KR20060123950A - Apparatus for composition of laser beam - Google Patents

Abstract

An apparatus for composing laser beams is provided to remove speckle phenomenon by using a vibrator to reduce coherency. A plurality of semiconductor lasers(100a,100b,100c) are used for outputting beams having different wavelengths. A plurality of optical fibers(120a,120b,120c) are coupled with the semiconductor lasers in order to transmit the beams having different wavelengths. A vibrator(130) includes a plurality of holes into which the optical fibers are inserted. The vibrator reduces coherency by vibrating the optical fibers. An optical composition unit(140) is connected with ends of the optical fibers in order to compose the beams having different wavelengths.

Description

Laser light synthesizing device {Apparatus for composition of laser beam}

1 is a schematic view of a conventional laser display device.

2 is a block diagram of a laser light synthesizing apparatus of the present invention.

3 is a view showing a state in which a semiconductor laser and an optical fiber are directly coupled.

4 is a view showing a state in which a plurality of optical fibers and the vibrator is fastened.

5 is a view showing a state in which the vibrator is fastened for each optical fiber.

6 is a view showing a state in which laser lights are synthesized in a light synthesis system.

Explanation of symbols on the main parts of the drawings

100a, 100b, 100c: semiconductor laser 110a, 110b, 110c: focusing lens

120a, 120b, 120c: optical fiber 130: vibrator

140: light synthesis system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser light synthesizing apparatus comprising: a laser light synthesizing apparatus for synthesizing each laser light after transmitting each laser light using an optical fiber and removing speckle phenomenon using a vibrator. It is about.

Recently, due to technical advances in high-power semiconductor lasers and small solid-state lasers using the same as a pumping light source, the possibility of commercializing a laser display has been increased.

In order to implement a laser display, a gas laser such as a helium-neon (He-Ne) laser is conventionally used. The gas laser has an optical energy conversion efficiency of 1% or less compared to electrical energy, and requires several tens of powers. There is a disadvantage in that the entire laser system is enlarged due to the need for a power supply device, a cooling water system, and a laser oscillator.

In contrast, high-power semiconductor lasers and solid-state lasers are very efficient at 40% or more for semiconductor lasers and 10% or more for solid-state lasers, which are very efficient, small in size, and air-cooled. There is an advantage of miniaturization, and research is being actively conducted as a light source of a laser display device.

Laser displays have a much wider range of colors than other displays, such as liquid crystal displays (LCDs) or cathode ray tubes (CRTs), enabling them to achieve colors close to natural colors. There is an advantage that can implement a small and efficient display using the.

1 is a schematic diagram of a conventional laser display device. As shown therein, the first, second and third semiconductor lasers 10a, 10b and 10c for generating light of red (R), green (G) and blue (B) wavelengths, and the first And a laser light synthesizing apparatus 20 for synthesizing light of red, green and blue wavelengths generated by the second and third semiconductor lasers 10a, 10b and 10c, and in the laser light synthesizing apparatus 20 An optical scanning unit 30 which scans the synthesized light to realize a planar image, and a screen 40 on which the planar image implemented in the optical scanning unit 30 is formed.

The laser light synthesizing apparatus 20 includes first, second and third focusing lenses 21a, 21b and 21c, and first, second and third light modulators 23a, 23b and 23c. And a total reflection mirror 25a, first and second dichroic mirrors 25b and 25c, and the optical scanning unit 30 includes a rotating multi-face mirror and a galvano mirror (not shown).

In the conventional laser display device configured as described above, the first, second and third semiconductor lasers 10a, 10b and 10c generate light of red (R), green (G) and blue (B) wavelengths. The first, second, and third focusing lenses 21a, 21b, and 21c may focus light of the red (R), green (G), and blue (B) wavelengths so that the first, second, and third focusing lenses Transfer to the optical modulators 23a, 23b, 23c.

The first, second, and third optical modulators 23a, 23b, and 23c convert light of the red (R), green (G), and blue (B) wavelengths into light output signals corresponding to an image signal. give. If the first, second and third semiconductor lasers 10a, 10b and 10c are employed as semiconductor lasers having a structure that is self-modulated to correspond to an image signal, the first, second and third semiconductor lasers 10a, 10b and 10c may be used. The optical modulators 23a, 23b, 23c are not necessary.

The red light modulated by the first light modulator 23a travels to the total reflection mirror 25a and is reflected by the total reflection mirror 25a to travel to the first dichroic mirror 25b. The green light modulated by the second optical modulator 23b travels to the first dichroic mirror 25b and is reflected by the first dichroic mirror 25b to reflect the second dichroic. Proceed to the mirror 25c.

In this case, the first dichroic mirror 25b transmits the red light reflected by the total reflection mirror 25a and is transmitted through the second light modulator 23b to reflect the incident green light. It combines the transmitted red light and the reflected green light.

The blue light modulated by the third light modulator 23c proceeds to the second dichroic mirror 25c and is reflected by the second dichroic mirror 25c. Here, the second dichroic mirror 25c transmits light incident from the first dichroic mirror 25b and modulates the incident light through the third light modulator 23c.

That is, the second dichroic mirror 25c transmits the light (red light + green light) synthesized in the first dichroic mirror 25b and is modulated by the third light modulator 23c. The incident blue light is reflected to synthesize the transmitted red light + green light and the reflected red light.

The light synthesized by the laser light synthesizing apparatus 20 is incident to the optical scanning unit 30, and a rotating polygon mirror (not shown) of the optical scanning unit 30 linearly scans the incident light, and the light A galvano mirror (not shown) of the scanning unit 30 scans the linearly scanned light again to make the light flat and scans the screen 40.

In the conventional laser display apparatus, the laser light synthesizing apparatus 20 synthesizes laser light through the total reflection mirror 25a, the first and second dichroic mirrors 25b and 25c, and thus the There is a disadvantage in that the optical fine alignment is difficult, there is a problem that the size of the laser light synthesis apparatus increases.

In the case of synthesizing laser light through the total reflection mirror 25a, the first and second dichroic mirrors 25b and 25c, the beam sizes of the blue, green, and red laser lights must be matched. There is a difficulty in controlling the size of the laser lights accurately.

In addition, since the laser light has a high coherency, a speckle phenomenon occurs. The speckle phenomenon indicates that the laser light is scattered by the roughness of the screen surface when the laser light is reflected on the screen. Say.

In other words, speckle may occur when light transmitted by a certain portion of the screen is coherent with light transmitted by an adjacent portion of the screen, where the mutual nose transmitted from adjacent portions of the screen. The warm light interferes with the light propagating out of the screen.

The viewer's field of view then incorporates this interference on the entire screen, which results in the viewer seeing many bright spots across the screen, which are called speckles, which are images projected from the screen. There is a problem in that the viewer's eyes are easily tired by lowering the visibility of.

An object of the present invention is to provide a laser light synthesizing apparatus which does not need to control the size of the system and control the light size of the laser lights by advancing and synthesizing the laser lights generated from the semiconductor laser through the optical fiber.

Another object of the present invention is to provide a laser light synthesizing apparatus that eliminates speckle phenomena appearing in an image of a laser display by reducing the coherence of laser light propagating through the optical fiber.

An embodiment of the laser light synthesizing apparatus of the present invention includes a plurality of semiconductor lasers that generate and emit light having different wavelengths, and different wavelengths that are coupled to each of the plurality of semiconductor lasers and are emitted from the plurality of semiconductor lasers. A plurality of optical fibers for transmitting the light of the plurality, and a plurality of holes are formed to enter the plurality of optical fibers therein, Vibrator for vibrating the optical fiber to reduce the interference of light transmitted through the optical fiber And an optical synthesis system connected to the ends of the plurality of optical fibers to synthesize light having different wavelengths emitted from the optical fibers.

The apparatus may further include a plurality of focusing lenses configured to focus light having different wavelengths generated by the plurality of semiconductor lasers and to the plurality of optical fibers.

The light having different wavelengths may include light having red, green, and blue wavelengths.

The plurality of semiconductor lasers may be first, second and third semiconductor lasers that generate and emit light having red, green, and blue wavelengths, respectively.

In the case of the first, second and third optical fibers, the diameter is 50 to 100 μm, and the length is 3 to 4 cm, and the optical synthesis system is made of an optical fiber or a glass tube.

Hereinafter, the laser light synthesizing apparatus of the present invention will be described in detail with reference to FIGS. 2 to 6. 2 is a view showing the structure of the laser light synthesizing apparatus of the present invention.

As shown therein, the first, second and third semiconductor lasers 100a, 100b and 100c which generate and emit the first to third light having different wavelengths, and the first, second and First to focus the first to third light generated by the third semiconductor laser (100a) (100b) (100c) and emitted to the first, second and third optical fiber (120a) (120b) (120c) And first and third transmitting second and third focusing lenses 110a, 110b and 110c, and first to third lights focused together by the focusing lenses 110a, 110b and 110c, respectively. The first, second and third optical fibers 120a, 120b and 120c and the first, second and third optical fibers 120a, 120b and 120c are vibrated to vibrate the first, second and third optical fibers 120a. Vibrator 130 for reducing the interfering interference of the first to third light transmitted through the (120b) (120c), and the first, second and third optical fiber (120a) (120b) (120c) It consists of a light synthesis system 140 for synthesizing the first to third light transmitted through the).

In the laser light synthesizing apparatus of the present invention configured as described above, the first, second and third semiconductor lasers 100a, 100b and 100c respectively generate and emit the first to third lights having different wavelengths.

Although the first, second, and third semiconductor lasers 100a, 100b, and 100c which generate the first to third light having different wavelengths are assumed here, a plurality of light emitting devices having different wavelengths are generated and output. It may also be composed of semiconductor lasers.

Here, the light of different wavelengths includes light of red, green, and blue wavelengths, and in particular, the first light is red (R) light having a value in a wavelength range of 630 to 660 nm, and the second light Is preferably green (G) light having a value in the wavelength region of 520 to 540 nm, and the third light is preferably blue (B) light having a value in the wavelength region of 440 to 470 nm.

The red light may be obtained using a GaAs semiconductor, and the blue light may be obtained using a GaN semiconductor. However, in the case of the green light, a semiconductor laser capable of directly obtaining the same has not been developed due to the properties of the material. It is obtained using a Pumped Solid State Laser (DPSS) using Harmonic Generation (SHG).

The first, second, and third semiconductor lasers 100a, 100b, and 100c are semiconductor lasers that are self-modulated in response to an externally input image signal. And the first, second and third semiconductor lasers 100a and 100b when the third semiconductor lasers 100a, 100b and 100c are not semiconductor lasers which are self-modulated in response to an image signal. There is a need for an optical modulator for converting the first to third light generated in the 100c into a light output signal corresponding to the image signal.

The first to third lights generated by the first, second and third semiconductor lasers 100a, 100b and 100c and emitted are focused through the focusing lenses 110a, 110b and 110c. Coupled with the second and third optical fibers 120a, 120b, 120c, and transmitted through the first, second, and third optical fibers 120a, 120b, 120c. Herein, in the case of the first, second and third optical fibers 120a, 120b and 120c, the total length is preferably 3 to 4 cm.

That is, in the case of laser light generated and emitted by the first, second and third semiconductor lasers 100a, 100b, and 100c, the radiation is emitted with an divergence angle of about 8 to 30 °, thereby focusing the first and second semiconductor lasers. A focusing lens for coupling to the second and third optical fibers 120a, 120b, and 120c is required.

In this case, as shown in FIG. 3, the laser light generated and emitted by the semiconductor laser 105 may be directly coupled to the optical fiber 125, which is referred to as a butt-coupling method. do.

That is, the laser light generated and emitted by the first, second and third semiconductor lasers 100a, 100b, and 100c of FIG. 2 has a beam size of about 3 μm. In the case of the second and third optical fibers 120a, 120b, and 120c, optical fibers having a diameter of about 50 to 100 μm are used.

A portion of the first, second, and third semiconductor lasers 100a, 100b, and 100c from which light is emitted and a core of the first, second, and third optical fibers 120a, 120b, and 120c are emitted. Directly facing the laser beams generated by the first, second, and third semiconductor lasers 100a, 100b, and 100c and emitted from the first, second, and third optical fibers 120a, 120b. Can be directly coupled to (120c).

In the case of using the butt-coupling method, there is an advantage that the focusing cost is not necessary because the focusing lens is not used, but the optical coupling efficiency is as small as 10% at most. In this case, the optical coupling efficiency is shorter than the distance between the first, second and third semiconductor laser (100a) (100b) (100c) and the first, second and third optical fiber (120a) (120b) (120c). The bigger it gets.

First to third light transmitted through the first, second and third optical fibers 120a, 120b and 120c are reduced by the vibrator 130 to reduce coherency.

As shown in FIG. 4, the vibrator 130 has a plurality of holes 135 to allow the first, second and third optical fibers 120a, 120b, and 120c to enter. The second and third optical fibers 120a, 120b, and 120c enter the holes 135 and penetrate the vibrator 130.

The first to third lights transmitted through the first, second, and third optical fibers 120a, 120b, and 120c are spatially coherent light, and proceed with the same phase. Therefore, when the first to third light are synthesized and transmitted through a portion of the screen, interference occurs with light transmitted from adjacent portions of the screen, resulting in a speckle phenomenon.

Therefore, the vibrator 130 vibrates the first, second, and third optical fibers 120a, 120b, 120c with an oscillation width of several hundreds of micrometers, thereby causing the first, second, and third optical fibers 120a. Reduces coherence of the first to third light transmitted through 120b and 120c.

As described above, in the laser light synthesizing apparatus of the present invention, the first to third light interferences transmitted through the first, second, and third optical fibers 120a, 120b, and 120c using the vibrator 130. By reducing the coherency, speckles in the image of the laser display can be eliminated.

As described above, the vibrator 130 may vibrate the first, second, and third optical fibers 120a, 120b, and 120c at once, as shown in FIG. Vibrators 130a, 130b, and 130c may be provided in each of the second and third optical fibers 120a, 120b, and 120c to vibrate each optical fiber individually.

The first to third lights having the reduced coherence through the vibrator 130 continue to pass through the first, second and third optical fibers 120a, 120b, and 120c, and then the light synthesis system 140 Are synthesized.

That is, as shown in Figure 6, the light synthesis system 140 is in contact with the ends of the first, second and third optical fibers 120a, 120b, 120c, the first to third light Emitted from the ends of the first, second and third optical fibers 120a, 120b, 120c and combined with the light synthesis system 140, wherein the first to third light are synthesized in the light synthesis system 140. do.

The optical synthesis system 140 may synthesize the first, third, and third light emitted from the ends of the first, second, and third optical fibers 120a, 120b, and 120c. The diameter size of the optical fibers 120a, 120b and 120c should be larger than the sum of the diameter sizes.

The length of the light synthesis system 140 is preferably set to 1 ~ 2 cm, the light synthesis system 140 is made of an optical fiber or glass tube.

On the other hand, while the present invention has been shown and described with respect to specific preferred embodiments, various modifications and variations of the present invention without departing from the spirit or field of the invention provided by the claims below It will be readily apparent to one of ordinary skill in the art that it can be used.

According to the present invention, by transmitting and synthesizing the laser light generated by the semiconductor laser using the optical fiber, it is not necessary to control the size of the laser light (beam size) generated by the semiconductor laser, it is possible to miniaturize the laser light synthesizing apparatus Will be.

In addition, by using the vibrator to vibrate the optical fiber by reducing the coherence of the laser light transmitted through the optical fiber, it is possible to eliminate the speckle phenomenon appearing in the image of the laser display.

Claims (6)

A plurality of semiconductor lasers generating and emitting light having different wavelengths; A plurality of optical fibers coupled to each of the plurality of semiconductor lasers and transmitting light of different wavelengths emitted from the plurality of semiconductors; A plurality of holes formed therein to allow the plurality of optical fibers to enter therein, the vibrator for vibrating the optical fibers to reduce the interference of light transmitted through the optical fibers; And And a light synthesizing system connected to the ends of the plurality of optical fibers to synthesize light of different wavelengths emitted from the optical fibers. The laser light synthesizing apparatus according to claim 1, further comprising a plurality of focusing lenses for focusing light of different wavelengths generated and emitted by the plurality of semiconductor lasers onto the plurality of optical fibers. The laser light synthesizing apparatus according to claim 1, wherein the light having different wavelengths comprises light having red, green, and blue wavelengths. The laser light synthesizing apparatus according to claim 1, wherein the plurality of semiconductor lasers are first, second and third semiconductor lasers which generate and emit light having red, green, and blue wavelengths, respectively. The laser light synthesizing apparatus according to claim 1, wherein the optical fiber has a diameter of 50 to 100 µm and a length of 3 to 4 cm. The laser light synthesizing apparatus according to claim 1, wherein the light synthesizing system is made of an optical fiber or a glass tube.

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