JPH0346614A - Ld light source device - Google Patents

Abstract

PURPOSE:To extract only collimated light by closing an opening part for projecting collimated luminous flux with cover glass and holding a semiconductor laser and a collimation optical system in the closed space by a holding member in specific position relation. CONSTITUTION:An outer package member 30 is in a box shape and has the opening part 30A, which is closed with the cover glass 40 to hold the inside of the outer package member 30 airtight. The semiconductor laser 1 and collimation optical system 2 are held by the holding member 50 and fixed at specific positions in the internal space of the outer package member 30. Light which is radiated by the semiconductor laser 1 and made incident on a micro-Fresnel lens is collimated. Then the size of the opening part 30A is so determined that only the light which is collimated by the collimation optical member 2 as to the light emitted by the semiconductor laser 1 is projected from the outer package member 30. Thus, only the collimated luminous flux of the luminous flux from the semiconductor laser can be extracted as effective luminous flux.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an LD light source device.

[Prior Art] LDs, that is, semiconductor lasers, have recently been used as light sources for various optical devices. As is well known, the luminous flux emitted from a semiconductor laser is divergent, and it is difficult to use it as it is, so in recent years, LD light sources have been developed that use a semiconductor laser as a light source and are unitized so that the luminous flux from this light source can be collimated and extracted. Devices have been proposed (for example, Japanese Patent Laid-Open Publication No. 63-314516).

FIG. 2 shows such an LD light source device in a simplified manner.

The semiconductor laser 1 and the collimating optical system 2 are housed in the exterior member 3 while maintaining a predetermined positional relationship. The exterior member 3 has an opening 3A, which is closed with a cover glass 4.

The collimating optical system 2 is a micro Fresnel lens,
The semiconductor laser 1 has a light emitting part that is connected to a collimating optical system 2.
It is placed near the object-side focal point of .

When the diverging light beam emitted from the semiconductor laser 1 enters the collimating optical system 2, it is converted into a parallel light beam, and is taken out through the cover glass 4 through the opening 3A.

[Problem to be solved by the invention] There are N and A that can be effectively used in a collimating optical system using a micro Fresnel lens.
The maximum value of A is about N, A = 0.5, and it is said that it is difficult to manufacture a collimating optical system with N and A larger than this.

When a collimating optical system with N and A of about 0.5 is used, among the diverging light flux from the semiconductor laser 1, in the direction corresponding to the maximum divergence angle, as shown in Fig. 2, rays A and B enters outside the area where the collimating optical system has a collimating action, and passes straight through the collimating optical system 2.

In FIG. 2, the light rays A and B are light rays that are not subjected to the collimating effect, as described above, and the light ray group C shows the light ray group that has been collimated by the collimating optical system 2.

When the light rays A and B are emitted outside the exterior member 3, they are not collimated, so if they enter the optical system 5 together with the collimated light ray group C, harmful components will affect the operation of the optical system 5. You will have to behave accordingly. Therefore, in order to prevent such harmful components from entering the optical system 5, it is necessary to block the uncollimated light beams through the aperture 6.

If the optical system 5 is placed sufficiently away from the aperture 3A, it is possible to prevent harmful components such as rays A and B from entering the optical system 5 without using an aperture. There is a problem that the distance from the LD light source device becomes large and the entire optical system becomes large.

The present invention was made in view of the above-mentioned circumstances, and
The purpose of this is to create a new L that can extract only collimated light from the semiconductor laser.
D. To provide a light source device.

1.Means to solve the problem] The present invention will be explained below.

The LD light source device of the present invention is a "light source device having a collimating function" and includes a semiconductor laser, a collimating optical system, and an exterior member.

A "semiconductor laser" emits a diverging laser beam.

The "collimating optical system" collimates a part of the diverging light flux from the semiconductor laser.

The "exterior member" has a light-shielding property and is formed with an opening for emitting the collimated light beam.

This opening is closed with a cover glass. In the interior space of the exterior member, a semiconductor laser and a collimating optical system are held in a predetermined positional relationship by a holding member.

The size of the "opening" is determined so that, of the light emitted from the semiconductor laser, only the light collimated by the collimating optical system is emitted to the outside of the exterior member.

[Function] As described above, in the LD light source device of the present invention, the opening of the exterior member is sized to block light that is not subjected to the collimating action of the collimating optical system from the outside. .

[Example] Hereinafter, description will be given based on specific examples.

In FIG. 1(I), numerals 1 and 2 indicate a semiconductor laser and a collimating optical system, as in FIG. 2. Further, reference numeral 30 indicates an exterior member, reference numeral 40 indicates a cover crow, and reference numeral 50 indicates a holding member.

The exterior member 30 is box-shaped and has an opening 30A,
This opening 30A is closed by a cover glass 40. The interior of the exterior member is thus airtight.

The semiconductor laser l and the collimating optical system 2 are held by a holding member 50 and fixed at a predetermined position in the internal space of the exterior member 30 by the holding member 50.

In this embodiment, the semiconductor laser 1 and the collimating optical system 2 are held by the same holding member 50, but the semiconductor laser 1 and the collimating optical system 2 are held by separate holding members. Also good.

The collimator I optical system is made up of a Fresnel lens formed as a microlens on a transparent plate-like material as a whole. The semiconductor laser 1 is arranged so that its light emitting part is located near the object-side focal point of the collimating optical system 2, and among the light emitted from the semiconductor laser 1, the light incident on the micro Fresnel lens 2 is collimated. It looks like this. In the collimating optical system 2, the micro Fresnel lens with a collimating function has N and A of approximately 0.5.
The angle at which the periphery of the micro Fresnel lens is viewed from the light emitting part of the semiconductor 1 noser 1 is about 53 degrees.

The luminous flux emitted from the semiconductor laser 1 is shown in Fig. 1 (II
), the beam is divergent, but the divergence angle of this beam is not uniform, and the cross-sectional shape of the divergent beam is elliptical. As shown in the figure, the maximum angle O among the divergence angles of the luminous flux
M is referred to as the maximum divergence angle, and the minimum angle ON is referred to as the minimum divergence angle.

In FIG. 1(I), the maximum divergence angle is in a plane parallel to the drawing, and the minimum divergence angle is in a plane perpendicular to the drawing. The maximum divergence angle is defined as e'-2 full angle and is approximately 66 degrees. Therefore, a part of the light beam from the semiconductor laser 1 protrudes from the micro Fresnel lens and is transmitted through the collimator I/optical system 2 without being collimated. Light rays that are not collimated in this way are designated by the symbols Al and Bl. The light ray B1 is a light ray that passes close to the periphery of the micro Fresnel lens. The distance between the positions where this light ray B1 enters the inner side surface (which is of course light-shielding) near the opening of the exterior member 30 is set as shown in the figure.
shall be.

Further, the symbol C indicates a luminous flux collimated by the collimating optical system 2 as in FIG. The diameter of this luminous flux (the diameter in the direction corresponding to the maximum divergence angle) is set to <CC as shown in the figure.

Note that the emitted light from the semiconductor laser 1 does not protrude from the micro Fresnel lens in the direction corresponding to the minimum divergence angle.

In FIG. 1(I), D indicates the diameter of the opening 30A provided in the exterior member 30. Of course, this diameter is the diameter in the direction corresponding to the maximum divergence angle of the emitted light beam of the semiconductor laser 1.

The feature of the present invention is that the magnitude relationship of the above BB, CC, and D is
It is at the point determined as B>D>CC. In this way, all the light beams C that have been collimated by the collimating optical system 2 are taken out through the opening 30A, but all the light beams that have not been collimated by the collimating optical system 2 are blocked by the exterior member and go outside the LD light source device. It won't leak.

The shape of the opening 30A may be a circular shape with a diameter.

Regarding the direction of the minimum divergence angle of the semiconductor laser]-, while maintaining the condition that the collimated light beam is not blocked,
The width of the opening 30A (width in the direction perpendicular to the drawing in FIG. 1(I)) can also be set smaller than the diameter of the micro Fresnel lens. Therefore, the shape of the opening 30A is
It can also be formed into an elliptical shape with its major axis extending in the vertical direction of FIG.

"Effects of the Invention" As described above, according to the present invention, a novel LD light source device can be provided. Since this device has the above-described configuration, only the collimated light beam out of the light beam from the semiconductor laser is used as an effective light beam. The leakage of harmful components that are not collimated can be prevented.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the present invention in detail, and FIG. 2 is a diagram for explaining the prior art and its problems. 116. Semiconductor laser, 200. collimating optics,
300

Claims (1)

[Claims] A light source device having a collimating function, comprising: a semiconductor laser; a collimating optical system that collimates a part of a diverging light beam from the semiconductor laser; and an opening for emitting the collimated light beam. the opening is closed with a cover glass, and has a light-shielding exterior member that holds the semiconductor laser and the collimating optical system in a predetermined positional relationship by a holding member in the inner space, The LD light source device is characterized in that the size of the opening is determined so that only the light collimated by the collimating optical system out of the emitted light is emitted to the outside of the exterior member.