JPH07281062A - Semiconductor laser module - Google Patents

Abstract

PURPOSE:To restrain the beam size within a standard range to different plural emitting distances regardless of dispersion of an emitting light characteristic of a semiconductor laser by actively controlling the emitting beam size, remove aberration outside of a lens, eliminate an increase in the number of part items, dispense with screw work, and improve reliability. CONSTITUTION:A semiconductor laser module is composed of a semiconductor laser 20, a lens 24 to condense the emitting light and a holder having their holding part and a through hole 25 to pass a light beam. Preferably, the holder is divided into a laser holder 22 to hold the semiconductor laser and a lens holder 26 to hole the lens and is formed as a mutually fitting structure. In the holder holding the lens, a slit 28 to restrict the beam size is arranged on the emitting side end surface. Respective parts are mutually integrally fixed together by a technique such as laser welding, adhesion, soldering or the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser module capable of collecting light emitted from a semiconductor laser with a lens and obtaining a beam of a desired size at a position separated by a desired distance. . This semiconductor laser module is mainly useful as a light source for a hand-held bar code reader or the like.

[0002]

2. Description of the Related Art A semiconductor laser module used as a light source such as a bar code reader or a laser pointer is a semiconductor laser that emits visible light (for example, a wavelength of 0.6).
The emitted light of 7 μm) is condensed using a lens, and a beam of a desired size (beam size is equal to or less than a specified value) is designed to be obtained at a position separated by a desired distance.

Conventionally, a semiconductor laser module for such an application has a structure as shown in FIG. 5, for example. A semiconductor laser 10 is mounted on a cylindrical laser holder 12 and a lens 1
4 are fixed to the lens holder 16 using an adhesive or the like. Inner peripheral surface of laser holder 12 and lens holder 1
Female threads and male threads are provided on the outer peripheral surface of 6, respectively, and they are screwed together. The emitted light of the semiconductor laser 10 is collected by the lens 14, and the desired laser beam is obtained by adjusting the distance between the semiconductor laser 10 and the lens 14 by rotating the screw.

[0004]

In this conventional structure, it is necessary to form a male screw and a female screw on the laser holder and the lens holder, respectively. In addition, in order to improve the accuracy of adjustment, it is necessary to use a very precise screw. is necessary. Therefore, the cost of parts increases. In addition, since the distance between the semiconductor laser and the lens is adjusted by screwing the screw, the amount of backlash of the screw is inevitably adjusted and the adjustment accuracy is low. Further, since the emitted light of the semiconductor laser is only condensed by the lens, the beam size (shape) depends on the emitted light characteristics of the semiconductor laser, and the variation is large.

Particularly when applied to a hand-held type bar code reader, the standard value (allowable range) of the beam size at a plurality of different emission distances is not the beam size at a point a certain distance away from the semiconductor laser module. Since it is determined by the specifications, it is often difficult to satisfy the specifications. This is shown in FIG. For example, the beam size standard is the distance d ₁
Is S ₁ , the distance d ₂ is S ₂ , and the distance d ₃ is S ₃ . The optical system is designed by adjusting the distance X ₀ from the semiconductor laser to the lens and selecting the focal length f of the lens to be used. The beam size change when X ₀ and f are changed using the same semiconductor laser and lens is as shown in FIG. Therefore, X ₀ and f are determined so as to meet the beam size specification from such characteristic curves, that is, to obtain the characteristic curve as shown in FIG. However, in reality, variations in characteristics such as the emission angle and spot size of the semiconductor laser, variations in characteristics of the lens used (for example, when using a relatively inexpensive gradient index rod lens, the refractive index distribution constant and (Variation in lens length), and further due to adjustment errors in assembly adjustment,
Even if X ₀ and f are constant, there may be a defective product that does not satisfy the specifications as shown by the characteristic curve in FIG.

As a solution to this problem, it is possible to select the semiconductor laser to be used according to the emission light characteristics. However, semiconductor lasers have large variations even among the same manufacturing lots, and therefore not only the sorting work is complicated, but also the semiconductor lasers are expensive and therefore costly, and such a method cannot be adopted at all. Therefore, there has been a demand for new measures that can positively and inexpensively control the beam size emitted from the semiconductor laser module. Furthermore, when a gradient index rod lens that is relatively inexpensive and easy to incorporate is used, the aberration becomes larger toward the outside of the lens because the numerical aperture (NA) is lower and the effective diameter is smaller than that of a high performance aspherical lens. As a result, the output beam size is disturbed. It is necessary to take measures to solve such problems at the same time.

The object of the present invention is to obtain a stable beam with a constant size and to obtain a stable beam even if the same semiconductor laser and lens as the conventional one are used, irrespective of variations in the emitted light characteristics of the semiconductor laser. An object of the present invention is to provide a highly reliable semiconductor laser module that does not increase in number and does not require screw processing.

[0008]

A semiconductor laser module according to the present invention comprises a semiconductor laser, a lens for converging its emitted light, a holder for these, and a holder having a through hole through which a light beam passes. ing. The holder holding the lens has a slit for limiting the beam size on the end face on the exit side. Then, the respective components are fixed to each other by a method such as laser welding, adhesion, soldering, or the like to be integrated.

Here, the holder may be an integrally molded product that simultaneously holds the semiconductor laser and the lens, or may have a structure in which a laser holder that holds the semiconductor laser and a lens holder that holds the lens are separately assembled. In the latter case, the laser holder and the lens holder are fitted to each other so that they can be coaxially slid with each other. It is preferable that the semiconductor laser and the holder are laser-welded, and the lens and the holder are bonded or soldered.

Particularly, the laser holder has a cylindrical structure having an annular step portion having a thin outer circumference as a holding portion for the semiconductor laser, and the lens holder has a structure having a circular fitting portion having a thin outer circumference as a holding portion for the laser holder. , Between the laser holder and the semiconductor laser, using their thin-walled part,
It is best to perform YAG laser welding in a superposition method between the lens holder and the laser holder.

[0011]

The light emitted from the semiconductor laser is condensed by the lens and emitted through the through hole. At that time, the slit formed on the emitting end face of the holder positively controls the beam size and does not depend on the emitting light characteristics of the semiconductor laser used,
It fulfills the function of keeping the beam sizes at a plurality of different emission distances within the standard values. Further, when an inexpensive gradient index rod lens is used, it functions to cut off the light passing through the outside of the lens and remove the influence of aberration and the like. Adjusting the distance between the laser diode and lens uses slide fitting instead of screws, and is integrated by being fixed by laser welding, bonding, soldering, etc. to improve adjustment accuracy and reliability of connection. In addition, the number of parts and the cost are reduced by forming the slit in the holder itself.

[0012]

1 is an explanatory view showing an embodiment of a semiconductor laser module according to the present invention, in which A is a sectional view and B is a side view on an emitting side. FIG. 2 is a partially cutaway perspective view thereof.
This semiconductor laser module includes a semiconductor laser 20 and
Laser holder 22 for holding it and semiconductor laser 20
Distribution type rod lens 2 that collects light emitted from
4 and a lens holder 26 for holding the rod lens 24
Consists of.

The laser holder 22 has a cylindrical shape as a whole and has an annular step portion 22a at one end as a holding portion for the semiconductor laser 20, and the outer peripheral wall thereof has a thin structure. The annular step portion 22a is
The semiconductor laser 20 is designed in such a size that the disc-shaped base portion of the semiconductor laser 20 just fits. The lens holder 26 has a circular fitting portion 26a that serves as a holding portion for the laser holder 22, and the outside thereof has a thin structure.
The laser holder 22 has a fitting structure that is coaxially slidable within a. Further, the lens holder 2
Reference numeral 6 denotes a circular through hole 2 having a circular concave portion 26b for holding the rod lens 24 and through which the light beam passes along the central axis.
5 and a slit 28 for limiting the beam size is provided on the end face on the exit side. This slit 28
Has a width t (smaller than the diameter of the through hole 25) set in advance so that the focused laser beam has a desired size at a desired distance, and is formed in the diameter direction on the front end face of the lens holder 26. Has been done. The direction of forming the slit 28 is such that the width direction thereof coincides with the direction in which the beam size needs to be limited.

The semiconductor laser 20 has a base portion fitted into an annular step portion 22a of a cylindrical laser holder 22 and is superposed through a thin outer peripheral wall thereof to form a YAG.
Laser welded. The circumferential welding mark is indicated by reference sign W ₁ . On the other hand, the rod lens 24 is fitted into the circular recess 26b of the lens holder 26 and is bonded or soldered. In the case of soldering, gold plating or the like is applied in advance to at least the place where soldering is required. The laser holder 22 to which the semiconductor laser 20 is fixed and the lens holder 26 to which the rod lens 24 is fixed are set on their respective holding jigs, and then the laser holder 22 is finely moved in the optical axis direction. The beam size is adjusted so that the desired beam size is obtained at a position separated from the front end surface of the laser module by a desired distance. And the lens holder 26 which was piled up
YAG laser welding is performed from the outside of the to the laser holder 22 using the thin outer peripheral wall. The welding mark at this time is shown by a symbol W ₂ . In this way, the respective components are fixed to each other, and the entire structure becomes an integral structure.

In this semiconductor laser module, the light emitted from the semiconductor laser 20 is condensed by the rod lens 24, passes through the central through hole 25, and is emitted from the slit 28. At this time, the peripheral portion of the laser beam that is wider than the slit 28 is shielded, and the beam size emitted from the slit 28 is regulated. Thereby, the outgoing beam size can be positively controlled, and the beam sizes at a plurality of preset outgoing distances can be kept within the specified ranges.

FIG. 3 shows another embodiment of the present invention.
This is an example in which the laser holder and the lens holder in the above embodiment are integrally formed. The rod lens 34 is fitted in the holder 36 and bonded or soldered. Then, the semiconductor laser 30 is directly fitted to the holder 36 to adjust the position, and YAG laser welding is performed from the outer peripheral side. The weld mark is indicated by reference sign W ₃ . The emitted light of the semiconductor laser 30 is condensed by the rod lens 34, passes through the central through hole 35, and is emitted from the slit 38. This structure has the same function as that of the above-described embodiment, but when the semiconductor laser 30 is finely adjusted and then welded by the YAG laser, the semiconductor laser 30 is easily tilted in the holder 36, and therefore, the high accuracy is obtained. Assembly is troublesome.

FIG. 4 shows still another embodiment of the present invention. This is a structure in which the holder is divided into a laser holder and a lens holder, as in the first embodiment. The semiconductor laser 40 is YAG laser welded to the laser holder 42 (welding mark is indicated by reference sign W ₄ ), and the rod lens 44 is adhered or soldered to the lens holder 46. In this embodiment, the lens holder 46 is fitted into the laser holder 42, and the position is adjusted and fixed. Slit 4 that limits the beam size
8 is formed on the end face on the exit side of the lens holder 46. The emitted light of the semiconductor laser 40 is condensed by the rod lens 44,
The light passes through the central through hole 45 and exits from the slit 48. This structure has the same functions as those of the above-described embodiments. However, when finely adjusting the lens holder 46 holding the rod lens 44, it is necessary to push and pull with a jig or the like from the emitting side of the rod lens 44, which blocks the emitted light.
Therefore, it is not possible to assemble while monitoring the beam size, which is not suitable for continuous mass production. Further, it is difficult to form a thin portion on the holder for performing YAG laser welding, and it is difficult to perform YAG laser welding.

As described above, functionally, the above-mentioned respective embodiments are
Although it is almost the same, the configuration shown in FIGS. 1 and 2 is the best from the viewpoint of ease of manufacturing.

[0019]

As described above, according to the present invention, since the slit is provided on the exit side end surface of the holder, the exit beam size can be positively controlled. That is, a substantially constant beam size (within the specified range) can be obtained for a plurality of different emission distances, regardless of the emission light characteristics of the semiconductor laser used (especially without selecting those having uniform characteristics). Therefore, particularly when applied to a light source such as a hand-held bar code reader, it becomes possible to accurately read bar codes of articles located at various distances such as in a warehouse. Further, since the slit cuts the light beam passing through the outside of the lens to remove the influence of aberration and the like, the dependence of the beam size on the variation of the lens characteristics can be suppressed. Therefore, instead of a high-performance aspherical lens, a gradient index rod lens or the like can be used, which is easy to assemble and inexpensive. Further, in the present invention, since the slit is formed directly on the holder, the number of parts does not increase. Also, since each part is joined by welding, adhesion, soldering, etc.,
It is a highly reliable module without the need to form screws or the like.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a semiconductor laser module according to the present invention.

FIG. 2 is a partially cutaway perspective view thereof.

FIG. 3 is an explanatory view showing another embodiment of the semiconductor laser module according to the present invention.

FIG. 4 is an explanatory view showing still another embodiment of the semiconductor laser module according to the present invention.

FIG. 5 is an explanatory diagram showing an example of a conventional technique.

FIG. 6 is a conceptual diagram showing the relationship between beam size and distance.

[Explanation of symbols]

 20, 30, 40 Semiconductor laser 22, 42 Laser holder 24, 34, 44 Rod lens 25, 35, 45 Through hole 26, 46 Lens holder 28, 38, 48 Slit

Claims (3)

[Claims] 1. A semiconductor laser, a lens for condensing emitted light from the semiconductor laser, a holder for holding the semiconductor laser, and a holder having a through hole through which a light beam passes, the end surface on the emitting side of the holder holding the lens. A semiconductor laser module in which a slit that limits the beam size is formed and each component is fixed and integrated together. 2. The holder comprises a combination of a laser holder for holding a semiconductor laser and a lens holder for holding a lens. The laser holder and the lens holder have a fitting structure, and the semiconductor laser and the laser holder are a laser. The semiconductor laser module according to claim 1, wherein the lens and the lens holder are bonded or soldered by welding. 3. A laser holder has a cylindrical outer peripheral thin-walled annular step portion as a holding portion for a semiconductor laser, and a lens holder has a thin outer peripheral circular fitting portion as a holding portion for the laser holder, 3. The semiconductor laser module according to claim 2, wherein the thin-walled portions are used to perform laser welding between the laser holder and the semiconductor laser and between the lens holder and the laser holder in an overlapping manner.