JPS61212861A - Light source device - Google Patents

Abstract

PURPOSE:To prevent positions of a laser generator and an optical system from varying due to a change in temperature by aligning the central axes of a package incorporating a semiconductor laser element and of fitting parts of the 1st, 2nd and 3rd holding members made of specific material approximately on the same axis. CONSTITUTION:The package 12, being the armour of the laser element 10 is positioned in the staged opening of a plate 21 in its outer periphery and the shoulder part of its flange part, and attains the fit-out state. The bottom of the package is backed up by a plate 22 and positioned in the axial direction. These plates 21 and 22 are formed with the 1st holding member such as copper, which has an excellent thermal conductivity. Then the 1st holding members 21 and 22 are fitted in by the 2nd heat insulating holding member 26 made of polyacetal, etc., which is fitted and held by the 3rd holding member 27 made of 'Invar(R)' having a low thermal expansion so that each central axis can be equal. With this constitution the relative position fluctuation between the laser element 10 and the optical system caused by the change in temperature is reduced to obtain stably a desired beam flux, and the production, assembly and adjustment of each constituting holding member can be facilitated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a light source device for a laser recording device or a laser reading device having a semiconductor laser beam.

[Conventional technology]

A light beam generated by a laser generator such as a semiconductor laser device passes through an optical system such as a collimator lens, and then is scanned and irradiated onto a recording medium or a document surface.

Figure 6 shows an example of a conventional light source device published in Japanese Patent Application Laid-open No. 59-15.
There is one shown in Publication No. 206.

In the figure, a semiconductor laser package 1 housing a semiconductor laser element SL is fixed on a temperature control device 2, and this temperature control device 2 is fixed on a heat sink 3. It is fixed to the laser member 6 with a double nut or the like.

[Problem that the invention seeks to solve]

The light beam emitted by the semiconductor laser element SL is required to be a light beam with extremely stable optical characteristics such as a light beam diameter, a light beam wavefront, a light beam traveling direction, and a traveling position. Furthermore, these characteristics must maintain stable accuracy within the allowable range of use even if the operating environment temperature fluctuates significantly. That is, the positional spacing, optical axis, etc. between the semiconductor laser element SL and the optical system must be determined extremely accurately, and if the positional accuracy deviates due to the influence of heat, the optical system may not function as intended. There is a risk that you will not be able to fully demonstrate your abilities.

However, the temperature change in the environment in which such a laser light source device is installed ranges from about 00C to 45C, and the heat generation of the laser element SL also has an effect, causing a problem of positional shift due to temperature change.

However, in the light source device as shown in FIG.
The semiconductor laser element SL is fixed to a temperature control device w2, while the collimator lens 4, which is on the same optical axis as the laser element SL, is held by a support member 5.6 and is independently beat synchronized. It is fixed on 3. Therefore, it is very difficult to maintain the relative position between the laser element SL and the collimator lens 4 with high precision due to the above-mentioned temperature changes, external vibrations, shocks, and the like.

[Means for solving problems]

The present invention eliminates the above-mentioned problems, and provides a light source device in which the relative position of the laser generator and the optical system can maintain high precision without shifting even when humidity or the like changes. The purpose is to

A light source device of the present invention that achieves this object includes a first holding member having good thermal conductivity that fits into a package containing a semiconductor laser element that generates a light beam, and a first holding member that fits into the first holding member. It consists of a heat insulating second holding member and a low expansion third holding member that fits into the second holding member, and the package and each of the first, second and third holding members. The central axes of the fitting portions are arranged substantially on the same axis.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of a light source device according to the present invention, with FIG. 1(A) being a side sectional view and FIG. 1(B) being a front view. FIG. 2 is a partially cutaway side view of a laser generator built into the light source device of the present invention. In these figures, the same reference numerals are given to the same structural parts as in FIG. 6.

In FIG. 2, a laser generator 10 includes a semiconductor laser element SL and a chip assembly 11 that supports and fixes the laser element SL.
, a package 12 that houses the laser element 10, a glass plate 13 that transmits the light beam emitted from the laser element SL, and a lead wire 14 that is electrically connected to the laser element SL and connected to an external laser oscillator. ing.

When a voltage is applied to the laser element SL, a current flows, and a light beam is emitted, which is taken out through the glass plate 13 to the outside.

The laser generator 10 is inserted into the central opening of the plate 21, as shown in FIG. That is, the package 12, which is the exterior body of the laser generator IO, is positioned and fitted into the stepped opening of the plate 21 by the outer diameter of its seven sink portions and the shoulder portion.

Additionally, the bottom of the package 12 is backed up and axially positioned by a plate ρ. After fitting the package 12 between the plates 21 and 4,
22 is integrated. This combined play) 21
, 22 are hereinafter referred to as holding members for the cylinder 1.

In this state, the central axis (beam optical axis) of the package 12
and the central axis of the first holding member are substantially aligned and fixed.

Here, as the material for the first holding member, that is, the material with high thermal conductivity, copper (40
3w-m-'-k-1) and aluminum (236w-m
"-1・k-1) is the most desirable. This is because the semiconductor laser element SL generates heat when emitting a light beam, so it is necessary to efficiently guide this heat to the outside (around the light source device). This is because there is.

22 has a temperature detection element n, for example, a surge
A star etc. are built in, and an electric pre-cooling element, such as a Peltier element array, is closely attached to the back of the plate. Further, a heat radiator 5 such as a heat sink is attached to the other surface of the Peltier element array. (However, lead wires, etc. are omitted.) The heat generated by the semiconductor laser element SL is
The heat is conducted to the plates 21 and 22 forming the first holding member, where the temperature is measured by the temperature detection element field in the plate 22, and the signal is sent to the Peltier element array having the Peltier effect. Control the current. When this current is controlled to flow through the Peltier element U, the conductive heat of the plate 22 is absorbed by the Peltier effect, and is further dissipated by the heat radiator 5. Thus package 12
The temperature inside is maintained constant.

FIG. 3 shows an electrical block diagram for temperature controlling and driving the light source device.

The first holding member and the second holding member having heat insulating properties are fitted and held such that their respective central axes coincide with each other. As the material for the second holding member, a material having appropriate rigidity, low thermal conductivity, and good workability is used, such as boria heptatar resin, polyamide resin, polycarbonate resin, phenol resin, etc. be.

The reason for this is that even if the ambient temperature of the light source device changes significantly, the laser generator 10 and the first holding member (plate)
21. , 22'), thereby increasing the heat insulation effect and maintaining the temperature of the laser generator constant.

The second holding member portion is further fitted and held in the third holding member 27 so that their respective central axes coincide. The third holding member 27 is preferably made of a material with a small coefficient of linear expansion. For example, Invar (Fe63%,
The linear expansion coefficient of Ni 36%, Mn 0.5% is I
X to -6℃-1, Super Invar (Fe63~
65%, Ni 30-32%, Co 5%, trace amount of Mn)
is 0.5 X LO-'°C-1, which is particularly suitable.

The third holding member 27 is fixed to the radiator 5 by a screw path. Note that 27A is a mounting surface that is a flat part of the outer circumferential surface of the third holding part, and 2'7B is a mounting reference hole.

On the other hand, a collimator lens CL for collimating the light beam emitted from the laser generator IO is held in the lens holder cabinet and fixed by a lens holder 31.

The lens holder (9) is screw-fitted to the mount member 32 and fixed by a locking nut 33 or the like.

Focusing of the collimator lens CL is performed by rotating and slightly moving the lens holder.

The mount member 32 is fixed to the end surface of the third holding member n with a screw 34. The material of the mount member 32 is also made of a material with a low coefficient of linear expansion similarly to the third holding member.

Next, the reason why a material with a low expansion coefficient is required as the material for the third holding member portion will be explained below. FIG. 4 shows an optical functional diagram of a laser beam scanning optical system using the above light source device. Further, FIG. 5 is a perspective view showing the optical system of the laser beam scanning recording device.

In these figures, 01 is the light exit surface from the semiconductor laser element SL, and the light beam passes through the collimator lens CL.
(for example, 7.=tom), fθ lens F (for example, 7.=tom), fθ lens F (for example, 7.=tom),
2=5ooa), a beam spot is imaged onto the final scanning plane 02. At this time, the horizontal magnification α and vertical magnification β of the optical system are given by the following equations.

d'/! fx zl This means that if the light emitting point of the laser element SL moves by 1 am in the 3'+ direction (X+-y due to rotational symmetry, OK if it is a plane) due to thermal expansion, then the scanning plane Ot On 50 times 50 Am, Yt means that the beam spot moves in the force direction. Furthermore, if the light emitting point of the laser element SL is moved by 1 μm in the 21 direction, the beam imaging position will be 2500 μm (2,5 wI
L) Moving in the Z direction, the beam spot becomes non-imaged (
D, efocns) state.

In general, in a precision laser beam recording device or reading device, it is necessary to scan the beam spot accurately without any trouble even if the environmental temperature difference in which the device is used changes by 40 to 50°C.

As described above, if materials with low coefficients of linear expansion are used for the third holding member that holds the laser element SL and forms the outer shell, and for the mount member 32 that forms the outer shell of the collimator lens CL, , optical system position fluctuations due to temperature fluctuations can be reduced.

Moreover, a package 12 for sealing the semiconductor laser element SL
, first holding member (plates 21, 22>, second
The holding member has a fitting structure with the third holding member 27,
Furthermore, by using a coaxial structure that is rotationally symmetrical, the package 12, the first holding member, and the second holding member are
Even if the holding member portion of the third holding member 2 tries to expand, the third holding member 2
7 functions as the outermost fitting member with low expansion properties,
In addition, since it has a rotationally symmetrical structure, positional fluctuation (displacement) components occur only in directions parallel to the axial direction. This means that the displacement component of the lateral magnification of the optical system is suppressed.

In addition, the displacement component in the axial direction is the third
Resin' which is sandwiched between the holding member n and the radiator 5 and has lower rigidity than the other holding members 21, 22, and 27! A
Since thermal expansion energy is accumulated as internal stress in the second holding member 26 made of plastic, the package 12,
Displacement components of the first holding members 21, 22 and the second holding member 26 do not appear. This means that the displacement component of the vertical magnification system of the optical system is suppressed.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to reduce the relative positional fluctuation between the laser element and the optical system due to temperature changes, so that the desired beam flux can be stably obtained, and each of the constituent holders This makes it easier to manufacture, assemble, and adjust parts.

[Brief explanation of the drawing]

1A and 1B are a side sectional view and a front view of a light source device according to the present invention, FIG. 2 is a partially cutaway side view of a laser generator built into the light source device of the present invention, and FIG. 4 is an electrical block diagram for controlling the temperature of the light source device, and FIG. first holding member), 23...Temperature detection element, 24
・・・・・・・・・Peltier element, 5・・・・・・・・・
・Radiator, ......Second holding member, nail...Third holding member, addition...
...Lens holder, 32...Mount member, SL...
・Semiconductor laser element.

Claims (4)

[Claims] (1) a first holding member with good thermal conductivity that fits into a package containing a semiconductor laser element that generates a light beam;
It consists of a heat-insulating second holding member that fits into the first holding member, and a low-expansion third holding member that fits into the second holding member, and is connected to the package and the first and second holding members. A light source device characterized in that the central axes of the fitting portions of the second and third holding members are arranged substantially on the same axis. (2) The thermal conductivity of the first holding member is 50w. m^-
^1. The light source device according to claim 1, wherein the light source is k^-^1 or more. (3) The thermal conductivity of the second holding member is 2w. m^-^
1. The light source device according to claim 1, characterized in that it is less than or equal to k^-^1. (4) The linear expansion coefficient of the third holding member is 20℃^-^1
A light source device according to claim 1, characterized in that: