JP3198059B2 - Laser beam separation device and free electron laser device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for separating laser beams of different wavelengths into laser beams of respective wavelengths and a free electron laser device using the same.

[0002]

2. Description of the Related Art In a free electron laser (hereinafter abbreviated as FEL) device, an electron beam is accelerated to near the speed of light by an electron accelerator, the electron beam is meandered in a periodic magnetic field of an undulator, and spontaneous emission light generated at that time is generated. Is reciprocated a number of times in the optical resonator to synchronize the outgoing light pulse with the subsequent electron beam pulse. When the light pulse exceeds an energy level above a predetermined level, it oscillates non-linearly to obtain FEL. The laser light obtained by such an FEL device is generally quasi-monochromatic light as compared with a conventional laser, but it is known that two or more types of FELs having different wavelengths are actually contained.

[0003]

However, even if such FELs having different wavelengths are included, these FELs cannot be actually separated. Focusing only on FEL, this is taken out of the optical resonator and made into monochromatic FEL light. As a conventional technique for separating the FELs having different wavelengths for each wavelength, for example, there is a beam splitter using an SiO ₂ plate (see FIG. 3). In this beam splitter, the laser beam of the FEL light is distributed using the ratio of the FEL light having the wavelength transmitted through the SiO ₂ plate and the FEL light having the reflected wavelength.

However, in this beam splitter, the usable wavelength range is limited by the material SiO ₂ , and the usable wavelength is limited. The FEL device can change the wavelength by changing the energy of electrons and the strength of the magnetic field of the undulator.
A major feature is that EL light can be obtained. In the beam splitter method in which usable wavelengths are limited, a beam splitter plate made of a different material must be prepared every time the wavelength of FEL light is set to a different wavelength range. However, at present, FEL devices are limited to those of monochromatic light.

On the other hand, recently, as an application field of laser,
Genetic engineering and bioscience have been highlighted. In the fine cell processing technology required in such a field, the wavelength and spot diameter of the laser beam must be appropriately changed depending on the irradiation target, but conventional laser devices cannot produce laser beams of various wavelengths. Because there is no
Since a laser device must be prepared for each wavelength, a versatile laser device in the above-mentioned fields is desired.

Therefore, the present invention is directed to the above-described conventional FE
Keeping in mind the current state of the technology for separating L light, assuming that the laser light contains different wavelength components, this light is separated for each wavelength using a deflection mirror with a simple configuration, and this separated laser light is separated into a minute spot. It is an object of the present invention to condense light so as to have a diameter so that laser light can be widely and effectively used in fields such as genetic engineering.

[0007]

According to the present invention, as a means for solving the above-described problems, a laser beam containing different wavelength components is used.
Equipped with a plurality of deflecting mirrors arranged along the transmission path, these deflecting mirrors are replaced by a plurality of deflecting mirrors with holes whose diameters are sequentially reduced, and deflecting mirrors without holes continually arranged on these deflecting mirrors with holes and then, apart roughly component by reflecting the laser beam for each wavelength in these deflection mirrors, separated min
Condensed by the condenser lens of the laser light of each wavelength that is to that the laser light separation apparatus in so that down the spot diameter of that near the wavelength.

According to the laser beam separation device of the present invention, laser beams containing different wavelength components are used as a precondition. This laser light is first guided to a deflecting mirror with holes,
Laser light large of a predetermined wavelength by the size sequentially hole diameter or
Crab is separated. When separating the laser light of each wavelength, Les
The laser light has good linearity during transmission, but has a slight divergence angle. Since this divergence angle has wavelength dependence, it is separated using the property that the larger the wavelength, the larger the divergence.

For example, when the laser beam is
Assuming that third and fifth harmonic components are included, each component has a wavelength of λ ₁ = λ, λ ₂ = λ / 3, and λ ₃ = λ / 5, and the fundamental wavelength is the largest. Spread, tertiary,
The divergence angle is reduced to the fifth order. Therefore, the hole diameter corresponding to this is set to the deflection mirror with holes, the fundamental wave is reflected by the first reflection mirror, the others pass through the hole, and the third harmonic component is reflected by the second reflection mirror. At the same time , each wavelength component can be roughly separated such that the others pass through holes. Then, the laser light the separated condensed by the condenser lens, the Filter spot diameter of the laser beam to its wavelength near Ru can use this laser beam into a fine processing technology.

Further, when the above-mentioned separation device is used, an electron accelerator for accelerating the electron beam to near the speed of light, a periodic magnetic field means for meandering the electron beam accelerated by the electron accelerator,
An optical resonator that generates spontaneous emission light generated by meandering of the electron beam by the periodic magnetic field means, is reflected by a pair of reflecting mirrors facing each other at predetermined intervals, and is amplified by reciprocating a plurality of times to generate laser light of a plurality of wavelength components. If this is composed of a plurality of deflection mirrors arranged along the transmission path of the output laser light from the optical resonator, and an optical separation device for roughly separating the laser light into each wavelength, the optical separation the deflection mirror device, and a plurality holes with deflection mirror which sequentially squeezed each hole diameter, the hole without deflecting mirror arranged in succession in these holes with a deflecting mirror, and roughly separated is reflected by these deflection mirrors the laser light of each wavelength component separated is condensed by the condenser lens, and free electron laser apparatus which so that down the spot diameter of that near the wavelength that
Can also .

[0011] free-electron laser equipment according to the invention amplifies a laser beam of different wavelength components by the optical resonator emitting. Therefore , the laser light extracted from the optical resonator is roughly separated for each wavelength component by the above-described optical separation device on the transmission path outside the optical resonator, and is condensed by the condenser lens. since the spot diameter is narrowed until near the wavelength, Ru can be subjected to fine processing by irradiating the like cells.

Further, the laser light of each wavelength separated by the deflection mirror is reflected by a laminated film mirror formed of a thin film having a reflection center wavelength characteristic corresponding to each wavelength, and only the laser light for each wavelength is reflected. May be separated. With this configuration, each laser beam roughly separated for each wavelength component by the above-mentioned laser separation device can be separated into laser beams of each wavelength component with higher accuracy by using a laminated film mirror.

That is, the above laser separation devicebyLes
The separation of laser light is a rough separation. this is,Above
IsolatedLaser lightToThe fundamental wave componentAlso 3
This is because the next and fifth harmonic components are slightly contained. Follow
Laser light separated into each wavelength component
When guided to a film mirror, this laminated film mirror has a specific wavelength component.
, And absorbs other wavelength components.
You.

Therefore, in the laminated film mirror, high quality laser light of only each wavelength component is obtained by changing only the material of the laminated thin film and reflecting only the laser light of each wavelength component. For example, as a thin film material, TiO ₂
/ SiO ₂ , H ₅ O ₂ / SiO _2, etc., which have characteristics of strongly reflecting around 0.5 μm and 0.3 μm, respectively. Further, the focal point of the condenser lens may be variable. With this configuration, the spot of the laser beam can be accurately adjusted to the specific portion of the irradiation target.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall schematic configuration diagram of the FEL device of the embodiment. 1 is an electron accelerator, 2, 3, 5 are deflection magnets, 4 is an undulator, 6 is a beam catcher,
7, 7 are a pair of reflection mirrors, and 8, 9 are total reflection mirrors.

Although not shown, the electron beam is generated by an electron beam generator such as an electron gun and sent to the electron accelerator 1. In the electron accelerator 1, the electron beam is accelerated to a speed close to the speed of light, and its trajectory is bent by the deflecting magnets 2 and 3 and guided into the periodic magnetic field of the undulator 4. The trajectory of the electron beam from the electron accelerator 1 to the beam catcher 6 is generally set in a vacuum duct, but the vacuum duct is not shown for simplicity.

In the undulator 4, the electron beam is meandered by the periodic magnetic field, and at that time, spontaneous emission light is generated, and the electron beam travels almost in parallel. When the electron beam has finished interacting with the undulator 4, its trajectory is bent by another deflecting magnet 5, led out, and extinguished by the beam catcher 6. As shown in the figure, the undulator 4 is provided between an optical resonator composed of a pair of reflection mirrors 7, 7, and the spontaneous emission light generated in the undulator 4 travels hundreds of times between the reflection mirrors 7, 7. Reciprocate without.

At this time, if the pulse interval of the succeeding electron beam is sent in synchronization with the pulse of the spontaneous emission light, the light energy of the spontaneous emission light reciprocating a large number of times is increased. The light is led out from a small hole 7a provided in the center of the reflection mirror 7. This is FEL light. It is known that the spontaneous emission light generated by the undulator 4 has two or more different wavelengths as shown in FIG.
The next order has the peak light intensity observed). In general, only the fundamental wave is extracted as FEL light. In this embodiment, however, the spontaneous emission light having the different wavelength is extracted as FEL light. ing.

FEL obtained by the optical resonator having the above configuration
Assuming that the wavelength of the fundamental wave is λ, the wavelengths of the other FEL lights are λ / 3 and λ / 5, and FEL light having a shorter wavelength than the fundamental wave can be obtained. FE of three wavelengths obtained in this way
After passing through the reflection mirror 7, the L light is separated into laser lights of respective wavelengths by the laser light separation device 10 via external total reflection mirrors 8 and 9. Laser beam separation device 10
Are three types of deflecting mirrors 11a as a first stage separation unit,
11b and 11c are provided.

11a and 11b have holes in the two deflecting mirrors, and 11c has no holes. The hole diameters of the two deflecting mirrors 11a and 11b are sequentially reduced from the upstream side of the laser beam flow. The relationship between the deflecting mirrors when the hole diameter is reduced is set as follows.
A laser beam is a light beam having a high rectilinearity, and when transmitted, has a slight divergence angle in its path. The divergence angle increases as the wavelength increases. Accordingly, laser light containing a large amount of fundamental wave components is distributed outside the concentric circle, and laser light containing third- and fifth-order high-order wavelength components is largely distributed inside.

For this reason, the hole diameter of each of the deflecting mirrors 11a and 11b is such that the mirror 11a reflects within a range of an effective diameter including a large number of fundamental waves, and a laser beam containing the third and fifth harmonic components is effective. Set to pass through the hole diameter corresponding to the diameter, and
The mirror 1b is set to have a diameter that reflects the third harmonic component and passes the fifth or higher harmonic component. Deflection mirror 11
By setting the hole diameters for a and 11b as described above, the laser beam is roughly separated into the fundamental wave, third-order, and fifth-order harmonic components, respectively. This is a rough separation method.

This is because the intensity distribution of the laser beam separated as described above does not include a third-order or fifth-order component at all even if it is a laser beam containing a large number of fundamental components. This does not mean that it does not include the fifth or higher order. When the fundamental wavelength changes, it is preferable that the hole diameter of the deflection mirrors 11a and 11b is made variable.

In this embodiment, taking into consideration the actual distribution state of the laser beam, a separating means using multilayer mirrors 13a, 13b, and 13c is employed as a second-step separating method (see FIGS. 1 and 2). (See FIG. 2). The multilayer mirror used for this separation means is, for example, TiO ₂ / Si
It is composed of a multi-layered dielectric thin film layer of O ₂ or H ₅ O / SiO ₂ with a layer thickness of λ / 2.

The dielectric thin film layer is made of TiO ₂ / SiO ₂
A high reflectance around a 0.5μm case, H ₅ O
_In the case of ₂ / SiO ₂ , it has a characteristic of high reflectance centering on 0.3 μm. Therefore, a multilayer mirror is formed by a thin film having a reflection center wavelength characteristic corresponding to the wavelength of each laser light, and this multilayer mirror is appropriately applied to laser light whose fundamental wave changes between 1 and several tens μm. When the laser light is reflected at the center wavelength of the multilayer film and other components are absorbed by the reflection mirror, the laser light can be separated into each wavelength with higher accuracy.

The deflection mirrors 11a, 11b, 11
c, the multi-layer mirrors 13a and 13
Each of the lasers filtered by b and 13c is, as shown in FIGS. 1 and 2, condensing lenses 12a, 12b and 12c.
The light is condensed by c. Each focused laser beam has a spot diameter of about each wavelength,
The object is irradiated.

In microfabrication of cells in fields such as genetic engineering, bioscience or biotechnology, a laser beam having a wavelength of about 10 μm is applied to irradiate the cells themselves, a laser beam having a wavelength of about 6 μm is applied to a cell membrane, and a cell nucleus is irradiated. Requires a laser beam of about 1 μm. As described above, this FEL device can change the wavelength of the laser light when output, and can also output laser light of the fundamental wavelength λ ₁ , the third harmonic λ ₂ , and the fifth harmonic λ _3. Therefore, it is possible to efficiently generate and irradiate a laser beam having a wavelength suitable for each cell, cell membrane, or cell nucleus.

In addition, this FEL device irradiates the cells with the laser beams narrowed down by the condenser lenses 12a, 12b and 12c until the spot diameter approaches each wavelength, thereby facilitating the fine processing of the cells. Further, the laser light from the FEL device can be applied to fine processing of a semiconductor element as in the case of an excimer laser or the like.

[0028]

As described in detail above, the laser beam separating apparatus according to the present invention is composed of a deflecting mirror having a hole diameter gradually narrowed from the upstream side of the laser beam and a deflecting mirror having no hole. By appropriately selecting each hole diameter, a laser beam for each of predetermined different wavelength components can be obtained,
It becomes possible to simultaneously distribute a predetermined amount of laser beams to a predetermined number of locations while being concentrated by a condenser lens,
In particular, there is obtained an advantage that it is extremely useful in using FEL in microfabrication technology for cells and the like.

Further, by using a laminated film mirror formed of thin films having different reflection center wavelengths and distributing them with higher precision for each wavelength, the roughly separated laser light of each wavelength can be further finely divided into a specific wavelength. Only monochromatic lasers can be separated from each other and distributed to a predetermined place, so that various utilization studies can be performed.

The FEL device according to the present invention generates laser beams of different wavelengths and can separate them by a light separating device. Therefore, for example, FEL beams of different wavelengths in a wide wavelength range of 1 μm to several tens μm are generated. Laser light of each fundamental wavelength is separated, and each laser light is simultaneously distributed in a state of being concentrated by a condenser lens, so that various utilization studies can be realized.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an FEL device according to an embodiment provided with a laser beam separation device.

FIG. 2 is a perspective view of a schematic configuration of a laser beam separation device.

FIG. 3 is a schematic diagram of a conventional light separation device.

FIG. 4 is a diagram showing an intensity distribution curve of FEL light generated by the FEL device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron accelerator 2, 3, 5 Deflection magnet 4 Undulator 6 Beam catcher 7, 7 Reflection mirror 8, 9 Total reflection mirror 10 Laser beam separation device 11a-c Deflection mirror 12a-c Condensing lens 13a-c Multilayer mirror

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01S 3 / 30,3 / 101 G02B 27/10

Claims (4)

(57) [Claims] A plurality of deflecting mirrors arranged along a transmission path of a laser beam containing different wavelength components, wherein the deflecting mirrors are provided with a plurality of holes whose diameters are sequentially reduced. a deflecting mirror, continuously in these holes with deflecting mirrors and no hole deflecting mirror lined up, separated roughly the laser beam by these deflecting mirrors is reflected for each wavelength component, the laser light of each separated min wavelength was condensed by the condenser lens, the laser light separation apparatus in so that down the spot diameter of that near the wavelength. 2. An electron accelerator for accelerating an electron beam to near the speed of light, periodic magnetic field means for meandering the electron beam accelerated by the electron accelerator, and spontaneous emission light generated by meandering of the electron beam by the periodic magnetic field means. An optical resonator that is reflected by a pair of reflecting mirrors facing each other at a predetermined interval and amplified by being reciprocated a plurality of times to generate laser light having a plurality of wavelength components; and a transmission of the laser light output from the optical resonator.
Is composed of a plurality of deflection mirrors arranged along the feed path, and an optical separation device for roughly separating the laser light into each wavelength, a deflection mirror for the beam splitting device, sequentially narrowed respective hole diameter Deflecting mirror with multiple holes, and a non-hole deflecting mirror that is continuously aligned with these deflecting mirrors with holes,
The light is reflected by these deflecting mirrors, roughly separated, and
The focused laser light of each wavelength component is focused by a focusing lens ,
As a free electron laser apparatus which so that down the spot diameter near the wavelength. 3. The laser of each wavelength separated by the deflecting mirror is reflected by a laminated film mirror formed of a thin film having a reflection center wavelength characteristic corresponding to each wavelength, and the reflected laser light of each wavelength is collected by the laser beam. The laser beam separation device according to claim 1 or a free electron laser device according to claim 2, wherein the laser beam is supplied to an optical lens. 4. A free-electron laser apparatus according to the laser beam splitter or claim 2 or 3 according to claim 1 or 3, characterized in that the focal point of the condenser lens in the variable.