JPH0531218B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a light source device using a semiconductor laser, and particularly to a light source device suitable for an optical disk device that requires a high output power from the semiconductor laser.

[Prior art]

In an optical disk device, a metal film formed on a rotating disk surface is irradiated with a laser beam, and when information is recorded, the irradiation power of the laser beam is modulated so that the metal film is irradiated with information according to “1” or “0” of the information. During playback, the metal film is irradiated with a weak laser beam, and information is recognized by detecting changes in reflected light depending on the presence or absence of pits. As a light source for such an optical disk device, a light source device that combines a small semiconductor laser element and a collimator lens system for laser beam focusing is applied, but it is possible to compensate for the lack of output power of the semiconductor laser and to record information. In order to obtain the high irradiation power necessary for forming pits at the time, it is necessary to make the numerical aperture of the collimator lens for focusing the semiconductor laser element light into parallel light as large as possible. However, as the numerical aperture is increased, the depth of focus of the collimator lens becomes shallower, so a sophisticated alignment technique is required to couple the semiconductor laser element and the lens system.

FIG. 1 is a diagram showing the configuration of a conventional light source device, in which 11 is a semiconductor laser element, 12 is a collimator lens system, and 13 is a lens holder. In this configuration, for example, if the numerical aperture of the collimator lens system 12 is 0.5 and the wavelength of the output light from the semiconductor laser element 11 is 830 μm, about 3 μm in the optical axis direction,
Positioning with an accuracy of approximately 20 to 30 μm is required in a plane perpendicular to the optical axis; if this range is exceeded, the collimation accuracy of the output light from the lens system 12 deteriorates, and the objective lens system aligns the output light onto the disk surface. When the light is narrowed down to form a light spot, deformation occurs due to spherical aberration and comatic aberration, resulting in the problem that a predetermined spot cannot be obtained.

On the other hand, regarding the semiconductor laser element 11,
Because there are variations in the precision with which the semiconductor pellet that serves as the light emitting point is attached to the substrate (stem) component, the position of the light emitting point and the direction of light irradiation differ slightly from element to element. Therefore, in order to align the semiconductor laser device 11 and the lens system 12, in addition to the three-dimensional alignment described above, the direction of the optical axis of the output light of the semiconductor laser device 11 and the optical axis of the lens system 12 is aligned. Adjustments will also be required to make this happen.

The above-mentioned complicated alignment work between the semiconductor laser element and the lens system can be performed using, for example, a laser power change measuring device that focuses on the self-coupling effect of the semiconductor laser,
This can be done using an auxiliary device such as a fine movement device that allows for dimensional movement and swing of the laser element, but in the conventional configuration shown in FIG. This is done by utilizing the space 14 between the lens holder 13 and the lens holder 13, and when the alignment is completed, the space 14 is filled with an adhesive 15 to fix the relative positional relationship between the two parts.

Therefore, the conventional light source device has a drawback in that instability due to changes in the adhesive 15 over time directly affects relative positional fluctuations between the laser section and the lens section. In addition, according to the conventional structure described above, the heat dissipation effect of the heat generated in the semiconductor laser element 11 is not sufficient, so in order to maintain stable laser operation, a heat dissipation fin is installed in the stem portion of the semiconductor laser element 11 as shown in FIG. 16
required installation. In this case, the overall size of the light source device increases, and at the same time, the heat dissipation fin 16
Since the adhesive-filled portion is easily deformed and damaged by external force applied to the light source device, there is a problem in that the light source device must be transported and handled with great care.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned conventional problems and provide a light source device that is small and has excellent mechanical strength.

Another object of the present invention is to provide a light source device having a structure that allows easy alignment of a semiconductor laser element section and a lens section.

[Summary of the invention]

In order to achieve the above object, the light source device of the present invention includes an element holder that holds a semiconductor laser element in close contact with its outer periphery, a lens holder that inserts and holds a lens system, and a cylinder that is interposed between the two holders. one end of the coupling member has a surface perpendicular to the central axis of the inner hole, the other end has a concave or convex spherical surface, and the front end of the element holder and the rear end of the lens holder are characterized in that each has a surface shaped to match the end of the coupling member.

[Embodiments of the invention]

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

FIG. 3 is a final assembly diagram of the light source device according to the present invention, in which 11 shows a semiconductor laser element and 12 shows a lens barrel of a collimator lens system. Semiconductor laser element 11
is inserted and held in the element holder 20 whose tip outer surface is formed into a spherical surface 20A, while the collimator lens system 12 is inserted and held in the circular hole of the lens holder 31 while being loaded into the rear part of the auxiliary cylinder 32. The rear end portion 31A of the lens holder 31 is formed in a plane perpendicular to the central axis of the circular hole, that is, the optical axis of the lens system 12. 30 is an element holder 20 and a lens holder 31
The front end surface 30A of the joining ring 30 is formed perpendicular to the central axis, and the rear end inner surface 30B is a curved surface that conforms to the spherical surface 20A at the front end of the element holder. There is. The coupling ring 30 and the element holder 20 are coupled by a screw 40, and in this case, by providing a through hole 33 larger than the outer diameter of the screw on the coupling ring side,
The mounting angle of the element holder 20 is adjustable. Similarly, the coupling ring 30 and the lens holder 3
1 are also screwed together so that the position can be adjusted.

According to the above configuration, by adjusting the attachment angle of the element holder 20 with respect to the coupling ring 30, the optical axis of the laser beam can be made parallel to the central axis of the coupling ring 30, while the coupling ring 30 and the lens holder By changing the abutting position with 31, the optical axis of the lens system can be moved parallel to the central axis of the coupling ring, so that the optical axes of the laser beam and the lens system can finally be made to coincide. Further, by moving the auxiliary cylinder 32 in the optical axis direction, the laser emission point can be made to coincide with the focal point of the lens system 12.

Next, the assembly procedure of the light source device will be described.

First, as shown in FIG.
1 is inserted from the rear of the element holder 20 and integrated using a thermally conductive adhesive such as "Lambdite", a trade name of Denki Kagaku Kogyo. On the other hand, as shown in FIG. 5, the lens barrel 12 of the collimator lens system is inserted into the rear part of the auxiliary cylinder 32, and after being integrated with epoxy adhesive, the auxiliary cylinder 32 is inserted into the lens holder 31, and the screw 42 Temporarily secure it.

Next, the element holder 20 and the coupling ring 30 are butted against each other, and the angle of the butt is adjusted while the element holder 20 and the coupling ring 30 are lightly fastened with the screw 40, so that the optical axis of the semiconductor laser and the central axis of the coupling ring 30 are aligned. This work is carried out using the element holder positioning device and, for example, arrow 5 in FIG.
This can be performed using an auxiliary laser beam (He--Ne laser) indicated by 0, a reflected light observation plate 51, and a plane mirror 52. That is, the element holder 11 is held by a positioning device and the semiconductor laser element 11 is opposed to the He-Ne laser at a predetermined distance, and the laser beam 50 is first directed to the light emitting chip located inside the output window 11a of the semiconductor laser element. When the surface is irradiated, the reflected and diffracted light from the light emitting chip surface is projected onto the observation plate 51. In this state, adjust the direction of the element holder 11 so that the zero-order light of the reflected diffracted light coincides with the light emission point of the He-Ne laser, that is, the center hole 50' of the observation plate 51, and fix the positioning device in this position. , the optical axis of the semiconductor laser beam is
This means that it coincides with the optical axis of the He--Ne laser beam 50. Next, the plane mirror 52 is attached to the coupling ring 30.
The He-Ne laser beam is placed in close contact with the end face 30A of the
While irradiating the beam, adjust the direction of the coupling ring 30 so that the reflected spot from the mirror matches the center hole 50' of the observation plate 51, and tighten the screw 40, so that the central axis of the coupling ring 30 aligns with the optical axis of the semiconductor laser. This means that it is aligned parallel to .

The thus obtained laser-side block is brought into contact with the lens-side block shown in FIG. 5 at surfaces 30A and 31A, and the contact position is adjusted so that the optical axes of both sides coincide. This positioning can be easily achieved by lightly coupling the coupling ring 30 and lens holder 31 with screws 41 and using the He--Ne laser used in FIG. 6, as described below.

First, with the lens block side held at a predetermined distance from the observation plate 51 and held by a positioning device, the He-
When the Ne laser beam 50 is irradiated, concentric reflected interference light from the lens surface is projected onto the observation plate 51. Therefore, the position of the lens block is adjusted so that the center of the interference light coincides with the light emitting point 50' of the He--Ne laser, and the position is fixed. When the semiconductor laser element 11 is caused to emit light in this state, a laser spot is formed at a position offset from the center point 50' on the observation plate 51 if the optical axis of the laser side does not coincide with the optical axis of the lens system. Therefore, by slightly loosening the screw 41, adjusting the position of the laser side block so that the laser spot coincides with the center point 50', and tightening the screw 41 at the aligned position, the optical axes of the laser side and the lens side are aligned. can be achieved. If the wavelength of the semiconductor laser element is near-infrared light (wavelength of about 830 nm), an infrared photosensitive material (for example, IR-PHOSPHOR, a product of Eastman Kodak, USA) may be used as the observation plate 50.

The final step of the assembly work is to align the light emitting point of the semiconductor laser element 11 and the focal point of the collimator lens system 12. For example, this alignment focuses on the self-coupling (resonance) phenomenon that occurs when the output light from the semiconductor laser element 11 is reflected by a conical prism placed in front of the lens system and returned to the light emitting point. The screw 42 that temporarily fixes the auxiliary cylinder 30 may be loosened, the auxiliary cylinder may be slightly adjusted back and forth, and the screw 42 may be fixed at a position where the laser beam intensity is maximum.

In the embodiment described above, the tip of the lens holder 20 is made into a spherical shape, and the coupling ring 3 in contact with the tip is made into a spherical shape.
The rear end of 0 was made into a curved surface that conforms to the above spherical surface,
As shown in FIG. 7, the coupling ring 30' may be formed with a spherical surface, and the lens holder 20' may be formed with a curved surface that matches the spherical surface. Although not shown in the drawings, the joint surface between the lens holder and the coupling ring may be a surface perpendicular to the optical axis, and the joint surface between the coupling ring and the lens holder may be a combination of a swingable spherical surface and a curved surface.

According to the present invention, by using an element holder and a lens holder and integrating them with a coupling ring interposed, the relative positional relationship between the laser emission point and the lens system can be set precisely and firmly. There is. In addition, since the semiconductor laser element is inserted into an element holder, and this element holder is connected to a lens holder via a coupling ring, each member is made of a material with good thermal conductivity, making it possible to Heat generated in the semiconductor laser element can be efficiently dissipated to the outside of the light source device without using special heat dissipation fins. In addition, even when the element holder is shaped with heat dissipation fins on the outer periphery to further enhance the heat dissipation effect, it is mechanically strong, and the outer shape of the coupling ring and lens holder can be adjusted to any shape suitable for mounting in an optical disk device. Since it can be designed in the shape of , it is extremely advantageous for handling as a light source device.

[Brief explanation of the drawing]

1 and 2 are diagrams showing the configuration of a conventional light source device, FIG. 3 is a sectional view showing an embodiment of the light source device according to the present invention, and FIGS. 4 to 6 are diagrams showing the configuration of a conventional light source device.
FIG. 7 is a diagram for explaining the assembly process of the device, and FIG. 7 is a diagram showing another embodiment of the light source device according to the present invention. [Explanation of symbols], 11... semiconductor laser element,
12... Lens system, 20... Element holder, 30...
...Coupling ring, 31...Lens holder, 32...
Auxiliary cylinder.

Claims (1)

[Scope of Claims] 1. A semiconductor laser element, an element holder that holds the semiconductor laser element in close contact with its outer periphery, a lens system for focusing laser light emitted from the semiconductor laser element, and the lens system. consisting of a lens holder for inserting and holding the element holder, and a cylindrical coupling member interposed between the element holder and the lens holder,
One end of the coupling member has a surface perpendicular to the central axis of the inner hole, the other end has a concave or convex spherical surface, and the front end of the element holder and the rear end of the lens holder are respectively connected to the coupling member. The lens holder has a surface shaped to match the end portion, and the lens holder includes an auxiliary cylindrical member for loading the lens system, and a cylindrical holding member that holds the auxiliary cylindrical member slidably in the axial direction, A light source device characterized in that the cylindrical holding member has an end surface that is compatible with the coupling member. 2. The light source device according to item 1, wherein the element holder and the coupling member, and the coupling member and the lens holder are engaged with each other so that their relative positional relationships can be adjusted at their respective end faces.