JP2005250390A - Light source unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a light source unit as small-sized as possible. <P>SOLUTION: The light source unit which is equipped with a semiconductor laser element 31 and a light guide type 2nd higher harmonic generating element 41 and makes projection light from the semiconductor laser element 31 incident on an optical waveguide of the 2nd higher harmonic generating element 41 to project a 2nd higher harmonic of the incident light is provided with a basic wave absorbing filter 51 which absorbs the light of a wavelength component of the basic wave projected from the 2nd higher harmonic generating element 41. The light projection surface of the basic wave absorbing filter 51 on the opposite side from the light incidence surface is arranged at an inclined attitude to the traveling direction of the light, and a reflecting film which reflects part of the light of the wavelength component of the 2nd higher harmonic projected from the 2nd higher harmonic generating element to travel to an optical sensor for output adjustment of the semiconductor laser element is formed on the light projection surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention comprises a semiconductor laser element and an optical waveguide type second harmonic generation element, and the light emitted from the semiconductor laser element is incident on the optical waveguide of the second harmonic generation element to The present invention relates to a light source device that emits a second harmonic.

Such a light source device is a device that takes out light emitted from a semiconductor laser element into an optical waveguide of a second harmonic generation element and extracts a second harmonic having a wavelength half that of the incident laser light.
In this optical waveguide type second harmonic generation element, since the fundamental wave, which is the emitted laser beam of the semiconductor laser element, is emitted in a state where the second harmonic thereof overlaps, the output of the second harmonic generation element is It is necessary to remove the wavelength component of the fundamental wave from the incident light.
In order to remove the wavelength component of the fundamental wave, as described in Patent Document 1 below, for example, if the fundamental wave has a wavelength in the infrared region, an IR cut filter is disposed in the optical path.

On the other hand, in order to control the optical output of the semiconductor laser device so that the second harmonic of the desired optical output can be obtained, a part of the light of the wavelength component of the second harmonic is branched by the beam splitter by the optical sensor It is also being measured.
Conventionally, as described in Patent Document 1 below, it is common to separately provide an IR cut filter and a beam splitter.
JP 2001-318396 A

Therefore, in the above-described conventional configuration, the number of optical components existing on the output side of the second harmonic generation element increases, and it is not possible to sufficiently meet the demand for downsizing of the light source device.
In particular, in order to remove the wavelength component of the fundamental wave emitted from the second harmonic generation element, an absorption filter is used instead of a thin film type reflection filter such as an interference filter, so that the fundamental wave is reflected from the filter. In the case where the light is configured to be prevented from being disturbed, it is necessary to increase the thickness of the absorption filter to some extent, which is also an obstacle to downsizing.
The present invention has been made in view of such circumstances, and an object of the present invention is to make the light source device as small as possible.

  A first invention of the present application includes a semiconductor laser element and an optical waveguide type second harmonic generation element, and makes emitted light of the semiconductor laser element enter an optical waveguide of the second harmonic generation element. In the light source device that emits the second harmonic of the incident light, a fundamental wave absorption filter that absorbs light having a wavelength component of the fundamental wave emitted from the second harmonic generation element is provided, and the fundamental wave absorption filter The light emitting surface located on the opposite side of the light incident surface is disposed in an inclined posture with respect to the light traveling direction, and the second harmonic wave emitted from the second harmonic generating element is disposed on the light emitting surface. A reflection film is formed to reflect part of the light of the wavelength component so as to go to the optical sensor for output adjustment of the semiconductor laser element.

  In other words, the fundamental wave emitted from the second harmonic generation element is absorbed by the base material itself of the fundamental wave absorption filter to suppress unnecessary reflection as much as possible, and the function corresponding to the beam splitter is constituted by a thin reflection film. Therefore, the reflection film is formed on the light exit surface of the fundamental wave absorption filter.

According to a second aspect of the present application, in addition to the configuration of the first aspect, reflection of light having a wavelength component of the second harmonic emitted from the second harmonic generation element on the light incident surface. An antireflection film for reducing the rate is formed.
Therefore, the light of the wavelength component of the second harmonic emitted from the second harmonic generation element and incident on the fundamental wave absorption filter can be efficiently passed through the light incident surface.

In addition to the configuration of the first or second invention, the third invention of the present application is configured such that the light incident surface and the light emitting surface are substantially parallel to each other.
In other words, the fundamental wave absorption filter is composed of a parallel plate thick plate material, and the thick plate material is arranged in an attitude inclined with respect to the traveling direction of the light. In view of the function of guiding to the sensor, the inclination angle of the fundamental wave absorption filter from the light traveling direction is inclined at an angle considerably smaller than 90 degrees (generally about 45 degrees).
Therefore, the effective fundamental wave absorption filter passes in the traveling direction of light, and sufficient fundamental wave absorption is possible even if the fundamental wave absorption filter is thin.

According to the first aspect of the invention, the fundamental wave emitted from the second harmonic generation element is absorbed by the base material itself of the fundamental wave absorption filter to suppress unnecessary reflection as much as possible, and has a function corresponding to a beam splitter. By forming the reflective film on the light emitting surface of the fundamental wave absorption filter, the number of optical components can be reduced while ensuring the necessary functions, and the light source device can be miniaturized as much as possible.
In addition, the cost of components constituting the light source device is also reduced.
Further, according to the second aspect of the invention, the light of the second harmonic wavelength component emitted from the second harmonic generation element and entering the fundamental wave absorption filter can be efficiently passed through the light incident surface. Therefore, the extraction efficiency of the second harmonic as the whole light source device can be improved.
According to the third aspect of the invention, the effective fundamental wave absorption filter in the light traveling direction is lengthened, and sufficient fundamental wave absorption is possible even when the fundamental wave absorption filter is thin. Thus, the light source device can be further reduced in size and cost.

Hereinafter, an embodiment in which the light source device of the present invention is provided as a light source for exposure in a photographic print system will be described with reference to the drawings.
The photographic print system DP exemplified in the present embodiment is known as a so-called digital minilab machine, and as shown in the block configuration diagram of FIG. 6, developed photographic film, memory card, MO or CD. An image input device IR for inputting image data for producing a photographic print from -R and the like, and an exposure / development device EP for exposing the photographic paper 2 to image data input by the image input device IR. Yes.

[Schematic configuration of image input device IR]
As schematically shown in FIG. 6, the image input device IR includes a film scanner 3 for reading frame images of a photographic film, an external input / output device 4 including a memory reader, an MO drive, a CD-R drive, and the like, A personal computer is provided with a main controller 5 for controlling the film scanner 3 and the external input / output device 4 in addition to controlling the film scanner 3 and the external input / output device 4. Further, the main controller 5 includes a finished print. A monitor 5a that displays a simulated image that simulates an image and various types of control information is connected to a console 5b that is used for manual setting of exposure conditions and for input of control information.

[Overall configuration of exposure / development apparatus EP]
The exposure / development apparatus EP includes an image exposure apparatus EX, a development processing apparatus PP for developing the photographic paper 2 exposed by the image exposure apparatus EX, and a photographic paper drawn from the photographic paper magazine 6 inside the casing. And a photographic paper transport system PT that transports 2 to the development processing apparatus PP by a number of transport rollers 9 or the like.
Although not shown, a sorter is provided outside the casing of the exposure / development apparatus EP to classify the photographic paper 2 that has been developed and dried by the development processing apparatus PP for each order. A conveyor 10 for conveying the photographic paper 2 is provided on the upper surface of the casing.
Further, in the middle of the transport path of the photographic paper transport system PT, a cutter 11 that cuts the long photographic paper 2 drawn out from the photographic paper magazine 6 into a set print size and a plurality of photographic papers 2 transported in a row. And a sorting device 12 for sorting to the transport rows.

[Configuration of image exposure apparatus EX]
The image exposure apparatus EX includes an exposure unit 13 that forms an exposure image on the photographic paper 2 by scanning the photographic paper 2 with a laser beam, and an exposure control device 14 that controls the exposure unit 13 as main parts. Has been.
[Configuration of Exposure Unit 13]
The exposure unit 13 employs a so-called laser exposure method in which an image is exposed on the photographic paper 2 using a laser as a light source, and a schematic configuration thereof is shown in a block configuration diagram of FIG.
The exposure unit 13 includes a red light source device 21, a green light source device 22, a blue light source device 23, and an acoustooptic modulator 24 (for modulating the intensity of the laser beam emitted from the green light source device 22 and the blue light source device 23). (Hereinafter abbreviated as “AOM element 24”), a mirror 25 that bends the optical path of the laser beam, a spherical lens 26, a cylindrical lens 27, a polygon mirror 28 that is rotationally driven by a motor (not shown), A lens group 29 having an f-θ characteristic and a surface tilt correction function is provided.

[Configuration of light source devices 21, 22, and 23]
Although not shown, the red light source device 21 includes a red semiconductor laser element and a condensing lens that condenses the emitted light of the red semiconductor laser element. Unlike the green light source device 22 and the blue light source device 23, the red light source device 21 is a semiconductor laser. The intensity of the emitted laser beam is modulated by directly modulating the drive current of the element.
The green light source device 22 and the blue light source device 23 have the same basic configuration, and these configurations will be described by using the green light source device 22 as a representative.
As shown in the side view of FIG. 1 and the perspective view of FIG. 3, the green light source device 22 generates a near-infrared semiconductor laser device 22a and a second harmonic of the laser beam emitted from the near-infrared semiconductor laser device 22a. The second harmonic generator 22b, and the wavelength component of the fundamental wave, that is, the wavelength component of the laser beam emitted from the near-infrared semiconductor laser device 22a, are removed from the emitted light from the second harmonic generator 22b. And a condensing lens unit 22d for condensing the second harmonic laser beam that has passed through the filter unit 22c to the light receiving opening of the AOM element 24.

As shown in FIG. 1, the near-infrared semiconductor laser device 22a supports a laser housing 32 containing a semiconductor laser element 31 and one end of an optical fiber 36 attached to the light emission opening side of the laser housing 32. A fiber support member 33 that supports the laser housing 32, and a thermoelectric cooling device 35 that adjusts the temperature of the semiconductor laser element 31. The light is guided to the second harmonic generator 22b by the optical fiber 36 that is accurately positioned at the light emission position of the laser element 31.
As shown in FIG. 1 and the like, the second harmonic generation device 22b includes an elongated rod-shaped second harmonic generation element 41, an SHG support base 42 that supports the second harmonic generation element 41, and a second harmonic generation. A thermoelectric cooling device 43 for adjusting the temperature of the element 41, a fiber support member 44 that supports one end of the optical fiber 36, a collimator lens 45 that collimates the emitted light from the second harmonic generation element 41, and the collimator lens 45 And a collimating lens support member 46 for supporting the lens.

The second harmonic generation element 41 is an optical waveguide type second harmonic generation element, and, as shown in the perspective view of FIG. 4, a periodically poled structure 41b is formed in the optical waveguide 41a. The optical waveguide 41a is positioned with one end (light incident end) of the optical waveguide 41a supported by the fiber support member 44. In FIG. 4, in order to make it easy to understand the formation state of the optical waveguide 41 a and the periodically poled structure 41 b, they are enlarged than the actual dimensions, and the lateral width of the second harmonic generation element 41 is also enlarged. It is shown.
In the present embodiment, LiNbO ₃ is used as the substrate of the second harmonic generation element 41, the optical waveguide 41a is formed by a proton exchange method or the like, and the periodically poled structure 41b is an electric field application method or a Ti diffusion method or the like. And by periodically inverting the polarization.

The filter unit 22c includes an infrared light absorption filter 51 as a fundamental wave absorption filter that absorbs the wavelength component of the fundamental wave emitted from the second harmonic generation element 41, and the infrared light absorption filter 51 is disposed on the filter support base. 52.
As shown in FIG. 2 showing the component arrangement in the vicinity of the filter unit 22c in plan view, the infrared light absorption filter 51 includes a light incident surface IS on which light from the second harmonic generator 22b is incident and a light incident surface IS. The filter support base 52 is formed of a parallel plate thick plate member that is substantially parallel to the light exit surface OS located on the opposite side, and the filter support base 52 has an inclined posture (specifically, the light exit surface OS is inclined with respect to the light traveling direction). Supports the infrared light absorption filter 51 so as to be inclined at 45 degrees from the optical axis.

On the light incident surface IS of the infrared light absorption filter 51, an antireflection film for reducing the reflectance of the light of the second harmonic wavelength component emitted from the second harmonic generation element 41 is formed. This antireflection film is a so-called AR coating, and is composed of a dielectric film having a refractive index and a film thickness suitable for the wavelength of the second harmonic.
On the light exit surface OS of the infrared light absorption filter 51, a part of the light of the second harmonic wavelength component emitted from the second harmonic generation element 41 is used as light for adjusting the output of the semiconductor laser element 31. A reflection film that reflects toward the photodiode 55 provided as a sensor is formed.
This reflective film is composed of a multilayer film such as a dielectric having a refractive index and a layer thickness adapted to the wavelength of the second harmonic, but may be composed of a metal vapor deposition film such as chromium.
The filter support base 52 includes an incident side through hole 52 a for guiding the light emitted from the second harmonic generation device 22 b to the infrared light absorption filter 51, and the light emission surface OS of the infrared light absorption filter 51. A reflection-side through hole 52 b for guiding a part of the reflected second harmonic to the photodiode 55 is formed.

Of the fundamental wave emitted from the second harmonic generation element 41 and incident on the infrared light absorption filter 51 and the second harmonic wave, the fundamental wave is absorbed in the process of passing through the inside of the infrared light absorption filter 51. The second harmonic wave passes through the inside of the infrared light absorption filter 51 with almost no attenuation and reaches the light emitting surface OS, and a part thereof is reflected. The other portion that has passed through the light emitting surface OS is directed toward the condenser lens unit 22d.
The detection signal of the photodiode 55 is input to an APC circuit (not shown), and the drive current of the semiconductor laser element 31 is adjusted so that the detection signal of the photodiode 55 becomes a constant value.

As shown in FIG. 1 and the like, the condenser lens unit 22d includes a condenser lens 61, a lens holder 62 that supports the condenser lens 61, and a lens support base 63 that supports the lens holder 62. The support base 63 is formed with a through hole 63 a for allowing the second harmonic transmitted through the infrared light absorption filter 51 to pass therethrough.
The near-infrared semiconductor laser device 22a, the second harmonic generation device 22b, and the filter unit 22c are mounted on the support plate 65, and the support plate 65 and the condenser lens unit 22d are mounted on the basic support plate 66. It has been.
The configuration of the green light source device 22 has been described above. However, as described above, the components of the blue light source device 23 are the same as the components of the green light source device 22, and the oscillation wavelength of the semiconductor laser element to be used, the second The portions related to the wavelength of light, such as the period of the periodically poled structure of the harmonic generation element, are different.

[Configuration of Exposure Control Device 14]
As schematically shown in FIG. 5, the exposure control device 14 exposes red, green and blue exposure image data input from the image input device IR in order to control the exposure unit 13 having the above configuration. A look-up table 71 for correcting the image data in consideration of the exposure characteristics of the unit 13, an image data memory 72 for storing the image data corrected by the look-up table 71 for each of red, green and blue colors, red, A D / A converter 73 that is provided for each color of green and blue and D / A converts the output data of the image data memory 72, and AOM that is modulated according to the input signal from the D / A converter 73 for green and blue The AOM control circuit 74 that generates a drive signal for the element 24 and the red light source device 21 according to the input signal from the D / A converter 73 for red. A LD driving circuit 75 for modulating the driving current of the semiconductor laser device is provided.

When the operator inputs image data to be printed from the film scanner 3 or the external input / output device 4, image processing or the like is appropriately performed, and the image data for exposure after image processing is transmitted to the lookup table 71.
Based on the red, green and blue exposure image data input from the image input device IR, the red, green and blue laser beams intensity-modulated by the AOM element 24 and the LD drive circuit 75 The laser beam that passes through and is irradiated on the reflection surface of the polygon mirror 28 and reflected by the reflection surface of the polygon mirror 28 that is driven to rotate is condensed on the photographic paper 2 by the lens group 29. The scanning direction of the laser beam (main scanning direction) is orthogonal to the conveyance direction (sub-scanning direction) of the photographic paper 2, and an image to be printed on the photographic paper 2 is scanned by the scanning of the laser beam and the conveyance movement of the photographic paper 2. Formed as a latent image. This is developed in the development processing apparatus PP and finished as a photographic print.

[Another embodiment]
Hereinafter, other embodiments of the present invention will be listed.
(1) In the above embodiment, the present invention is applied to the green light source device 22 and the blue light source device 23, and the oscillation wavelengths of the semiconductor laser elements provided in the light source devices 22 and 23 are both infrared light. Since the wavelength of the fundamental wave emitted from the second harmonic generation element is infrared light, the infrared light absorption filter 51 is illustrated as the fundamental wave absorption filter. However, the oscillation of the semiconductor laser element provided in the light source device is illustrated. The present invention can also be applied when the wavelength is other than infrared light.

(2) In the above embodiment, the case where the light source device of the present invention is used as the exposure light source of the photographic print system DP is exemplified. However, the present invention is applied to various applications where it is desired to generate a second harmonic of a short wavelength. Applicable.
(3) Although the photodiode 55 is illustrated as an optical sensor for adjusting the output of the semiconductor laser element in the above embodiment, various types of optical sensors can be used without being limited to the photodiode.

The side view of the light source device concerning embodiment of this invention The fragmentary top view of the light source device concerning embodiment of this invention The perspective view of the light source device concerning embodiment of this invention The perspective view of the 2nd harmonic generation element concerning embodiment of this invention 1 is a schematic configuration diagram of an image exposure apparatus according to an embodiment of the present invention. 1 is a schematic configuration diagram of a photo print system according to an embodiment of the present invention.

Explanation of symbols

31 Semiconductor Laser Element 41 Second Harmonic Generation Element 51 Infrared Light Absorption Filter 55 Optical Sensor

Claims (3)

A semiconductor laser element and an optical waveguide type second harmonic generation element;
A light source device for emitting the second harmonic of the incident light by causing the emitted light of the semiconductor laser element to enter the optical waveguide of the second harmonic generation element;
A fundamental wave absorption filter that absorbs light having a wavelength component of the fundamental wave emitted from the second harmonic generation element;
The light exit surface located on the opposite side of the light incident surface in the fundamental wave absorption filter is disposed in an inclined posture with respect to the traveling direction of the light,
A reflective film that reflects a part of the light of the wavelength component of the second harmonic emitted from the second harmonic generation element toward the light emitting surface so as to go to the optical sensor for output adjustment of the semiconductor laser element Is a light source device formed.   2. The light source device according to claim 1, wherein an antireflection film is formed on the light incident surface to reduce the reflectance of light having a wavelength component of the second harmonic emitted from the second harmonic generation element.   The light source device according to claim 1, wherein the light incident surface and the light emitting surface are configured to be substantially parallel.

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