JP3181381B2 - Semiconductor laser module - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention is used in the laser beam scanning device for scanning by emitting a laser beam
The present invention relates to a semiconductor laser module .

[0002] Laser beam scanning devices are widely used in bar code readers, laser printers, and the like. To secure the depth of focus of a laser beam, a beam waist in a vertical vibration direction and a beam waist in a horizontal vibration direction are used. Must be set independently and freely.

[0003]

2. Description of the Related Art In recent years, a laser light source used in a laser beam scanning device has been replaced with a semiconductor laser from a He-Ne laser device, and has been reduced in size and cost. However, it is more difficult to shape an emission beam with a semiconductor laser. It is.

Conventionally, in shaping a laser beam emitted from a semiconductor laser, a maximum diameter is regulated by using a pinhole aperture, and a beam emitted from the semiconductor laser is received by a collimator lens, and a vertical vibration direction and a horizontal vibration direction are controlled. A plurality of cylindrical lenses or prisms are arranged to make each beam waist position of a desired position.

[0005]

However, if a plurality of cylindrical lenses and prisms are provided at the emitting end of the semiconductor laser in addition to the collimator lens, the number of components is large and the apparatus becomes complicated, and the adjustment work of the beam waist is also required. The disadvantage is that it is not easy, so that the parts and assembly adjustments are very costly.

Accordingly, the present invention provides a semiconductor device used in a laser beam scanning device capable of easily adjusting a beam waist in a vertical vibration direction and a horizontal vibration direction with a simple configuration.
An object is to provide a laser module .

[0007]

In order to achieve the above object, a semiconductor used in a laser beam scanning device according to the present invention is provided.
A laser module includes a semiconductor laser 1 for emitting a laser beam as shown in FIG.
The semiconductor laser tilted with respect to the optical axis of the laser beam to converge the laser beam and independently control the beam waist position in the vertical vibration direction and the beam waist position in the horizontal vibration direction A converging lens 12 disposed near a laser beam emitting end of the laser 11; and a beam scanning unit 20 for continuously and regularly changing the traveling direction of the laser beam passing through the converging lens 12. It is characterized by.

The converging lens 12 may be arranged so as to be inclined in the vertical oscillation direction of the laser beam, and may be provided with an inclination angle control means 18 for changing the inclination angle of the converging lens 12.

The converging lens 12 is formed by a spherical or aspherical lens, and the converging lens 1 is
2 is provided with a pinhole aperture 13 for regulating the outer diameter of the laser beam passing through the converging lens 12.
The beam shaping of the laser beam may be performed by the pinhole aperture 13 and the pinhole aperture 13.

[0010]

As shown in FIG. 5, in the semiconductor laser 91, the light emitting point differs between the light wave in the vertical vibration direction and the light wave in the horizontal vibration direction. 5 μm to several tens μm from the emission point 93 of
There is an astigmatic difference located only outside.

Therefore, as shown in FIG. 6, when the laser beam emitted from the semiconductor laser 91 is converged by one convex lens 94, the beam waist 95 in the vertical vibration direction becomes the beam waist in the horizontal vibration direction. It is formed farther than 96.

However, depending on the purpose of use, the position of the beam waist 95 in the vertical vibration direction may be closer to the position of the beam waist 96 in the horizontal vibration direction, or both beam waists 95 and 96 may have to be at the same position. .

Therefore, as shown in FIG.
When 4 is tilted with respect to the optical axis in the plane in the vertical vibration direction, only the position of the beam waist 95 in the vertical vibration direction approaches the convex lens 94 side.

This phenomenon is caused by coma aberration generated when the convex lens 94 has an angle with respect to the optical axis. As the convex lens 94 is more greatly inclined, the beam waist position in the inclined direction becomes closer to the convex lens 94 side. .

The present invention utilizes this development.
By arranging the converging lens 12 at an angle with respect to the optical axis of the laser beam, the beam waist in the tilted direction approaches the converging lens 12 side. By changing the inclination direction and the inclination angle of the converging lens 12, The beam waist in any direction can be set at any position.

As a result, the laser beam whose traveling direction is continuously and regularly changed by the beam scanning means 20 can obtain the most desirable depth of focus for the object to be scanned. If the inclination angle control means 18 is provided, the inclination angle of the converging lens 12 can be freely changed.

Further, by providing a pinhole aperture 13 for regulating the outer diameter of the laser beam passing through the converging lens 12, the beam shaping of the laser beam can be performed only by the converging lens 12 and the pinhole aperture 13.

[0018]

An embodiment will be described with reference to the drawings. FIG. 2 shows an embodiment in which the present invention is applied to a barcode scanner.

In FIG. 1, reference numeral 10 denotes a semiconductor laser module containing a semiconductor laser 11 for emitting a laser beam and a converging lens 12 for converging the laser beam emitted from the semiconductor laser 11.

As the converging lens 12, a spherical or aspherical convex lens is used, which is disposed so as to face the laser beam emitting end of the semiconductor laser 11 and in the vicinity thereof.
The laser beam emitting portion of the semiconductor laser module 10 has a pinhole aperture 13 formed therein, and the outer diameter of the laser beam is regulated here.

The laser beam emitted from the semiconductor laser module 10 is reflected by the plane mirror 19 and enters the scanning optical system 20. Then, the light is reflected by the small flat mirror portion 22 formed at the center of the concave mirror 21 and travels toward the reflection surface of the polygon mirror 23.

The polygon mirror 23 is driven to rotate at a constant speed. Therefore, the laser beam is reflected while continuously changing its direction on the reflecting surface of the polygon mirror 23. Then, the light is reflected toward the bottom mirror 25 by one of the three plane mirrors constituting the three-plane mirror 24.

On the surface of the scanning optical system 20, a refractive index distribution type hologram window 26 in which a hologram material having a different refractive index is formed on a transparent plate, or a relief type hologram window in which a diffraction grating formed by irregularities is formed on a transparent plate. A hologram window is provided, and the laser beam reflected by the bottom mirror 25 is refracted and converged by passing through the hologram window 26.

The rotation of the polygon mirror 23 causes the laser beam to scan in one direction at a high speed with the vertical oscillation direction of the light wave as the scanning direction.
It is reflected at 00.

FIG. 3 is a side view of the scanning optical system 20.
The laser beam reflected on the bar code 100 outside the hologram window 26 passes through the hologram window 26, is reflected by the bottom mirror 25, the three-sided mirror 24, and the polygon mirror 23 in this order, and then continues to the concave mirror 2
After being reflected and converged by 1 and reflected by a small plane mirror 27, it is incident on a photodetector 28 disposed at the converging point of the laser beam by the concave mirror 21 and is converted into an electric signal.

As described above, in the scanning optical system 20, the laser beam is scanned by the rotation of the polygon mirror 23, and the bar code 100 can be read by the output signal from the photodetector 28.

FIG. 1 shows a configuration inside the semiconductor module 10, wherein the converging lens 12 is fixed to a lens holder 14. The lens holder 14 can be freely tilted in the vertical oscillation direction of the laser beam around the axis 15 arranged in the horizontal oscillation direction of the laser beam emitted from the semiconductor laser 11.

The gear 16 fixed to the shaft 15 is driven by a motor 18 via a reduction gear 17. 18a is a motor driver circuit, and 11a is a semiconductor laser driver circuit.

With such a configuration, the converging lens 12 is disposed so as to be inclined in the vertical oscillation direction of the laser beam.
As shown in FIG. 7, the beam waist in the vertical vibration direction has moved closer to the converging lens 12 than the beam waist in the horizontal vibration direction.

Then, at the time of assembling or as necessary, the tilt angle of the converging lens 12 is changed by driving the motor 18 so that the beam waist position in the vertical vibration direction can be adjusted independently of the beam waist in the horizontal vibration direction. it can.

As a result, it is possible to adjust the beam shape of the scanning beam to a circular beam or an elliptical beam at an arbitrary position having a spatial spread to obtain the most desirable depth of focus for the bar code 100 to be read. it can.

FIG. 4 shows a second embodiment of the present invention, in which the present invention is applied to a scanning device of a laser printer in which a hologram disk 31 is rotated to scan a laser beam. , 32 are photosensitive drums.

In this case, the beam waists in the vertical and horizontal vibration directions are at the same position, and the photosensitive drum 3
The angle of the converging lens 12 is fixed so that a circular beam is irradiated on the two surfaces.

The present invention is not limited to the above embodiment. For example, the angle of the converging lens 12 can be changed not only in the vertical oscillation direction of the laser beam but also in the horizontal oscillation direction. It may be.

[0035]

According to the onset light according to the present invention, optionally convergent lens laser beam simply arranged to be inclined with respect to the optical axis independently of each other the beam waist position and beam waist position in the horizontal direction of vibration of the vertical vibration direction , And as a result, the most desirable depth of focus and beam shape can be easily obtained.

Since the laser beam can be shaped only by the converging lens and the pinhole aperture,
The configuration of the device can be made very simple, and the cost of parts and the cost of assembly and adjustment can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a semiconductor laser module according to a first embodiment.

FIG. 2 is a perspective view of the laser beam scanning device according to the first embodiment.

FIG. 3 is a side view of the scanning optical system according to the first embodiment.

FIG. 4 is a perspective view of a laser beam scanning device according to a second embodiment.

FIG. 5 is a diagram illustrating characteristics of a semiconductor laser.

FIG. 6 is an explanatory diagram of characteristics of a semiconductor laser.

FIG. 7 is an explanatory diagram of characteristics of a semiconductor laser.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Semiconductor laser 12 Convergent lens 13 Pinhole aperture 20 Scanning optical system (beam scanning means)

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanori Okawa 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Yuichiro Takashima 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited ( 56) References JP-A-63-316819 (JP, A) JP-A-61-175617 (JP, A) JP-A-3-15808 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , (DB name) G02B 26/10

Claims (1)

(57) [Claims] A semiconductor laser for emitting a laser beam; and a laser beam for converging the laser beam and independently controlling a beam waist position in a vertical vibration direction and a beam waist position in a horizontal vibration direction. Driving the converging lens disposed near the laser beam emitting end of the semiconductor laser so as to be tiltable in the vertical vibration direction of the laser beam about an axis disposed toward the horizontal vibration direction of the laser beam; A drive source for adjusting the inclination angle of the convergent lens, and regulating the outer diameter of the laser beam passing through the convergent lens.
Semiconductors, characterized in that it comprises an aperture for shaping Te
Body laser module .