JP2009301853A - High energy particle generating device, light collecting device, high energy particle generating method, and light collecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high energy particle generating device, a light collecting device, a high energy particle generating method, and a light collecting method. <P>SOLUTION: This device is equipped with a laser beam irradiation device 10 to irradiate main laser light and sub-laser light, a steering mirror 41 to reflect the main laser light and the sub-laser light from a light guide tube group 20, an off-axis paraboloid mirror 44 into which the main laser light is made incident, a target part 50 to which the main laser light collected by the off-axis paraboloid mirror 44 is irradiated, an inclination angle sensor 48 to detect an inclination angle formed by a light axis of the sub-laser light and a normal line of its light receiving face, a CCD camera 49 to detect a rotation angle around the light axis of the sub-laser light, and a control device to obtain the rotation angle of the sub-laser light, to extract the optimum inclination angle of the corresponding sub-laser light from the preset optimum inclination angle data, and to rotate the steering mirror 41 so that the sub-laser light is received by the inclination angle sensor 48 at the optimum inclination angle. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high-energy particle generation device, a laser condensing device, a high-energy particle generation method, and a condensing method, and in particular, applied to a case where laser light is reliably condensed at the focal point of an off-axis parabolic mirror. It is useful.

  Conventionally, a nondestructive inspection method has been used to inspect the state of an object to be inspected such as various pipes of electric power equipment. As an example of the nondestructive inspection method, an X-ray transmission inspection method is known in which X-rays are irradiated to a pipe or the like, and the presence or absence of stress corrosion cracking in the pipe and the degree of thinning are inspected.

  Various apparatuses for generating such X-rays are known. For example, a laser light source capable of outputting high-energy laser light, a light guide tube group for guiding the laser light source to a predetermined remote position, and a light guide tube There is a high-energy X-ray generator including an X-ray generator that collects laser light emitted from a group and generates X-rays by irradiating the target with the focused laser light (for example, Patent Document 1). reference).

  The light guide tube group is configured such that light guide tubes each having a bent portion are pivotally connected via bearings, and incident laser light is guided to the bent portions of each light guide tube. A mirror for reflecting in the bending direction is provided. That is, if each light guide tube is appropriately rotated, the laser light from the laser light source can be guided to an arbitrary place.

  According to such a high energy X-ray generator, since the laser light source and the X-ray generator are connected via the light guide tube group, the X-ray generator that can be formed in a small size is placed near the object to be inspected. It is possible to arrange a relatively large laser light source at a location away from it. For this reason, a non-destructive inspection can be performed by irradiating a high-energy X-ray even to a narrow portion where a large number of pipes are concentrated.

Here, the target that is the final target of the laser beam irradiation needs to be irradiated with a high-energy laser beam in order to generate X-rays, but the laser beam having that energy was irradiated from the laser light source. Then, the mirror disposed in the light guide tube is worn out. Therefore, in the prior art, a laser beam having a diameter of 10 mm, an energy of 10 mJ, and a pulse width of 50 fs is generated from the laser light source, and the laser beam is condensed to a diameter of 2 μm on the target. This makes it possible to irradiate the target with high-intensity laser light of 5 × 10 ¹⁸ W / cm ² without damaging the mirror.

  The condensing of the laser light will be described with reference to FIG. FIG. 10 is a schematic plan view illustrating the configuration of the X-ray generation unit according to the conventional technique.

  As illustrated, the X-ray generator 100 includes an optical system L1 and an optical system L2. The optical system L1 includes a steering mirror 103, a dichroic mirror (beam splitter) 104, a folding mirror 105, and an off-axis parabolic mirror 106, and a main laser from a laser light source (not shown) via these mirrors. Light is irradiated to the target 101.

  The steering mirror 103 is disposed so as to be rotatable about the X axis and the Y axis, and is configured to be angle-adjusted by a control device (not shown) described later. By changing the angle of the steering mirror 103, it is possible to adjust the angle at which the main laser beam is incident on the off-axis parabolic mirror 106.

  On the other hand, the optical system L2 includes a steering mirror 103 and a dichroic mirror 104, and the sub-laser light from the laser light source is separated from the main laser light by the dichroic mirror 104 and irradiated to the tilt angle sensor 102.

  The tilt angle sensor 102 includes a plano-convex lens 107 and a position sensor 108. The position sensor 108 receives the sub laser beam via the plano-convex lens 107, and based on the received position, the optical axis of the sub laser beam and An inclination angle which is an angle formed with the normal line of the light receiving unit is detected.

  Since the main laser light and the sub laser light share the optical axis from the laser light source to the dichroic mirror 104, if the angle of the steering mirror 103 is appropriately set according to the tilt angle of the sub laser light, the main laser light Is incident parallel to the axis of the off-axis parabolic mirror 106 and is focused on the focal point of the off-axis parabolic mirror 106. And if the target 101 is arrange | positioned in the condensing point, the high energy laser beam condensed on the target 101 can be irradiated.

  The angle adjustment of the steering mirror is performed as follows by a control device (not shown).

  First, an objective lens and a CCD camera (not shown) are arranged in the vicinity of the focal point of the off-axis parabolic mirror 106 in place of the target 101, and an image of the main laser light received by the CCD camera is displayed via the objective lens. A display device (not shown) is prepared. Next, the angle of the steering mirror 103 is adjusted so that the image of the main laser beam displayed on the display device is minimized. When the image of the main laser beam is minimized, the tilt angle of the sub laser beam measured by the tilt angle sensor 102 is recorded. The tilt angle when the image of the main laser beam is minimized is referred to as the optimum tilt angle.

  After that, the target 101 is provided in place of the objective lens, and the control apparatus that inputs the tilt angle of the sub laser light measured by the tilt angle sensor 102 cancels the deviation between the tilt angle and the optimum tilt angle. The angle of the steering mirror 103 is adjusted.

  As a result, even if the optical axis of the laser beam is deviated due to a change in the posture of the light guide tube group, the angle of the steering mirror 103 is appropriately adjusted by the control device, and the main laser beam is off the axis of the off-axis paraboloidal mirror 106. It enters in parallel to. As a result, the target 101 is always irradiated with the condensed main laser beam.

  Here, an image of the main laser light imaged through the objective lens will be described.

  FIG. 11 is a schematic diagram showing the relationship between the main laser light incident on the off-axis parabolic mirror and its image. FIGS. 9A to 9D show images of main laser light reflected by the off-axis paraboloid mirror 106 and imaged through the objective lens. This image is called a light collection profile. According to the condensing profile, it is possible to observe the size and shape of the image of the main laser beam and the brightness of the main laser beam.

  As shown in FIG. 11A, when the main laser light is incident parallel to the axis of the off-axis paraboloidal mirror 106, the main laser light is condensed at the focal point, so that it has high brightness and reaches the diffraction limit. A small dot image is displayed near the center of the display device. Further, as shown in FIG. 11B, if the main laser beam is parallel to the axis of the off-axis parabolic mirror 106, no matter which position of the off-axis parabolic mirror 106 is incident, As in a), the light is focused on the focal point. On the other hand, as shown in FIG. 11C, when the main laser light is incident with an inclination with respect to the axis of the off-axis parabolic mirror 106, the main laser light is not focused on the focal point, Is captured as a shaped image (astigmatism).

  Here, as shown in FIG. 11D, even if the main laser light is rotated around its optical axis by rotating the laser light source or the light guide tube group, the main laser light is off-axis parabolic mirror. If the light is incident parallel to the axis 106, the main laser light is considered to be focused on the focal point of the off-axis paraboloidal mirror 106 as in FIGS. 11A and 11B.

  However, after focusing on the focal point, the main laser beam was rotated around the optical axis and the focusing profile was observed. As a result, astigmatism was observed without maintaining the focused state on the focal point. That is, if the steering mirror 103 is not adjusted after considering not only the angle at which the main laser beam is incident on the off-axis parabolic mirror 106 but also the rotation around the optical axis, the main laser beam is released off-axis. It was confirmed that the light cannot be focused on the focal point of the object mirror 106.

  The above event will be described below based on the concept of distortion and aberration of the wavefront (phase distribution) of the main laser beam.

  First, it is generally known that aberration is observed when laser light with wavefront distortion is condensed. Aberration means coloring that occurs when an image is formed by a lens, and blurring or distortion of the image.

  FIG. 12 shows Seidel's five aberrations. As shown in the figure, aberrations are classified into primary wavefront aberrations such as distortion, image surface curvature, and secondary wavefront aberrations such as astigmatism, coma aberration, and spherical aberration. The primary component does not necessarily reduce the intensity of the condensed light, so it can be corrected by adjusting the position of the target 101 (in the xyz direction). However, if the secondary or higher component is large, the main laser beam can be condensed to the diffraction limit. Becomes difficult. FIG. 13 shows the wavefront shape of the main laser beam corresponding to these aberrations. Each wavefront shape corresponding to each aberration indicates that the bright part of the light / dark distribution is convex and the dark part is concave. Also, the wavefront shape for distortion, astigmatism and coma is not point symmetric about the center point.

  When laser light including such wavefront distortion is incident parallel to the axis of the off-axis paraboloidal mirror 106, theoretically, as shown in FIG. Observed.

  However, astigmatism among the aberrations classified in FIG. 12 is included in the main laser light by the off-axis parabolic mirror 106 itself by adjusting the steering mirror 103 as shown in FIG. 14B. Astigmatism components can be canceled. However, as a compensation, it is considered that the main laser beam is no longer parallel to the axis of the off-axis parabolic mirror 106 but is incident at an angle.

  This is because when the main laser beam is made incident on the axis of the off-axis paraboloidal mirror 106 without being focused on the focal point, astigmatism occurs (see FIG. 11 (c)). If this is used, it can be considered that the aberration due to wavefront distortion is canceled out by the astigmatism due to this inclination, and as a result, the main laser beam is focused on the focal point.

  Therefore, if the main laser light is rotated in a state where the aberration due to the wavefront distortion is canceled, the wavefront shape is not point-symmetric, so that the canceling effect is lost and the aberration appears again.

  Considering that the main laser light includes wavefront distortion, FIG. 11 is modified as shown in FIG. FIG. 15 is a schematic diagram showing the relationship between the main laser light incident on the off-axis parabolic mirror and its image.

  As shown in FIG. 15A, when the steering mirror 103 is adjusted so that the main laser beam is focused on the focal point based on the condensing profile, the main laser beam is focused on the axis of the off-axis paraboloid mirror 106. The incident light is inclined. At this time, as described above, the aberration due to the wavefront distortion of the main laser light is canceled. Further, as shown in FIG. 15B, when the optical axis of the main laser beam is moved in parallel, the focal point is the same as in FIG. It is focused on.

  However, as shown in FIG. 15C, when the main laser light is incident on the axis of the off-axis parabolic mirror 106 at an inclination angle other than the original inclination angle, the main laser light is focused on the focal point. For example, it is imaged as astigmatism. Similarly, as shown in FIG. 15D, even when the main laser beam rotates around its optical axis, it is imaged as astigmatism.

  In this way, not only the inclination of the main laser beam with respect to the axis of the off-axis parabolic mirror 106 but also the rotation angle around the optical axis is taken into consideration, and the light is reliably focused on the focal point of the off-axis parabolic mirror 106. It is necessary to let

  Note that the above-described circumstances are not limited to the case of generating high energy X-rays, and similarly exist when condensing high energy laser light.

JP 2008-71547 A

  In view of the circumstances described above, the present invention provides a light collecting device that can reliably collect high-energy laser light, a high-energy particle generator that can irradiate high-energy particles using the light collecting device, and high-energy particle generation. It is an object to provide a method and a light collection method.

  In order to achieve the above object, a first aspect of the present invention includes a pulsed main laser beam and a laser light source that emits a sub laser beam sharing an optical axis with the main laser beam, and the main laser beam and the sub laser. Light guiding means for guiding light to a position remote from the laser light source, and angle adjustment configured to be rotatable so that the main laser light and the sub laser light from the light guiding means can be reflected at an arbitrary angle. High-energy particles are irradiated with the main laser light collected by the off-axis parabolic mirror, the off-axis paraboloid mirror on which the main laser light is incident from the angle adjusting mirror, and the off-axis parabolic mirror. A target to be generated, and an inclination angle detection means for detecting the inclination angle formed by the optical axis of the auxiliary laser light and the normal line of the light receiving surface while receiving the auxiliary laser light on the light receiving surface from the angle adjusting mirror; The light guiding means Rotation angle detection means for detecting the rotation angle of the secondary laser light received from the angle adjustment mirror around the optical axis with reference to the secondary laser light before entering, and the focal point of the off-axis paraboloidal mirror Control means in which optimum tilt angle data that determines an optimum tilt angle, which is a tilt angle of the sub laser beam when the main laser beam is condensed, for each rotation angle is set in advance. Obtains the rotation angle of the sub laser light from the rotation angle detection means, extracts the optimum tilt angle of the sub laser light corresponding to the rotation angle from the optimum tilt angle data, and uses the sub laser at the optimum tilt angle. In the high energy particle generating apparatus, the angle adjusting mirror is rotated so that light is received by the tilt angle detecting means.

  In the first aspect, the tilt angle and the rotation angle of the sub laser light are detected, and the main laser light is controlled off-axis and focused on the focal point of the parabolic mirror. As a result, even when the main laser beam is guided to a remote narrow part, the main laser beam can be reliably condensed and the target can always be irradiated with the high-energy main laser beam.

  According to a second aspect of the present invention, in the high-energy particle generator according to the first aspect, the optimum tilt angle data is obtained by converting the image of the main laser light into image data near the focal point of the off-axis paraboloidal mirror. The angle of the angle adjusting mirror is adjusted so as to obtain image data in which the main laser beam is imaged at one point, and the tilt angle at this time is created in association with the rotation angle. It exists in the high energy particle generator characterized by being.

  In the second aspect, it is possible to create optimum tilt angle data that can reliably collect the main laser beam.

  According to a third aspect of the present invention, in the high-energy particle generator according to the first or second aspect, the tilt angle detection unit includes the position of the image of the sub laser beam on the light receiving surface and the position of the light receiving surface. While calculating the difference with a predetermined position, it is comprised so that the said secondary laser beam may be irradiated from the said mirror for angle adjustment through the lens focused on the said predetermined position, From the said difference and the focal distance of the said lens In the high energy particle generator, the inclination angle is calculated.

  In the third aspect, it is possible to easily detect the tilt angle of the sub laser light, thereby detecting the tilt angle of the main laser light incident on the off-axis paraboloid mirror.

  According to a fourth aspect of the present invention, in the high-energy particle generator according to any one of the first to third aspects, the first through-hole disposed between the laser light source and the light guide unit. And a shaping mask having a second through-hole, and the sub laser light is divided into two by passing through the first through-hole and the second through-hole, and the rotation angle detecting means has two The first image and the second image, which are images of the sub-laser light divided into two, are received, and a straight line connecting the first through-hole and the second through-hole is used as a reference line, and the first image In the high energy particle generator, the angle of the second image from the reference line is calculated as the rotation angle.

  In the fourth aspect, the rotation angle of the sub laser beam can be easily detected, and thereby the rotation angle of the main laser beam incident on the off-axis paraboloid mirror can be detected.

  According to a fifth aspect of the present invention, in the high-energy particle generator according to any one of the first to fourth aspects, the target is a target sample that generates high-energy electrons upon incidence of the main laser beam. And an X-ray conversion material that generates high-energy X-rays by interaction with the high-energy electrons.

  In the fifth aspect, high energy X-rays can be reliably irradiated to a remote narrow part or the like.

  According to a sixth aspect of the present invention, in the high-energy particle generator according to any one of the first to fifth aspects, the light guide means includes a plurality of light guide tubes having bent portions via bearings. And a mirror that reflects the incident main laser light and sub laser light in the direction in which the light guide tube is bent is disposed at the bent portion of each light guide tube. The high-energy particle generator is characterized.

  In the sixth aspect, the main laser light and the sub laser light can be guided while avoiding an obstacle from the laser light source to a remote position.

  According to a seventh aspect of the present invention, pulsed main laser light from a laser light source and sub laser light sharing an optical axis with the main laser light are incident through a light guide, and these main laser lights And an angle adjusting mirror configured to be rotatable so that the sub laser light can be reflected at an arbitrary angle, and the main laser light is incident from the angle adjusting mirror and collected at the focal point. An off-axis paraboloid mirror that emits light, and an inclination angle detection unit that receives the sub laser light from the angle adjusting mirror on the light receiving surface and detects an inclination angle formed by the optical axis of the sub laser light and the light receiving surface. Rotation angle detection means for detecting a rotation angle of the secondary laser light received from the angle adjustment mirror around the optical axis with reference to the secondary laser light before entering the light guide means, and the shaft Parabolic Mira Control means in which optimum tilt angle data that determines an optimum tilt angle, which is a tilt angle of the sub laser beam when the main laser beam is condensed at the focal point, for each rotation angle is set in advance, The control means acquires the rotation angle of the sub laser light from the rotation angle detection means, extracts the optimum tilt angle of the sub laser light corresponding to the rotation angle from the optimum tilt angle data, and uses the optimum tilt angle to In the condensing device, the angle adjusting mirror is rotated so that the sub laser light is received by the tilt angle detecting means.

  In the seventh aspect, the tilt angle and the rotation angle of the sub laser light are detected, and control is performed so that the main laser light is off-axis and focused on the focal point of the parabolic mirror. Thus, even when the main laser beam is guided to a remote narrow part, the main laser beam can be reliably condensed.

  According to an eighth aspect of the present invention, there is provided a laser light source that irradiates a pulsed main laser light and a sub laser light sharing an optical axis with the main laser light, and the main laser light and the sub laser light are remote from the laser light source. A light guide means for guiding to the position, an angle adjusting mirror configured to be rotatable so that the main laser light and the sub laser light from the light guide means can be reflected at an arbitrary angle, and the angle adjustment. An off-axis paraboloid mirror on which the main laser light is incident from a mirror for mirror, a target that is irradiated with the main laser light focused by the off-axis paraboloid mirror to generate high energy particles, and the angle The secondary laser beam is received by the light receiving surface from the adjustment mirror, and the tilt angle detecting means for detecting the tilt angle formed by the optical axis of the secondary laser light and the normal line of the light receiving surface is incident on the light guide means. Before A high energy particle generating method using a high energy particle generating device comprising a rotation angle detecting means for detecting a rotation angle around the optical axis of the sub laser beam received from the angle adjusting mirror with reference to a laser beam. Then, optimum tilt angle data is obtained in which an optimum tilt angle, which is a tilt angle of the sub laser beam when the main laser beam is focused on the focal point of the off-axis paraboloid mirror, is determined for each rotation angle. A rotation angle of the sub laser beam is obtained from the rotation angle detecting means, an optimum tilt angle of the sub laser beam corresponding to the rotation angle is extracted from the optimum tilt angle data, and the sub tilt light is extracted at the optimum tilt angle. And a step of rotating the angle adjusting mirror so that a laser beam is received by the tilt angle detecting means. That.

  In the eighth aspect, the tilt angle and the rotation angle of the sub laser light are detected, and the main laser light is off-axis and focused on the focal point of the parabolic mirror. As a result, even when the main laser beam is guided to a remote narrow part, the main laser beam can be reliably condensed and the target can always be irradiated with the high-energy main laser beam.

  According to a ninth aspect of the present invention, a pulsed main laser beam from a laser light source and a sub laser beam sharing an optical axis with the main laser beam are incident through a light guide, and these main laser beams And an angle adjusting mirror configured to be rotatable so that the sub laser light can be reflected at an arbitrary angle, and the main laser light is incident from the angle adjusting mirror and collected at the focal point. An off-axis paraboloid mirror that emits light, and an inclination angle detection unit that receives the sub laser light from the angle adjusting mirror on the light receiving surface and detects an inclination angle formed by the optical axis of the sub laser light and the light receiving surface. And a rotation angle detecting means for detecting a rotation angle of the sub laser light received from the angle adjusting mirror around the optical axis with reference to the sub laser light before entering the light guide means. Using an optical device A concentrating method, wherein an optimum inclination angle, which is an inclination angle of the sub laser light when the main laser light is condensed at the focal point of the off-axis parabolic mirror, is determined for each rotation angle. Obtaining the angle data; obtaining the rotation angle of the sub laser beam from the rotation angle detecting means; extracting the optimum tilt angle of the sub laser beam corresponding to the rotation angle from the optimum tilt angle data; and And a step of rotating the angle adjusting mirror so that the sub laser light is received by the tilt angle detecting means at an angle.

  In the ninth aspect, the tilt angle and rotation angle of the sub laser light are detected, and the main laser light is off-axis and focused on the focal point of the parabolic mirror. Thus, even when the main laser beam is guided to a remote narrow part, the main laser beam can be reliably condensed.

  ADVANTAGE OF THE INVENTION According to this invention, the high energy particle generator which can irradiate a high energy particle using the condensing apparatus which can condense a high energy laser beam reliably, and the condensing apparatus is provided.

  Hereinafter, the best mode for carrying out the present invention will be described. In the present embodiment, a high energy X-ray generator that generates high energy X-rays will be described as an example of a high energy particle generator.

  FIG. 1 is a schematic configuration diagram of a high-energy X-ray generator provided with a condensing device according to the present embodiment. As shown in the figure, the high-energy X-ray generator includes a laser light irradiation device 10 that is a laser light source that irradiates pulsed main laser light and sub laser light that shares an optical axis with the main laser light, and the main laser light. And a light guide tube group 20 which is an example of a light guide means for guiding the sub laser light to the X-ray generation unit 30, and the main laser which is incident with the main laser light and the sub laser light and condenses the main laser light. And an X-ray generator 30 that generates high-energy X-rays using light.

  FIG. 2 is a schematic configuration diagram of the laser beam irradiation apparatus. As shown in the figure, the laser beam irradiation apparatus 10 is a device that sends out a pulsed main laser beam and a sub laser beam sharing an optical axis with the main laser beam. More specifically, the laser beam irradiation apparatus 10 guides the main laser beam emitted from the main laser light source 11 to the light guide tube group 20 via the dichroic mirror 14 and also emits the sub laser beam emitted from the sub laser light source 12. Is adjusted to a predetermined diameter by the beam expander 13 and then guided to the light guide tube group 20 through the secondary laser beam mirror 15 and the dichroic mirror 14 while sharing the optical axis with the main laser beam. ing.

  As will be described in detail later, a shaping mask 16 having a first through hole 17 and a second through hole 18 is disposed between the sub laser beam mirror 15 and the dichroic mirror 14, and the sub laser beam Is divided into two parts by passing through the first through hole 17 and the second through hole 18. Therefore, the image immediately after the main laser beam and the sub laser beam are combined by the dichroic mirror 14 passes through the first through-hole 17 which is one of the divided main laser beams having a diameter of 10 mm, for example. The composite image 19 is composed of the image of the sub laser light having a diameter of 6 mm and the image of the sub laser light having a diameter of 1 mm that has passed through the second through hole 18 as the other.

  The main laser light source 11 that emits a pulsed main laser beam is preferably one that can irradiate an ultrashort pulse laser beam or a femtosecond laser beam. For example, titanium sapphire that can irradiate a laser beam having an energy of 10 mJ with a pulse width of 30 fs. A laser apparatus etc. are mentioned. Further, as the sub laser light source for transmitting the sub laser light, a light source capable of irradiating a laser having a wavelength in the visible light region is preferable. For example, an Nd-YAG laser device capable of irradiating a laser beam having a wavelength of 532 nm may be used. Note that the secondary laser light is not pulsed laser light but laser light that is continuously irradiated.

  FIG. 3 is a schematic configuration diagram of the light guide tube group. As shown in the drawing, the light guide tube group 20 is configured by a plurality of light guide tubes 21 having bent portions being connected to each other via a bearing 23 so as to be rotatable. One of the two end light guide tubes 21 is connected to the base 24, and the other is connected to the X-ray generator 30. Each bent portion is provided with a light guide tube mirror 22 that reflects the incident main laser light and sub laser light in the direction in which the light guide tube 21 is bent. In the present embodiment, the light guide tube group 20 includes a total of seven light guide tubes 21 and a total of eight light guide tube mirrors 22. The light guide tube 21 is provided with a weight 26 in order to stabilize its position.

  According to the light guide tube group 20 having such a configuration, the main laser light and the sub laser light from the laser light irradiation device 10 are introduced into the light guide tube 21 through the mirror 25 provided on the base 24 and guided. The light is reflected by the light tube mirror 22 and guided to the X-ray generator 30. Since each light guide tube 21 is rotatable, for example, a single light guide path can be formed so as to avoid an obstacle existing up to the X-ray generation unit 30.

  FIG. 4 is a schematic configuration diagram of the X-ray generation unit. As shown in the figure, the X-ray generation unit 30 includes a condensing unit 40 that condenses main laser light, and a target unit 50 that generates high-energy X-rays when irradiated with the main laser light.

  As shown in the figure, the condensing unit 40 includes an optical system L1, an optical system L2, an inclination angle sensor 48 as an example of an inclination angle detection unit, a CCD camera 49 as an example of a rotation angle detection unit, and a main laser beam. The control apparatus (not shown) which is an example of the control means for controlling the condensing of is provided.

  The optical system L1 includes a steering mirror 41, which is an example of an angle adjusting mirror, a dichroic mirror (beam splitter) 42, a folding mirror 43, and an off-axis paraboloidal mirror 44. Laser light irradiation is performed via these mirrors. The main laser beam from the apparatus 10 (see FIG. 1) is applied to the target unit 50.

  The steering mirror 41 is disposed so as to be rotatable about its X axis and Y axis, and is configured to be angle-adjusted by a control device (not shown) described later. By changing the angle of the steering mirror 41, it is possible to adjust the angle at which the main laser beam is incident on the off-axis parabolic mirror 44.

  On the other hand, the optical system L2 includes a steering mirror 41, a dichroic mirror 42, and a half mirror 45. The sub laser light is separated from the main laser light by the dichroic mirror 42 and applied to a tilt angle sensor 48 which is an example of a tilt angle detecting unit. Further, the sub laser beam is branched by the half mirror 45 and is irradiated to a CCD camera 49 which is an example of a rotation angle detecting unit.

  The tilt angle sensor 48 includes a plano-convex lens 46 and a position sensor 47. The position sensor 47 receives the sub-laser light through the plano-convex lens 46, and the optical axis of the sub-laser light is determined based on the received position. An inclination angle which is an angle formed with the normal line of the light receiving unit is detected. Details of the calculation of the tilt angle will be described later.

  The CCD camera 49 detects the rotation angle around the optical axis of the sub laser light received from the steering mirror 41 with reference to the sub laser light before entering the light guide tube group 20. Details of the detection of the rotation angle will be described later.

  The control device receives the tilt angle from the tilt angle sensor 48, receives the rotation angle obtained from the shaping mask image of the CCD camera 49, and the steering mirror 41 based on these angles and preset optimum tilt angle data. It controls the attitude of the. With this control, the main laser light is always focused on the focal point of the off-axis parabolic mirror 44. Details of this control will be described later.

  The target unit 50 includes a target sample 51 that generates high-energy electrons upon incidence of main laser light, and an X-ray conversion material 52 that generates high-energy X-rays by interaction with the high-energy electrons. . Note that the target sample 51 itself may be regarded as the X-ray conversion material 52.

  In the present embodiment, the target unit 50 further includes a sample support shaft 53 and a winding shaft 54. A target sample 51 formed in a tape shape is wound around the sample support shaft 53, and a winding shaft 54 is configured to wind up the tape-shaped target sample 51. The target sample 51 is stretched between the sample support shaft 53 and the take-up shaft 54 so as to pass through the focal point of the off-axis parabolic mirror 44.

  When the target sample 51 is irradiated with the main laser beam condensed by the off-axis parabolic mirror 44, high-energy electrons are generated. High energy X-rays are generated from the X-ray conversion material 52 by the interaction between the high energy electrons and the X-ray conversion material 52.

  The material of the target sample 51 is not particularly limited as long as it can generate high-energy electrons with a pulsed main laser beam. The target sample 51 may be, for example, metal or plastic, but when the target sample 51 itself is regarded as the X-ray conversion material 52 and X-rays are directly generated, the target sample 51 is preferably composed of atoms having a higher atomic number. . When an atom having a higher atomic number is used, more high-energy X-rays are generated by bremsstrahlung. For example, copper, tantalum tape, etc. can be used suitably. Also, the shape of the target sample 51 is not particularly limited as long as it can generate high-energy electrons with pulsed laser light.

  Here, the detection of the tilt angle of the sub laser light by the tilt angle sensor 48 will be described in detail with reference to FIG. FIG. 5 is a schematic diagram showing the secondary laser light incident on the tilt angle sensor and a schematic diagram showing the position of the secondary laser light measured by the position sensor.

  FIG. 5A is a plan view of the XZ plane when the position sensor 47 and the plano-convex lens 46 are viewed from the Y-axis direction. As shown in the figure, the plano-convex lens 46 is disposed in focus at a predetermined position O on the light receiving surface of the position sensor 47, and the sub laser beam is inclined with respect to the normal line of the light receiving surface of the position sensor 47. Yes.

The tilt angle θ _X formed by the sub laser beam and the normal line at this time is detected as follows. First, the difference between the position of the condensing point I on the light receiving surface of the position sensor 47 and the predetermined position O on the light receiving surface is calculated for the X component. In other words, it calculates the difference [delta] _X, as shown in FIG. 5 (c). Here, if the focal length of the plano-convex lens 46 is f, the relationship δ _X = f × θ _X is established. Therefore, it is possible to detect the inclination angle θ _X formed by the normal line in the XZ plane and the sub laser beam.

The tilt angle θ _Y formed by the normal line in the YZ plane and the sub laser beam can be calculated in the same manner. FIG. 5B is a plan view of the YZ plane when the position sensor 47 and the plano-convex lens 46 are viewed from the X-axis direction. As shown in the figure, the plano-convex lens 46 is disposed in focus at a predetermined position O on the light receiving surface of the position sensor 47, and the sub laser beam is inclined with respect to the normal line of the light receiving surface of the position sensor 47. Yes.

The inclination angle θ _Y formed by the sub laser beam and the normal line at this time is detected as follows. First, the difference between the position of the condensing point I on the light receiving surface of the position sensor 47 and the predetermined position O on the light receiving surface is calculated for the Y component. That is, the difference δ _Y is calculated as shown in FIG. Here, if the focal length of the plano-convex lens 46 is f, the relationship δ _Y = f × θ _Y is established. Therefore, it is possible to calculate the inclination angle theta _Y formed between the normal line and the sub laser light in Y-Z plane.

  Next, detection of the rotation angle of the sub laser light around the optical axis by the CCD camera 49 will be described in detail with reference to FIG. FIG. 6A is a front view of the shaping mask, and FIG. 6B is a schematic view showing an image of the secondary laser light incident on the rotation angle sensor. Here, a circular opening is shown as an example of the through hole, but the shape is not limited to this as long as the pattern can be easily recognized.

  As shown in FIG. 6A, the shaping mask 16 is provided with a first through hole 17 and a second through hole 18, and a straight line connecting the centers of these through holes is defined as a reference line La. If the secondary laser light passes through the first through hole 17 and the second through hole 18 and is divided into two parts and does not rotate around the optical axis, the camera lens causes the first through hole 17 and the second through hole to be divided. The images of the two sub laser beams picked up by the CCD camera 49 in a state where the hole 18 is in focus should be observed while maintaining the positional relationship between the first through hole 17 and the second through hole 18.

  However, if the sub laser light rotates around its optical axis when passing through the light guide tube group 20 and the optical systems L1 and L2, as shown in FIG. A certain first image 61 and second image 62 are observed. That is, the first image 61 on the reference line La and the second image 62 shifted from the reference line La are captured by the CCD camera 49. Therefore, if the angle formed by the straight line Lb connecting the first image 61 and the second image 62 and the reference line La is obtained, the rotation angle of the sub laser light can be detected.

  Specifically, the rotation angle α is detected using image recognition processing for image data captured by the CCD camera 49. FIG. 7 is a diagram for explaining image recognition processing for detecting a rotation angle. First, as shown in FIG. 7A, the image data 60 is scanned with a first image pattern 71 having the same shape as the first image 61. At this time, the difference in luminance between the first image pattern 71 and the image data 60 is calculated for each position in the image data 60. Thereby, it is recognized that the first image 61 is located at the position where the difference in luminance is the smallest.

  Next, as shown in FIG. 7B, a second image pattern 72 having the same shape as the second image 62 is rotated from the reference line La around the first image 61 recognized in the image data 60. Move. The brightness difference between the second image pattern 72 and the image data 60 is calculated for each position during the rotation. Thereby, it is recognized that the second image 62 is located at the position where the difference in luminance is the smallest. Therefore, the angle at which the second image 62 is rotated at this time is the rotation angle α around the optical axis of the sub laser light.

As described above, the tilt angles θ _X and θ _{Y of the} sub laser light are detected from the tilt angle sensor 48, and the rotation angle α of the sub laser light around the optical axis is detected from the CCD camera 49.

The control device controls the steering mirror so that the main laser beam is always focused on the focal point of the off-axis paraboloidal mirror 44 based on the tilt angles θ _X and θ _{Y, the} rotation angle α, and the optimum tilt angle data. 41 is controlled.

  Here, the optimum tilt angle data is obtained by determining the optimum tilt angle, which is the tilt angle of the sub laser beam when the main laser beam is focused on the focal point of the off-axis paraboloid mirror 44, for each rotation angle. . The optimum tilt angle data is created as follows.

  First, an objective lens and a CCD camera are arranged in the vicinity of the focal point of the off-axis paraboloidal mirror 44 in place of the target unit 50, and a display device that displays an image of main laser light received by the CCD camera via the objective lens ( Prepare (not shown). Next, the angle of the steering mirror 41 is adjusted so that the image of the main laser beam displayed on the display device is minimized. Whether or not the image of the main laser beam is minimized may be determined by visual observation or may be performed by a known image recognition process.

Next, the optimum tilt angles θ _X and θ _Y , which are the tilt angles of the sub laser light detected by the tilt angle sensor 48 when the image of the main laser light is minimized, are sub laser light detected by the CCD camera 49. Are recorded in association with the rotation angle α. Thereafter, the sub laser light is rotated around the optical axis, and the optimum tilt angles θ _X and θ _Y are recorded in association with the rotation angle α each time. As described above, the optimum inclination angle data is obtained by associating the optimum inclination angles θ _X and θ _Y with the rotation angle α.

In the present embodiment, the optimum inclination angles θ _X and θ _Y (mrad) are measured and recorded in the case where the rotation angle α is 0, 45, 90, 135, 180, 225, 270, 315, 360 degrees. These rotation angles and the optimum inclination angle theta _X and plotted graph shown in FIG.

In FIG. 8, the measured values of the optimum inclination angle θ _X at each rotation angle obtained by the experiment are represented by square and triangular points. Since the period is 2π (rad), a Fourier series having the rotation angle α as a variable is obtained and shown as a line graph. Optimum inclination angle theta _X is shown also the rotation angle other than the rotation angle of the thereby measured. The optimum inclination angle theta _X at each rotational angle is not constant value, it can be seen that the fluctuations. This confirms that the rotation angle must also be taken into account when the main laser beam including aberration is incident on the off-axis parabolic mirror.

Likewise, to create the optimum inclination angle theta _Y at each rotation angle. FIG. 9 shows a graph in which the optimum inclination angles θ _X and θ _Y corresponding to the respective rotation angles are plotted. The Fourier series obtained by fitting is as follows.

As shown in the drawing, for example, when the rotation angle is 45 degrees, the optimum inclination angle θ _X is about −0.6 (mrad), and the optimum inclination angle θ _Y is about 0.05.

  The control device controls the attitude of the steering mirror 41 using the optimum tilt angle data as shown in FIG. 9 as follows.

First, the control device acquires the rotation angle of the sub laser light from the CCD camera 49. For example, assume that the rotation angle at this time is 90 degrees. Next, the control device extracts the optimum inclination angle θ _X and the optimum inclination angle θ _Y corresponding to the rotation angle of 90 degrees from the optimum inclination angle data. Thus, 0 as the optimum inclination angle _{θ X (mrad), 0.5 (} mrad) is extracted as the optimum tilt angle theta _Y. Thereafter, the control device sets the tilt angle θ _X and the tilt angle θ _Y input from the tilt angle sensor 48 to 0 (optimal tilt angle θ _X when the rotation angle is 90) and 0.5 (when the rotation angle is 90, respectively). The attitude of the steering mirror 41 is controlled so that the optimum inclination angle θ _Y ) is obtained.

  With such control, when the sub laser light is incident on the tilt angle sensor 48 with the optimum tilt angle, the main laser beam is incident on the off-axis paraboloid mirror 44 with the optimum tilt angle. As a result, the main laser beam is focused on the focal point of the off-axis parabolic mirror 44 without aberration.

  As described above, in the high energy X-ray generator, the main laser light and the sub laser light are guided from the laser light irradiation device 10 to the X-ray generator 30 through the light guide tube group 20. Then, the X-ray generation unit 30 detects the tilt angle and rotation angle of the sub laser light, and controls the main laser light to be off-axis and focused on the focal point of the parabolic mirror 44. Thereby, even if the main laser light is rotated by rotating each light guide tube 21 so as to guide the main laser light to a remote narrow part or the like, the main laser light is reliably condensed, and the main laser beam is always high-energy. The target unit 50 can be irradiated with laser light. Thereby, a high energy X-ray generator capable of reliably irradiating a remote position from the laser light irradiation device 10 via the light guide tube group 20 with high energy X-rays is provided.

In addition, the high energy particle generator which can irradiate various high energy particles is provided not only when irradiating with high energy X-rays but by appropriately configuring the target unit 50. For example, a high energy ion beam generator that generates a high energy ion beam may be configured. Such an ion beam is expected to be applied to cancer treatment. In general, when a high-energy pulse laser having an intensity of 10 ¹⁸ W / cm ² or more is irradiated onto a thin film having a thickness of several μm, the number MeV having directivity in the normal direction of the thin film back surface (the back surface of the laser light irradiation surface) It is known that a high energy ion beam of several tens MeV is generated. Therefore, by configuring the target unit 50 of the present invention so that a main laser beam is irradiated with a thin film such as plastic, a high energy ion generator that generates a high energy ion beam can be obtained.

  Further, the condensing unit 40 of the present invention is useful as a condensing device that can reliably condense laser light from the light source at the focal point of the off-axis paraboloidal mirror 44.

  INDUSTRIAL APPLICABILITY The present invention can be effectively used in the industrial field where non-destructive inspection is performed using X-rays and the industrial field used for cancer treatment using ion beams.

It is a schematic block diagram of the high energy X-ray generator which concerns on embodiment of this invention. It is a schematic block diagram of the laser beam irradiation apparatus which concerns on embodiment of this invention. It is a schematic block diagram of the light guide tube group which concerns on embodiment of this invention. It is a schematic block diagram of the X-ray generation part which concerns on embodiment of this invention. It is the schematic which shows the position of the secondary laser beam measured by the schematic diagram and position sensor which show the secondary laser beam which injects into an inclination angle sensor. It is the schematic which shows the front view of a shaping mask, and the image of the secondary laser beam which injects into a rotation angle sensor. It is a figure explaining the image recognition process which detects a rotation angle. It is the rotation angle and the optimum inclination angle theta _X and plotted graph. It is the graph which plotted optimal inclination-angle (theta) _X , (theta) _Y corresponding to each rotation angle. It is a schematic plan view explaining the structure of the X-ray generation part which concerns on a prior art. It is the schematic which shows the relationship between the main laser beam which injects into an off-axis paraboloid mirror, and its image. It is a figure which shows 5 aberrations of Seidel. It is a figure which shows the wavefront shape of the main laser beam corresponding to an aberration. It is a figure explaining a main laser beam and an aberration. It is the schematic which shows the relationship between the main laser beam which injects into an off-axis paraboloid mirror, and its image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laser beam irradiation apparatus 11 Main laser light source 12 Sub laser light source 13 Beam expander 14 Dichroic mirror 15 Sub laser beam mirror 16 Shaping mask 17 First through hole 18 Second through hole 19 Composite image 20 Light guide tube group 21 Light guide Tube 22 Light guide tube mirror 23 Bearing 24 Base 25 Mirror 26 Weight 30 X-ray generation unit 40 Condensing unit 41 Steering mirror 42 Dichroic mirror 43 Folding mirror 44 Off-axis parabolic mirror 45 Half mirror 46 Plano-convex lens 47 Position sensor 48 Tilt angle sensor 49 CCD camera 50 Target unit 51 Target sample 52 X-ray conversion material 53 Sample support shaft 54 Take-up shaft 60 Image data 61 First image 62 Second image 71 First image pattern 72 Second image pattern 100 X Line generator 101 Target 102 Inclination Degree sensor 103 steering mirror 104 dichroic mirror 105 folding mirror 106 off-axis parabolic mirror 107 plano-convex lens 108 position sensor

Claims (9)

A laser light source for irradiating pulsed main laser light and sub laser light sharing an optical axis with the main laser light;
A light guiding means for guiding the main laser light and the sub laser light to a position remote from the laser light source;
An angle adjusting mirror configured to be rotatable so that the main laser light and the sub laser light from the light guiding means can be reflected at an arbitrary angle;
An off-axis parabolic mirror on which the main laser light is incident from the angle adjusting mirror;
A target that is irradiated with the main laser light collected by the off-axis parabolic mirror to generate high-energy particles;
A tilt angle detecting means for receiving the sub laser beam from the angle adjusting mirror on a light receiving surface and detecting a tilt angle formed by an optical axis of the sub laser beam and a normal line of the light receiving surface;
Rotation angle detection means for detecting a rotation angle around the optical axis of the sub laser light received from the angle adjusting mirror with reference to the sub laser light before entering the light guide means;
Optimum tilt angle data is set in advance, in which an optimum tilt angle, which is the tilt angle of the sub laser beam when the main laser beam is focused on the focal point of the off-axis parabolic mirror, is determined for each rotation angle. Control means,
The control unit obtains the rotation angle of the sub laser light from the rotation angle detection unit, extracts the optimum tilt angle of the sub laser beam corresponding to the rotation angle from the optimum tilt angle data, and uses the optimum tilt angle. The high energy particle generating apparatus, wherein the angle adjusting mirror is rotated so that the sub laser beam is received by the tilt angle detecting means. In the high energy particle generator according to claim 1,
The optimum tilt angle data is obtained so that an image of the main laser beam is obtained as image data in the vicinity of the focal point of the off-axis paraboloidal mirror, and image data in which the main laser beam is formed at one point is obtained. A high-energy particle generator characterized in that the angle of the adjustment mirror is adjusted, and the tilt angle at this time is created in association with the rotation angle. In the high energy particle generator according to claim 1 or 2,
The tilt angle detecting means calculates a difference between the position of the image of the sub laser light on the light receiving surface and a predetermined position of the light receiving surface, and uses the lens for adjusting the angle through a lens focused on the predetermined position. The high-energy particle generator is configured to irradiate the sub-laser light from a mirror, and calculates the tilt angle from the difference and the focal length of the lens. In the high energy particle generator according to any one of claims 1 to 3,
A shaping mask having a first through hole and a second through hole disposed between the laser light source and the light guide;
The sub laser light is divided into two by passing through the first through hole and the second through hole,
The rotation angle detection means receives a first image and a second image that are images of the sub-laser light divided into two, and forms a straight line connecting the first through hole and the second through hole. A high energy particle generating apparatus, characterized in that an angle from the reference line of the second image with the first image as a center is calculated as the rotation angle. In the high energy particle generator according to any one of claims 1 to 4,
The target is composed of a target sample that generates high-energy electrons upon incidence of the main laser beam, and an X-ray conversion material that generates high-energy X-rays by interaction with the high-energy electrons. A high energy particle generator. In the high energy particle generator according to any one of claims 1 to 5,
The light guide means, a plurality of light guide tubes having a bent portion are connected to each other through a bearing,
The high energy particle generator according to claim 1, wherein a mirror for reflecting the incident main laser light and sub laser light in a direction in which the light guide tube is bent is disposed in the bent portion of each light guide tube. The pulsed main laser light from the laser light source and the sub laser light sharing the optical axis with the main laser light are incident through the light guiding means, and the main laser light and the sub laser light are set at arbitrary angles. An angle adjusting mirror configured to be rotatable so that it can be reflected;
An off-axis paraboloidal mirror that receives the main laser light from the angle adjusting mirror and focuses the main laser light on a focal point thereof;
Inclination angle detection means for detecting the inclination angle formed by the optical axis of the sub laser light and the light receiving surface while receiving the sub laser light from the angle adjusting mirror on the light receiving surface;
Rotation angle detection means for detecting a rotation angle around the optical axis of the sub laser light received from the angle adjusting mirror with reference to the sub laser light before entering the light guide means;
Optimum tilt angle data is set in advance, in which an optimum tilt angle, which is the tilt angle of the sub laser beam when the main laser beam is focused on the focal point of the off-axis parabolic mirror, is determined for each rotation angle. Control means,
The control unit obtains the rotation angle of the sub laser light from the rotation angle detection unit, extracts the optimum tilt angle of the sub laser beam corresponding to the rotation angle from the optimum tilt angle data, and uses the optimum tilt angle. The condensing device, wherein the angle adjusting mirror is rotated so that the sub laser light is received by the tilt angle detecting means. A laser light source for irradiating pulsed main laser light and sub laser light sharing the optical axis with the main laser light;
A light guiding means for guiding the main laser light and the sub laser light to a position remote from the laser light source;
An angle adjusting mirror configured to be rotatable so that the main laser light and the sub laser light from the light guiding means can be reflected at an arbitrary angle;
An off-axis parabolic mirror on which the main laser light is incident from the angle adjusting mirror;
A target that is irradiated with the main laser light collected by the off-axis parabolic mirror to generate high-energy particles;
A tilt angle detecting means for receiving the sub laser beam from the angle adjusting mirror on a light receiving surface and detecting a tilt angle formed by an optical axis of the sub laser beam and a normal line of the light receiving surface;
High energy particles comprising rotation angle detection means for detecting a rotation angle of the sub laser light received from the angle adjusting mirror around the optical axis with reference to the sub laser light before entering the light guide means. A high energy particle generation method using a generator,
Obtaining optimum tilt angle data in which an optimum tilt angle, which is a tilt angle of the sub laser beam when the main laser beam is focused on the focal point of the off-axis parabolic mirror, is determined for each rotation angle;
The rotation angle of the sub laser beam is acquired from the rotation angle detecting means, the optimum tilt angle of the sub laser beam corresponding to the rotation angle is extracted from the optimum tilt angle data, and the sub laser beam is transmitted at the optimum tilt angle. And a step of rotating the angle adjusting mirror so as to be received by the tilt angle detecting means. The pulsed main laser light from the laser light source and the sub laser light sharing the optical axis with the main laser light are incident through the light guiding means, and the main laser light and the sub laser light are set at arbitrary angles. An angle adjusting mirror configured to be rotatable so that it can be reflected;
An off-axis paraboloidal mirror that receives the main laser light from the angle adjusting mirror and focuses the main laser light on a focal point thereof;
Inclination angle detection means for detecting the inclination angle formed by the optical axis of the sub laser light and the light receiving surface while receiving the sub laser light from the angle adjusting mirror on the light receiving surface;
And a rotation angle detection unit that detects a rotation angle of the sub laser light received from the angle adjusting mirror around the optical axis with respect to the sub laser light before entering the light guide unit. A condensing method using
Obtaining optimum tilt angle data in which an optimum tilt angle, which is a tilt angle of the sub laser beam when the main laser beam is focused on the focal point of the off-axis parabolic mirror, is determined for each rotation angle;
The rotation angle of the sub laser beam is acquired from the rotation angle detecting means, the optimum tilt angle of the sub laser beam corresponding to the rotation angle is extracted from the optimum tilt angle data, and the sub laser beam is transmitted at the optimum tilt angle. And a step of rotating the angle adjusting mirror so as to be received by the tilt angle detecting means.