JPH0346286A - Laser oscillator - Google Patents

Abstract

PURPOSE:To enable the disturbed form and the intensity distribution of an output laser beam to be freely controlled by a method wherein a total reflection mirror is made to serve as a reflection type spatial light modulator which is optionally controllable in reflectivity spatial distribution or light phase change spatial distribution. CONSTITUTION:A total reflection mirror 14 of an optical resonator is formed of a reflection type spatial light modulator which is optionally controllable in reflectivity spatial distribution or light phase change spatial distribution. The reflection type spatial light modulator is a reflectivity spatial distribution type spatial light modulator 14A which takes advantage of a double refraction effecft of an electro-optical crystal 20. That is, when laser rays are made incident on the electro-optical crystal 20 through a polarizer 22 from a transparent electrode 24 side, they are reflected by a dielectric multilayered film 28 and travel through the electro-optical crystal 20 back in the opposite direction, whereby phase difference is induced in laser rays and the polarized wavefront is rotated. The laser rays, which pass through the polarizer 22 goes out of the electro-optical crystal 20, are converted in intensity change corresponding to the rotation of the polarized wavefront. By this setup, the ununiformity of laser output rays in intensity distribution can be optionally corrected or laser output rays can be set to an optional intensity distribution.

Description

[Detailed description of the invention] [Industrial application field]

This invention relates to a laser oscillator.

[Conventional technology]

It is generally known that the shape of an output laser beam from a laser oscillator changes depending on the shape of a mirror constituting an optical resonator or a spatial filter placed in the laser oscillator. Furthermore, when modulating the laser oscillation light by inserting an electro-optic crystal or an acousto-optic element into the laser oscillator to modulate the laser oscillation light or directly modulating the excitation source, the output It is known that the laser beam becomes irregularly shaped. In particular, when squid light from a laser oscillator is incident on a nonlinear optical crystal to obtain wavelength-converted light, there are variations in conversion efficiency due to non-uniformity of the nonlinear optical crystal, and wavelength conversion efficiency is proportional to the incident light density. It is known that the intensity distribution of the wavelength-converted light is such that the original incident light intensity distribution is emphasized, resulting in a more disordered output laser beam shape.

[Problem to be solved by the invention]

Conventionally, the laser beam shape shaping method used to shape the disturbance in the output laser beam shape as described above is as follows:
Since this is done using a fixed-shaped optical resonator mirror or spatial filter, there is a problem in that precise or flexible beam shaping corresponding to the shape of each laser beam is difficult. In particular, in solid-state lasers such as Nd and YAG lasers, there are large variations in characteristics between individual laser rods or excitation lamps, and the above-mentioned conventional methods cannot correct the irregular intensity distribution caused by such variations. The problem was that it was impossible. This invention was made in view of the above problems, and
It is an object of the present invention to provide a laser oscillator which can freely shape a disordered output laser beam shape and can freely adjust the intensity distribution of output light.

[Means to solve the problem]

The present invention includes a laser medium, an excitation source, and an optical resonator, and uses a total reflection mirror in the optical resonator to perform reflective spatial light modulation that can arbitrarily adjust the reflectance spatial distribution or the optical phase change spatial distribution. The above object is achieved by a laser oscillator characterized by having a laser oscillator. Further, the second invention includes a laser medium, an excitation source, and an optical resonator, and a transmittance spatial distribution or The above object is achieved by a laser oscillator characterized by disposing a transmissive spatial light modulator that can arbitrarily adjust the optical phase change spatial distribution. Furthermore, a third aspect of the present invention is a reflective space that includes a laser medium, an excitation source, and an optical resonator, and in which a total reflection mirror in the optical resonator can be arbitrarily adjusted to have a reflectance spatial distribution or an optical phase change spatial distribution. In addition to serving as an optical modulator, a transmissive space in which the transmittance spatial distribution or optical phase change spatial distribution can be arbitrarily adjusted is placed at any position in the optical path between the total reflection mirror and the exit side of the output mirror in the optical resonator. The above object is achieved by a laser oscillator characterized by disposing an optical modulator. Further, in the first, second or third invention, the above object is achieved by providing a feedback system that guides a part of the laser beam emitted from the output mirror in the optical resonator as writing light for the spatial light modulator. It is something to be achieved. Furthermore, in the first, second, or third invention, an imaging device that converts a part of the laser beam emitted from the output mirror in the optical resonator into a video signal, and processes this video signal to generate the spatial light. The above object is achieved by configuring the feedback system including an image processing device that converts the signal into an image signal as writing light of the modulator and outputs it to the spatial light modulator. Furthermore, in the first, second, or third aspect of the invention, the above object is achieved by providing an image signal generation device that generates an image signal as writing light for the spatial light modulator.

[Effect]

In the first invention of this application, the total reflection mirror in the optical resonator is constituted by a reflection type spatial/light modulator that can arbitrarily adjust the reflectance spatial distribution or the optical phase change spatial distribution, and the second invention is, A transmissive spatial light modulator capable of arbitrarily adjusting the transmittance spatial distribution or optical phase change spatial distribution is disposed at an arbitrary position in the optical path between the total reflection mirror and the exit side of the output mirror in the optical resonator, and In the third invention, the total reflection mirror is a reflection type spatial light modulator as described above, and a transmission type spatial light modulator is arranged at an arbitrary position in the optical path between the total reflection mirror and the output side of the output mirror. Therefore, by adjusting these reflectance spatial distributions or optical phase change spatial distributions in accordance with the output laser beam shape, the laser beam shape can be shaped freely.

【Example】

Examples of the first invention will be described below. The first invention, as shown in FIG.
, an excitation source 12 , a total reflection mirror 14 and an output mirror 1
6, and the total reflection mirror 14 is a reflective spatial light modulator in which the reflectance spatial distribution or optical phase change spatial distribution can be arbitrarily adjusted. There are various reflective spatial light modulators as optical parallel processing devices, but in the first embodiment of the first invention, as shown in FIG. 2, a reflectance spatial light modulator 14A is used.
This utilizes the birefringence effect of the electro-optic crystal 20. In FIG. 2, reference numeral 22 is a polarizer disposed between the laser a body 10 and the electro-optic crystal 20, and 24 and 26 are transparent T@ formed on the surface of the electro-optic crystal 20 on the polarizer 22 side.
and an antireflection film, and 28 indicates a dielectric multilayer mirror formed on the opposite side of the electro-optic crystal 20 from the transparent electrode. In the electro-optic crystal 20, the plane of polarization is rotated in accordance with the birefringence effect based on the anisotropy of the refractive index within the crystal, and after being reflected by the dielectric multilayer mirror 28, the electro-optic crystal 20 is redirected to the same polarizer 22.
When the light is passed through, intensity modulation occurs, which results in spatial intensity modulation. That is, depending on the applied voltage, the refractive index difference Δn in the x and y axis directions
(x, y) = nx (xSyi ny (X, y)) When an electric charge or potential spatial distribution is applied to the surface of the dielectric multilayer mirror 28 by a write signal using an electro-optic crystal 2o that produces 57 surface positions. The difference V from the constant potential vo applied to the transparent amount '@24 according to the distribution V (X, V)
(x, y) Refractive index difference spatial distribution Δn(
x, y) occurs. When laser light is incident on such an electro-optic crystal 20 from the transparent electrode 24 side through a polarizer 22 whose light leakage axis is in the 45° direction with respect to the x and y axes of the crystal, the linear leakage x and y axis polarization plane components of the laser light are By being reflected by the multilayer mirror 28 and reciprocating through the electro-optic crystal 20, Δn(x, y)
A phase difference corresponding to this occurs, leading to rotation of the waste wavefront.The light that exits the electro-optic crystal 20 and passes through the light leaker 22 again is converted into an intensity change in accordance with the rotation of the waste wavefront. That is, a reflectance spatial distribution can be effectively obtained according to the potential spatial distribution V(X, y) of the dielectric multilayer mirror 28. Next, a second embodiment of the first invention shown in FIG. 3 will be described. This second embodiment uses a Fapley-Bello interference effect type spatial light modulator 14B. This spatial light modulator 14B has an optical path length (n
xd; refractive index×thickness) An optical material 30 in which a change Δ(nd) occurs is used, and a transparent type @3 is used on the surface on the laser medium 10 side.
2 and a dielectric mirror 34 are laminated in this order, and a dielectric mirror 36 is laminated on the other surface. Here, the dielectric mirrors 34 and 36 have a reflectance R of 100%.
It is a partially reflecting mirror with a value slightly lower than that of optical material 3.
It is said to be a Fapley-Bello resonator with 0 as an etalon (spacer) layer. Alternatively, the optical material 30 may be an electro-optic material whose refractive index n in the direction perpendicular to the applied voltage changes depending on the voltage, or an electro-optical material having a thickness d.
There is a translucent piezoelectric material (piezoelectric polymer, piezoelectric ceramic, etc.) that changes depending on the voltage. In this embodiment, when an electric charge or potential spatial distribution is applied to the surface of the dielectric mirror 36, A transparent type f! that emits light according to the potential distribution V (x, y). Constant voltage VO applied to 32
Difference between V(X,'/) Optical path length change Δ corresponding to Vo
(nd) (X, y) occurs. When a laser beam with a wavelength λ is incident on such an optical material 30 from the transparent type i32 side, the reflected light intensity changes depending on the optical path length nd due to optical interference. That is, a reflectance spatial distribution can be effectively obtained according to the potential spatial distribution V(X, y) of the dielectric mirror 36. Next, a third embodiment shown in FIG. 4 will be described. This third embodiment utilizes an equal phase plane spatial distribution type spatial light modulator 14C, and includes an electro-optical material 38 whose refractive index n in the direction of the applied voltage changes according to the applied voltage, and this electrical A transparent electrode 40 and an antireflection film 42 are laminated in this order on the surface of the optical material 38 on the laser medium 10 side, and the transparent f! 40 and a dielectric mirror 44 formed on the opposite surface. In this embodiment, when a charge or potential distribution is applied to the surface of the dielectric mirror 44, the surface potential distribution v (X
, y), a refractive index spatial distribution n(x, y) corresponding to the difference V(X, Y) Vo from the constant voltage VO applied to the transparent mold @40 is generated. When a laser beam is incident on such an electro-optic material 38 from 40 transparent i8 poles, a phase change occurs according to n(x, y), and the equiphase plane of the laser beam is incident on the electro-optic material 38. It will change before and after exit. Such a change in the equal phase plane results in light leakage that bends the traveling direction of light, as in the case of an optical lens. Next, reflective spatial light modulators 14A to 14C as described above
An example in which a charge or potential distribution is applied to the surfaces of the dielectric mirrors 28, 36, and 44 will be described. This includes writing using optical signals, that is, optical writing, and writing using electrical signals, or electrical writing. FIG. 5 shows an example of optical writing using a photoconductor. In this embodiment, a dielectric mirror 46 (the dielectric mirror 2
8.36.44 (the same applies hereafter),
A light shielding layer 48, a photoconductor 50, and a transparent electrode 52 are laminated in this order. The photoconductor 50 has a property that the electrical resistance of the portion irradiated with light decreases, and is made of a dielectric mirror 46 made of, for example, Si, amorphous Si, amorphous Se, CdS, etc., and is light-shielding. Layer 48 is CdT
It is composed of e-membrane, etc. In this embodiment, when a light writing image is incident from the transparent electrode 52 while a constant potential V1 is applied to the transparent electrode 52, a spatial potential distribution corresponding to the pattern is generated on the surface of the dielectric mirror 46. . Here, the light shielding layer 48 is for preventing a part of the laser light from passing through the dielectric mirror 46 and entering the photoconductor #50, and even if the amount of transmitted light is negligible. If so, it is not necessarily necessary to provide it. Next, the embodiment shown in FIG. 6 will be described. This embodiment uses a photocathode, and the photocathode 5
After the optically written image is converted into an electronic image by 4, it passes through an electronic lens system 56 to a microchannel plate (MCP).
) 58, the charges are multiplied several thousand times and accumulated as a charge image on the surface of the dielectric mirror 46. Reference numeral 60 in FIG. 6 is a secondary electron collecting electrode mesh, which enables writing and erasing of charge images by utilizing the secondary electron emission effect of the surface material of the dielectric mirror 46. Note that the space between the dielectric mirror 46 and the photocathode 54 is a vacuum. Next, the case of electric writing using an electron beam shown in FIG. 7 will be explained. In this embodiment, an electron beam from an electron gun 62 is scanned over a dielectric mirror 46 by an electron lens system 64 to write and accumulate a charge image. Similar to the embodiment shown in FIG. 6, in this embodiment,
By arranging the secondary electron collecting electrode 0 between the electron lens system 64 and the dielectric mirror 46, it is possible to write and erase the electron'R image. Further, the space between the electron gun 62 and the dielectric mirror 46 is a vacuum. Next, the case of electrical writing using a CCD (charge coupled device) shown in FIG. 8 will be explained. In this embodiment, a light shielding layer 48 is provided externally to the dielectric mirror 46.
, a CCD readout structure 66, and a CCD surface channel parallel structure 68 are stacked in this order, and converts input time-series electrical signals into a two-dimensional information frame,
It is stored as charge packets in the D array. Next, an embodiment in which the feedback system of the first invention shown in FIG. 9 is provided will be described. This embodiment uses a Nd or YAG rod as the laser medium 10, a reflectance R=10% as the output mirror 16, and a spatial light modulator 14C shown in FIG. 4 as the reflective spatial light modulator. Furthermore, as a writing means, a photocathode 54 and an electron lens system 56 as shown in FIG.
, MCP58.Secondary electron collection tf! Using a mirror with 0 output mirror, the output mirror 16 has a reflectance of 2%.
A feedback system 72 including mirrors 72A, 72B, and 72C that includes a partial reflection beam splitter 70 and guides a portion of the output laser beam reflected therefrom to the photocathode 54.
．． is arranged. Here, LiNbO3 crystal is used as the electro-optic material 38, and the dielectric mirror 44 has a reflectance of 100%. Furthermore, both end faces of the Nd;YAG rod serving as the laser medium 10 are processed at the Brewster angle θ. In this embodiment, the laser beam from the laser medium 10, after reciprocating through the spatial light modulator 14C, becomes elliptically polarized light due to the rotation of the wavefront, as described above, and the end surface of the Nd; By the action of the polarizer, the light is converted into intensity-modulated linear leakage light. The intensity distribution of the output pattern of the laser beam emitted from the output mirror 16 is non-uniform due to non-uniform refractive index within the laser medium 10, non-uniform distribution of Nd ions, non-uniformity of the resonator mirror, and the like. Furthermore, as shown by the two-dot chain line in FIG.
i Nb O3, KTP Aluminum When obtaining wavelength converted light through a nonlinear optical crystal 74 such as BBO, the wavelength conversion efficiency is proportional to the incident light density, so the non-uniformity of the intensity distribution of the converted light is This is more noticeable than with YAG laser light. In this embodiment, a part of the output light from the output mirror 16 or the converted light from the nonlinear optical crystal 74 is taken out by the beam splitter 70, and the feedback system 72 is used to extract the output light from the output mirror 16 or the converted light from the nonlinear optical crystal 74 to the photocathode 54, which is the optical writing section of the spatial light modulator 14C. Feedback is incident on. In this way, the optical writing section can write on the photocathode 54, the MCP
58 is used, it has high photosensitivity, and the method of writing charges to the dielectric mirror 44 can be changed to mesh potential,
This can be addressed by changing the setting of the crystal backside potential. For example, by generating a charge space distribution that has a reflectance distribution opposite to the incident light intensity distribution on the photocathode 54, or by using threshold processing, the incident light intensity distribution below a certain value is cut and the light intensity above the threshold value is reduced. A charge space distribution or reflectance distribution corresponding to the pattern can be created. Therefore, the spatial light modulator 14C can be operated so that the non-uniformity of the intensity distribution of the laser beam or the converted light is corrected. In this embodiment, for example, FIG. 10(A)
In this embodiment, the disordered output light pattern of a conventional Nd;YAG laser as shown in FIG.
A uniform light intensity distribution as shown in B) could be obtained. Here, by using a defleftron or the like as the electron lens system 56 of the writing section in the spatial light modulator 14C, it becomes possible to enlarge, reduce, rotate, and translate the charge image, and various pre-processing operations can be performed. It is also possible to switch the laser oscillation by temporally changing the reflectance by a binary switching operation of the voltage applied to the back surface of the spatial light modulator 14C while accumulating the charge image. That is, it can also be operated as a Q switch. In the example shown in FIG. 9, a Brewster cut YAG lot having a polarizing effect was also used as the laser medium 10, but this was done by inserting another same optical element into the resonator without performing a Brewster cut. Good too. Next, the embodiment shown in FIG. 11 will be described. This embodiment uses an electrical writing type spatial light modulator 14C that generates an equal phase plane spatial distribution, and the input signal to the writing section is an image signal from an image signal generation device 76. . The writing section in this embodiment utilizes an electron gun 62, an electron lens system 64, and a secondary electron collecting electrode shown in FIG. Since the other configurations are the same as the embodiment shown in FIG. 9 except for the feedback system 72, the same parts are given the same reference numerals as in FIG. 9 and their explanation will be omitted. Note that Nd and YAG rods are used as the laser medium 10.
The Brewster cut is not made. In this embodiment, a spatial refractive index distribution occurs within the electro-optic material 38 depending on the charge distribution on the surface of the dielectric mirror 44 and the voltage applied to the transparent electrode 40. This refractive index distribution causes a phase distribution of the laser light wavefront, and deformation of the equiphase front leads to light polarization as in the case of an optical lens. Therefore, the spatial distribution of the radius of curvature of the total reflection mirror is formalized. As described above, the spatial light modulator 14C corrects the phase change and optical path shift caused by refractive index nonuniformity in the optical system including the laser medium 10, the optical resonator 18, or the wavelength conversion nonlinear optical crystal 74. . As an electric writing signal for this correction, an image signal for correction is outputted from the image signal generation device y176 to the electron gun 62 and the electron lens 64 in accordance with the phase change and optical path shift caused by the refractive index non-uniformity. . In this case, the image signal is stored in advance in the image signal generation device 76 according to the type of laser medium 10, the characteristics of the nonlinear optical crystal 74, and the like. In this embodiment, as well as the embodiment shown in FIG. 9, a part of the output light from the output mirror 16 or the converted light from the nonlinear optical crystal 74 is taken out by the beam splitter 70 and used. Then, the image signal generation device 7
An image signal for correction may be output from 6. That is, a part of the laser output light is split by a beam splitter 70, imaged by a television camera 78, stored in a frame memory 80, etc., and the pattern is appropriately processed by an image signal generation device 76 to perform spatial light modulation. This is the write signal for the device 14C. The intensity distribution of the laser beam when the beam splitter 70 is used and the output laser pattern is imaged by the television camera 78 is shown in FIG. 12 (A). The pattern shown in FIG. 12 (A) is modified,
The image signal generation device 76 uses an electric signal corresponding to the charge distribution as an image signal as shown in FIG. 12(B).
When inputted as a write signal to the spatial light modulator, the output laser light pattern corrected by this becomes as shown in FIG. 12(C). It should be noted that although each of the above-mentioned embodiments relates to the case of a single wavelength oscillation laser beam, the present invention is naturally applicable to the case of a multi-wavelength simultaneous oscillation laser and a broadband wavelength oscillation laser. In this case, characteristics different from those of the above embodiments are exhibited. That is, the phase change Δ accompanying the refractive index change Δn of the electro-optic crystal
φ occurs, and in the case of a reflective spatial light modulator, the following wavelength dependence occurs. Δφ(λ)=4πΔnd/λ−21π (d: crystal thickness, m: integer, 0≦Δφ×2π) Therefore, by adjusting Δn, that is, adjusting the voltage distribution value, Δφ(λ) can be made the same even at different wavelengths. It can be any value, or it can be a very different value. For this reason, for example, He-Cd metal vapor laser,
In the case of a laser that emits three colors of blue, green, and red at the same time, the laser output pattern can also be modified and the intensity ratio of the three colors can be arbitrarily adjusted to generate a composite color. Further, in the case of a broadband wavelength oscillation laser such as a Dye laser or a Ti:AJzOs laser, it is possible to make it function as an optical laser by oscillating only a narrow spectrum within a wide spectrum. Next, the principle of the second invention will be explained with reference to FIG. This second invention provides a laser oscillator comprising a laser medium 10, an excitation source 12, and an optical resonator including a total reflection mirror 14 and an output mirror 16. A transmissive spatial light modulator 82, which can arbitrarily adjust the transmittance spatial distribution or optical phase change spatial distribution, is arranged at an arbitrary position in the optical path between the two sides. FIG. 13(A) shows a transmissive spatial light modulator 82 disposed between the total reflection mirror 14 and the laser medium 10;
13(B) shows a transmissive spatial light modulator 82 placed between the laser medium 10 and the output mirror 16, and FIG. 13(C) shows a transmissive spatial light modulator 82 placed on the output side of the output mirror 16. This is what was placed. Furthermore, in FIG. 13 <D>, the output mirror itself is constructed from a transmissive spatial light modulator 82. A first embodiment of the transmissive spatial light modulator 82 is of a transmittance spatial distribution type using the birefringence effect shown in FIG. This is because an antireflection film 84 is used instead of the dielectric multilayer mirror 28 in the spatial light modulator 14A shown in FIG.
This anti-reflection 1! ! i! 84 to give a charge or potential spatial distribution to the surface. The operation of this transmission type spatial light modulator 82A is the same as that of the reflectance spatial light modulator 14A shown in FIG. The explanation will be omitted. The transmissive spatial light modulator 82A according to this embodiment has the thirteenth
Although it can be used for the arrangement of figures (A) to (C),
It cannot be used as the output mirror shown in D). Transmissive spatial light modulator 82B of the embodiment shown in FIG.
can also be used as an output mirror. This transmissive spatial light modulator 82B is shown in FIG.
This configuration includes a reflective spatial light modulator 14B that utilizes the Fapley-Bello interference effect and a temporal structure. Since the structure of the pond is the same as that in the embodiment shown in FIG. 3, the same reference numerals will be used to omit the explanation. FIG. 16 shows the reflective spatial light modulator 1 in FIG.
4C, and is a transmissive spatial light modulator 82C in which an antireflection film 88 is provided in place of the dielectric mirror 44 in the embodiment shown in FIG. This embodiment also differs only in that it is a transmission system, whereas the embodiment shown in FIG. 4 is a reflection system.
Components that are the same as those in the illustrated embodiment are given the same reference numerals, and their explanation will be omitted. However, in this equiphase plane spatially distributed spatial light modulator 82C, an equiphase plane is formed on the exit side of the antireflection 11188, as shown in FIG. Next, the anti-reflection wA84 of the transmissive spatial light modulators 82A to 88C, the dielectric mirror 86B or the anti-reflection wA8
An example for applying charge or potential distribution to 8 will be described. The embodiment shown in FIG. 17 corresponds to the structure of the embodiment shown in FIG. The surface (corresponding to the anti-reflection film 84, 88 or dielectric mirror 86B) 90 is arranged obliquely offset with respect to the optical axis of the laser beam transmitted through it so as not to interfere with the laser beam. . In this embodiment, 2 in the embodiment of FIG.
A secondary electron collecting electrode ring 92 is provided in place of the secondary electron collecting electrode 0. In the case of this embodiment as well, the structure and operation are the same as the embodiment shown in FIG. 4, except for the difference in reflection and transmission, so the explanation will be omitted. Next, the embodiment shown in FIG. 18 will be described. In this embodiment, electrical writing is performed using an electron beam, and the reflective type in the embodiment shown in FIG. 7 is applied to a transmissive type. In this embodiment as well, similar to the embodiment shown in FIG. 17, electronic! The Pt62 and the electron lens system 64 are obliquely offset from the central optical axis of the laser beam transmitted through the electro-optical material fjr (F1 surface 90) and are arranged so as not to interfere with the laser beam. A secondary electron collecting electrode ring 92 is provided in place of the secondary electron collecting electrode mesh.The operation is also the same as the embodiment shown in FIG. This will be omitted. Next, an embodiment shown in FIG. 19 in which a feedback system is provided will be described. The 16th
This is a combination of the equiphase plane spatial distribution type spatial light transformer 82C shown in the figure and the writing means for optically writing on the optical surface shown in FIG. 17, and also uses a total reflection mirror 14. . Since the other ellipses are the same as those in FIG. 9, they will be given the same reference numerals and the explanation will be omitted. Furthermore, since the operations are the same except for the difference between reflection and transmission, the explanation will be omitted. Even in the case of this transmission type, as in the case of the reflection type, the output light pattern in the laser medium 10 is as shown in FIG. 20(A).
By feeding back a part of the output light in the feedback system 72, the non-uniformity of the output light pattern is corrected as shown in FIG.
The output light was modified to be uniform as shown in FIG. 20(B). Next, the embodiment shown in FIG. 21 will be described. This embodiment is a transmission type version of the embodiment shown in FIG. 11, and uses the transmission type spatial light modulator 82C shown in FIG. 16 and the electron gun 62 shown in FIG. 18. This is a combination of writing means and a total reflection mirror 14. Since the structure of the pond is the same as that in the embodiment shown in FIG. 11, the same parts will be given the same reference numerals and the explanation will be omitted. Also, regarding the operation, the only difference is that the embodiment shown in FIG. 11 is a reflection system, whereas this embodiment is a transmission system, and since the operation is the same as that of the embodiment shown in FIG. 11, a description thereof will be omitted. . Next, the third invention shown in FIG. 22 will be explained. This third invention includes a reflective spatial light modulator 14 as a total reflection mirror, and a transmissive spatial light modulator in the middle of the optical path between the reflective spatial light modulator 14 and the output side of the output mirror 16. 82 are arranged. FIG. 22(A) shows a transmissive spatial light modulator 82 disposed between the total reflection mirror 14 and the laser medium 10;
22(B) shows a case in which a transmissive spatial light modulator 82 is arranged between the laser medium 10 and the output mirror 16, and FIG. 22(C) shows a case in which the output mirror itself is composed of the transmissive spatial light modulator 82. In FIG. 22(D), a transmissive spatial light modulator 82 is placed on the output side of the output mirror 16. Note that when a transmissive spatial light modulator is disposed in place of the output mirror, it must be the transmissive spatial light modulator 82B shown in FIG. 15 above. In this embodiment of the third invention, both a reflective spatial light modulator as a total reflection mirror and a transmission spatial light modulator 82 arranged on the optical path between the total reflection mirror and the exit position of the output mirror are used. , the intensity distribution of the laser output light can be more strongly corrected.

【Effect of the invention】

Since the present invention is configured as described above, it has an excellent effect in that non-uniformity in the intensity distribution of the laser output light can be arbitrarily corrected or the distribution can be adjusted to an arbitrary distribution.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the basic configuration of the first invention;
4 to 4 are cross-sectional views showing the first to third embodiments of the spatial light modulator in the first invention, and FIGS. 5 to 8 are cross-sectional views showing the dielectric mirror of the spatial light modulator in the first invention. FIG. 9 is a sectional view showing the first to fourth embodiments of the writing means; FIG. 9 is a implied sectional view showing an embodiment provided with the feedback system of the first invention; FIG.
The figure is a diagram showing the state of the output laser beam before and after correction in the same embodiment, FIG. 11 is a suggested cross-sectional view showing an embodiment using the image signal generation device of the first invention, and FIG. 12 is A diagram showing the correction state of the output laser beam of the same example,
FIG. 13 is a block diagram showing the basic configuration of the second invention, FIGS. 14 to 16 are cross-sectional views showing the first to third embodiments of the transmissive spatial light modulator in the second invention, and FIG. 17 and the first
FIG. 8 is a sectional view showing the first and second embodiments of the writing means for the spatial light modulator in the second invention, and FIG. 19 is a implied sectional view showing the embodiment provided with a feedback system according to the second invention. FIG. 20 is a diagram showing the state of the output laser beam before and after correction in the same embodiment; FIG. 21 is a implied cross-sectional view showing an embodiment using the image signal generation device of the second invention; FIG. 22 is a block diagram showing the configuration of the third invention. 0... Laser medium, 2... Excitation source, 4... Total reflection mirror (reflection type spatial light modulator), 4A.
...Reflectance spatial distribution type spatial light modulator, 4B, 14C...
- Spatial light modulator, 2... Feedback system, 4... Nonlinear optical crystal, 6... Image signal generation device, 8... Television camera, O... Frame memory, 2.82A, 82B, 82C: Transmissive spatial light modulator. Figure 2 Figure 3

Claims (12)

[Claims] (1) A reflective spatial light modulator that includes a laser medium, an excitation source, and an optical resonator, and can arbitrarily adjust the reflectance spatial distribution or optical phase change spatial distribution of the total reflection mirror in the optical resonator. A laser oscillator characterized by: (2) The laser oscillator according to claim 1, further comprising a feedback system that guides a part of the laser beam emitted from the output mirror in the optical resonator as writing light for the spatial light modulator. (3) In claim 2, there is provided an imaging device that converts a part of the laser beam emitted from the output mirror in the optical resonator into a video signal, and processes the video signal as writing light for the spatial light modulator. and an image processing device that converts the image signal into an image signal and outputs the image signal to the spatial light modulator. (4) The laser oscillator according to claim 1, further comprising an image signal generation device that generates an image signal as writing light for the spatial light modulator. (5) Including a laser medium, an excitation source, and an optical resonator, transmittance spatial distribution or optical phase change can be applied at any position in the optical path between the total reflection mirror and the exit side of the output mirror in the optical resonator. A laser oscillator characterized by disposing a transmissive spatial light modulator whose spatial distribution can be arbitrarily adjusted. (6) The laser oscillator according to claim 5, further comprising a feedback system that guides a portion of the laser light emitted from the output mirror in the optical resonator as writing light for the spatial light modulator. (7) In claim 6, there is provided an imaging device that converts a part of the laser beam emitted from the output mirror in the optical resonator into a video signal, and processes the video signal as writing light for the spatial light modulator. and an image processing device that converts the image signal into an image signal and outputs the image signal to the spatial light modulator. (8) The laser oscillator according to claim 5, further comprising an image signal generation device that generates an image signal as writing light for the spatial light modulator. (9) A reflective spatial light modulator that includes a laser medium, an excitation source, and an optical resonator, and can arbitrarily adjust the reflectance spatial distribution or the optical phase change spatial distribution by using a total reflection mirror in the optical resonator. At the same time, a transmissive spatial light modulator capable of arbitrarily adjusting the transmittance spatial distribution or optical phase change spatial distribution is provided at an arbitrary position in the optical path between the total reflection mirror and the output side of the output mirror in the optical resonator. A laser oscillator characterized by the following: (10) The laser oscillator according to claim 9, further comprising a feedback system that guides a part of the laser beam emitted from the output mirror in the optical resonator as writing light for the spatial light modulator. (11) In claim 10, there is provided an imaging device that converts a part of the laser beam emitted from the output mirror in the optical resonator into a video signal, and processes the video signal as writing light for the spatial light modulator. and an image processing device that converts the image signal into an image signal and outputs the image signal to the spatial light modulator. (12) The laser oscillator according to claim 9, further comprising an image signal generation device that generates an image signal as writing light for the spatial light modulator.