JPH03208386A - Laser system - Google Patents

Abstract

PURPOSE:To make it possible to obtain parallel rays, whose intensity can be modulated and have an even intensity distribution, by a method wherein the intensity of a laser beam from a laser is varied and intensity modulated light is spatially converted into the parallel rays. CONSTITUTION:A beam emitted from a laser module 11 capable of leading out a laser beam via an optical fiber 14 is linked to an acoustooptic modulator 12. An optical system for leading out the laser beam through the fiber 14 is mounted integrally on a laser along with the fiber 14. An optical fiber input/ output type is used as the modulator 12, the primary diffracted output of the modulator 12 is incided on a collimator lens 13 through an optical fiber 15 and converted into parallel rays 17 of an arbitrary intensity by the lens 3 constituted by combining two sheets or more of lenses with each other. Thereby, large-aperture parallel laser rays having a high spatial evenness can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a laser device used as an irradiation light source in optical parallel information processing, optical image processing, and optical measurement.

[Conventional technology] FIG. 4 is an explanatory diagram of a conventional laser device.

The light 2 emitted from one end face of the laser 1 enters an acousto-optic modulator 3 for intensity modulating. The first-order diffracted light from the acousto-optic modulator 3 is converted into parallel light 6 of an arbitrary diameter using two lenses 4 and 5. At this time, spatial noise such as the transverse mode of the laser beam is removed by the pinhole 7 between the lenses 4 and 5.

[Problem to be solved by the invention]

However, in the conventional laser device described above, the optical path is disturbed due to minute positional changes between the laser l and the acousto-optic modulator 3, the incident angle to the acousto-optic modulator changes, and the diffraction efficiency fluctuates, resulting in the intensity of the output light. or the angle of emission of the emitted light. In addition, due to its basic characteristics, the emitted light of an acousto-optic modulator is emitted with a certain diffraction angle, so its optical system cannot be constructed in a straight line.Also, because the angle is small, the optical path must be separated from the O-order diffracted light. It is necessary to have a long length, which makes the construction of the optical system extremely difficult and disadvantageous in that it is large. Furthermore, in order to improve the spatially non-uniform intensity distribution of the laser beam, the diameter of the pinhole 7 is made small. However, if the diameter of the pinhole 7 is increased in order to obtain sufficient light intensity, only parallel light with a non-uniform intensity distribution can be obtained.

The present invention has been made in view of the above circumstances, and its purpose is to provide a small laser device that has an excellent optical system stability, is capable of intensity modulation, and is capable of obtaining parallel light with a uniform intensity distribution. Our goal is to provide the following.

[Means for Solving the Problems] In order to solve the above problems, the present invention includes a laser, an intensity modulation means for varying the intensity of the laser light from the laser, and a spatially parallel light beam for the intensity modulated light. It is characterized by being equipped with an optical lens system that provides

[For production]

In the laser device of the present invention, a modulated laser is guided to an optical lens system via an optical fiber. As a result, a parallel laser beam with a uniform intensity distribution and a large diameter can be obtained.

[Example J Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a laser device of the present invention. As shown in FIG. 1, this embodiment includes a laser module 11 that can extract light through an optical fiber output;
It consists of an optical fiber input/output type acousto-optic modulator 12 and a fiber input type collimator lens 13.

Next, the operation of the laser device of this embodiment will be explained with reference to FIG. Output light emitted from a laser module 11 from which laser light can be extracted through an optical fiber 14 is connected to an acousto-optic modulator 12. An optical system for extracting laser light from the optical fiber 14 is integrally attached to the laser together with the optical fiber 14. Any lens can be used as long as it has a condensing function, such as a convex lens, a spherical lens, or a cylindrical lens. Acousto-optic modulator 1
2 uses an optical fiber input/output type. The first-order diffraction output of the acousto-optic modulator 12 is input to a collimator lens 13 via an optical fiber 15. The optical fiber 16 is a fiber for extracting zero-order light. A cross-sectional view of the collimator lens 13 is shown in FIG. A collimator lens is a combination of two or more lenses that converts the light into parallel light of any size. 31 is an input optical fiber, which corresponds to the optical fiber 15 in FIG.

32 and 33 are lenses with focal lengths f+ and fx, respectively. The lens 3 is configured such that the light emitted from the optical fiber 31 is focused by the lens 32 at the focal position of the lens 33.
By arranging 2 and 33, parallel light 34 is obtained. By selecting the aperture of the lens 33, the focal length f, and the arrangement of the optical system, parallel light 34 of any diameter can be obtained. Any lens can be used as the collimator lens 13 as long as it has a condensing function, such as a convex lens, a spherical lens, or a cylindrical lens. The collimator lens and optical fiber are fixed with adhesive and covered with a strong box. In addition, by using a single mode fiber of a certain length (usually 1 m or more), the optical fiber 14.15 acts as a spatial filter and can confine light up to the core diameter of the optical fiber, so it is not a pinhole. An ideal point light source can be obtained without loss of differential light intensity, and therefore parallel light with high spatial uniformity can be obtained. Furthermore, by using an optical fiber in the optical system, the optical axis can be changed freely, and laser light can be irradiated in any direction. It goes without saying that instead of the acousto-optic modulator, an electro-optic modulator or other modulator of other configuration can be used with an optical fiber input/output type.

For example, in the device configuration shown in FIG. 1, a He-Ne laser (light output 15 mW) that oscillates at a wavelength of 633 nm is used as the laser module 11, and
As Example 2, a laser device was constructed using an acousto-optic modulator with an ultrasonic frequency of 120 MHz and a switching rise time of 100 ns, and an optical fiber with a core diameter of 4 μm. In order to cancel the cladding mode of the laser beam in the optical fiber, a 20 m single mode optical fiber was used as the optical fiber 14. Additionally, the end face of the optical fiber was polished diagonally to prevent light from returning to the laser. The optical power at the output end of the optical fiber 14 was 5 mW, and the optical power of the output light 17 was 1 mW. Using this configuration, we were able to obtain parallel light with a maximum modulation frequency of 10 MHz, a diameter of 20 mm, and spatial non-uniformity of light intensity within 10%.

FIG. 3 shows an embodiment in which a semiconductor laser is used as the laser. This example consists of a semiconductor laser module 21 from which an optical output can be taken out from an optical fiber 22 and a collimator lens 23 similar to that shown in FIG. A semiconductor laser can easily intensity-modulate its optical output by modulating its injection current using a modulation circuit, for example.

For example, in the device configuration shown in FIG. 3, an InGaAIP semiconductor laser (optical output 5 mW) oscillating at a wavelength of 67 Qnm was used as the semiconductor laser, and an optical fiber with a core diameter of 4 μm was used to configure the laser device. Since the spatial coherence of semiconductor lasers is not as good as that of gas lasers,
Optical fibers with small core diameters are particularly effective as spatial filters. As output light 24, parallel light with an optical power of 1 mW and a diameter of 20+sm could be obtained. Further, the modulation frequency could be up to IGH2.

The present invention has been specifically explained above based on examples, but
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to obtain parallel laser light with extremely high spatial uniformity and a large diameter. Further, the laser device of the present invention has the advantage that it is small, has an excellent optical system stability, can emit output light in any direction, and can be transmitted over long distances using an optical fiber. Therefore, it has the advantage that it can be widely used as a light source in optical parallel information processing, optical image processing, and optical measurement.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the laser device of the present invention, FIG. 2 is a sectional view showing the configuration of a collimator lens, and FIG. 3 is a configuration of an embodiment using a semiconductor laser as the laser. FIG. 4 is a block diagram showing the configuration of a conventional laser device. 1... Laser, 3.12... Optical frequency modulator, 4, 5. 32. 33... Lens, 11... Laser modier, 13, 23... Collimator lens, 14, 15. 16.22.31...Optical fiber, 21
...Semiconductor laser module.

Claims (1)

[Claims] 1) A laser, an intensity modulation means for varying the intensity of the laser light from the laser, an optical fiber that transmits the intensity modulated light and serves as a point light source, and a spatially parallel light source for the light emitted from the optical fiber. What is claimed is: 1. A laser device characterized by comprising an optical lens system for