JPH0445478A - Laser display - Google Patents

Abstract

PURPOSE:To obtain a laser display device whose thinness of the device, light weight, long service life, high stability, and low cost can be applied to a high-definition television by using as a light source a semiconductor laser, a solid-state laser, which is a combination of a semiconductor laser and a second higher harmonic wave generating element, or a solid- state laser, which is a combination of a semiconductor laser and a non-linear type optical element. CONSTITUTION:The small red laser light source, which is a combination of the 1,300nm wavelength semiconductor laser and the second higher harmonic wave generating element of the waveguide type composed of a LiTaO3 substrate and a LiNbO3 thin film formed thereon, the small green laser light source, which is a combination of the 1,090nm wavelength semiconductor laser and the element of the same type, and the small blue laser light source, which is a combination of the 880nm wavelength semiconductor laser and the element of the same type, are used as the laser light sources. Each laser beam is condensed by a lens so that it enter from the end of a light deflector 1 of the waveguide type. At this time, by changing the incident angle of each laser beam and by changing a voltage applied to an electrode, the deviation in deflection angle made by the wavelength is corrected so that the optical paths of the laser beams emitting from deflector 1 are always coincident with each other. These laser beams are abutted on a 11mm high, octahedron polygon mirror 2. The laser beams of the three primary colors deflected in horizontal and vertical directions by the mirror 2, are projected onto a screen after correction by a lens.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a display device using a laser beam as a light source, and is particularly applicable to a thin, lightweight, long-life, high-stability, low-priced, and high-definition television. This invention relates to a laser display device that can be used.

(Prior art) Laser displays display and record images by scanning an output medium such as a screen or film with a laser beam spot whose intensity is modulated by a video signal. It has various advantages such as single wavelength property, and is widely used in various industrial and medical fields.

As such a laser display, for example, NHK Technical Monthly Report, pp. 330-334, 1985, 3
A gas laser such as a He-Ne laser (red), an Ar laser (green), or a He-Cd (blue) is used as a primary color laser light source, and after being modulated by an optical modulator, it is collimated by a lens system, and then horizontally An apparatus has been disclosed in which an image is projected by deflecting the image using a polygon mirror, further deflecting the image in the vertical direction using a galvanometer, and scanning the image on a screen.

(Problems to be Solved by the Invention) However, such laser displays use gas lasers as light sources, and gas lasers are large, expensive, unstable and short-lived, and require an external modulator. As a result, the entire device becomes complicated, large, and heavy.

In addition, small solid-state lasers such as semiconductor lasers have a wavelength of 600 nm.
Shorter wavelength regions have not been put to practical use, and it has been difficult to obtain practical semiconductor lasers for green and blue, which are necessary for the three primary colors.

In addition, the deflection speed of the polygon mirror and galvanometer is
The limits are about 30 kHz and about 60 to 100 Hz, respectively. In order to use a polygon mirror and a galvanometer for horizontal and vertical deflection of laser light, the required performance of the display is 30K in the horizontal direction.
Since a deflection speed of Hz or higher and a deflection speed of 60Hz or higher in the vertical direction is required, the device must be used at the limit of its performance, and for long periods of time.
It has been practically difficult to use a television set that operates continuously.

As a result of intensive research, the present inventors have found that by using a semiconductor laser as a light source, a solid-state laser that combines a semiconductor laser and a second harmonic generation element, or a solid-state laser that combines a semiconductor laser and a nonlinear optical element, The inventors have newly discovered that the above-mentioned problems can be solved by obtaining the red, green, and blue laser beams necessary for the primary colors, and by using a waveguide-type optical deflection element as the horizontal deflection means, and have completed the present invention. .

(Means for solving the problem) The present invention uses laser beams having multiple wavelengths as a light source, modulates these laser beams with an image signal, and then deflects the laser beams in the horizontal and vertical directions by a deflection means, and A laser display that outputs an image corresponding to an image signal on an output medium by scanning the top, and the light source is a semiconductor laser, a solid-state laser combining a semiconductor laser and a second harmonic generation element, or a semiconductor laser. A waveguide type optical deflection element is configured by a combination of a solid-state laser that is a combination of a laser and a nonlinear optical element, and uses an electro-optic effect or an acousto-optic effect as a deflection means for deflecting the laser beam in the horizontal direction. This laser display is characterized in that a rotating polygon mirror or a rotating hologram disk is used as a deflecting means for deflecting the image in the vertical direction.

(Function) The present invention uses laser light having multiple wavelengths as a light source, modulates the laser light with an image signal, and then deflects the laser light in the horizontal and vertical directions using a deflection means to scan the output medium. is necessary.

By scanning the laser ribbon over the output medium in this manner, the image information contained in the electrical signal can be clearly visualized on the output medium.

Preferably, the output medium is a screen.

The screen may be made of cloth or paper coated with glass powder, glass or translucent glass, or plastic.

It is preferable that the light source consists of three primary colors of red, green, and blue laser light.

The light source used in the present invention must be composed of a semiconductor laser, a solid-state laser that combines a semiconductor laser and a second harmonic generation element, or a combination of a solid-state laser that combines a semiconductor laser and a nonlinear optical element. .

The reason for this is that solid-state lasers are cheaper, smaller, more stable, have a longer lifespan, and are better suited for mass production than gas lasers.

Further, the second harmonic generating element is an element for halving the wavelength of light, and the nonlinear optical element is
Sum frequency mixing (when light with wavelengths λ1 and λ2 enters a nonlinear optical element, the wavelength λ3 of the output light is 1/λ1+1/λ2-1
/λ3, and the action of such a nonlinear optical element is called sum frequency mixing), so these second harmonic generation elements By injecting semiconductor laser light in the infrared wavelength range, which has already been put into practical use, into a nonlinear optical element, it is possible to obtain green or blue laser light, which has not been previously possible with solid-state lasers.

The three primary color laser beams constituting the light source include the following 1:
) to 3) are preferable.

1) A configuration in which a semiconductor laser is used as the red laser, and a solid-state laser that is a combination of a semiconductor laser and a second harmonic generation element is used as the green laser and the blue laser.

The reason why a semiconductor laser is directly used as the red laser is that a 600 nm band semiconductor laser is already in practical use, and it is more efficient to use a semiconductor laser as a direct light source.

Further, the wavelengths of the semiconductor lasers used for the red laser, green laser, and blue laser are 600 to 84, respectively.
0nm, 980-1100nm, 760-980n
Advantageously, m.

2) As red laser, green laser and blue laser,
A form that uses a solid-state laser that combines a semiconductor laser and a second harmonic generation element.

The wavelength of the semiconductor laser used for the red laser, green laser, and blue laser is 1200 to 160, respectively.
Advantageously, the wavelength is 0 nm, 980-1100 nm, 760-980 nm.

3) As red laser, green laser and blue laser,
A form that uses a solid-state laser that combines two types of semiconductor lasers with different wavelengths, a second harmonic generation element, and a nonlinear optical element.

The two types of semiconductor lasers having different wavelengths are 1200~
Laser light A emitted from the semiconductor laser A preferably has a wavelength of 1600 nm (semiconductor laser A) and a wavelength of 760-980 nm (semiconductor laser B).
The harmonic generation element converts the laser beam B into a red laser beam, and the second harmonic generation element converts the laser beam B into a blue laser beam. Furthermore, the laser beam A and the laser beam B are simultaneously converted into a nonlinear optical element. incident,
Green laser light can be obtained by performing sum frequency mixing, and the second harmonic generation element used in the present invention can be either a bulk type or a waveguide type, but is not limited to the following. In particular, the second harmonic generation element shown below, that is, the second harmonic generation element in which a thin film waveguide layer is formed on a substrate, has a fundamental laser light wavelength (λμm), a film thickness of the thin film waveguide layer. (1μm), fundamental laser light wavelength (λμm
), the ordinary refractive index of the thin film waveguide layer (n(IF+)) at the fundamental laser wavelength (λμm), and the extraordinary refraction of the substrate at the second harmonic wavelength (λμm/2). The extraordinary refractive index (nBz) of the thin film waveguide layer at the index (n*sZ) and the second harmonic wavelength (λμm/2) is expressed by the following relational expression: Preferably, it is a second harmonic generating element.

However, N in the above relational expression (A) is also N2 in the above relational expression (B). The second harmonic generation element is formed by forming a thin film waveguide layer on a substrate, and has an ordinary refractive index of the substrate and the thin film waveguide layer for the fundamental laser beam, and for the second harmonic. By setting the extraordinary light refractive index and the thickness of the thin film waveguide layer to a structure that satisfies the above relational expression (A) or (B), it is possible to generate second harmonic light with respect to a specific fundamental laser light.

The structure of the second harmonic generation element needs to be such that a thin film waveguide layer is formed on a substrate.

The reason for this is that the generation of second harmonic light in a second harmonic generation element in which a thin film waveguide layer is formed on a substrate can utilize the energy of light concentrated in the thin film, and that the light waves are confined within the thin film. Not only does it have the advantage of not spreading, allowing interaction to occur over a long distance, but it also cannot be phase matched with conventional second harmonic generation elements using bulk single crystals. This is because even materials have the advantage of being able to achieve phase matching by utilizing the mode dispersion of a thin film.

The second harmonic generation element has a fundamental laser light wavelength (λ
μm), the film thickness of the thin film waveguide layer (1 μm), and the ordinary refractive index of the substrate at the fundamental laser light wavelength (λ μm) (n031
), the ordinary refractive index (n.Fl) of the thin film waveguide layer at the fundamental laser light wavelength (λμm), and the second harmonic wavelength (λ
The extraordinary refractive index (n*sz) of the substrate at the wavelength (μm/2) and the extraordinary refractive index (naF) of the thin film waveguide layer at the second harmonic wavelength (λμm/2) are (neF□ esZ or ( It is necessary to satisfy one of the relational expressions 11aF□tr52.

However, N in the above formula (A) is: This is because unless the structure satisfies either of the relational expressions (A) or CB), the conversion efficiency to second harmonic light will be low and it will not be practical.

In particular, in order to obtain high conversion efficiency to second harmonic light, the wavelength of the fundamental laser light (λμm), the thickness of the thin film waveguide layer (Tμm)
), the ordinary refractive index of the substrate (nllsll) at the fundamental laser light wavelength (λμm), the fundamental laser light wavelength (λ
Ordinary refractive index of thin film waveguide layer (nllF+) in μm)
, the extraordinary refractive index (nssz) of the substrate at the second harmonic wavelength (λμm/2) and the second harmonic wavelength (λμm/2
), the extraordinary refractive index (n*rz) of the thin film waveguide layer is
(naF□−n1□) It is preferable to satisfy the following relational expression (A′), and it is especially advantageous to satisfy the following relational expression (A″).

λ3 T However, it is preferable that N in the above relational expressions (A) and (A'') satisfy the following relational expression (B), and in particular, it is preferable that the following relational expression (B'') be satisfied. It is advantageous.

However, N2 in the above relational expressions (Bo) and (B'') is such that the second harmonic generation element has an incident angle (θ) of the fundamental laser beam with respect to the optical axis (Z axis) of the thin film waveguide layer. ,0±1
Preferably, the angle is within the range of 5° or 90±15°.

The reason is that the incident angle (θ) of the fundamental laser beam is
This is because within the above range, the conversion efficiency to the second harmonic is extremely high. The angle of incidence of the fundamental laser beam is preferably within the range of 0±5° or 90±5°.

The wavelength (λ) of the fundamental laser beam incident on the SHG element of the present invention is preferably 0.4 to 1.6 μm.

The reason for this is that although it is advantageous for the fundamental wave laser light (λ) to have a wavelength as short as possible, it is practically impossible to generate laser light with a wavelength shorter than 0.4 μm using a semiconductor laser. This is because it is difficult;
On the other hand, when a fundamental laser beam with a wavelength longer than 1.6 μm is used, the wavelength of the second harmonic obtained is 1/2 of the fundamental laser beam, so it can be generated relatively easily by directly using a semiconductor laser. This is because no advantage can be found in using the second harmonic generation element in the wavelength range where it can be used. Wavelength of fundamental wave laser light (λ)
is 0.6 to 1, which is relatively easy to obtain a semiconductor laser light source.
．． 3 μm is advantageous, especially 0.68-0.94
μm is practically suitable.

The thickness (T) of the thin film waveguide layer of the second harmonic generating element is preferably 0.1 to 20 μm.

The reason is that the thickness (T) of the thin film waveguide layer is 0.1 μm.
This is because if it is thinner than 20 μm, it is difficult to make the fundamental laser beam incident and the incidence efficiency is low, making it difficult to obtain substantially high SHG conversion efficiency.On the other hand, if it is thicker than 20 μm, the optical power density is low, SHG conversion efficiency becomes low (
However, in either case, it is difficult to use it as a second harmonic generating element. The thickness of the thin film waveguide layer is preferably 0.2 to 10 μm, and particularly preferably 0.4 to 8 μm for practical purposes.

Various optical materials can be used for the substrate and one-film thick wave layer in the second harmonic generation element, and examples of the thin film waveguide layer include L i N b Oy, α-quartz, and KTiO.
PO, (KTP), β-BaBzOa (BBO), KB
,O,・4 H20(KBs ),KH2PO,(KD
P), KD2PO, (KD'″P), NH,H,PO
, (ADP), C, H2ASOa (CDA), C
s Dz As0a (CD'''A), RbH2P○
= (RDP), RbHz AsO, (RDA), B
eS○,・4H,○,LiClO43Hz O,Li
IOs ,α-LiCdBO,l,L i B,O,(
LBO), urea, polyvalanitroaniline (p-PN
A), polydiacetylene (DCH), 4- (N, N-
dimethylamino) 3-acetamidonitochonzene (D
AN), 4-nitrobenzaldehyde hydrazine (N
BAH), 3-methoquino-4-nitrobenzaldehyde hydrazine, 2-methyl-4-21-roaniline (M
NA), etc., and as a substrate, for example, LiTaO3
, LiNbO3 substrate with LiTa0z Fit film formed, optical grade LiNb○ with LiTa03gt film formed, substrate, SiO□, alumina, KTP,
BBO5LB○, KDP, and similar compounds, soda glass, Pyrexos glass, polymethyl methacrylate (
PMMA) etc. can be used. The materials for the substrate and thin film waveguide layer include Na, Cr, Mg, Nd, T.
By containing a different element such as i, the refractive index can be adjusted.

As a method for incorporating different elements such as Na, Cr, Mg, Nd, and Ti, the raw materials and impurities are mixed in advance, and a thin film waveguide layer is formed on a single crystal substrate using the LPE method. Alternatively, it is preferable to use a diffusion method in which impurities such as Na, MgNd, and Ti are diffused into the single crystal substrate or thin film waveguide layer.

Further, as a combination suitable for the second harmonic generating element,
The thin film waveguide layer/single crystal substrate is 2-methyl-4-nitroaniline (MNA)/SiOz; 2-methyl-
4-nitroaniline (MNA)/alumina; KT i
OPO, (KTP)/Alumina; βBaB, O, (B
BO)/Alumina; 4-(NN-dimethylamine)~3
-acetamidonitrohenzene (DAN)/Si○z;
4(N,N-methylamine)-3-ruatamide nitride (DAN)/polymethyl methacrylate (PMM,
A) i L + Bz Os (L Be)/B
BO, LB○/Be Mina, RbH, PO, (RDP)/
K.H.

PO, (KDP)i polyparanitroaniline (ρPNA
)/PMMA, etc.

Among the combinations suitable for the second harmonic generation element, a combination using LiTaO3 as the single crystal substrate and L + N b Oy as the thin film waveguide layer is particularly suitable.

The reason for this is that LiNbOx has a large nonlinear optical constant, low optical loss, and can form a uniform film, and LiTaO3 has a similar crystal structure to LiNb○3. and the LiNb
0. This is because it is easy to form a yi film and it is easy to obtain high quality and inexpensive crystals.

Further, it is advantageous that the second harmonic generation element is a channel type having a width of 1 to 10 μm. The reason why a chisene-type SHG element is advantageous is that it can increase the optical power density compared to a slab type, and it also has a width of 1
The reason why it is advantageous to have a width of ~10 μm is that the width is 1 μm.
This is because if the width is smaller, it is difficult to introduce the incident light into the waveguide, and the incidence efficiency is low, resulting in a low SHG conversion efficiency.On the other hand, the incidence efficiency is higher as the width is larger, but it is larger than lOl, Im. This is because the optical power density decreases and the SHG conversion efficiency decreases. Said second
It is desirable that the harmonic generation element has a wavelength-selective thin film formed at its input end to selectively transmit fundamental wavelength light.

It is desirable that the second harmonic generation element of the present invention has a wavelength selective thin film formed on its output side to remove fundamental wavelength light.

Furthermore, by forming the wavelength-selective thin film directly on the emission end face and adjusting it to satisfy the anti-reflection conditions for second harmonic light, a large difference in refractive index between the lithium niobate single crystal thin film layer and air can be realized. Because of this, it is possible to reduce the loss due to reflection that occurs at the output end face, and it is possible to improve the SHG output.

The wavelength-selective thin film may be formed at a position remote from the output end face behind the output end face, or may be fixed on the output end face using a suitable adhesive.

When fixing on the output end face using the adhesive, it is desirable to improve the SHG output by adjusting the refractive index and thickness of the adhesive layer to meet anti-reflection conditions for the second harmonic light.

The wavelength selective thin film may include a colored glass filter,
A glass substrate coated with a wavelength-selective interference film can be used.

Materials for the wavelength selective thin film include SiOx, M
oxides such as gO, ZnCL Al2O2, Li NbO
3, L 1Taoz, Yx Gas○1, Gd3Ga
, 01□, etc., or a composite oxide such as PMMA, MNA, etc. can be used, and a multilayer thin film made by stacking these can also be used.

Methods for producing the wavelength selective thin film include sputtering method, liquid phase epitaxial method, vapor deposition method, and MBE (Molecular Beam Epitaxial method).
M Epitaxial) method, MOCVD (Meta
l Organic Chemical Vap
or Deposit.

n) method, ion blating method, LB method, spin code method, Dimbu method, etc. can be used.

The method for manufacturing the channel-type second harmonic generating element includes, for example, forming a thin film waveguide layer on the substrate by sputtering or liquid phase epitaxial growth, and then further forming the thin film waveguide layer on the thin film waveguide layer. A Ti waveguide pattern is formed by photolithography and RF sputtering, and this is used as an etching mask to perform ion beam etching to adjust the thickness of the phase matching film, or after forming an etching mask, ion beam etching is performed. , then remove the enching mask,
It is possible to use a method such as performing ion beam etching again and adjusting the thickness of the phase matching film to create a channel type second harmonic generating element.

Further, it is desirable that the second harmonic generation element used in the present invention has a cladding layer formed on the thin film waveguide layer.

The reason for this is that by providing the cladding layer on the thin film waveguide layer, the substrate, the thin film waveguide layer, and the cladding layer become nearly symmetrical with respect to the refractive index. The distribution can be made symmetrical, and even if the thickness of the thin film waveguide layer does not completely match the theoretical phase matching film thickness, the decrease in the output of the second harmonic light can be alleviated. This is because a second harmonic generation element with a wide tolerance range and high conversion efficiency can be obtained.

Further, the cladding layer functions as a protective layer, and can prevent light scattering due to breakage of the waveguide layer or adhesion of dust and dirt, and can completely prevent chipping of the waveguide layer, which is a problem in end face polishing.

Further, it is desirable that the cladding layer satisfies relational expressions 1) and 2).

nos 0.50≦nOc≦no, -0,05...Formula 1
) n,,s O,70≦n1lc≦n, s-0,15
- Equation 2) n05: Ordinary refractive index of the substrate at the fundamental laser light wavelength (λμm) n6c: Ordinary refractive index n of the cladding layer at the fundamental laser light wavelength (λμm), 5: Second harmonic wavelength (λμm/ The extraordinary refractive index of the cladding layer at the second harmonic wavelength (λμm/2) is the extraordinary refractive index of the substrate n*c' in 2). This is because the electric field distribution of the second harmonic light and the fundamental laser light can be maximized, and a second harmonic generation element with a wide tolerance range of phase matching film thickness and high conversion efficiency can be obtained.

In particular, in order to expand the allowable range of phase matching errors in film thickness, it is preferable to satisfy equations 3) and 4).

n,, -0,25≦noc≦nosO,10...Formula 3
) neS-o, ss≦n, c≦n@$-0,20-, Formula 4) n0 Ordinary refractive index of the substrate at the fundamental laser light wavelength (λμm) - noc at the fundamental laser light wavelength (λμm) Ordinary refractive index of the cladding layer n, , : Extraordinary refractive index of the substrate at the second harmonic wavelength (λμm/2) n, c: Extraordinary refractive index of the cladding layer at the second harmonic wavelength (λμm/2) , the thickness of the cladding layer of the second harmonic generating element is:
A thickness of 0.2 to 30 μm is desirable. The reason for this is 0.2μm
This is because if it is thinner, the guided light cannot be confined, and if it is thicker than 30 μm, the crystallinity of the cladding layer decreases and the optical characteristics deteriorate.

The cladding layer preferably has a thickness of 0.5 to 10 μm, and a thickness of 1 to 10 μm.
8 μm is suitable.

The cladding layer can use various optical materials,
Zn○, MgO1A 1. z Os , P M M
A.

SiO□, Pyrex glass, soda glass, etc. can be used, and ZnO is particularly suitable.

In the second harmonic generation element used in the present invention, it is preferable that the hair tip of the semiconductor laser is bonded to form a pancage so that the laser beam is incident on the thin film waveguide layer of the SHG element.

The package is preferably airtight,
Preferably, an inert gas such as nitrogen gas is sealed.

Further, it is preferable that the laser beam emitting portion of the package is formed with a window into which a wavelength selective plate or thin film is fitted.

Next, the second harmonic generation element used in the present invention can be manufactured by forming a thin film waveguide layer on a single crystal substrate by a method such as sputtering or liquid phase epitaxial growth. Then, a T1 waveguide pattern is formed on the thin film waveguide layer by photolithography and RF sputtering, and this is used as a etching mask for ion beam etching, or after this, the etching mask is removed and ion beam etching is performed again. The film thickness can be adjusted by beam etching to create a channel type second harmonic generating element.

In the present invention, it is preferable that the plurality of modulated laser beams be manually applied to the deflecting means after propagating along the same path.

The reason for this is that when complex laser beams propagate through separate paths, each laser beam requires an optical component, a space for propagation, and a separate deflection means, which increases the number of components. This is because the equipment becomes large and expensive, and mass productivity decreases.

It is advantageous for the same path to be an optical fiber or an optical waveguide. For example, there may be a plurality of laser beam entrance parts, and a plurality of optical fibers or optical waveguides for guiding the laser light from the entrance parts may be connected to one midway. Possible structures include a structure assembled along the route of a book.

When an optical waveguide is used as the same path, it is preferable that a second harmonic generation element or a nonlinear optical element is incorporated in the optical waveguide itself.

In the present invention, a deflection means is necessary for scanning the scanning line, and the horizontal direction deflection is performed by a waveguide type optical deflection element using the electro-optic effect or the acousto-optic effect, and the vertical direction deflection is , it is necessary to use a polygon mirror (rotating polygon mirror) or a rotating hologram disk.

The reason why a waveguide-type optical deflection element using an electro-optic effect or an acousto-optic effect is used as the horizontal deflection means is that the waveguide-type optical deflection element using an electro-optic effect or an acousto-optic effect is: High-speed scanning of several hundred KHz to several tens of MHz is possible, and there is sufficient margin compared to the scanning speed of several tens of kHz required for horizontal deflection, allowing continuous use for long periods of time and providing high reliability. It is from.

Further, since the waveguide type optical deflection element using the electro-optic effect or the acousto-optic effect is a non-mechanical deflector, it has advantages such as being small and stable, low cost, lightweight, and having little vibration and noise.

Furthermore, the reason why a polygon mirror (rotating polygon mirror) or a rotating hologram disk is used as the vertical deflection means is that the vertical scanning speed may be about 60 Hz, so a polygon mirror, which is a mechanical deflector, is used. Alternatively, even if a rotating hologram disk is used, there is sufficient margin and it can withstand continuous use for a long time.

Further, the distance from the waveguide type optical deflection element using the electro-optic effect or the acousto-optic effect to the polygon mirror is 2
It is preferable that it is 0 mm or less.

The reason for this is explained as follows.

The deflection angle of the waveguide type optical deflection element using the electro-optic effect or the acousto-optic effect is preferably 30° or more, and considering reliability and stability during high-speed rotation of the polygon mirror, The weight must be as light as possible, so the height of the polygon mirror is 10 mm.
Since the degree of deflection is a limit, it is preferable to set the distance from the waveguide type optical deflection element to the polygon mirror to be 20 mm or less in order to receive and reflect all the deflected light on the deflection surface of the polygon mirror.

The waveguide type optical deflection element used in the present invention has a thin film waveguide layer formed on a substrate, and has a light input section on one side.
The other side has an output section, and the thin film waveguide layer has a means for changing the effective refractive index of the waveguide by an electro-optic effect, or a means for deflecting light within the plane of the waveguide by an electro-optic effect or an acousto-optic effect. It is desirable to have the following.

The input section is preferably of an edge incidence, prism incidence, or grating incidence type.

The output section can take out the light deflected within the waveguide plane as it is at the end face, or by using a prism coupler or a grating coupler. Providing a prism coupler or grating coupler that can emit light is advantageous because a large deflection angle can be obtained in the direction perpendicular to the waveguide surface.

Further, it is preferable that the prism coupler has a means for changing the refractive index, such as an electrode.

Furthermore, if the incident light is to be deflected in the plane of the waveguide, a grating with a specific angle relative to the incident light is advantageous as an output.

By using such a grating as the output part,
A large deflection angle can be obtained in the direction perpendicular to the waveguide plane.

The grating having a specific angle with respect to the incident light may have a form in which the period changes continuously in a fan shape, and a grating having an inclination angle φ with respect to the direction perpendicular to the direction of incidence of the guided light in the waveguide plane. Although the latter configuration is advantageous, a larger deflection angle can be obtained.

The inclination angle φ is preferably 30 to 85 degrees.

The reason for this is that the larger φ is, the larger the output deflection angle can be obtained even if the in-plane deflection angle is small, but the larger φ is, the lower the deflection efficiency is, so the above range is desirable.

It is preferable that the inclination angle φ is 45 to 80''.

The means for changing the effective refractive index of the waveguide of the optical deflection element of the present invention by an electro-optic effect, and the means for deflecting light within the plane of the waveguide by an electro-optic effect or an acousto-optic effect are provided on both sides of the channel-type waveguide. A method of changing the effective refractive index of a channel waveguide using the electro-optic effect by providing an electrode and applying an electric field.A method of changing the effective refractive index of a channel waveguide by applying an electric field to the lower part of the substrate and the upper part of the slab type or channel type waveguide. A method of changing the effective refractive index of a slab-type or channel-type waveguide by electro-optic effect, applying an electric field by providing a comb-shaped or other shaped electrode within the waveguide or at the top or bottom of the waveguide corresponding to the optical propagation path of the waveguide. A method of deflecting light within a plane using the electro-optic effect, and a method of creating a surface acoustic wave in the optical propagation path by applying an electric field by providing a comb-shaped electrode for generating surface acoustic waves in the plane of the waveguide. Therefore, a method in which light is deflected within a plane by an acousto-optic effect is preferable.

Further, as a means for changing the effective refractive index of the waveguide by electro-optic effect, it is possible to provide the waveguide with a gradient in the direction perpendicular to the light propagation direction and deflect the light within the waveguide plane.

As the waveguide of the optical leakage element used in the present invention, Li
Ta0. A thin film of L IN b Oz is formed on a single crystal substrate, and a thin film of LiTa01 is formed on a L i N b Oz substrate.
A thin film was formed and then LiNb○, a thin film was formed, LiTa0. SrX Bat-x N on a single crystal substrate
bz 06 (SBN) with Fi film formed, 5BNFi on 31 substrate with 510zTil film formed on the surface layer
Qd3 Gas olZ (GGG
), Ndi Gas○l 2 (Nd G G
), S m 3 Gas OIz (S m G
5BNI film formed on a garnet substrate such as G), BaTiO3 single crystal thin film formed on a PbTiO3 single crystal substrate, KN b O, K on a single crystal substrate
(Nb.

Ta1-)Oi (KTN)Fi film formed.

Although a PLZTi film formed on a PLZT ceramic substrate can be used, in particular, a LiNb Ox thin film formed on a LiTa01 single crystal substrate is most suitable because of its large electro-optic effect.

Devices that modulate the intensity of laser light using image signals used in the present invention include bulk type or waveguide type optical modulators using an acousto-optic effect, and bulk type or waveguide type optical modulators using an electro-optic effect. Although there are direct modulation methods in which a modulation signal is input to a modulator or even a semiconductor laser as a light source, the direct modulation method is particularly desirable.

The reason for this is that when considering high-definition televisions such as high-definition television, a modulation band of 20 to 30 MHz is required, but ordinary semiconductor lasers can directly modulate up to several hundred MHz, and the direct modulation method is used. This is because an external modulator is not required, making it possible to reduce the cost and size.

In addition, the optical system of the present invention is as shown in FIG. The light can be input to the waveguide type optical deflector by end face incidence, end face incidence after condensing with a lens, prism incidence, grating incidence, or the like.

It is preferable that the laser beam emitted from the waveguide type optical deflector is focused or beam-shaped by a lens or the like as necessary, and then made incident on a polygon mirror or a rotating hologram disk. Furthermore, the laser beam reflected from the polygon mirror or the laser beam emitted from the rotating hologram disk is passed through an optical system such as a lens for tilt correction or beam shaping, if necessary, before being projected onto the screen. Projection is preferred.

Although Fig. 2 shows a waveguide-type optical deflector that uses a grating output coupler to deflect light in a direction perpendicular to the waveguide surface, it is also possible to use an electro-optic effect or an acousto-optic effect. It is also possible to use a waveguide type optical deflector that deflects light in a plane.

[Example C Hereinafter, the present invention will be explained in more detail with reference to Examples.

As a laser light source, a semiconductor laser with a wavelength of 1300 nm and LiTa0. A small red laser light source that combines a waveguide type second harmonic generation (SHG) element formed by forming an L+NbO3 thin film on a substrate, and a waveguide type formed by forming a semiconductor laser with a wavelength of 11090n and a LiNb0z thin film on a LiTaO35 plate. A small green laser light source that combines an SHG element, a semiconductor laser with a wavelength of 880 nm, and LiT
a0. Using a small blue laser light source that combines a waveguide type SHG element formed by forming a thin film of L+Nb0 on a substrate, the light is focused by each lens, and the end face is connected to a waveguide type optical deflector using an electro-optic effect. It was made incident from At this time, red,
The green, blue, and blue laser beams each have different incident angles with respect to the grating output coupler, and the electro-optic effect is synchronized with the modulation signal applied to the semiconductor laser to oscillate the red, green, and blue laser beams. By changing the voltage applied to the electrodes to cause optical deflection, the deviation in the deflection angle due to wavelength is corrected, and the optical paths of the red, green, and blue laser beams emitted from the waveguide type optical deflector are always aligned. I decided to do so.

This laser beam was applied to an octahedral polygon mirror with a height of 11 mm, and the polygon mirror was rotated at 450 revolutions per minute to deflect the light at 60 Hz in the vertical direction. In this way, 30 in each horizontal and vertical direction.
Laser beams of three primary colors, which were deflected at KHz and 60 KHz, were projected onto a screen after correction for surface tilt etc. using an f/theta lens and a cylindrical lens.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide a laser display device that is thin, lightweight, long-life, excellent in stability, and can be applied to high-definition televisions such as high-definition television at a low price. can.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of the present invention, and particularly shows a method of vertical deflection using a polygon mirror. FIG. 2 is a perspective view illustrating the deflection means of the present invention,
FIG. 2 is a diagram showing horizontal optical deflection by a waveguide type optical deflector and vertical optical deflection by a polygon mirror. 1... Waveguide type optical deflector 2... Polygon mirror 3... Lens 4... Screen 5... Laser light source

Claims (1)

[Claims] 1) Using laser beams having multiple wavelengths as a light source, modulating these laser beams with an image signal, and then deflecting the laser beams in the horizontal and vertical directions by a deflection means to scan an output medium. A laser display that outputs an image corresponding to an image signal on an output medium, the light source being a semiconductor laser, a solid-state laser combining a semiconductor laser and a second harmonic generation element, or a semiconductor laser and a nonlinear optical element. A waveguide-type optical deflection element using an electro-optic effect or an acousto-optic effect as a deflection means for deflecting the laser light in the horizontal direction, and a waveguide type optical deflection element that deflects the laser light in the vertical direction. 1. A laser display characterized in that a rotating polygon mirror or a rotating hologram disk is used as a deflecting means for deflecting. 2) Claim 1 in which the second harmonic generation element is formed by forming a LiNbO_3 thin film waveguide layer on a LiTaO_3 substrate.
Laser display described in. 3) The light source includes a red laser made of a semiconductor laser;
2. The laser display according to claim 1, comprising a green laser and a blue laser, each of which is a solid-state laser that is a combination of a semiconductor laser and a second harmonic generation element. 4) The wavelength of the semiconductor laser used for the red laser, green laser, and blue laser is 600 to 84, respectively.
4. The laser display according to claim 3, which has a wavelength of 0 nm, 980 to 1100 nm, and 760 to 980 nm. 5) The laser display according to claim 1, wherein the light source includes a red laser, a green laser, and a blue laser, each of which is a solid-state laser that is a combination of a semiconductor laser and a second harmonic generation element. 6) The wavelengths of the semiconductor lasers used for the red laser, green laser, and blue laser are each 1200 to 1
600nm, 980-1100nm, 760nm-98
The laser display according to claim 5, which has a wavelength of 0 nm. 7) The light source includes two types of semiconductor lasers with different wavelengths,
The laser display according to claim 1, comprising a second harmonic generation element and a nonlinear optical element. 8) The laser display according to claim 1, wherein the plurality of modulated laser beams are input to the deflection means after propagating along the same path. 9) The laser display according to claim 8, wherein the same path is an optical fiber or an optical waveguide. 10) The laser display according to claim 1, wherein the waveguide type optical deflection element is formed by forming a LiNbO_3 thin film waveguide layer on a LiTaO_3 substrate. 11) The laser display according to claim 1, wherein the distance between the waveguide type optical deflection element and the rotating polyhedron is 20 mm or less.