voltage for the light receiving element 104a can be supplied through the external connection terminal 104c, and a signal photoelectrically converted by the light receiving element 104a can be output to the outside.

The composite optical member 105 shown in FIGS.
The incident surface 105a and the outgoing surface (return light incident surface) 105b are formed by integral molding of a resin having high transmittance, and the optical axis N
The main part is a truncated cone-shaped base part 105c provided on both end faces in the direction perpendicular to the optical axis N, and a trapezoidal projection part 105d having an inclined surface part 105d 'formed so as to protrude from the incident surface 105a. It is configured.

The base portion 105c is formed such that its diameter decreases as it goes in the direction (forward) of the emission surface 105b. Further, a columnar portion 105j having a first restricting portion, that is, a cylindrical surface 105j '(restricting surface) is formed at a front end portion of the base portion 105c. The emission surface 105b is a front end surface of the columnar portion 105j.

The columnar portion 105j of the base portion 105c
On the outer peripheral surface of the rear end portion 105k on the opposite side, four protruding portions 105k 'are formed substantially evenly in the circumferential direction. Note that the second regulating portion, that is, the tip surface (regulating surface) of each protrusion 105k 'is a columnar surface. In FIG. 3, a columnar position regulating protrusion 105m is integrally formed on the lower surface of the central portion of the base portion 105c so as to protrude downward.

As shown in FIGS. 3, 4, and 12,
On the incident surface of the base portion 105c and the rear end surface of the protruding portion 105d, between each protruding portion 105k ', the second diffraction grating 105g and the three-beam diffraction grating 105h, a buffer region, that is, a space portion 105s is formed. A counterbore is formed at a predetermined depth in the direction of the axis N.

The first diffraction means, that is, the rectangular first diffraction grating 1
05f is formed. The surface of the inclined surface portion 105d 'is coated with an optical film (not shown), so that a return light reflecting surface 105d "is formed on the inner wall surface of the inclined surface portion 105d'.
5d "is provided with a second diffraction means, that is, a reflection-type second diffraction grating 105g.
In a region including the optical axis N, a three-beam diffraction grating 105h for generating three beams for CD tracking control is formed. The region other than the first diffraction grating 105f on the exit surface 105b and the region other than the three-beam diffraction grating 105h on the entrance surface 105a are mirror-finished reference planes (reference planes). It has areas facing each other.

Further, the return light reflecting surface 1 of the protrusion 105d
On the side wall surface opposite to 05d ″, a flat surface 105n is formed so as to extend over the base portion 105c.
05n, the cylinder surface 105i for the astigmatism method, which is a focus control method, is shifted from the optical axis N by a predetermined angle α.
A groove is formed in an oblique direction (see FIG. 6), and the inner wall of the cylinder surface 105i is a return light emission surface 105p. In the present embodiment, the composite optical member 105 is formed by integral molding using a molding die together with the first and second diffraction gratings 105f and 105g, the three-beam diffraction grating 105h, and the cylinder surface 105i.

In this embodiment, the outgoing surface 105b and the return light incident surface are the same, but the outgoing surface and the return light incident surface are separately provided, and the first diffraction grating is formed on the return light incident surface. You may do so. The details of the first and second diffraction gratings 105f and 105g and the three-beam diffraction grating 105h in the composite optical member 105 will be described later.

The housing 106 shown in FIGS.
It is made of an aluminum die-cast block and mainly includes a cylindrical body 106g and mounting portions 106h and 106i projecting outward from both ends of the cylindrical body 106g. These mounting portions 106h and 106i have rectangular mounting surfaces 106h 'and 106i', respectively.

The two-wavelength laser diode 10 shown in FIG. 2 is located on the left end (rear end) of the cylindrical body 106g in FIG.
A receiving chamber 106a for inserting the second laser diode 2 and a mounting hole 106b for positioning and mounting the two-wavelength laser diode 102 are formed on the left end face.

A housing chamber 106c is formed at the right end (front end) of the housing 106 so as to be connected to the housing chamber 106a along the central axis N '. Containment room 106
c is a space surrounded by a truncated conical surface for inserting the composite optical member 105 shown in FIG. 3, and is configured such that the diameter decreases toward the front end along the central axis N ′. Have been. In addition, the front and rear ends of the accommodation chamber 106c have first and second regulation receiving portions 106j formed of cylindrical surfaces,
106k (regulation receiving surface).

The diameter of the first regulation receiving portion 106j is equal to the columnar portion 105j (diameter D) of the composite optical member 105 (see FIG. 3).
1) is set to a dimension that can be fitted with high accuracy. Also, the diameter of the second regulation receiving portion 106k is
5 is set to a predetermined dimension that is shorter than the diameter D2 (see FIG. 4) of a circumscribed circle that circumscribes the tip of each projection 105k 'provided at the rear end 105k.

A positioning portion for positioning the composite optical member 105 in the direction of the optical axis N, that is, an abutting surface 106c 'is formed at the front end of the accommodation chamber 106c.
Further, an entrance / exit opening which is opened forward, that is, a circular opening 106f is formed in the abutting surface 106c 'of the accommodation chamber 106c so that the first diffraction grating 105f provided in the composite optical member 105 is exposed. Has become.

FIG. 8 shows the accommodation chambers 106a and 106c.
A U-shaped hole-shaped position regulating groove 106d, which is cut out forward from the rear end of the accommodation chamber 106a, is formed in the middle lower wall portion so as to penetrate the outer wall of the cylindrical body 106g. Further, from the rear end of the position regulating groove 106d,
A wide guide groove 106d 'is formed so as to connect to the opening edge of the cylindrical body and penetrate the outer wall of the cylindrical body 106g.

The groove width of the position regulating groove 106d is set to a predetermined size such that the outer diameter of the position regulating protrusion 105m provided on the composite optical member 105 can be fitted with high precision.

Further, the cylindrical body 10 covering the through hole 106d is formed.
An arrangement surface 106e for disposing the light receiving member 104 is formed on the outer wall surface of 6g. And the mounting part 10
6h and 106i are the mounting surfaces 106 provided respectively.
h 'and 106i' are formed integrally with the cylindrical body 106g so as to provide a step higher than the arrangement surface 106e.

The block used for the housing 106 is not only an aluminum die-cast but also a zinc die-cast.
It may be made of a magnesium alloy or another metal.

Next, referring to FIG.
Two-wavelength laser diode 102, light receiving member 104,
The assembled state of the composite optical member 105 will be described.

First, the composite optical member 105 is inserted through the mounting hole 106b of the housing 106, and the surface of the incident surface 105a except the diffraction grating 105h is uniformly pressed by a predetermined jig (not shown). , Its base part 1
05c is fitted into the accommodation room 106c. Further, when the composite optical member 105 is pressed, the outer edge of the emission surface 105b abuts against the abutting surface 106c 'formed in the housing chamber 106c of the housing 106, and positioning with respect to the housing 106 in the direction of the central axis N' is performed. You.

At this time, the cylindrical portion 105j provided on the base portion 105c fits into the first regulation receiving portion 106j of the storage chamber 106c.
The cylindrical surface 105j 'of the cylindrical portion 105j of FIG.
) Comes into contact with the first regulation receiving portion 106j, and the base portion 10
The position of the front end of 5c in the direction perpendicular to the optical axis N is regulated with high accuracy.

The rear end portion 105k is press-fitted into a second regulation receiving portion 106k provided in the accommodation room 106c. At this time,
As shown in FIG. 12, each of the protrusions 105k 'formed on the outer peripheral surface of the rear end 105k is in a state of being uniformly crushed, and the front end surface (restriction surface) of each of the protrusions 105k' is in the second control position. The rear end 1 of the base portion 105c contacts the receiving portion 106k.
The position of the composite optical member 105 in the direction orthogonal to the optical axis N at 05k is regulated with high accuracy.
06c is prevented from coming off.

In the above-described press-fit state, the protruding portion 105k 'is crushed, so that a part of the press input received from the second regulation receiving portion is buffered by the deformation of the protruding portion so that the press input more than necessary can be performed by the composite optical member. The occurrence of distortion in the optical function unit, that is, the second diffraction grating 105g and the three-beam diffraction grating 105h can be reduced so as not to cause such a problem. Further, space portions 105s (see FIGS. 3, 4, and 12) which are buffer regions are formed between each protrusion 105k ', the second diffraction grating 105g, and the three-beam diffraction grating 105h, respectively. In addition, the force applied by the press input in the direction of the optical function unit can be further buffered by the space 105s, and the occurrence of distortion of the optical function unit can be further reduced.

On the other hand, the position restricting projection 105m formed on the composite optical member 105 is connected to the cylindrical body 10 of the housing 106.
It is inserted from the opening of the guide groove 106d 'formed in 6g. When the composite optical member 105 is pushed forward in the direction of the optical axis N and is accommodated in the accommodation chamber 106c, the position regulating protrusion 105m is guided by the guide groove 106d 'and fits into the position regulation groove 106d. In this state, the position of the base portion 105c in the rotation direction around the optical axis N is regulated with high accuracy in this state.

In this way, the position of the composite optical member 105 with respect to the housing 106 in the direction orthogonal to the optical axis N, the position in the rotation direction around the optical axis N, and the position in the direction of the optical axis N are regulated. It has become so. The optical axis N coincides with the central axis N 'of the base 106g of the housing 106.

Next, the two-wavelength laser diode 102
The cap 102e (see FIG. 3) side is the housing 1
06, and is fixed to the housing 106 by being press-fitted into the mounting hole 106b formed in the housing 106 at the outer edge on the one flat surface 102a 'side of the substrate 102a.

The housing 106 in which the composite optical member 105 and the two-wavelength laser diode 102 are incorporated as described above.
As shown in FIG. 13, the tip surface 1 of the laser chip 103 built in the two-wavelength laser diode 102
03 ′ and the incident surface 105a of the composite optical member 105 are arranged in parallel and at a predetermined interval. At this time, the central axis N of the composite optical member 105 is configured to coincide with the optical axis of the laser beam 103a 'emitted from the light source 103a (see FIG. 2).

Further, the light receiving member 104 is
The light receiving window 104b 'of 4b is disposed in a state of being inserted into a through hole 107a provided in the printed circuit board 107, and the external connection terminal 104c is soldered to a land (not shown) formed on the surface of the printed circuit board 107. To be fixed to the printed circuit board 107. If necessary, the package 104b may be connected to the printed circuit board 107 or the housing 106.
It may be fixed by an adhesive or the like and reinforced.

The printed circuit board 107 to which the light receiving member 104 is fixed has a light receiving window 104b '
6 are placed on the mounting surfaces 106h 'and 106i' of the mounting portions 106h and 106i in a state where they are arranged so as to face the position regulating grooves 106d formed in 6, and are fastened and fixed to the housing 106 by screws 108. You.

The light receiving member 104 is arranged at an angle of 90 degrees with respect to the two-wavelength laser diode 102 with the composite optical member 105 as a starting point. In addition, the printed circuit board 107 on which the light receiving member 104 is mounted is previously provided with first and second diffraction gratings for returning laser beams 103a 'and 103b' from the light sources 103a and 103b by a predetermined reference optical system. 105f and 1
After being adjusted so as to be optimally guided to the predetermined position P of the light receiving element 104a when diffracted at 05 g, the mounting surface 10
6h 'and 106i'.

Next, D by the optical pickup device 100
The reproduction operation of VD62 and CD61 will be described.

In the above configuration, when reproducing the DVD 62, as shown in FIG. 1, the laser light 103 emitted from the light source 103a of the two-wavelength laser diode 102 is used.
a ′ transmits through the three-beam diffraction grating 105 h formed on the entrance surface 105 a of the composite optical member 105 and is converted into three beams, then transmits through the first diffraction grating 105 f, and exits from the exit surface 1.
05b.

The laser beam 103a 'is deflected at an angle of 90 degrees by a reflection mirror 300 arranged at an angle of 45 degrees with respect to the traveling direction of the laser beam 103a', and arranged above the reflection mirror 300. The light is incident on the collimating lens 400. The collimated lens 400 converts the laser beam 10 into substantially parallel light.
3a 'enters the objective lens 200 and the objective lens 200
Is focused on the information recording surface of the DVD 62.

Thereafter, the laser beam (return light) 103a 'reflected by the DVD 62 passes through the objective lens 200 and the collimator lens 400 again, is reflected by the reflection mirror 300, and then enters the return light entrance surface, ie, the exit surface shown in FIG. 105
b, which is a first-order diffracted light that is incident on the first diffraction grating 105f formed at b and is diffracted at a predetermined diffraction angle.
a'-2. The return light 103a'-2 is further reflected by the return light reflecting surface 105d "formed on the composite optical member 105 and enters the light receiving position P of the light receiving element 104a of the light receiving member 104.

At this time, the return light 103a'-2 received by the light receiving element 104a is photoelectrically converted to a DV.
The reproduction signal is generated by converting the current output corresponding to the signal on the information recording surface of D62 into a voltage signal, output from the external connection terminal 104b of the light receiving member 104, and transmitted to the outside through the printed circuit board 107. A part of the return light 103a'-2 received by the light receiving element 104a is used for focus and tracking control.

On the other hand, when reproducing the CD 61, the laser beam 103b 'emitted from the light source 103b of the two-wavelength laser diode 102 is diffracted by three beams formed on the incident surface 105a of the composite optical member 105 as shown in FIG. After being transmitted through the grating 105h and converted into three beams, the light is transmitted through the first diffraction grating 105f and emitted from the emission surface 105b. Then, the laser beam 103b 'is guided to the objective lens 200 as in the case of the DVD 62, and
By the light condensing action of 00, an image is formed on the information recording surface of the CD 61.

Thereafter, the return light 103 reflected by the CD 61
b ′ is the objective lens 200 and the collimating lens 40 again.
After passing through 0 and being reflected by the reflection mirror 300, the light is incident on the first diffraction grating 105f and becomes return light 103b'-2, which is the first-order diffracted light diffracted at a predetermined diffraction angle. The return light 103b'-2 is further reflected by the return light reflecting surface 105d "formed on the composite optical member 105 and enters the cylinder surface 105i.

The return light 10 on the cylinder surface 105i
3b'-2 is provided with astigmatism for focus control, and exits the return light exit surface 105p, and receives the light receiving element 104a.
At the light receiving position P. At this time, the light receiving element 104
The return light 103b'-2 received at a is photoelectrically converted to convert a current output corresponding to the signal on the information recording surface of the CD 61 into a voltage signal, thereby generating a reproduction signal. The signal is output from the connection terminal 104b and transmitted to the outside through the printed circuit board 107.
The return light 103b 'received by the light receiving element 104a
Part of -2 is focus control by the astigmatism method, and 3
Used for tracking control by the beam method.

In the optical pickup device 100, the laser light 103a 'emitted from the emission surface 105b,
A wavelength filter or the like for regulating the diameter of the light beam 103b 'may be provided in the optical path between the emission surface 105b and the objective lens 200.

Next, the function of the composite optical member 105 will be described.

As shown in FIG. 13, the composite optical member 10
5, a laser beam 103a 'emitted from the emission surface 105b,
DVD62 and CD61 for 103b 'respectively
Return light 103a'-2 is diffracted by the first diffraction grating 105f formed on the emission surface 105b.
And 103b'-2. At this time, since the return light 103b'-2 corresponding to the CD 61 has a longer wavelength than the return light 103a'-2 corresponding to the DVD 62,
The diffraction angle of b'-2 is larger than the diffraction angle of the return light 103a'-2 (a diffraction grating uses the principle that the longer the wavelength, the larger the diffraction angle).

By utilizing the difference between the diffraction angles, the laser beam 103a ', 103b' whose distance between the optical axes is D before being diffracted is returned to the light reflection surface 105.
When the return lights 103a'-2 and 103b'-2 return to "d", the arrival positions of both light beams coincide with each other.

However, on the return light reflecting surface 105d ″ of the composite optical member 105, the return lights 103a′-2 and
Simply reflecting 3b'-2 causes the incident angles of the two laser beams to be different, so that the two return lights 103a'-2 and 103b'-2 are directed to the light receiving position P of the light receiving element 104a so as to coincide with each other. It is not possible. To correct this, a second diffraction grating 105g is provided on the return light reflecting surface 105d ". That is, the return lights 103a'-2 and 103b'-2 incident on the second diffraction grating 105g are re-wavelength. Light reflection surface 1 using the difference in diffraction angle due to the difference in
Return light 103a'-2 and 103 reflected at 05d "
The optical axes of both b'-2 are matched.

Thus, the first diffraction grating 105f
Return lights 103a'-2 and 103 diffracted at
b′-2 can be corrected so that both light are received at the light receiving position P of the light receiving element 104a.
Even when using the light receiving members a and 103b, the light receiving member 104 having one light receiving element 104a can receive both laser beams.

Next, a method for inspecting the composite optical member 105 will be described with reference to FIGS. 14 to FIG.
FIG. 15 shows a schematic composite optical member 105 depicting only the three-beam diffraction grating 105h and the first diffraction grating 105f.

First, the entrance plane 105a and the exit plane 10
A method of inspecting the diffraction characteristics of the three-beam diffraction grating 105h and the first diffraction grating 105f respectively formed in FIG. 5b will be described.

For example, when inspecting the first diffraction grating 105f, the light 110 such as a laser beam enters the inside of the composite optical member 105 from a predetermined position on the reference surface of the incident surface 105a (an area other than the three-beam diffraction grating 105h). Through the first diffraction grating 105 formed on the exit surface 105b.
f is irradiated with the light 110 and the zero-order light 110a and the diffracted light 110b of the light transmitted through the first diffraction grating 105f are referred to, for example, the diffraction characteristics such as the diffracted light rate and the diffraction angle of the diffracted light 110b. Can be inspected.

Similarly, when inspecting the three-beam diffraction grating 105h, as shown in FIG.
From the predetermined position on the reference plane (region other than the first diffraction grating 105f) into the inside of the composite optical member 105.
11 are transmitted obliquely, and 3 formed on the incident surface 105a.
The beam 111 is irradiated with the light 111 on the beam diffraction grating 105h, and the zero-order light 111a of the light transmitted through the three-beam diffraction grating 105h.
And diffracted light 111b, for example,
The diffraction characteristics such as the diffracted light rate and the diffraction angle of the diffracted light 111b can be inspected.

As described above, when inspecting one diffraction grating, it is possible to inspect the diffraction characteristics independently and accurately without receiving interference from the other diffraction grating.

Next, the entrance surface 105a and the exit surface 105
A method for inspecting the surface accuracy of b will be described.

The case of inspecting the surface accuracy of the exit surface 105b will be described. As shown in FIG.
b, an optical plate (not shown) having a reference surface 150 is provided, and inspection light, that is, white illumination light 112 for inspection is applied to the optical plate from the side opposite to the composite optical member 105 of the optical plate. And the transmitted light 112 passing through the optical plate
c and the reflected light 112b reflected on the reference surface 150, irradiates the transmitted light 112c to the reference surface of the emission surface 105b, and transmits the reflected light 112a reflected on this reference surface to the optical plate through a reverse path, thereby transmitting the transmitted light. The surface accuracy of the emission surface 105b can be inspected with reference to the interference light between the reflected light 112a and the reflected light 112b.

As described above, by inspecting the surface accuracy of the reference surface of the emission surface 105b, the molding accuracy of the emission surface 105b after molding can be evaluated.
It is possible to evaluate the surface accuracy (for example, flatness) of the surface of the first diffraction grating 105f provided in 5b. Note that the inspection of the surface accuracy of the incident surface 105a is the same as the inspection of the emission surface 105b, and a description thereof will be omitted.

Next, a method for inspecting the parallelism of the incident surface 105a and the outgoing surface 105b and the transmitted wavefront aberration will be described.

As shown in FIG. 16, an optical plate (not shown) having a reference surface 151 is provided so as to face the emission surface 105b, and a reference plane reflector is provided so as to face the incidence surface 105a. 152 is provided. Then, the optical plate is irradiated with the inspection laser beam 113 from the side opposite to the composite optical member 105 of the optical plate to generate transmitted light 113c transmitted through the optical plate and reflected light 113b reflected by the reference surface 151. Then, the transmitted light 113c is made incident on the reference surface of the emission surface 105b, transmitted through the composite optical member 105, emitted from the reference surface of the incident surface 105a to the reference plane reflector 152, and reflected by the reference plane reflector 152. Through the optical plate in the reverse path, and the transmitted reflected light 113a and reflected light 11
3b, the incident surface 105a and the exit surface 10
The parallelism of 5b and the transmitted wavefront aberration can be inspected.

As described above, by inspecting the parallelism and the transmitted wavefront aberration of the two reference surfaces, the relative molding accuracy between the entrance surface 105a and the exit surface 105b after molding can be evaluated.
This makes it possible to evaluate the parallelism and the transmitted wavefront aberration of the three-beam diffraction grating 105h and the first diffraction grating 105f respectively provided on the entrance surface 105a and the exit surface 105b.

As described above, according to the present embodiment, as shown in FIG. 1, the housing 106 is attached to the optical pickup 100,
, A two-wavelength laser diode 102, a light receiving member 104, and a composite optical member 105 are attached and fixed. The two-wavelength laser diode 102 emits a laser diode 103a that emits a short-wavelength laser for DVD and emits a long-wavelength laser for CD. Composite optical member 1 having laser diode 103b
Reference numeral 05 denotes an incident surface 105a on which light emitted from the two-wavelength laser diode 102 is incident and an emission surface 105b on which light is emitted.
And an optical disk D1 (D
First diffraction grating 105 that diffracts the return light reflected in 2)
f, and a return light reflecting surface 105d "for reflecting the return light diffracted by the first diffraction grating 105f to the light receiving member 104. The return light reflecting surface 105d" receives light having different wavelengths together. Since the second diffraction grating 105g for forming an image with the optical axis coincident with the light receiving position P is provided, one composite optical unit 101 can be used for the optical pickup device 100 using two different wavelengths. The number of the light receiving members 104 may be one, and
It is only necessary to adjust only the position and adjust the position, so that the cost in the adjustment step does not increase.

The two-wavelength laser diode 102 includes a substrate 102a, a cap 102e, and a glass plate 102f.
The light receiving member 104 includes a package 104b having a built-in light receiving element 104a and an external connection terminal 104c provided on the package 104b. Since the composite optical unit 101 is a discrete component, and the composite optical unit 101 is formed using members that are manufactured individually at a low cost, the handling of each member is easy, and the assembling work into the housing 106 is facilitated. Member costs and process costs can be reduced.

Further, the composite optical member 105 is made of inexpensive resin, and the first and second diffraction gratings 105f and 105g, the three-beam diffraction grating 105h, the cylinder Since the surface 105i and the surface 105i are integrally formed at the same time, the molding time can be shortened, and the manufacturing cost of the composite optical member 105 can be further reduced.

Further, as described in this embodiment,
The composite optical unit 101 on which the composite optical member 105 of the present invention is mounted has an optical disk 6 on which the objective lens 200 is mounted.
1 (62) Optical pickup device 1 for recording or reproducing
00 is also applicable.

In the present embodiment, as shown in FIG. 2, two light sources 103a having different wavelengths are used as light emitting members.
Although the two-wavelength laser diode 102 having the 103b is used, the present invention can be applied to a case where a light-emitting member having three or more light sources having different wavelengths is used.

[0084]

As described above, according to the present invention,
Integrally formed by molding, light input surfaces and output surfaces are provided at both end surfaces in the optical axis direction, and a diffraction grating is formed in a region including the optical axis of the incident surface and the output surface, respectively. Since the entrance surface and the exit surface each have a mirror-finished reference surface separately from the respective diffraction gratings, light is transmitted from one reference surface to the inside of the composite optical member, and the light is transmitted to the other diffraction grating. And a composite optical member that can independently inspect the diffraction characteristics of the diffraction grating by referring to the zero-order light and the diffracted light transmitted through the diffraction grating. In addition, by inspecting the surface accuracy of the reference surface, it is possible to evaluate the molding accuracy of the entrance surface or the exit surface after molding, and thereby it is possible to evaluate the surface accuracy of the diffraction grating provided on the entrance surface or the exit surface. Can be provided.

Further, light is transmitted from one of the reference planes to the inside of the composite optical member, the other diffraction grating is irradiated with the light, and the zero-order light and the diffracted light of the light transmitted through the diffraction grating are transmitted. Since the diffraction characteristic of the diffraction grating is inspected by reference, the inspection of the diffraction characteristic is performed independently and accurately without being interfered by the other diffraction grating when inspecting one diffraction grating. be able to.

Further, an optical plate having a reference surface is provided so as to face one of the reference surfaces or the other of the reference surfaces, and the optical plate is placed on the optical plate from a side of the optical plate opposite to the composite optical member. By irradiating inspection light, to generate transmitted light transmitted through the optical plate and reflected light reflected by the reference surface, and irradiate the transmitted light to the one reference surface or the other reference surface, The transmitted light reflected by the reference surface or the other reference surface is transmitted through the optical plate in a reverse path, and the surface of the incident surface or the emission surface is referred to with reference to interference light between the transmitted light and the reflected light. Since the accuracy is inspected, by inspecting the surface accuracy of the reference surface, it is possible to evaluate the molding accuracy after molding the incident surface or the exit surface, and thereby, the surface of the diffraction grating provided on the entrance surface or the exit surface Accuracy can be evaluated.

Further, the light emitting device is integrally formed by molding, and has an incident surface and an outgoing surface of light orthogonal to the optical axis on both end surfaces in the optical axis direction, respectively, and a region including the optical axis of the incident surface and the outgoing surface. In the inspection method of the composite optical member, each of which has a diffraction grating, the entrance surface and the exit surface each have a mirror-finished reference surface separately from the respective diffraction grating so as to face each other, An optical plate having a reference surface is provided so as to face one of the reference surfaces, and a reference plane reflector is provided so as to face the other reference surface,
The optical plate is irradiated with laser light from the side opposite to the composite optical member of the optical plate to generate transmitted light transmitted through the optical plate and reflected light reflected at the reference surface, and the transmitted light is The incident light enters one reference surface, passes through the composite optical member, exits from the other reference surface to the reference plane reflection plate, and transmits the transmitted light reflected by the reference plane reflection plate through the reverse path to the optical plate. The parallelism and the transmitted wavefront aberration between the incident surface and the emission surface are inspected with reference to the interference light between the transmitted laser light and the reflected light. By inspecting the wavefront aberration, it is possible to evaluate the relative molding accuracy after molding between the entrance surface and the exit surface, thereby evaluating the parallelism and the transmitted wavefront aberration of the diffraction gratings respectively provided on the entrance surface and the exit surface. It is possible to do.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an optical pickup device 100 according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional perspective view of a two-wavelength laser diode 102 according to the embodiment of the present invention.

FIG. 3 is a composite optical member 105 according to an embodiment of the present invention.
FIG.

FIG. 4 is a left side view of FIG. 3;

FIG. 5 is a right side view of FIG. 3;

FIG. 6 is a view as seen from a direction 6 in FIG. 3;

FIG. 7 is a plan view of the housing 106 according to the embodiment of the present invention.

8 is a sectional view taken along line 8-8 in FIG. 7;

FIG. 9 is a left side view of FIG.

FIG. 10 is a right side view of FIG.

FIG. 11 is a view as viewed from a direction 11 in FIG. 8;

FIG. 12 is a partial sectional view taken along line 12-12 in FIG. 1;

FIG. 13 is a composite optical member 10 according to an embodiment of the present invention.
FIG. 5 is an explanatory diagram for explaining a function of No. 5;

FIG. 14 is a composite optical member 10 according to an embodiment of the present invention.
It is a schematic diagram for demonstrating the inspection method of No. 5.

FIG. 15 is a composite optical member 10 according to an embodiment of the present invention.
It is a schematic diagram for demonstrating the inspection method of No. 5.

FIG. 16 is a composite optical member 10 according to an embodiment of the present invention.
It is a schematic diagram for demonstrating the inspection method of No. 5.

FIG. 17 is a partial cross-sectional view of a conventional optical unit 50.

FIG. 18 is a perspective view of a composite optical member 49 according to a conventional optical unit 50.

[Explanation of symbols]

 61 CD (optical disk) 62 DVD (optical disk) 100 Optical pickup device 101 Composite optical unit 102 Two-wavelength laser diode (light emitting member) 103a, 103b Light source 104 Light receiving member 104a Light receiving element 105 Composite optical member 105a Incident surface 105b Exit surface 105d "Return Light reflecting surface 105f First diffraction grating 105g Second diffraction grating 105h Three-beam diffraction grating 105j 'Cylindrical surface (restriction surface) 105k' Projection 105m Position restriction projection 105p Return light emission surface 105s Space 106 Housing 106c Housing Chamber 106c 'abutment surface (positioning portion) 106f inlet / outlet port 106j first regulated receiving portion (regulated receiving surface) 106k second regulated receiving portion (regulated receiving surface) 112 inspection white illumination light (inspection light) 113 inspection laser Light 150, 151 Surface 152 reference plane reflector 200 objective lens 300 reflecting mirror 400 collimating lens 500 carriage (pickup body)

Claims (4)

[Claims] 1. An optical element, comprising: a light incident surface and a light exit surface on both end surfaces in an optical axis direction; and a diffraction grating in a region of the incident surface and the light exit surface including the optical axis. The composite optical member is formed, and the entrance surface and the exit surface each have a mirror-finished reference surface separately from the respective diffraction gratings. 2. The method for inspecting a composite optical member according to claim 1, wherein light is transmitted from one of the reference planes to the inside of the composite optical member, and the other diffraction grating is irradiated with the light.
A method for inspecting a composite optical member, wherein the diffraction characteristic of the diffraction grating is inspected by referring to the zero-order light and the diffracted light of the light transmitted through the diffraction grating. 3. The method for inspecting a composite optical member according to claim 1, wherein an optical plate having a reference surface is disposed so as to face one of the reference surfaces or the other of the reference surfaces. Irradiating inspection light to the optical plate from the side opposite to the composite optical member of the plate to generate transmitted light transmitted through the optical plate and reflected light reflected on the reference surface, and the transmitted light is reflected on the one side. Irradiating the reference surface or the other reference surface, the transmitted light reflected on the one reference surface or the other reference surface is transmitted through the optical plate in a reverse path, and the transmitted light and the reflected light A method for inspecting a composite optical member, wherein the surface accuracy of the incident surface or the exit surface is inspected with reference to interference light. 4. A region which is formed integrally by molding and has an incident surface and an exit surface of light orthogonal to the optical axis on both end surfaces in the optical axis direction, respectively, and a region including the optical axis of the incident surface and the exit surface. In the inspection method of the composite optical member, each of which has a diffraction grating, the entrance surface and the exit surface each have a mirror-finished reference surface separately from the respective diffraction grating so as to face each other, An optical plate having a reference surface is provided so as to face one of the reference surfaces, and a reference plane reflecting plate is provided so as to face the other reference surface, and the composite optical member of the optical plate Irradiates the optical plate with an inspection laser beam from the opposite side to generate transmitted light transmitted through the optical plate and reflected light reflected on the reference surface, and the transmitted light is incident on the one reference surface. Through the composite optical member to reach the other reference surface Out to the reference plane reflector, the transmitted light reflected by the reference plane reflector is transmitted through the optical plate in a reverse path, and the transmitted light is referred to the interference light between the reflected light and the light. A method for inspecting a composite optical member, wherein the parallelism and the transmitted wavefront aberration between an entrance surface and the exit surface are inspected.