JPH09231596A - Optical pickup and optical pickup for phase transition type optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To practically prevent the deterioration of optical characteristic of an optical pickup due to the generation of aberration in a cover member by non-rotatably providing the cover member to a housing member at the time of the volume change of a joining member. SOLUTION: A joining member 18 is mounted inside a cap 15. It is preferable to machine the joining member 18 in a shape lining along the aperture 15a of the cap 15 in order to facilitate the positioning of a cover member 16 to the cap 15. The cover member 16 is arranged on the upper surface of the joining member 18. By this constitution, since the positioning of the cover member 16 to the cap 15 and the joining member 18 is easily and exactly performed only by dropping it on the cap 15, the inclination of the cover member 16 is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup for recording or reproducing information on or from an optical element, an optical disc or the like, and an optical pickup for a phase change type optical disc.

[0002]

2. Description of the Related Art Conventionally, it has been desired to reduce the size of an optical disk device for recording and reproducing information by using a laser beam. Have been done. Small optical pickup
The reduction in weight is advantageous not only for downsizing the entire apparatus but also for improving performance such as shortening access time. In recent years, use of a hologram optical pickup has been cited as a means for reducing the size and weight of an optical pickup, and some of them have been put to practical use.

Of the conventional optical pickup constructions,
The mounting portion of the cap and the cover member will be described with reference to the drawings. FIG. 18 is a cross-sectional view of a conventional cap and cover member before attachment, and FIG. 19 is a cross-sectional view of a conventional cap and cover member after attachment. First, the adhesive glass 523 having a predetermined shape is attached to the cap 5
As shown in FIG. 19, the temperature of the adhesive glass is raised to a predetermined temperature to melt and solidify the adhesive glass in a state where the adhesive glass is placed inside 22 and the cover member 516 is placed thereon. The configuration can be obtained.

[0004]

However, in the conventional optical pickup, it was difficult to accurately position the adhesive glass 523 and the cover member 516, so that the cover member 516 and the adhesive glass 523 were slightly displaced from each other. It was often placed in position. Therefore, as shown in FIG. 19, after the adhesive glass 523 is melted, the area of the adhesive glass in contact with the cover member 516 does not correspond to the left and right, so that the asymmetric stress is generated in the process of the molten adhesive glass 523 solidifying. Occurs, the joined cover member 516 tilts, and the light transmitted through the cover member 516 suffers from aberration.

The present invention solves the above-mentioned problems, and the cover member is provided so that the contact area of the adhesive glass is symmetrical or the cover member is fitted into the housing member, and therefore, the cover member has excellent optical characteristics not to be inclined. It is an object of the present invention to provide a high-performance optical pickup and an optical pickup for a phase change type optical disk.

[0006]

To achieve this object, the cover member is provided non-rotatably with respect to the accommodating member when the joining member is solidified and the volume contracts.

[0007]

According to a first aspect of the present invention, there is provided a light source and a plurality of inclined portions which are inclined with respect to an incident direction of light emitted from the light source. An optical guide member that guides light from the medium to a predetermined position through the plurality of inclined portions while guiding the light to the medium through the inclined portion, and light receiving means that receives the light and converts the received optical signal into an electrical signal. A housing member that houses the light source, the light guide member, and the light receiving unit and has an opening at a light entrance / exit portion, and closes the opening of the housing member,
A cover member that serves as a light entrance / exit portion, and a joining member that joins the cover member and the housing member are provided, and the cover member does not rotate relative to the housing member when the volume of the joining member changes. By providing the cover member, it is possible to prevent the cover member from inclining due to volume contraction when the joining member is solidified.

According to a second aspect of the present invention, there is provided a light source and a plurality of inclined portions which are inclined with respect to the incident direction of the light emitted from the light source, and the light from the light source is passed through the plurality of inclined portions. A light guide member that guides the light from the medium to a predetermined position through the plurality of inclined portions, a light receiving unit that receives the light and converts the received optical signal into an electrical signal, the light source, A housing member that houses the light guide member and the light receiving unit and has an opening at a light entrance / exit portion; a cover member that closes the opening of the housing member to serve as a light entrance / exit portion; A joint member that joins the housing member, and after the volume contraction of the joint member, the cover member is provided substantially perpendicular to the optical axis of the light passing through the cover member. ,cover It is possible to prevent the astigmatic aberration is generated in light passing through the timber.

According to the third aspect of the present invention, the light source and the plurality of inclined portions that are inclined with respect to the incident direction of the light emitted from the light source are provided, and the light from the light source is passed through the plurality of inclined portions. A light guide member that guides the light from the medium to a predetermined position through the plurality of inclined portions, a light receiving unit that receives the light and converts the received optical signal into an electrical signal, the light source, A housing member that houses the light guide member and the light receiving unit and has an opening at a light entrance / exit portion, and a cover member that seals the opening of the housing member and serves as a light entrance / emission portion, By fitting the cover member and the bottom of the housing member together, it is possible to prevent the cover member from tilting even when the volume of the joining member changes.

According to a fourth aspect of the present invention, there is provided a light source and a plurality of inclined portions that are inclined with respect to the incident direction of the light emitted from the light source, and the light from the light source is passed through the plurality of inclined portions. A light guide member that guides the light from the medium to a predetermined position through the plurality of inclined portions, a light receiving unit that receives the light and converts the received optical signal into an electrical signal, the light source, A housing member that houses the light guide member and the light receiving unit and has an opening at a light entrance / exit portion, and a cover member that seals the opening of the housing member and serves as a light entrance / emission portion, Since the outer peripheral shape of the cover member and the inner peripheral shape of the bottom of the storage member are substantially the same, it is possible to prevent the cover member from inclining when the joining member is solidified.

According to a fifth aspect of the present invention, there is provided a light source and a plurality of inclined portions that are inclined with respect to the incident direction of the light emitted from the light source, and the light from the light source is passed through the plurality of inclined portions. A light guide member that guides the light from the medium to a predetermined position through the plurality of inclined portions, a light receiving unit that receives the light and converts the received optical signal into an electrical signal, the light source, A housing member that houses the light guide member and the light receiving unit and has an opening at a light entrance / exit portion, and a cover member that seals the opening of the housing member and serves as a light entrance / emission portion, The cover member is configured to generate almost no aberration with respect to the light guided from the light source to the optical medium after the volume change at the time of joining the joining members, thereby improving the optical characteristics of the optical pickup. Door can be.

According to the structure of claim 6, since the cover member is provided with the taper, the cover member can be positioned more accurately.

The packaging of the optical pickup according to the embodiment of the present invention will be described below with reference to the drawings.

1 and 2 are sectional views showing the packaging structure of an optical pickup according to an embodiment of the present invention.

Reference numeral 1 denotes a light source. As the light source 1, various lasers such as a semiconductor laser and a gas laser such as He-Ne can be considered. Here, it is preferable to use a semiconductor laser which is the smallest among these, can reduce the size of the entire device, and has an output of several mW to several tens mW which is inexpensive. Semiconductor lasers made of AlGaAs, InGaAsP, I
nGaAlP, ZnSe, GaN, and the like are conceivable. Here, AlGaAs, which is most commonly used and is inexpensive, is used. Furthermore, when performing high-density recording, the spot diameter on the recording medium can be made smaller, and
It is preferable to use a semiconductor laser such as InGaAlP or ZnSe having a shorter wavelength than s.

Reference numeral 2 denotes a submount, and the submount 2 has a rectangular parallelepiped shape or a plate shape, and the light source 1 is attached to the upper surface thereof. This submount 2 is a light source 1
And has the function of releasing the heat generated by the light source 1. Considering heat conduction and the like in joining the submount 2 and the light source 1, Au is previously formed on the upper surface of the submount 2.
-Sn or the like is plated and soldered at high temperature, or Au-Sn, Sn-Ag, Sn-Sb, Sn-P.
It is preferable to use a method of pressing a foil of b-In or the like (thickness: several μm to several tens of μm) at high temperature. In addition, if the light source 1 and the submount 2 are not mounted substantially horizontally, aberrations in the optical system and a decrease in coupling efficiency may be caused. Therefore, at the time of joining, it is preferable that the light source 1 be mounted on the submount 2 at a predetermined position at a predetermined height and substantially horizontally. Further, an electrode surface 2a is provided on the upper surface of the submount 2 so as to make electrical contact with the lower surface of the light source 1. The electrode surface 2a is for supplying power to the light source 1, and it is preferable to use a thin Au film in consideration of conductivity and corrosion resistance as a metal film constituting the electrode surface 2a. Further, the submount 2 has a high thermal conductivity and a linear expansion coefficient of that of the light source 1 (approximately 6.5 × 10 ⁻⁶ /) due to heat generated from the light source 1 and problems such as attachment to the light source 1.
C) are preferred. Specifically, the coefficient of linear expansion is 3
A substance having a thermal conductivity of 100 W / mK or more at 10 × 10 ⁻⁶ / ° C., for example, AlN, SiC, T-cBN, Cu
/ W, Cu / Mo, Si, and the like, and particularly, when a high-output laser is used, it is preferable to use diamond or the like when the thermal conductivity must be extremely large. When the linear expansion coefficients of the light source 1 and the submount 2 are set to be equal or close to each other, the occurrence of distortion between the light source 1 and the submount 2 can be suppressed. It is possible to prevent inconveniences such as detachment of the attachment portion and cracking of the light source 1. However, if the distance is out of this range, a large distortion is generated between the light source 1 and the submount 2, and there is a possibility that the attachment portion between the light source 1 and the submount 2 is detached, and a crack or the like occurs in the light source 1. Get higher. Further, by making the thermal conductivity of the submount 2 as large as possible, the heat generated in the light source 1 can be efficiently released to the outside. However, when the thermal conductivity is equal to or less than this limit, the heat generated by the light source 1 is difficult to escape to the outside, so that the temperature of the light source 1 increases, the output of the light source 1 decreases, and the life of the light source 1 is shortened. In the worst case, the light source 1 is likely to be broken. In the present embodiment, AlN which is very excellent in both of these two characteristics is used. Furthermore, in order to improve the bondability with the light source 1 on the upper surface of the submount 2, Ti, Pt,
It is preferable to form a thin film in the order of Au. When Si is used as the material of the submount 2, it is preferable to form an insulating layer such as an Al ₂ O ₃ film or a surface oxide film on the surface of the member before the Ti layer.

Reference numeral 3 denotes a block. The block 3 is basically rectangular parallelepiped and has a large protrusion 3a on its side surface, and the submount 2 is attached to the upper surface thereof. Similar to the submount 2, this block 3 also has a high thermal conductivity and a linear expansion coefficient close to that of the submount 2 due to problems such as heat generated in the light source 1 and attachment to the submount 2, for example, It is preferable to use Mo, Cu, Fe, FeNiCo alloy, FeNi alloy, or the like other than those shown in the material examples of the submount 2. However, the requirements for these characteristic values are not so strict as compared with the submount 2, so that it is preferable to select them with emphasis on cost.
Here, the block 3 is formed of a material such as Cu or Mo which is very inexpensive as compared with AlN and has relatively excellent characteristics. In consideration of heat conduction and the like for joining the block 3 and the submount 2, Au-Sn, Sn-Ag, Sn-Sb, S are also used as in the case of the submount 2 and the light source 1.
It is preferable to crimp a solder foil of n-Pb-In or the like (thickness several μm to several tens μm) at high temperature. It is preferable that the melting point of the solder stay is set in consideration of the order of assembling so that the members that have been once joined can be prevented from being displaced.

Here, the submount 2 and the block 3
Are formed separately, but when the output of the light source 1 is high and a higher thermal conductivity is required for these members, these members are integrally formed in order to improve the thermal conductivity. Is preferred. In this case, it is preferable to use those having extremely high thermal conductivity such as AlN.

Further, it is desirable that the block 3 is larger than the submount 2 to have a large contact area with the substrate 4.

Since the light source 1 is required to have high accuracy with respect to the optical axis, it is preferable that the upper surface of the submount 2 is horizontal with high accuracy. Therefore, it is preferable to attach the submount 2, the block 3 and the substrate 4 in the same manner.

The substrate 4 has a function of radiating the heat generated by the light source 1 and transmitted through the submount 2 and the block 3 by conduction or the like to the outside, and various members forming an optical pickup are mounted on the substrate 4. And is the basis of packaging. As the material of the substrate 4, it is preferable to use a metal material having high thermal conductivity such as Cu, Al, or Fe, or an alloy material such as FeNi alloy or FeNiCo alloy. This is because welding, which will be described later, is easy to perform and also has an effect as an electromagnetic shield that shields noise such as electromagnetic waves from the high frequency superposition circuit. Among these, especially Fe, FeNi alloys, FeNi
Since the Co alloy has low thermal resistance, good heat dissipation, and low cost, the heat generated in the light source 1 can be efficiently radiated to the outside, and the characteristics of the light from the light source 1 are excellent. It becomes possible to provide a good optical pickup at a low price.

It is preferable that the above-mentioned block 3 and the substrate 4 are joined together by using the solder stay or Ag solder as described above. The block 3 may be formed by punching out the substrate 4 with a press or the like.

The board 4 is provided with a hole 4a, which is used for inserting a jig for adjusting the position of each member. This makes it possible to easily align the positions of the respective members inside the optical pickup that require delicate alignment.

The members mounted on the substrate 4 will be described below. First, attachment of the block 3 and the substrate 4 will be described. The block 3 is fixed to the upper surface of the substrate 4 by a method such as brazing or solder foil with the submount 2 and the light source 1 fixed in advance.

Further, the substrate 14 is provided with terminals 14. The terminal 14 supplies power to the light source 1 and outputs a detected signal to the outside. Then, the plurality of holes 4b provided in the substrate 4 while being prevented from making electrical contact with the substrate 4 made of the metal material described above.
Has been inserted. The material of this terminal 14 is FeN
It is preferable to use iCo alloy, FeNi, FeCr or the like. As a means for cutting off the electrical contact, it is preferable that an insulating film or the like is provided on a portion of the hole 4b which is in contact with the terminal 14 and the substrate 4, and the portion is hermetically sealed so that outside air does not enter from this portion. You need to do it. As such a member, it is preferable to use a hermetic seal or the like that can simultaneously perform both insulation and sealing. Here, it is particularly preferable to use an alignment sealing type or compression sealing type hermetic seal. This is because both insulation and sealing can be performed very easily, and the cost is extremely low, so that the process of attaching the terminal 14 to the substrate 4 can be simplified and the manufacturing cost of the optical pickup can be reduced. .

By using this matching sealing type hermetic seal as the terminal 14, high airtightness and insulation can be maintained over a wide temperature range, and the terminal shape can be deformed relatively freely. The reliability of the optical pickup can be increased and the degree of freedom in design can be increased.

The light guide member 5 has a rectangular parallelepiped shape,
It has a plurality of slopes and various films formed on these slopes inside, and has the function of emitting the light emitted from the light source and guiding the returned light to a predetermined position. There is. Further, the light guide member 5 has a block 3 on its side surface.
Is joined to the end face portion 3b of the protruding portion 3a. As the bonding material used here, it is preferable to use a photo-curable adhesive that is cured by irradiation with light having a predetermined wavelength. Among them, it is particularly preferable to use light in the infrared region, the ultraviolet region, and the visible light region where light emission is particularly easy. Good workability can be easily obtained by using such a bonding material, and further shortening of the bonding time can be easily achieved by controlling the amount and energy of the irradiation light to be optimum. Become. Note that a moisture-absorbing-curing instant adhesive may be used. Also in this case, good workability can be easily obtained.

The light receiving element 13 is composed of various electric circuits formed on a plate-shaped semiconductor wafer, and is attached to the bottom surface of the light guide member 5. At the time of attachment, the position is adjusted by using a position adjusting means such as an air brush inserted through the hole 4a provided in the substrate 4. Light receiving element 13
When the optical guide member 5 and the optical guide member 5 are attached to each other, large adhesive strength, workability that can be fixed at an arbitrary moment, change in volume before and after curing, and change in volume due to temperature and humidity are small, that is, a condition such as low shrinkage ratio. Are required, and by satisfying these requirements, workability and stability of the joint surface are improved. Further, the light receiving element 13 has a plurality of light receiving portions that receive the optical signal emitted from the light source 1, reflected by the light guide member 5, the recording medium, or the like and returned. The light signal detected by the light receiving unit is converted into an electric signal according to the light amount. This electric signal has the magnitude of the current value at the beginning of the conversion. However, this current has the disadvantages that it is very weak and that noise is easily picked up. For this reason, it is preferable here to use, as the light receiving element 13, an element formed with an IV amplifier having a function of converting a current value to a correlated voltage value and amplifying it. Further, it is preferable that the response of the output voltage to the incident frequency of light is good. The surface of the light receiving element 13 is provided with a plurality of electrodes composed of a thin film of Al or the like for taking out the received information as a signal, and the terminal 14
Is connected by a method such as wire bonding.

Reference numeral 15 denotes a cap, which is bonded to the substrate 4 so as to cover the light source 1, the light guide member 5, the light receiving element 13, etc., and the light source 1, the light guide member 5, the light receiving element 13, etc. are directly exposed to the outside air. It has a function of preventing the light from coming into contact with water and moisture, and also preventing the light mixed from the outside from entering the inside of the light guide member 5 and becoming noise.
In many cases, the cap 15 has a dome shape or a top hat shape, and an opening 15a is provided in a portion through which light passes, so that the passing light is not adversely affected. It is composed. The material of the cap 15 is preferably metal, resin or the like, which can be easily bonded to the substrate 4 and has a stable shape. Particularly, when the cap 15 is made of metal, it is possible to suppress unnecessary radiation from the power supply circuit that supplies electric power to the light source 1 and noise from other high frequency superposition circuits. Therefore, since noises resulting from these are not superimposed on various electric signals output from the optical pickup, it is possible to provide a high-performance optical pickup having a low noise level. Further, among the metal materials used for the cap 15, FeNiCo alloy, FeNi alloy, and the like are preferable because they facilitate the formation of the cap 15, have a high ability to suppress unnecessary radiation, and have good bondability with the substrate 4. It is a material.

Reference numeral 16 denotes a cover member. The cover member 16 prevents dust and dirt from adhering to the light guide member 5, the light receiving element 13 and the like, and improves the light transmission efficiency. It is attached to the opening 15a via a bonding material. The bonding material used here may be glass for adhesion, epoxy resin, or the like. In particular, the bonding glass is made of Fe used as a material for the cap 15.
It is a preferable material because it has almost the same thermal expansion coefficient over a wide temperature range as NiCo alloy or FeNi alloy and glass as the material of the cover member 16 and can prevent the mixing of moisture from the atmosphere. In addition, the cover member 16
The material, and crystalline glass PbO · B ₂ O ₃ · ZnO system, it is preferably used an optical glass such as BK-7. Further, it is preferable to form anti-reflection films 16a on both upper and lower surfaces of the cover member 16 to prevent reflection.
The cover member 1 is formed by forming the antireflection film 16a.
Since the reflection and refraction of light in 6 can be suppressed,
The light utilization efficiency can be improved. It is preferable that the antireflection film 16a is made of a material such as MgF ₂ because the antireflection can be efficiently performed.

Here, the cap 15 and the cover member 16 will be described with reference to the drawings. FIG. 10 is a cross-sectional view of the vicinity of the cap in the embodiment of the present invention. A joining member 18 is placed inside the cap 15. It is preferable that the joining member 18 is processed into a shape along the opening 15 a of the cap 15 in terms of the ease of positioning the cover member 16 with respect to the cap 15. Further, as the joining member 18, it is preferable to use low melting point adhesive glass having a melting point lower than that of the cover member 16 so that the structure of the cover member 16 can be prevented from being distorted due to heat and the like, and the cover member 16 and the cap can be accurately covered. This is preferable because 15 bondings can be performed. Examples of the material of the low melting point adhesive glass used for the joining member 18 include PbO / B ₂ O ₃ / SiO ₂ and Na ₂ O / B.
₂ O ₃ / SiO ₂ , PbO / B ₂ O / SiO ₂ , CaO / B ₂
O / SiO ₂ , ZnO / B ₂ O ₃ / SiO ₂ , MgO / B ₂
It is preferable to use a material such as O ₃ / SiO ₂ because excellent bonding strength and a high yield can be realized in a sealing process in a short time. Further, it is preferable that the joining member 18 be formed so as to cover the opening 15a without being cut after melting, from the viewpoint of maintaining airtightness inside the package of the optical pickup and preventing dew condensation.

Further, the cover member 1 is provided on the upper surface of the joining member 18.
6 are arranged. At this time, it is preferable that the shape of the cover member 16 is formed along the inner cross-sectional shape 15c of the cap 15. That is, it is preferable that when the inner cross-sectional shape 15c of the cap 15 is circular, it is formed into a circular shape having almost the same radius, and when it is rectangular, it is formed into a rectangular shape with substantially the same vertical and horizontal lengths. With such a configuration, the cover member 16 can be easily and accurately aligned with the cap 15 and the joining member 18 only by dropping it into the cap 15. The inclination of the member 16 can be prevented, and thus the deterioration of the optical characteristics of the optical pickup due to the occurrence of aberration in the cover member 16 can be almost prevented. Therefore, it is possible to provide a highly reliable optical pickup having good optical characteristics. Although the shape of the cover member 16 is formed so as to follow the inner cross-sectional shape 15c of the cap 15 in the present embodiment, if the same effect can be obtained, for example, the four corners of the cover member 16 may be cut or a part thereof may be cut. You may cut it out.

Next, another structure of the cap 15 and the cover member 16 according to the embodiment of the present invention will be described with reference to the drawings. The material of each member used in the present embodiment is the same as that described above. FIG.
And FIG. 12 is a cross-sectional view of the vicinity of the cap according to the embodiment of the present invention. In FIG. 11, the inner surface portion 15b of the cap 15 is provided with a taper. This taper may be provided on the entire circumference or a part thereof.
The side surface 16b of the cover member 16 is provided with a taper whose inclination is substantially equal to that of the inner surface portion 15b of the cap 15.
When the joining member 18 is melted or the like, the inner surface portion 15b of the cap 15 and the side surface 16b of the cover member 16 are fitted together. With such a configuration, more accurate positioning can be performed, so that the occurrence of inclination of the cover member 16 can be further reduced. Therefore, the optical characteristics of the optical pickup can be further improved.

Further, as shown in FIG. 12, the end surface portion 15d of the opening 15a of the cap 15 is also tapered, and at the same time, the side surface 16b of the cover member 16 is also tapered, and further, the end surface portion 15d and the side surface 16b. A joining member 18 is arranged between them. With such a configuration, since the positional relationship between the cap 15 and the cover member 16 can be made substantially on the same plane, the height of the cap 15 can be reduced and the height direction of the optical pickup can be reduced. Since the size can be reduced and the cover member 16 can be downsized, the optical pickup can be reduced in size and cost. In the present embodiment, it is preferable to change the taper direction according to the pressure inside the package. That is, when the pressure inside the package is a positive pressure, the taper is provided in the direction shown in FIG. 12, and conversely, when the pressure inside the package is a negative pressure, the taper is provided in the opposite direction to the direction shown in FIG. The configuration. With such a configuration, the holding force due to the taper is added to the joining force of the joining member 18, so that an optical pickup having a stronger joining strength and a high reliability can be obtained.

The joining member 18 described above may be a separate molded member, or the cap 1 may be previously formed.
5 or at least one of the cover members 16 may be formed in advance by vacuum vapor deposition, sputtering, or the like. When formed in advance, the thickness of the joining member 18 can be reduced, so that the cover member 16 and the cap 15 can be attached more accurately.

The inclination angle of the taper provided here is preferably 5 ° or less with respect to the optical axis of the light transmitted through the cover member 16. The reason for this is that if the inclination angle is 5 ° or more, the cover member 1 can be used during assembly or handling of the optical pickup.
There is a possibility that the sharp end portion of the side surface portion of 6 may be easily damaged. The reliability of the optical pickup may be deteriorated from the damaged portion at this time by cracks due to aging or heat during use of the optical pickup. That is, by setting the angle to 5 ° or less, it is possible to minimize damage to the taper end while enjoying the effect of providing the taper.

When the cover member 16 and the cap 15 are joined together, it is necessary to press them together.
This is preferable because it is possible to eliminate the stress difference that occurs at any time when the solidification occurs, and thus it is possible to more accurately suppress the occurrence of inclination in the cover member 16.

Next, a manufacturing process for joining the cap 15 and the cover member 16 using the frit glass of the preform will be described with reference to FIGS. 13 to 17.

First, as shown in FIG. 13, the opening 15
The cover member 1 is formed by arranging the cap 15 so that a is at the bottom and is formed along the side wall of the opening 15a.
6 is inserted to obtain the state shown in FIG. At this time, a taper may be provided on at least one of the side surface of the opening and the side surface of the cover member. Further, it is preferable that the cover member 16 projects from the bottom surface of the cap 15 on the inner surface side. By doing so, the bonding material, which will be described later, can be easily installed. Then, as shown in FIG. 15, a frit glass 1 pre-formed as a bonding material in advance.
9 is fitted around the protruding cover member 16 to obtain the state shown in FIG. Then, in this state, the frit glass 19 is put into a furnace and heated at a predetermined temperature for a predetermined time to melt the frit glass 19 as shown in FIG. To do.

The cap 15 is formed by the method as shown above.
By joining the cover member 16 with the cover member 16, it is not necessary to handle a liquid or gel-like joining material, so that the manufacturing process can be simplified, and the manufacturing time can be shortened and the manufacturing cost can be reduced accordingly. Can be encouraged. In addition, the cover member 1 is provided in the opening 15a of the cap 15.
The configuration in which 6 is fitted is preferable because the height of the optical pickup can be reduced by the thickness of the cap 15 and the positioning of the cover member 16 with respect to the cap 15 can be performed accurately.

Inside the optical pickup, the light source 1 and the light receiving element 13 are prevented from being oxidized and the light guide member 5 and the cover member 1 are provided.
6, gas such as N ₂ or Ar, N
It is preferable to fill an inert gas such as e or He. In that case, the gap 1 existing between the substrate 4 and the light receiving element 13
It is necessary to fill 7 with a bonding material having characteristics such as small shrinkage, low water absorption, high airtightness (excellent leak characteristics), for example, epoxy potting agent or solder, or to close the hole 4a with a plate member or the like. is there. Thereby, the inside airtightness can be improved.

By using the configuration shown above,
Since the thermal resistance of the substrate 4 and the cap 15 can be made smaller than in the conventional case, the heat generated in the light source 1 can be easily emitted to the outside as compared with the conventional case. Further cap 1
Since the clearance required for joining with the substrate 4 in 5 is very small, the substrate 4 and the cap 15 can be miniaturized, and therefore a compact optical pickup that meets the needs of the market can be provided. Further, since the substrate 4 and the cap 15 are made of a metal material, the entire package is electrically at the ground level except for the cover member 16, so that a strong shielding effect against electromagnetic waves from a high frequency superposition circuit or the like is provided. Have. Therefore, the optical pickup is highly reliable and has a large resistance to noise such as electromagnetic waves.

By mounting the substrate 4 and the cap 15 in an atmosphere filled with at least one type of N ₂ gas, inert gas or dry air, a predetermined gas can be easily supplied to the inside of the package at a predetermined pressure. Can be enclosed,
As a result, it is possible to prevent the light source 1 and the light receiving element 13 from being deteriorated and to prevent the optical characteristics from being greatly deteriorated due to the dew condensation on the light guide member 5 and the like.

Next, a method of attaching the substrate 4 and the cap 15 in the optical pickup of this embodiment will be described.
The substrate 4 and the cap 15 have at least the light source 1,
The block 3, the light guide member 5, and the terminal 14 are attached so as to be included therein. The mounting is performed in an atmosphere filled with N ₂ gas, an inert gas, or dry air at a predetermined pressure because the predetermined gas can be easily sealed at a predetermined pressure inside the package. preferable. Then, the substrate 4 and the cap 15 are arranged in a predetermined positional relationship, set in a resistance welding machine, and the electrodes of the welding machine sandwich the substrate 4 and the inner surface portion 15b of the cap 15 to apply a predetermined current to the substrate 4 and the cap 15. The substrate 4 and the cap 15 are welded by flowing the inner surface portion 15b of the substrate 15. At this time, when the substrate 4 and the cap 15 are welded, it is preferable to apply a pressure of about several hundred g / cm ² to several kg / cm ² because the bondability between the substrate 4 and the cap 15 is improved.
A condenser resistance welding machine was used as the welding equipment.

Further, in order to improve the weldability of both, it is preferable to provide a projection (projection portion having a triangular cross section) on at least one of the substrate 4 and the cap 15. As a result, the electric current concentrates on the top portion of the projection, so that portion can be easily melted. Therefore, the weldability between the substrate 4 and the cap 15 can be improved, and the value of the electric current flowing during welding can be reduced, and the welding time can be shortened, so that the manufacturing cost can be reduced. become.

Next, the operation of the optical pickup according to the embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a conceptual diagram of the operation of the optical pickup according to the embodiment of the present invention, and FIG. 4 is a perspective view of the light guide member according to the embodiment of the present invention.

In FIGS. 3 and 4, the laser light emitted horizontally from the light source 1 mounted horizontally on the substrate 4 via the submount 2 and the block 3 is a light guide member 5 having a plurality of parallel inclined surfaces. From the surface 5f of the light guide member 5
Of the reflection type having a function of converting the diffusion angle of the light which is incident on the second inclined surface 5b of the light guide member 5 and which is converted to the diffusion angle of the incident light (hereinafter referred to as NA conversion). Reach the diffusion angle conversion hologram 7. The light whose NA has been converted and reflected by the diffusion angle conversion hologram 7 is reflected by the reflection type diffraction grating 6 formed on the first slope 5a as a 0th-order diffracted light (hereinafter referred to as a main beam) and ± 1st-order diffracted light (hereinafter referred to as a side beam). ). The main beam and side beams generated by the diffraction grating 6 are incident on the first polarization-selective beam splitter film 9 (hereinafter simply referred to as the first beam splitter film).
The first beam splitter film 9 has a transmittance of almost 100% with respect to light having an oscillating component parallel to the incident surface (hereinafter simply referred to as P-polarized component), and has a vertical oscillating component (hereinafter simply referred to as S (Referred to as the polarization component) has a constant reflectance. Of the light incident on the first beam splitter film 9, the light passing through the first beam splitter film 9 is the light source 1
It is used as the monitor light of the light emitted from. The main beam and the side beam linearly polarized to the S-polarized component reflected by the first beam splitter film 9 pass through the surface 5e of the light guide member 5 and the cover member 16 and enter the objective lens 26, and the objective lens An image is formed on the recording medium surface 27 a of the recording medium 27 by the condensing action of 26. This time,
On the recording medium surface 27a, the beam spots 29a and 29c of the two side beams are imaged at positions substantially symmetrical with respect to the beam spot 29b of the main beam. Information recording or reproduction signals, tracking, and focusing, so-called servo signals are read from the recording medium surface 27a by beam spots 29b, 29a, and 29c of main beams and side beams.

The divergence angle conversion hologram 7 corresponds to the divergence angle of the light beam of the light emitted from the light source 1 which can enter the divergence angle conversion hologram 7.
The angle of diffusion of the light reflected from the object is converted. Further, the light can be converted into parallel light having no diffusion angle by the diffusion angle conversion hologram 7. Also, the same diffusion angle conversion hologram 7
Thus, as shown in FIG. 3, the light flux emitted from the light guide member 5 becomes an ideal spherical wave 30 from which the wavefront aberration accumulated in the midway path is removed. Therefore, the light incident on the objective lens 26 becomes an ideal spherical wave 30, and the beam spot on the recording medium 27 by the objective lens 26 is narrowed down to almost the diffraction limit to have an ideal size, so that information can be easily recorded or reproduced. Can be.

The return light of the main beam and the side beam reflected by the information recording surface 27a of the recording medium 27 passes through the objective lens 26 and the surface 5e of the light guide member 5 again,
The light enters the first beam splitter film 9 formed on the second inclined surface 5b of the light guide member.

Of the return light from the recording medium 27, the light transmitted from the first beam splitter film 9 is the light guide member 5.
A second polarization-selective beam splitter film 11 formed on a third slope 5c parallel to the first slope 5a of FIG.
(Hereinafter simply referred to as a second beam splitter film). The second beam splitter film 11 is similar to the first beam splitter film 9 in that the P beam component is almost 10
It has a transmittance of 0% and a constant reflectance for the S-polarized light component.

Here, the transmitted light 117 of the light flux incident on the second beam splitter film 11 will be described. The transmitted light 117 enters the polarization plane conversion substrate 31 laminated on the third inclined surface 5c.

FIG. 5 is a perspective view of a polarization plane conversion substrate according to one embodiment of the present invention, and FIG. 6 is a diagram showing a light receiving portion arrangement and signal processing of an optical pickup according to one embodiment of the present invention. The polarization plane conversion substrate 31 is the first other inclined surface 31.
a (hereinafter simply referred to as the first other slope) and the first other slope 31
The second other inclined surface 31b substantially parallel to a (hereinafter simply referred to as the second
(Referred to as another slope), and the reflection film 1 is provided on the first other slope 31a.
26, the polarization separation film 12 is formed on the second other inclined surface 31b. The transmitted light 117 enters the polarization splitting film 12 formed on the second other slope 31b. Second other slope 31b
Is formed such that the angle formed by the polarization plane 117a of the transmitted light 117 and the incident surface 128 is approximately 45 × (2n + 1) °: (n is an integer). As a result, the P-polarized component 117p and the S-polarized component 117s of the transmitted light 117 have an intensity ratio of about 1: 1. The P polarization component 117p having a polarization component parallel to the incident surface 128 is almost 100% transmitted by the polarization separation film 12, while the S polarization component 117s having a polarization component perpendicular to the incidence surface 128 is on the second other inclined surface 31b. Approximately 100% is reflected by the polarization separation film 12 and the first other slope 31
The light enters the a-plane, is reflected by the reflection film 126, and is guided to the light receiving element 13. The P-polarized component 117p guided to the light-receiving element 13 is sent to the light-receiving unit 170, and the S-polarized component 117s
Reaches the light receiving unit 171, and creates an RF signal.

Next, the reflected light 123 of the light beam incident on the second beam splitter film 11 shown in FIG. 3 will be described. The reflected light 123 is incident on the astigmatism generating hologram 10 formed by a reflection type hologram on the second inclined surface 5b. The reflected light 123 generates astigmatism by the astigmatism generation hologram 10 and is further reflected by the reflecting films 124 and 125, and the return light of the main beam is transmitted to the light receiving section 172 on the light receiving element 13 to the side beam. The returning light of the above reaches the light receiving portions 176 and 177 on the light receiving element 13.

Next, in the embodiment of the present invention, the structure of an optical pickup particularly adapted to a phase change type optical disk will be described with reference to the drawings. Phase-change optical discs record information by irradiating light to change the crystal structure in the recording medium, and require more light than conventional optical recording / reproducing devices to change the crystal structure. Therefore, a more efficient optical system is required. FIG. 7 is a configuration diagram of an optical pickup for a phase-change optical disk according to an embodiment of the present invention. Note that members having the same numbers as those shown in FIGS. 1, 2 and 3 have the same functions and configurations, and thus description thereof will be omitted.

The laser light emitted from the light source 1 is incident on the light guide member 41 from the surface 41f of the light guide member 41 having a plurality of parallel inclined surfaces, and the diffusion angle conversion hologram 7, the diffraction grating 6 and the polarization selective light. A certain beam splitter film 3
5 (hereinafter, referred to as a beam splitter film), and is emitted from the surface 41 e of the light guide member 41. Unlike the embodiment shown in FIG. 3, the beam splitter film 35 has an S-polarized component reflectance of 95% or more and a P-polarized component reflectance of about 1%. Beam splitter film 3
Of the light incident on the light source 5, the light that passes through the beam splitter film 35 (a P-polarized component is about a few percent of the total light amount) is used as the monitor light of the light emitted from the light source 1. The light emitted from the surface 41 e of the light guide member 41 passes through the λ / 4 plate 33 provided on the cover member 16. FIG. 8 is a schematic view of a λ / 4 plate according to the embodiment of the present invention. λ
The / 4 plate 33 is installed so that its extraordinary optical axis is π / 4 · (2m−1); (where m is a natural number: the same below) with respect to the plane of polarization of the incident light from the light guide member 41. , The phase difference between the extraordinary component of the incident light and the ordinary component is π / 2 · (2m-
It has the function of generating only 1). Generally, a uniaxial crystal material is used as a material forming the λ / 4 plate 33.
Among them, it is preferable to use quartz which is low in cost and excellent in light transmittance. In uniaxial crystals have abnormal optical axis 616 and ordinary light axis 617, and has a different refractive index, called extraordinary refractive index n _e and ordinary index n _o for each of the optical axes. Since the optical distances of extraordinary light and ordinary light are different, λ /
Assuming that the substrate thickness of the four plate 33 is QD and the incident light wavelength is λ, a phase difference Δ determined by the following relational expression occurs. The thickness QD of the λ / 4 plate 33 is determined so that the phase difference Δ is π / 2 · (2m−1).

Δ = 2π · (n _e −n _o ) · QD / λ In the present embodiment, the wavelength λ = 790 nm, the extraordinary refractive index ne = 1.5477, and the ordinary refractive index no = 1.5388.
(However, the refractive index differs depending on the cutting angle of the substrate. In this case, the cutting is performed in parallel with a plane including both the extraordinary optical axis and the ordinary optical axis.) The substrate thickness of the λ / 4 plate 33 is 21. It becomes 9 · (2m−1) μm. Under such conditions, light that has entered as linearly polarized light at an incident angle of 0 degrees can be converted into circularly polarized light. That is, linearly polarized light including only the S-polarized light component emitted from the light source 1 can be converted into circularly polarized light. Although the crystal of 21.9 μm is provided on the cover member 16 as the λ / 4 plate 33 here, it may be provided on the surface 41e of the light guide member 41 or the objective lens 26.

The circularly polarized light transmitted through the λ / 4 plate 33 enters the objective lens 26 and is focused on the recording medium surface 27a of the recording medium 27 by the condensing action of the objective lens 26.
Is reflected. The rotation direction of the circularly polarized light reflected by the recording medium surface 27a is reversed, so that when the return light passes through the objective lens 26 and again through the λ / 4 plate 33, P
It is converted into linearly polarized light containing only the polarized component. The return light converted in this way again passes through the surface 41e of the light guide member 41 and again enters the beam splitter film 35 formed on the second inclined surface 41b of the light guide member 41. As described above, the beam splitter film 35 has a transmittance of about 100% for the P-polarized component and a reflectance of about 100% for the S-polarized component. Therefore, the return light having only the P-polarized component almost passes through the beam splitter film 35.

Then, the returned light is incident on the half mirror 34 formed on the third slope 41c parallel to the first slope 41a of the light guide member 41. The half mirror 34 has a function of reflecting a predetermined amount of the incident light and transmitting the rest.

Of the light flux that has entered the half mirror 34, the transmitted light 117 is guided to the light receiving section 37 provided on the light receiving element 36.

Next, the reflected light 123 of the light beam incident on the half mirror 34 shown in FIG. 7 will be described. FIG. 9 is a layout diagram of a light receiving portion provided in a light receiving element of an optical pickup for a phase change optical disc according to an embodiment of the present invention. The reflected light 123 is incident on the astigmatism generating hologram 10 formed of a reflection type hologram on the second inclined surface 41b. The reflected light 123 is the astigmatism generating hologram 10
While astigmatism is generated by the reflection film 124,
The light reflected by the reflection film 125 returns the main beam to the light receiving section 38 on the light receiving element 36, and returns the side beam to the light receiving sections 39 and 40 on the light receiving element 36.

In the optical pickup having the above-mentioned structure, the λ / 4 plate 33 is provided between the beam splitter film 35 and the recording medium 27, and the emitted light, which is the linearly polarized light of the S-polarized component, is circularly polarized light. The light reflected by the recording medium 27 is converted, and then the circularly polarized light, which is reflected by the recording medium 27 and whose rotation direction is reversed, is converted into linearly polarized light having only a P-polarized component and made incident on the beam splitter film 35. Of the S-polarized light component of the beam splitter film 35 can be significantly increased, and thus the amount of light with which the recording medium 27 is irradiated can be increased. . That is, the recording medium 27 can be efficiently irradiated with the limited output of the light source 1, and
The reflected light from the recording medium 27 can be efficiently guided to the light receiving element 36.

[0062]

The present invention has a light source and a plurality of inclined portions that are inclined with respect to the incident direction of the light emitted from the light source, and allows the light from the light source to pass through the plurality of inclined portions. An optical guide member that guides the light from the medium to a predetermined position via the plurality of inclined portions, and a light receiving unit that receives the light and converts the received optical signal into an electrical signal.
A housing member that houses the light source, the light guide member, and the light receiving unit and has an opening at a light entrance / exit portion; and a cover member that closes the opening of the housing member to serve as a light entrance / exit portion, A joint member that joins the cover member and the storage member together is provided, and when the volume of the joint member changes, the cover member is provided non-rotatably with respect to the storage member, so that the joint member is solidified. It is possible to prevent the cover member from inclining even when the volume contracts. As a result, it is possible to prevent deterioration of the optical characteristics of the optical pickup due to the occurrence of aberration in the cover member. Therefore, it is possible to provide a highly reliable optical pickup having good optical characteristics and an optical pickup for a phase change type optical disc.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of packaging of an optical pickup according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of the optical pickup packaging according to the embodiment of the present invention;

FIG. 3 is a conceptual diagram of an operation of the optical pickup according to the embodiment of the present invention;

FIG. 4 is a perspective view of a light guide member according to one embodiment of the present invention.

FIG. 5 is a perspective view of a polarization plane conversion substrate according to an embodiment of the present invention.

FIG. 6 is a diagram showing a light receiving unit arrangement and signal processing of the optical pickup according to one embodiment of the present invention;

FIG. 7 is a configuration diagram of an optical pickup for a phase-change optical disc according to an embodiment of the present invention.

FIG. 8 is a schematic view of a λ / 4 plate according to an embodiment of the present invention.

FIG. 9 is a layout view of a light receiving portion of an optical pickup for a phase change optical disc according to an embodiment of the present invention.

FIG. 10 is a sectional view of the vicinity of the cap according to the embodiment of the present invention.

FIG. 11 is a sectional view of the vicinity of the cap according to the embodiment of the present invention.

FIG. 12 is a sectional view of the vicinity of the cap according to the embodiment of the present invention.

FIG. 13 is an assembly diagram of the cap and the cover member according to the embodiment of the present invention.

FIG. 14 is an assembly diagram of the cap and the cover member according to the embodiment of the present invention.

FIG. 15 is an assembly diagram of the cap and the cover member according to the embodiment of the present invention.

FIG. 16 is an assembly diagram of the cap and the cover member according to the embodiment of the present invention.

FIG. 17 is an assembly diagram of the cap and the cover member according to the embodiment of the present invention.

FIG. 18 is a cross-sectional view of a mounting portion before joining a conventional cap and cover member.

FIG. 19 is a cross-sectional view of a mounting portion after joining a conventional cap and cover member.

[Explanation of symbols]

1 Light Source 2 Submount 2a Electrode Surface 3 Block 3a Projection 3b End Face 4 Substrate 4a Hole 4b Hole 5 Light Guide Member 5a First Slope 5b Second Slope 5c Third Slope 5e Face 5f Face 6 Diffraction Grating 7 Diffuse Angle conversion hologram 9 First beam splitter film 10 Astigmatism generation hologram 11 Second beam splitter film 12 Polarization separation film 13 Light receiving element 13a Electrode 14 Terminal 15 Cap 15a Opening 15b Inner surface 15c Inner cross-section 15d End surface 16 Cover member 16a Antireflection film 16b Side surface 17 Gap 18 Joining member 19 Frit glass 26 Objective lens 27 Recording medium 27a Recording medium surface 29a, 29b, 29c Beam spot 30 Ideal spherical wave 31 Polarization plane conversion substrate 31a 1st other inclined surface 31b 2nd Other slope 33 λ / 4 plate 34 c Surf mirror 35 Beam splitter film 36 Light receiving element 37, 38, 39, 40 Light receiving part 41 Light guide member 41a First slope 41b Second slope 41c Third slope 41e Surface 41f Surface 117 Transmitted light 117a Polarization surface 117s S polarization component 117p P-polarized component 123 Reflected light 124 Reflective film 125 Reflective film 126 Reflective film 128 Incident surface 170, 171, 172, 172a, 172b, 172
c, 172d, 176, 177 Light receiving part 616 Extraordinary optical axis 617 Ordinary optical axis

Claims (17)

[Claims] 1. A medium having a light source and a plurality of inclined portions inclined with respect to an incident direction of light emitted from the light source, and guiding light from the light source to the medium via the plurality of inclined portions. A light guide member that guides light from the light source to a predetermined position via the plurality of inclined portions, a light receiving unit that receives the light and converts the received light signal into an electric signal, the light source, the light guide member, and the light guide member. A housing member that houses the light receiving means and has an opening at the light entrance / exit portion, a cover member that closes the opening of the housing member and serves as a light entrance / exit portion, and the cover member and the housing member are joined together. And a cover member which is provided so as not to rotate with respect to the storage member when the volume of the joint member changes. 2. A medium having a light source and a plurality of inclined portions inclined with respect to an incident direction of light emitted from the light source, and guiding the light from the light source to the medium through the plurality of inclined portions and the medium. A light guide member that guides light from the light source to a predetermined position via the plurality of inclined portions, a light receiving unit that receives the light and converts the received light signal into an electric signal, the light source, the light guide member, and the light guide member. A housing member that houses the light receiving means and has an opening at the light entrance / exit portion, a cover member that closes the opening of the housing member and serves as a light entrance / exit portion, and the cover member and the housing member are joined together. And a cover member which is provided substantially perpendicular to an optical axis of light passing through the cover member after the volume of the joint member is contracted. 3. A medium having a light source and a plurality of inclined portions inclined with respect to an incident direction of light emitted from the light source, and guiding the light from the light source to the medium through the plurality of inclined portions. A light guide member that guides light from the light source to a predetermined position via the plurality of inclined portions, a light receiving unit that receives the light and converts the received light signal into an electric signal, the light source, the light guide member, and the light guide member. The light receiving means is housed, and a housing member having an opening at a light entrance / exit portion, and a cover member which seals the opening of the housing member and serves as a light entrance / emission part, are provided. An optical pickup characterized by being fitted to the bottom of a member. 4. A medium having a light source and a plurality of inclined portions inclined with respect to an incident direction of light emitted from the light source, and guiding the light from the light source to the medium via the plurality of inclined portions. A light guide member that guides light from the light source to a predetermined position via the plurality of inclined portions, a light receiving unit that receives the light and converts the received light signal into an electric signal, the light source, the light guide member, and the light guide member. An outer peripheral shape of the cover member, which is provided with a storage member that stores the light receiving means and has an opening at a light input / output portion, and a cover member that seals the opening of the storage member and serves as a light input / output portion. And an inner peripheral shape of the bottom portion of the storage member are substantially the same shape. 5. A medium having a light source and a plurality of inclined portions inclined with respect to an incident direction of light emitted from the light source, and guiding the light from the light source to the medium via the plurality of inclined portions and the medium. A light guide member that guides light from the light source to a predetermined position via the plurality of inclined portions, a light receiving unit that receives the light and converts the received light signal into an electric signal, the light source, the light guide member, and the light guide member. The light receiving means is housed, and a storage member having an opening at a light entrance / exit portion, and a cover member which seals the opening of the housing member and serves as a light entrance / emission part, the cover member being the joint An optical pickup characterized in that after the volume is changed when the members are joined, almost no aberration is generated with respect to the light guided from the light source to the optical medium. 6. The optical pickup according to claim 1, wherein the cover member is provided with a taper. 7. The optical pickup according to claim 6, wherein an inclination angle of the taper is in a range of 1 ° to 5 ° with respect to an optical axis of light transmitted through the cover member. 8. A medium having a light source and a plurality of inclined portions inclined with respect to an incident direction of light emitted from the light source, and guiding the light from the light source to the medium through the plurality of inclined portions and the medium. A light guide member that guides light from the light source to a predetermined position via the plurality of inclined portions, a light receiving unit that receives the light and converts the received light signal into an electric signal, the light source, the light guide member, and the light guide member. A housing member that houses the light receiving means and has an opening at the light entrance / exit portion, a cover member that closes the opening of the housing member and serves as a light entrance / exit portion, and the cover member and the housing member are joined together. An optical pickup for a phase-change optical disc, wherein the cover member is provided non-rotatably with respect to the housing member when the volume of the joining member changes. 9. A medium having a light source and a plurality of inclined portions that are inclined with respect to an incident direction of light emitted from the light source, and guides the light from the light source to the medium through the plurality of inclined portions. A light guide member that guides light from the light source to a predetermined position via the plurality of inclined portions, a light receiving unit that receives the light and converts the received light signal into an electric signal, the light source, the light guide member, and the light guide member. A housing member that houses the light receiving means and has an opening at the light entrance / exit portion, a cover member that closes the opening of the housing member and serves as a light entrance / exit portion, and the cover member and the housing member are joined together. A phase change type, wherein the cover member is provided substantially perpendicular to the optical axis of the light passing through the cover member after the volume contraction of the joint member. Optical disc for optical disc Up. 10. A medium having a light source and a plurality of inclined portions inclined with respect to an incident direction of light emitted from the light source, and guiding the light from the light source to the medium through the plurality of inclined portions and the medium. A light guide member for guiding the light from the light source to a predetermined position through the plurality of inclined portions, a light receiving means for receiving the light and converting the received light signal into an electric signal, the light source, the light guide member and the The light receiving means is housed, and a housing member having an opening at a light entrance / exit portion, and a cover member that seals the opening of the housing member and serves as a light entrance / emission part are provided. An optical pickup for a phase-change optical disc, characterized in that the bottom of a member is fitted. 11. A medium having a light source and a plurality of inclined portions inclined with respect to an incident direction of light emitted from the light source, and guiding the light from the light source to the medium via the plurality of inclined portions and the medium. A light guide member that guides light from the light source to a predetermined position via the plurality of inclined portions, a light receiving unit that receives the light and converts the received light signal into an electric signal, the light source, the light guide member, and the light guide member. An outer peripheral shape of the cover member, which is provided with a storage member that stores the light receiving means and has an opening at a light input / output portion, and a cover member that seals the opening of the storage member and serves as a light input / output portion. An optical pickup for a phase-change optical disc, wherein the inner peripheral shape of the bottom of the housing member is substantially the same. 12. A medium having a light source and a plurality of inclined portions inclined with respect to an incident direction of light emitted from the light source, and guiding the light from the light source to the medium via the plurality of inclined portions and the medium. A light guide member that guides light from the light source to a predetermined position via the plurality of inclined portions, a light receiving unit that receives the light and converts the received light signal into an electric signal, the light source, the light guide member, and the light guide member. The light receiving means is housed, and a storage member having an opening at a light entrance / exit portion, and a cover member which seals the opening of the housing member and serves as a light entrance / emission part, the cover member being the joint An optical pickup for a phase-change type optical disc, which is characterized in that after the volume is changed when the members are joined, almost no aberration is generated with respect to the light guided from the light source to the optical medium. 13. The optical pickup for a phase-change optical disc according to claim 8, wherein the cover member is provided with a taper. 14. The optical pickup for a phase-change optical disk according to claim 13, wherein the taper inclination angle is in the range of 1 ° to 5 ° with respect to the optical axis of the light transmitted through the cover member. 15. A λ / 4 plate is provided between the light emitting surface of the light guide member and the optical medium, and the λ / 4 plate and the optical axis of the light are substantially perpendicular to each other. (14) An optical pickup for a phase change type optical disc according to any one of (1) to (14). 16. An inclined surface is provided with a light guide means for transmitting or reflecting light and at least one of the light guiding means is provided through the inclined surface.
The optical pickup for a phase-change type optical disc according to any one of claims 8 to 15, wherein the reflected light from the optical medium is guided to a light receiving means. 17. The optical pickup for a phase-change optical disk according to claim 16, wherein the light guiding means is a half mirror.