Optical beam scanning device, optical property measurement device, optical beam scanning method, and optical property measurement method

Abstract

It includes a first scanning mirror, a second scanning mirror, a first mirror rotation mechanism, and a first moving mechanism. The object is irradiated with a light beam that is two-dimensionally scanned by the first scanning mirror and the second scanning mirror. The first mirror rotation mechanism can change the orientation of the first scanning mirror. The first moving mechanism can change the first position of the first scanning mirror. Regardless of the orientation of the first scanning mirror, the first position of the first scanning mirror is changed according to the orientation of the first scanning mirror so that the light beam reflected by the first scanning mirror passes through a reference position between the first scanning mirror and the second scanning mirror.

Description

Technical Field

[0001] The present disclosure relates to a light beam scanning device, an optical property measurement device, a light beam scanning method, and an optical property measurement method.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2010-185803 (Patent Document 1) discloses a wavefront aberration measurement device including a first stage, a light source, a condenser lens, a rotary stage, a gonio stage, a second stage, and a Shack-Hartmann sensor supported by the second stage. The first stage is movable in at least one axial direction. The light source and the condenser lens are mounted on the first stage. The rotary stage holds the lens to be inspected. The second stage is supported by the gonio stage and is movable in at least two axial directions. While controlling the first stage, the rotary stage, the second stage, and the gonio stage, the Shack-Hartmann sensor detects the wavefront of light emitted from the light source and transmitted through the lens to be inspected.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] The light beam scanning device of the present disclosure includes a first scanning mirror, a second scanning mirror, a first mirror rotation mechanism, and a first moving mechanism. The first scanning mirror can scan a light beam. The second scanning mirror can scan the light beam scanned by the first scanning mirror. An object is irradiated with a light beam two-dimensionally scanned by the first scanning mirror and the second scanning mirror. The first mirror rotation mechanism can change the orientation of the first scanning mirror. The first moving mechanism can change the first position of the first scanning mirror. Regardless of the orientation of the first scanning mirror, the first position of the first scanning mirror is changed according to the orientation of the first scanning mirror so that the light beam reflected by the first scanning mirror passes through a reference position between the first scanning mirror and the second scanning mirror.

Brief Description of the Drawings

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[0006] [Problems to be Solved by the Present Disclosure] An object of the first aspect of the present disclosure is to provide a light beam scanning device and a light beam scanning method capable of scanning a light beam similar to the light beam output from a light beam scanning device included in a device to which an object is applied, for objects with a wider range of specifications. An object of the second aspect of the present disclosure is to provide an optical property measuring device and an optical property measuring method capable of measuring the optical properties of objects with a wider range of specifications with a light beam similar to the light beam output from a light beam scanning device included in a device to which an object is applied.

[0007] [Effects of the Present Disclosure] The light beam scanning device and the light beam scanning method of the present disclosure enable scanning a light beam similar to the light beam output from a light beam scanning device included in a device to which an object is applied, for objects with a wider range of specifications. The optical property measuring device and the optical property measuring method of the present disclosure enable measuring the optical properties of objects with a wider range of specifications with a light beam similar to the light beam output from a light beam scanning device included in a device to which an object is applied.

[0008] [Outline of Embodiment] First, embodiments of the present disclosure will be listed and described.

[0009] (1) The light beam scanning device of the present disclosure includes a first scanning mirror, a second scanning mirror, a first mirror rotation mechanism, and a first movement mechanism. The first scanning mirror can scan a light beam. The second scanning mirror can scan the light beam scanned by the first scanning mirror. The object is irradiated with a light beam that is two-dimensionally scanned by the first scanning mirror and the second scanning mirror. The first mirror rotation mechanism can change the orientation of the first scanning mirror. The first movement mechanism can change the first position of the first scanning mirror. Regardless of the orientation of the first scanning mirror, the first position of the first scanning mirror is changed so that the light beam reflected by the first scanning mirror passes through a reference position between the first scanning mirror and the second scanning mirror.

[0010] The object is irradiated with a light beam that is two-dimensionally scanned by the first scanning mirror and the second scanning mirror. Also, regardless of the orientation of the first scanning mirror, the first position of the first scanning mirror is changed according to the orientation of the first scanning mirror so that the light beam reflected by the first scanning mirror passes through the reference position. Therefore, optically, while the first scanning mirror can be regarded as being present at the reference position, in reality, the first scanning mirror can be arranged farther away from the second scanning mirror and the object. Even if the sizes of the first scanning mirror and the second scanning mirror are large compared to the distance between the second scanning mirror and the object and the distance between the first scanning mirror and the second scanning mirror defined by the specifications of the object, it is possible to prevent mechanical interference between two of the first scanning mirror, the second scanning mirror, and the object. For an object with a wider range of specifications, it becomes possible to scan a light beam similar to the light beam output from the light beam scanning device included in the device (for example, a laser processing device) to which the object is applied.

[0011] (2) The light beam scanning device according to (1) above further includes a controller. The controller controls the first movement mechanism according to the orientation of the first scanning mirror so that the light beam reflected by the first scanning mirror passes through the reference position regardless of the orientation of the first scanning mirror.

[0012] Therefore, the first position of the first scanning mirror is automatically changed according to the orientation of the first scanning mirror so that the light beam reflected by the first scanning mirror passes through the reference position.

[0013] (3) In the light beam scanning device according to (1) or (2) above, the reference position is closer to the second scanning mirror than the first scanning mirror.

[0014] Therefore, even if the distance between the scanning mirrors defined by the specifications of the object is short, it is possible to scan the object with the light beam. It becomes possible to scan the light beam on objects with a wider range of specifications.

[0015] (4) The light beam scanning device according to any one of (1) to (3) above further includes a second moving mechanism capable of adjusting the second position of the object. By adjusting the second position, the distance between the second scanning mirror and the object is adjusted.

[0016] Therefore, according to the specifications of the object, the distance between the second scanning mirror and the object can be adjusted. It becomes possible to scan the light beam on objects with a wider range of specifications.

[0017] (5) The light beam scanning device according to any one of (1) to (4) above further includes a third moving mechanism capable of changing the third position of the second scanning mirror. The second scanning mirror includes a plurality of mirrors with different sizes. The third position of the second scanning mirror is changed so that the light beam is scanned by one of the plurality of mirrors.

[0018] When the distance between the second scanning mirror and the object has to be reduced according to the specifications of the object, the light beam can be scanned with a mirror having a smaller size. Therefore, it is possible to prevent the second scanning mirror from mechanically interfering with the object. It becomes possible to scan the light beam on objects with a wider range of specifications.

[0019] (6) The optical beam scanning device according to any one of (1) to (3) above further includes an optical path length adjuster disposed on the optical path of the optical beam incident on the first scanning mirror. The optical path length adjuster can adjust the optical path length of the optical beam incident on the first scanning mirror so that the optical path length of the optical beam from the incident end of the optical path length adjuster to the reference position remains constant regardless of the first position of the first scanning mirror.

[0020] Therefore, even when the optical beam enters the optical beam scanning device while spreading, the beam diameter of the optical beam at the reference position can be kept constant. The optical characteristics of the object can be measured more accurately.

[0021] (7) The optical characteristic measuring device of the present disclosure includes the optical beam scanning device according to any one of (1) to (6) above, a light source capable of emitting an optical beam, and a light detector capable of detecting an optical beam that has been two-dimensionally scanned by the first scanning mirror and the second scanning mirror and has passed through the object.

[0022] Therefore, the optical characteristic measuring device of the present disclosure can measure the optical characteristics of objects with a wider range of specifications using an optical beam similar to the optical beam output from the optical beam scanning device included in the device to which the object is applied.

[0023] (8) The optical characteristic measuring device according to (7) above further includes a beam selector. The light source includes a first light source capable of emitting a first optical beam having a first wavelength and a second light source capable of emitting a second optical beam having a second wavelength different from the first wavelength. The beam selector causes either the first optical beam or the second optical beam to be incident on the first scanning mirror as the optical beam.

[0024] Therefore, an optical beam having a wavelength specified by the specifications of each object can be irradiated onto each object. The optical characteristic measuring device can measure the optical characteristics of objects with a wider range of specifications.

[0025] (9) In the optical characteristic measuring device according to (7) or (8) above, the light detector is a wavefront sensor that detects the wavefront of the optical beam that has passed through the object.

[0026] Therefore, it becomes possible to measure the optical characteristics (e.g., aberration, etc.) of an object with a wider range of specifications.

[0027] (10) In the optical characteristic measuring apparatus according to any one of (7) to (9) above, the object is an fθ lens.

[0028] Therefore, it becomes possible to measure the optical characteristics (e.g., aberration, etc.) of an fθ lens with a wider range of specifications.

[0029] (11) The light beam scanning method of the present disclosure includes scanning a light beam by rotating a first scanning mirror, scanning the light beam scanned by the first scanning mirror by rotating a second scanning mirror, irradiating an object with the light beam two-dimensionally scanned by the first scanning mirror and the second scanning mirror, and changing a first position of the first scanning mirror according to the orientation of the first scanning mirror so that the light beam reflected by the first scanning mirror passes through a reference position between the first scanning mirror and the second scanning mirror regardless of the orientation of the first scanning mirror.

[0030] The object is irradiated with a light beam that is two-dimensionally scanned by a first scanning mirror and a second scanning mirror. Also, regardless of the orientation of the first scanning mirror, the first position of the first scanning mirror is changed according to the orientation of the first scanning mirror so that the light beam reflected by the first scanning mirror passes through a reference position. Therefore, optically, while the first scanning mirror can be regarded as being present at the reference position, in reality, the first scanning mirror can be placed farther away from the second scanning mirror and the object. Even if the sizes of the first scanning mirror and the second scanning mirror are large compared to the distance between the second scanning mirror and the object and the distance between the first scanning mirror and the second scanning mirror specified by the specifications of the object, mechanical interference between two of the first scanning mirror, the second scanning mirror, and the object can be prevented. For an object with a wider range of specifications, it becomes possible to scan a light beam similar to the light beam output from the light beam scanning device included in the device (e.g., a laser processing device) to which the object is applied.

[0031] (12) In the light beam scanning method according to (11) above, the reference position is closer to the second scanning mirror than the first scanning mirror.

[0032] Therefore, even if the distance between the scanning mirrors specified by the specifications of the object is short, it becomes possible to scan the object with a light beam. It becomes possible to scan a light beam for an object with a wider range of specifications.

[0033] (13) The light beam scanning method according to (11) or (12) above further includes adjusting the distance between the second scanning mirror and the object.

[0034] Therefore, according to the specifications of the object, the distance between the second scanning mirror and the object can be adjusted. It becomes possible to scan a light beam for an object with a wider range of specifications.

[0035] (14) The optical beam scanning method according to any one of (11) to (13) above further includes changing the third position of the second scanning mirror. The second scanning mirror includes a plurality of mirrors having different sizes from each other. By changing the third position, the optical beam is scanned by one of the plurality of mirrors.

[0036] When the distance between the second scanning mirror and the object needs to be decreased according to the specifications of the object, the optical beam can be scanned with a mirror having a smaller size. Therefore, it is possible to prevent the second scanning mirror from mechanically interfering with the object. It becomes possible to scan an object with a wider range of specifications with the optical beam.

[0037] (15) The optical beam scanning method according to any one of (11) to (14) above further includes adjusting the optical path length of the optical beam incident on the first scanning mirror by using an optical path length adjuster disposed on the optical path of the optical beam incident on the first scanning mirror so that the optical path length of the optical beam from the incident end of the optical path length adjuster to the reference position is constant regardless of the first position of the first scanning mirror.

[0038] Therefore, even when the optical beam enters the optical beam scanning device while spreading, the beam diameter of the optical beam at the reference position can be kept constant. The optical characteristics of the object can be measured more accurately.

[0039] (16) The optical characteristic measurement method of the present disclosure includes the optical beam scanning method according to any one of (11) to (15) above, emitting an optical beam from a light source, and detecting the optical beam that has been two-dimensionally scanned by the first scanning mirror and the second scanning mirror and has passed through the object.

[0040] Therefore, the optical characteristic measurement method of the present disclosure can measure the optical characteristics of an object with a wider range of specifications with an optical beam similar to the optical beam output from the optical beam scanning device included in the device to which the object is applied.

[0041] (17) The optical property measurement method according to the above (16) further includes causing either the first light beam or the second light beam to be incident on the first scanning mirror as a light beam. The light source includes a first light source capable of emitting a first light beam having a first wavelength and a second light source capable of emitting a second light beam having a second wavelength different from the first wavelength.

[0042] Therefore, a light beam having a wavelength specified in the specification of each object can be irradiated onto each object. The optical property measurement method enables measurement of the optical properties of objects with a wider range of specifications.

[0043] (18) In the optical property measurement method according to the above (16) or (17), detecting the light beam means detecting the wavefront of the light beam transmitted through the object.

[0044] Therefore, it becomes possible to measure the optical properties (for example, aberration, etc.) of objects with a wider range of specifications.

[0045] (19) In the optical property measurement method according to any one of the above (16) to (18), the object is an fθ lens.

[0046] Therefore, it becomes possible to measure the optical properties (for example, aberration, modulation transfer function (MTF), telecentric error, or light transmittance, etc.) of fθ lenses with a wider range of specifications.

[0047] [Details of Embodiments] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

[0048] (Embodiment 1) Referring to FIGS. 1 and 2, the optical property measuring apparatus 1 and the light beam scanning apparatus 2 of Embodiment 1 will be described. The optical property measuring apparatus 1 can measure the optical properties (e.g., aberration, etc.) of the object 30. The object 30 is, for example, an optical component. More specifically, the object 30 is a lens such as an fθ lens, an fsinθ lens, or a condenser lens.

[0049] The optical property measuring apparatus 1 includes a light source 11, an optical fiber 13, a collimator lens 15, a beam splitter 16, a beam expander 18, a photodetector 17, a light beam scanning apparatus 2, and a mirror 33.

[0050] The light source 11 can emit a light beam 12. In this embodiment, the light source 11 is a fiber laser. The light source 11 may be a laser light source such as a solid laser, a semiconductor laser, or a gas laser (e.g., a carbon dioxide laser, etc.), a light emitting diode (LED), or a lamp. When the light source 11 is an LED or a lamp, the optical property measuring apparatus 1 may further include a wavelength selection element that selects light having a wavelength specified by the specifications of the object 30 from the light emitted from the LED or the lamp. The wavelength selection element is, for example, a band-pass filter, a prism, or a grating.

[0051] The optical fiber 13 is, for example, a silica optical fiber or a plastic optical fiber. The collimator lens 15 collimates the light beam 12 emitted from the optical fiber 13. The beam splitter 16 allows the light beam 12 that has passed through the collimator lens 15 to pass through. The beam splitter 16 reflects a part of the light beam 12 reflected by the mirror 33 toward the photodetector 17.

[0052] The beam expander 18 expands the beam diameter of the light beam 12 that travels from the light source 11 to the light beam scanning device 2. The beam expander 18 includes lenses 18a and 18b. The lens 18a expands the beam diameter of the light beam 12, for example. The lens 18b collimates the light beam 12, for example. The light beam 12 that has passed through the beam expander 18 is incident on the light beam scanning device 2 (specifically, the first scanning mirror 20). The beam expander 18 reduces the beam diameter of the light beam 12 that travels from the light beam scanning device 2 to the beam splitter 16.

[0053] The mirror 33 is, for example, a spherical mirror. When the object 30 is a lens, the center of curvature of the spherical mirror is arranged at the condensing position of the light beam 12 by the object 30. The light beam 12 emitted from the object 30 is reflected by the mirror 33 and travels in the reverse direction. The light beam 12 passes through the object 30, is reflected by the second scanning mirror 25 and the first scanning mirror 20, and is emitted from the light beam scanning device 2. The light beam 12 passes through the beam expander 18 and is incident on the beam splitter 16. A part of the light beam 12 is reflected by the beam splitter 16 and is incident on the photodetector 17.

[0054] The photodetector 17 can detect the light beam 12 that has been two-dimensionally scanned by the light beam scanning device 2 and has passed through the object 30. The photodetector 17 is, for example, a wavefront sensor that detects the wavefront of the light beam 12 that has passed through the object 30. The wavefront sensor is, for example, a Shack-Hartmann wavefront sensor. The photodetector 17 detects the light beam 12 that has passed through the object 30 twice. The optical property measuring device 1 is a double-pass optical system.

[0055] The light beam scanning device 2 includes a first scanning mirror 20, a first mirror rotation mechanism 21, a first movement mechanism 22, a second scanning mirror 25, a second mirror rotation mechanism 26, a second movement mechanism 31, and a mirror movement mechanism 34. The light beam scanning device 2 may further include a controller 40.

[0056] The first scanning mirror 20 can scan the light beam 12 emitted from the light source 11. The first scanning mirror 20 is a rotatable mirror including, for example, a vibrating mirror such as a galvanometer mirror and a polygon mirror. The size of the first scanning mirror 20 is larger than the largest beam diameter among the beam diameters defined by the specifications of the object 30 for which the optical characteristics are assumed to be measured.

[0057] The first mirror rotation mechanism 21 includes, for example, a motor connected to the first scanning mirror 20. The motor is, for example, a galvanometer motor, a stepping motor, or a servo motor. The first mirror rotation mechanism 21 can rotate the first scanning mirror 20 to change the orientation of the first scanning mirror 20. Specifically, the first mirror rotation mechanism 21 is connected to the first scanning mirror 20 and the controller 40. The first mirror rotation mechanism 21 can be controlled by the controller 40 to change the orientation of the first scanning mirror 20. The first scanning mirror 20 oscillates to scan the light beam 12 in the first direction on the incident surface of the object 30.

[0058] The first movement mechanism 22 can move the first scanning mirror 20 to change the first position of the first scanning mirror 20. The first movement mechanism 22 can move the first scanning mirror 20, for example, along the optical path of the light beam 12 incident on the first scanning mirror 20 or along an arc-shaped orbit. Specifically, the first movement mechanism 22 is connected to the first scanning mirror 20 and the controller 40. The first mirror rotation mechanism 21 can be controlled by the controller 40 to change the first position of the first scanning mirror 20. The first movement mechanism 22 is, for example, a linear stage that supports the first mirror rotation mechanism 21.

[0059] The second scanning mirror 25 can scan the light beam 12 scanned by the first scanning mirror 20. The second scanning mirror 25 is a rotatable mirror including, for example, a vibrating mirror such as a galvanometer mirror and a polygon mirror.

[0060] The second mirror rotation mechanism 26 includes, for example, a motor connected to the second scanning mirror 25. The motor is, for example, a galvanometer motor, a stepping motor, or a servo motor. The second mirror rotation mechanism 26 can rotate the second scanning mirror 25 to change the orientation of the second scanning mirror 25. Specifically, the second mirror rotation mechanism 26 is connected to the second scanning mirror 25 and the controller 40. The second mirror rotation mechanism 26 can be controlled by the controller 40 to change the orientation of the second scanning mirror 25. The second scanning mirror 25 oscillates to scan the light beam 12 in a second direction perpendicular to, for example, a first direction on the incident surface of the object 30.

[0061] The controller 40 is, for example, a microcomputer including a processor, a storage device such as a RAM (Random Access Memory), and a ROM (Read Only Memory). As the processor, for example, a CPU (Central Processing Unit) can be adopted. The RAM functions as a working memory that temporarily stores data processed by the processor. The storage device stores, for example, a program executed by the processor. In this embodiment, by the processor executing the program stored in the storage device, the controller 40 controls the light beam scanning device 2 and the optical property measuring device 1. Instead of the microcomputer, an FPGA (Field-Programmable Gate Array) may be adopted as the controller 40. Various processes in the controller 40 are not limited to being executed by software and may be realized by dedicated hardware (electronic circuits).

[0062] The controller 40 can control the first mirror rotation mechanism 21, the first movement mechanism 22, the second mirror rotation mechanism 26, the second movement mechanism 31, and the mirror movement mechanism 34.

[0063] By controlling the first mirror rotation mechanism 21, the controller 40 controls the orientation of the first scanning mirror 20, causing the first scanning mirror 20 to swing. By controlling the second mirror rotation mechanism 26, the controller 40 controls the orientation of the second scanning mirror 25, causing the second scanning mirror 25 to swing. The object 30 is irradiated with the light beam 12 that is two-dimensionally scanned by the first scanning mirror 20 and the second scanning mirror 25.

[0064] Regardless of the orientation of the first scanning mirror 20, the controller 40 can control the first moving mechanism 22 according to the orientation of the first scanning mirror 20 such that the light beam 12 reflected by the first scanning mirror 20 passes through the reference position 24 between the first scanning mirror 20 and the second scanning mirror 25. The distance between the reference position 24 and the second scanning mirror 25 is, for example, the distance between the first scanning mirror 20 and the second scanning mirror 25 (scanning mirror distance) defined by the specifications of the object 30. The reference position 24 may be closer to the second scanning mirror 25 than the first scanning mirror 20.

[0065] The second moving mechanism 31 can move the object 30 to adjust the second position of the object 30. Specifically, the second moving mechanism 31 is connected to the object 30 and the controller 40. The second moving mechanism 31 can be controlled by the controller 40 to change the second position of the object 30. By adjusting the second position of the object 30 using the second moving mechanism 31, the distance between the second scanning mirror 25 and the object 30 is adjusted to the distance defined by the specifications of the object 30. The second moving mechanism 31 is, for example, a linear stage that supports the object 30.

[0066] The mirror moving mechanism 34 can move the mirror 33 so that the mirror 33 reflects the light beam 12 that is two-dimensionally scanned by the light beam scanning device 2. Specifically, the mirror moving mechanism 34 is connected to the mirror 33 and the controller 40. The mirror moving mechanism 34 can be controlled by the controller 40 to move the mirror 33. The mirror moving mechanism 34 is, for example, a three-dimensional moving stage that supports the mirror 33.

[0067] Referring to FIGS. 1 and 2, an example of the optical beam scanning method and the method for measuring the optical characteristics of the object 30 according to the present embodiment will be described.

[0068] The controller 40 controls the second moving mechanism 31 to adjust the second position of the object 30 so that the distance between the second scanning mirror 25 and the object 30 becomes the distance specified in the specifications of the object 30.

[0069] The light source 11 emits an optical beam 12. The optical beam 12 enters the collimator lens 15 through the optical fiber 13. The optical beam 12 is collimated by the collimator lens 15. The optical beam 12 enters the optical beam scanning device 2 through the beam splitter 16 and the beam expander 18. The beam expander 18 expands the beam diameter of the optical beam 12.

[0070] The controller 40 controls the first mirror rotation mechanism 21 to rotate the first scanning mirror 20. The first scanning mirror 20 swings to scan the optical beam 12. The optical beam 12 scanned by the first scanning mirror 20 enters the second scanning mirror 25. The controller 40 controls the second mirror rotation mechanism 26 to rotate the second scanning mirror 25. The second scanning mirror 25 swings to scan the optical beam 12 scanned by the first scanning mirror 20. Thus, the optical beam 12 emitted from the light source 11 is two-dimensionally scanned by the first scanning mirror 20 and the second scanning mirror 25. The object 30 is irradiated with the optical beam 12 two-dimensionally scanned by the first scanning mirror 20 and the second scanning mirror 25.

[0071] When scanning the light beam 12, regardless of the orientation of the first scanning mirror 20, the controller 40 changes the first position of the first scanning mirror 20 according to the orientation of the first scanning mirror 20 so that the light beam 12 reflected by the first scanning mirror 20 passes through a reference position 24 between the first scanning mirror 20 and the second scanning mirror 25. For example, regardless of the orientation of the first scanning mirror 20, the first position of the first scanning mirror 20 is changed along the optical path of the light beam 12 incident on the first scanning mirror 20 or along an arc-shaped orbit so that the light beam 12 passes through the reference position 24. Therefore, optically, it can be regarded that the first scanning mirror 20 is arranged at the reference position 24. The distance between the reference position 24 and the second scanning mirror 25 is, for example, the distance between the first scanning mirror 20 and the second scanning mirror 25 (scanning mirror distance) defined by the specifications of the object 30. The reference position 24 may be closer to the second scanning mirror 25 than the first scanning mirror 20.

[0072] The controller 40 controls the mirror moving mechanism 34 to move the mirror 33 so that the light beam 12 scanned two-dimensionally can be reflected by the mirror 33. The light beam 12 that has passed through the object 30 is reflected by the mirror 33 and travels in the reverse direction. The light beam 12 passes through the object 30, is reflected by the second scanning mirror 25 and the first scanning mirror 20, and exits from the light beam scanning device 2. The light beam 12 passes through the beam expander 18 and is incident on the beam splitter 16. A part of the light beam 12 is reflected by the beam splitter 16 and is incident on the photodetector 17.

[0073] The photodetector 17 detects the light beam 12 that has been scanned two-dimensionally by the first scanning mirror 20 and the second scanning mirror 25 and has passed through the object 30. The photodetector 17 is, for example, a wavefront sensor such as a Shack-Hartmann wavefront sensor. The photodetector 17 detects the wavefront of the light beam 12 that has passed through the object 30 through the light beam scanning device 2. The wavefront of the light beam 12 reflects the optical characteristics (such as aberration, etc.) of the object 30. Therefore, the optical characteristics of the object 30 are calculated from the wavefront of the light beam 12. In this way, the optical characteristics of the object 30 can be measured.

[0074] The operation of this embodiment will be described while contrasting with the comparative example. In the comparative example, the position of the second scanning mirror 25 is set so that the distance between the second scanning mirror 25 and the object 30 becomes the distance specified by the specifications of the object 30. The position of the first scanning mirror 20 is set so that the distance between the first scanning mirror 20 and the second scanning mirror 25 becomes the distance between the first scanning mirror 20 and the second scanning mirror 25 (scanning mirror distance) specified by the specifications of the object 30.

[0075] In the comparative example, depending on the specifications of the object 30, the size of the first scanning mirror 20, and the size of the second scanning mirror 25, two of the first scanning mirror 20, the second scanning mirror 25, and the object 30 may mechanically interfere with each other. Therefore, in the comparative example, it was not possible to measure the optical characteristics of the object 30 having a certain specification. Also, there were cases where the optical characteristics of the object 30 could not be measured with a light beam 12 having the same beam diameter, incident position on the object 30, and incident angle on the object 30 as the light beam output from the light beam scanning device included in the device (for example, a laser processing device) to which the object 30 is applied.

[0076] On the other hand, in this embodiment, the object 30 is irradiated with the light beam 12 that is two-dimensionally scanned by the first scanning mirror 20 and the second scanning mirror 25. Further, regardless of the orientation of the first scanning mirror 20, the first position of the first scanning mirror 20 is changed according to the orientation of the first scanning mirror 20 so that the light beam 12 reflected by the first scanning mirror 20 passes through the reference position 24. The distance between the reference position 24 and the second scanning mirror 25 is the scanning mirror distance specified by the specifications of the object 30. Therefore, optically, while the first scanning mirror 20 can be regarded as existing at the reference position 24, in reality, the first scanning mirror 20 can be arranged farther away from the second scanning mirror 25 and the object 30 (for example, an fθ lens).

[0077] Even if the sizes of the first scanning mirror 20 and the second scanning mirror 25 are large compared to the distance between the second scanning mirror 25 and the object 30 defined in the specifications of the object 30 and the distance between the first scanning mirror 20 and the second scanning mirror 25 (distance between scanning mirrors), mechanical interference between two of the first scanning mirror 20, the second scanning mirror 25, and the object 30 can be prevented. According to the present embodiment, for an object 30 with a wider range of specifications, it is possible to scan a light beam 12 having the same beam diameter, incident position on the object 30, and incident angle on the object 30 as the light beam output from the light beam scanning device included in the device (for example, a laser processing device) to which the object 30 is applied. The optical characteristics of the object 30 can be measured with the light beam 12 having the same beam diameter, incident position on the object 30, and incident angle on the object 30 as the light beam output from the light beam scanning device included in the device (for example, a laser processing device) to which the object 30 is applied.

[0078] (Embodiment 2) With reference to FIGS. 3 and 4, the optical property measurement apparatus 1 and the light beam scanning apparatus 2 of Embodiment 2 will be described. The optical property measurement apparatus 1 and the light beam scanning apparatus 2 of the present embodiment are configured in the same manner as the optical property measurement apparatus 1 and the light beam scanning apparatus 2 of Embodiment 1, but are mainly different from the optical property measurement apparatus 1 and the light beam scanning apparatus 2 of Embodiment 1 in the following points.

[0079] In this embodiment, the second scanning mirror 25 includes a plurality of mirrors with different sizes from each other. The plurality of mirrors are, for example, a first mirror 25a, a second mirror 25b, and a third mirror 25c. The first mirror 25a has a size larger than that of the second mirror 25b. The second mirror 25b has a size larger than that of the third mirror 25c. The first mirror 25a is used to scan the light beam 12 having a first beam diameter. The second mirror 25b is used to scan the light beam 12 having a second beam diameter smaller than the first beam diameter. The third mirror 25c is used to scan the light beam 12 having a third beam diameter smaller than the second beam diameter. The first mirror 25a, the second mirror 25b, and the third mirror 25c are connected to each other. The first mirror 25a is connected to the second mirror rotation mechanism 26.

[0080] The light beam scanning device 2 of this embodiment further includes a third moving mechanism 27. The third moving mechanism 27 can change the third position of the second scanning mirror 25. Specifically, the third moving mechanism 27 is connected to the second scanning mirror 25 and the controller 40. The third moving mechanism 27 can be controlled by the controller 40 to change the third position of the second scanning mirror 25. The controller 40 can control the third moving mechanism 27 so that the light beam 12 is scanned by one of the plurality of mirrors (for example, the first mirror 25a, the second mirror 25b, and the third mirror 25c). A mirror for scanning the light beam 12 is selected from the plurality of mirrors. The third moving mechanism 27 is, for example, a linear stage that supports the second mirror rotation mechanism 26.

[0081] Referring to FIGS. 3 and 4, the light beam scanning method and the optical property measurement method of this embodiment will be described. The light beam scanning method and the optical property measurement method of this embodiment have the same steps as the light beam scanning method and the optical property measurement method of Embodiment 1, but are mainly different from the light beam scanning method and the optical property measurement method of Embodiment 1 in the following points.

[0082] In the light beam scanning method and the optical property measurement method of this embodiment, the third position of the second scanning mirror 25 including a plurality of mirrors (for example, the first mirror 25a, the second mirror 25b, and the third mirror 25c) having different sizes from each other is changed. By changing the third position, the light beam 12 is scanned by one of the plurality of mirrors.

[0083] When the distance between the second scanning mirror 25 and the object 30 has to be decreased according to the specifications of the object 30, the light beam 12 is scanned by a mirror having a smaller size (for example, the third mirror 25c). Therefore, it can be prevented that the second scanning mirror 25 mechanically interferes with the object 30. Further, when the beam diameter of the light beam 12 defined by the specifications of the object 30 is small, the light beam 12 is scanned by a mirror having a smaller size (for example, the third mirror 25c).

[0084] (Embodiment 3) With reference to FIGS. 5 and 6, the optical property measurement apparatus 1 and the light beam scanning apparatus 2 of Embodiment 3 will be described. The optical property measurement apparatus 1 and the light beam scanning apparatus 2 of this embodiment are configured in the same manner as the optical property measurement apparatus 1 and the light beam scanning apparatus 2 of Embodiment 2, but are mainly different from the optical property measurement apparatus 1 and the light beam scanning apparatus 2 of Embodiment 2 in the following points.

[0085] The light beam scanning apparatus 2 of this embodiment further includes an optical path length adjuster 36. The optical path length adjuster 36 is disposed on the optical path of the light beam 12 incident on the first scanning mirror 20. The optical path length adjuster 36 can adjust the optical path length of the light beam 12 incident on the first scanning mirror 20 so that the optical path length of the light beam 12 from the incident end of the optical path length adjuster 36 to the reference position 24 becomes constant regardless of the first position of the first scanning mirror 20. The optical path length adjuster 36 includes, for example, mirrors 36a, 36b, a right-angle prism 36c, and a fourth moving mechanism 37.

[0086] The right-angled prism 36c has two reflecting surfaces. The light beam 12 emitted from the light source 11 passes through the collimator lens 15 and the beam splitter 16 and enters the mirror 36a. The mirror 36a is the incident end of the optical path length adjuster 36. The light beam 12 is reflected by the mirror 36a and enters the right-angled prism 36c. The light beam 12 is reflected by the two reflecting surfaces of the right-angled prism 36c. The light beam 12 is reflected by the mirror 36b and exits from the optical path length adjuster 36.

[0087] The fourth moving mechanism 37 can move the right-angled prism 36c to change the distance between the mirrors 36a and 36b and the right-angled prism 36c. Specifically, the fourth moving mechanism 37 is connected to the right-angled prism 36c and the controller 40. The fourth moving mechanism 37 can be controlled by the controller 40 to change the position of the right-angled prism 36c. The distances between the mirrors 36a and 36b, the right-angled prism 36c, and the object 30 are adjusted, and the optical path length of the light beam 12 incident on the first scanning mirror 20 is adjusted. The fourth moving mechanism 37 is, for example, a linear stage that supports the right-angled prism 36c.

[0088] The controller 40 can control the optical path length adjuster 36 (more specifically, the fourth moving mechanism 37). Specifically, the controller 40 controls the optical path length adjuster 36 according to the first position of the first scanning mirror 20. The optical path length adjuster 36 adjusts the optical path length of the light beam 12 incident on the first scanning mirror 20 so that the optical path length of the light beam 12 from the incident end of the optical path length adjuster 36 to the reference position 24 is constant regardless of the first position of the first scanning mirror 20.

[0089] Referring to FIGS. 5 and 6, the light beam scanning method and the optical property measurement method of the present embodiment will be described. The light beam scanning method and the optical property measurement method of the present embodiment have the same steps as the light beam scanning method and the optical property measurement method of Embodiment 2, but are mainly different from the light beam scanning method and the optical property measurement method of Embodiment 2 in the following points.

[0090] In the light beam scanning method and the optical property measurement method of the present embodiment, the optical path length of the light beam 12 from the incident end of the optical path length adjuster 36 to the reference position 24 is made constant regardless of the first position of the first scanning mirror 20, by using the optical path length adjuster 36 disposed on the optical path of the light beam 12 incident on the first scanning mirror 20, the optical path length of the light beam 12 incident on the first scanning mirror 20 is adjusted.

[0091] The light beam 12 having a divergence angle defined by the specifications of the object 30 may be incident on the object 30. The light beam 12 having a divergence angle is generated by shifting at least one position of the lens 18a or the lens 18b along the optical path of the light beam 12. If there is no optical path length adjuster 36 when the light beam 12 incident on the first scanning mirror 20 has a divergence angle, when the first position of the first scanning mirror 20 changes, the optical path length of the light beam 12 from the collimator lens 15 to the reference position 24 changes, and the beam diameter of the light beam 12 at the reference position 24 changes. Therefore, the optical properties of the object 30 cannot be measured using the light beam 12 having the beam diameter defined by the specifications of the object 30.

[0092] On the other hand, in the present embodiment, the optical path length adjuster 36 adjusts the optical path length of the light beam 12 incident on the first scanning mirror 20 so that the optical path length of the light beam 12 from the incident end of the optical path length adjuster 36 to the reference position 24 is constant regardless of the first position of the first scanning mirror 20. Therefore, even if the light beam 12 incident on the first scanning mirror 20 has a divergence angle, the beam diameter of the light beam 12 at the reference position 24 can be kept constant regardless of the first position of the first scanning mirror 20.

[0093] Therefore, the optical characteristics of the object 30 can be measured using the optical beam 12 having the beam diameter specified in the specifications of the object 30. The optical characteristics of the object 30 can be measured more accurately. Also, the optical characteristics of the object 30 can be measured with an optical beam 12 similar to the optical beam output from the optical beam scanning device included in the apparatus (for example, a laser processing apparatus) to which the object 30 is applied. According to the present embodiment, it becomes possible to scan an optical beam 12 similar to the optical beam output from the optical beam scanning device included in the apparatus (for example, a laser processing apparatus) to which the object 30 is applied, with respect to the object 30 having a wider range of specifications. The optical characteristics of the object 30 having a wider range of specifications can be measured with an optical beam 12 similar to the optical beam output from the optical beam scanning device included in the apparatus to which the object 30 is applied.

[0094] Note that the optical path length adjuster 36 may include two movable mirrors instead of the right-angled prism 36c.

[0095] (Embodiment 4) With reference to FIGS. 7 and 8, the optical characteristic measurement apparatus 1 of Embodiment 4 will be described. The optical characteristic measurement apparatus 1 of the present embodiment is configured in the same manner as the optical characteristic measurement apparatus 1 of Embodiment 3, but is mainly different from the optical characteristic measurement apparatus 1 of Embodiment 3 in the following points.

[0096] In the optical characteristic measurement apparatus 1 of the present embodiment, the light source 11 includes a plurality of light sources. Each of the plurality of light sources can emit an optical beam having a wavelength different from that of the others. The plurality of light sources are, for example, a first light source 11a, a second light source 11b, and a third light source 11c. The first light source 11a can emit a first optical beam 12a having a first wavelength. The second light source 11b can emit a second optical beam 12b having a second wavelength different from the first wavelength. The third light source 11c can emit a third optical beam 12c having a third wavelength different from the first wavelength and the second wavelength.

[0097] The optical fiber 13 includes a plurality of optical fibers. The plurality of optical fibers are, for example, a first optical fiber 13a, a second optical fiber 13b, and a third optical fiber 13c. The first optical fiber 13a is connected to the first light source 11a. The first light beam 12a travels through the first optical fiber 13a. The second optical fiber 13b is connected to the second light source 11b. The second light beam 12b travels through the second optical fiber 13b. The third optical fiber 13c is connected to the third light source 11c. The third light beam 12c travels through the third optical fiber 13c.

[0098] The optical property measuring apparatus 1 of the present embodiment further includes a beam selector 38 (see FIG. 8). The beam selector 38 causes any one of a plurality of light beams (for example, the first light beam 12a, the second light beam 12b, and the third light beam 12c) to be incident on the light beam scanning device 2 (more specifically, the first scanning mirror 20) as the light beam 12. Specifically, the beam selector 38 is connected to the first optical fiber 13a, the second optical fiber 13b, the third optical fiber 13c, and the controller 40. The beam selector 38 is controlled by the controller 40 to optically couple any one of the first optical fiber 13a, the second optical fiber 13b, or the third optical fiber 13c to the first scanning mirror 20 through the collimator lens 15, the beam splitter 16, and the beam expander 18. Thus, any one of the first light beam 12a, the second light beam 12b, or the third light beam 12c is incident on the light beam scanning device 2. The beam selector 38 is, for example, a moving stage that supports the first optical fiber 13a, the second optical fiber 13b, and the third optical fiber 13c.

[0099] Referring to FIGS. 7 and 8, the optical property measuring method of the present embodiment will be described. The optical property measuring method of the present embodiment includes steps similar to those of the optical property measuring method of Embodiment 3, but is mainly different from the optical property measuring method of Embodiment 3 in the following points.

[0100] In the optical property measurement method of this embodiment, any one of a plurality of light beams (for example, the first light beam 12a, the second light beam 12b, or the third light beam 12c) is made incident on the first scanning mirror 20 as the light beam 12. Specifically, the controller 40 controls the beam selector 38 to optically couple any one of the first optical fiber 13a, the second optical fiber 13b, or the third optical fiber 13c to the first scanning mirror 20 through the collimator lens 15, the beam splitter 16, and the beam expander 18. In this way, any one of the first light beam 12a, the second light beam 12b, or the third light beam 12c enters the light beam scanning device 2 by the beam selector 38. Any one of the first light beam 12a, the second light beam 12b, or the third light beam 12c selected by the beam selector 38 has, for example, a wavelength specified by the specifications of the object 30.

[0101] The object 30 is two-dimensionally scanned by any one of the first light beam 12a, the second light beam 12b, or the third light beam 12c. The optical properties of the object 30 can be measured by any one of the first light beam 12a, the second light beam 12b, or the third light beam 12c. The optical properties of objects 30 with a wider range of specifications can be measured. Note that the number of a plurality of light sources and the number of a plurality of optical fibers are not limited to three, and may be two or four or more.

[0102] (Embodiment 5) Referring to FIGS. 8 and 9, the optical property measurement device 1 of Embodiment 5 will be described. The optical property measurement device 1 of this embodiment is configured in the same manner as the optical property measurement device 1 of Embodiment 4 and has the same effects as the optical property measurement device 1 of Embodiment 4. However, it is mainly different from the optical property measurement device 1 of Embodiment 4 in the following points.

[0103] The optical property measurement device 1 of this embodiment, the beam selector 38 includes an optical combiner 43 and a plurality of optical shutters. The plurality of optical shutters are, for example, the first optical shutter 38a, the second optical shutter 38b, and the third optical shutter 38c.

[0104] The optical combiner 43 combines a plurality of optical beams (for example, the first optical beam 12a, the second optical beam 12b, and the third optical beam 12c), and optically couples the plurality of optical beams to the first scanning mirror 20 through the collimator lens 15, the beam splitter 16, and the beam expander 18. The optical combiner 43 includes, for example, mirrors 44a, 44b and optical wavelength multiplexers 45a, 45b. The optical wavelength multiplexers 45a, 45b are, for example, optical filters such as dichroic filters. The first optical beam 12a emitted from the first light source 11a enters the collimator lens 15 through the optical wavelength multiplexers 45a, 45b. The second optical beam 12b emitted from the second light source 11b is reflected by the mirror 44a and the optical wavelength multiplexer 45a and enters the collimator lens 15. The third optical beam 12c emitted from the third light source 11c is reflected by the mirror 44b and the optical wavelength multiplexer 45b and enters the collimator lens 15.

[0105] The first optical shutter 38a is disposed in the optical path of the first optical beam 12a. The first optical shutter 38a is disposed, for example, between the first light source 11a and the optical wavelength multiplexer 45a. The first optical shutter 38a transmits or blocks the first optical beam 12a. The second optical shutter 38b is disposed in the optical path of the second optical beam 12b. The second optical shutter 38b is disposed, for example, between the second light source 11b and the mirror 44a. The second optical shutter 38b transmits or blocks the second optical beam 12b. The third optical shutter 38c is disposed in the optical path of the third optical beam 12c. The third optical shutter 38c is disposed, for example, between the third light source 11c and the mirror 44b. The third optical shutter 38c transmits or blocks the third optical beam 12c. The first optical shutter 38a, the second optical shutter 38b, and the third optical shutter 38c are, for example, electro-optical shutters such as liquid crystal optical shutters, or mechanical shutters including movable light-shielding plates.

[0106] The beam selector 38 is connected to the controller 40. The controller 40 controls the beam selector 38 to open one of the first optical shutter 38a, the second optical shutter 38b, or the third optical shutter 38c, and block the rest of the first optical shutter 38a, the second optical shutter 38b, or the third optical shutter 38c. In this way, one of the first light beam 12a, the second light beam 12b, or the third light beam 12c enters the first scanning mirror 20 through the collimator lens 15, the beam splitter 16, and the beam expander 18.

[0107] Referring to FIGS. 8 and 9, the optical property measurement method of this embodiment will be described. The optical property measurement method of this embodiment includes the same steps as the optical property measurement method of Embodiment 4 and has the same effects as the optical property measurement method of Embodiment 4. However, it is mainly different from the optical property measurement method of Embodiment 4 in the following points.

[0108] In the optical property measurement method of this embodiment, one of the first light beam 12a, the second light beam 12b, or the third light beam 12c is made to enter the first scanning mirror 20 as the light beam 12. Specifically, the controller 40 controls the beam selector 38 to open one of the first optical shutter 38a, the second optical shutter 38b, or the third optical shutter 38c, and block the rest of the first optical shutter 38a, the second optical shutter 38b, or the third optical shutter 38c. In this way, the beam selector 38 optically couples one of the first light beam 12a, the second light beam 12b, or the third light beam 12c to the light beam scanning device 2. One of the first light beam 12a, the second light beam 12b, or the third light beam 12c selected by the beam selector 38 is, for example, the wavelength specified by the specifications of the object 30.

[0109] The object 30 is two-dimensionally scanned by any one of the first light beam 12a, the second light beam 12b, or the third light beam 12c. The optical characteristics of the object 30 can be measured by any one of the first light beam 12a, the second light beam 12b, or the third light beam 12c. The optical characteristics of the object 30 with a wider range of specifications can be measured. Note that the number of the plurality of light sources and the number of the plurality of optical shutters are not limited to three each, and may be two or four or more.

[0110] (Embodiment 6) Referring to FIGS. 10 and 11, the optical characteristic measuring apparatus 1 of Embodiment 6 will be described. The optical characteristic measuring apparatus 1 of the present embodiment is configured in the same manner as the optical characteristic measuring apparatus 1 of Embodiment 4 and has the same effects as the optical characteristic measuring apparatus 1 of Embodiment 4. However, the optical characteristic measuring apparatus 1 of the present embodiment is mainly different from the optical characteristic measuring apparatus 1 of Embodiment 4 in the following points.

[0111] The optical characteristic measuring apparatus 1 of the present embodiment does not include a beam splitter 16, and instead of the mirror 33, includes a detection optical system 46. The detection optical system 46 includes, for example, a lens 47, a relay lens 48, and a photodetector 17. The optical characteristic measuring apparatus 1 of the present embodiment includes a detection optical system moving mechanism 35 instead of the mirror moving mechanism 34 (see FIG. 8).

[0112] The detection optical system 46 is an optical system for detecting the light beam 12 that has passed through the object 30. The lens 47 collimates the light beam 12 that has passed through the object 30. For example, when the object 30 is a lens, the lens 47 is arranged so that the focal position of the lens 47 coincides with the condensing position of the light beam 12 by the object 30. The light beam 12 collimated by the lens 47 enters the photodetector 17 through the relay lens 48.

[0113] The detection optical system moving mechanism 35 moves the detection optical system 46. Specifically, the detection optical system moving mechanism 35 can move the lens 47, the relay lens 48, and the photodetector 17 so that the light beam 12 that has been two-dimensionally scanned by the light beam scanning device 2 and has passed through the object 30 is incident on the photodetector 17. For example, the detection optical system moving mechanism 35 is connected to the lens 47, the relay lens 48, and the photodetector 17. The detection optical system moving mechanism 35 is controlled by the controller 40 to move the lens 47, the relay lens 48, and the photodetector 17. The detection optical system moving mechanism 35 is, for example, a three-dimensional moving stage that supports the lens 47, the relay lens 48, and the photodetector 17.

[0114] The photodetector 17 detects the light beam 12 that has been two-dimensionally scanned by the light beam scanning device 2 and has passed through the object 30. The photodetector 17 detects the light beam 12 that has passed through the object 30 once. The optical property measurement device 1 is a single-pass optical system.

[0115] Referring to FIGS. 10 and 11, the optical property measurement method of the present embodiment will be described. The optical property measurement method of the present embodiment includes the same steps as the optical property measurement method of Embodiment 4 and has the same effects as the optical property measurement method of Embodiment 4. Specifically, in the optical property measurement method of the present embodiment, the controller 40 controls the detection optical system moving mechanism 35 to move the lens 47, the relay lens 48, and the photodetector 17 so that the light beam 12 that has been two-dimensionally scanned by the light beam scanning device 2 and has passed through the object 30 is incident on the photodetector 17. The photodetector 17 detects the light beam 12 that has passed through the object 30 once, and measures the optical properties of the object 30.

[0116] The disclosed Embodiments 1-6 should be considered illustrative in all respects and not restrictive. As long as there is no contradiction, at least two of the disclosed Embodiments 1-6 may be combined. The scope of the present disclosure is indicated by the claims rather than the above-described embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope.

Explanation of Reference Numerals

[0117] 1 Optical property measuring device, 2 Light beam scanning device, 11 Light source, 11a First light source, 11b Second light source, 11c Third light source, 12 Light beam, 12a First light beam, 12b Second light beam, 12c Third light beam, 13 Optical fiber, 13a First optical fiber, 13b Second optical fiber, 13c Third optical fiber, 15 Collimator lens, 16 Beam splitter, 17 Photodetector, 18 Beam expander, 18a, 18b Lenses, 20 First scanning mirror, 21 First mirror rotation mechanism, 22 First moving mechanism, 24 Reference position, 25 Second scanning mirror, 25a First mirror, 25b Second mirror, 25c Third mirror, 26 Second mirror rotation mechanism, 27 Third moving mechanism, 30 Object, 31 Second moving mechanism, 33 Mirror, 34 Mirror moving mechanism, 35 Detection optical system moving mechanism, 36 Optical path length adjuster, 36a, 36b Mirrors, 36c Right-angle prism, 37 Fourth moving mechanism, 38 Beam selector, 38a First optical shutter, 38b Second optical shutter, 38c Third optical shutter, 40 Controller, 43 Optical combiner, 44a, 44b Mirrors, 45a, 45b Optical multiplexers, 46 Detection optical system, 47 Lens, 48 Relay lens.

Claims

1. A first scanning mirror capable of scanning a light beam; a second scanning mirror capable of scanning the light beam scanned by the first scanning mirror; a first mirror rotation mechanism capable of changing the orientation of the first scanning mirror; a first moving mechanism capable of changing a first position of the first scanning mirror; an object is illuminated with the light beam that is scanned two-dimensionally by the first scanning mirror and the second scanning mirror; an optical beam scanning device, wherein the first position is changed according to the orientation of the first scanning mirror so that the optical beam reflected by the first scanning mirror passes through a reference position between the first scanning mirror and the second scanning mirror, regardless of the orientation of the first scanning mirror.

2. Further comprising a controller, 2. The light beam scanning device according to claim 1, wherein the controller controls the first moving mechanism in accordance with the orientation of the first scanning mirror so that the light beam reflected by the first scanning mirror passes through the reference position regardless of the orientation of the first scanning mirror.

3. 2. The optical beam scanning device according to claim 1, wherein the reference position is closer to the second scanning mirror than to the first scanning mirror.

4. a second moving mechanism capable of adjusting a second position of the object; 2. The optical beam scanning device of claim 1, wherein adjusting the second position adjusts a distance between the second scanning mirror and the object.

5. a third moving mechanism capable of changing a third position of the second scanning mirror; the second scanning mirror includes a plurality of mirrors having different sizes; 2. The optical beam scanning device of claim 1, wherein the third position is changed so that the optical beam is scanned by one of the plurality of mirrors.

6. an optical path length adjuster disposed on an optical path of the light beam incident on the first scanning mirror; 2. The light beam scanning device of claim 1, wherein the optical path length adjuster is capable of adjusting the optical path length of the light beam incident on the first scanning mirror so that the optical path length of the light beam from the incident end of the optical path length adjuster to the reference position is constant regardless of the first position of the first scanning mirror.

7. The light beam scanning device according to any one of claims 1 to 6, a light source capable of emitting said light beam; an optical detector capable of detecting the light beam that has been two-dimensionally scanned by the first scanning mirror and the second scanning mirror and that has passed through the object;

8. Further comprising a beam selector; The light source includes a first light source capable of emitting a first light beam having a first wavelength and a second light source capable of emitting a second light beam having a second wavelength different from the first wavelength; 8. The optical characteristic measuring apparatus according to claim 7, wherein the beam selector causes either the first light beam or the second light beam to be incident on the first scanning mirror as the light beam.

9. 8. The optical characteristic measuring device according to claim 7, wherein the light detector is a wavefront sensor that detects a wavefront of the light beam that has passed through the object.

10. 8. The optical characteristic measuring apparatus according to claim 7, wherein the object is an fθ lens.

11. Scanning the light beam by rotating a first scanning mirror; Scanning the light beam scanned by the first scanning mirror by rotating a second scanning mirror; irradiating an object with the light beam that is two-dimensionally scanned by the first scanning mirror and the second scanning mirror; changing a first position of the first scanning mirror in accordance with an orientation of the first scanning mirror so that the light beam reflected by the first scanning mirror passes through a reference position between the first scanning mirror and the second scanning mirror, regardless of an orientation of the first scanning mirror.

12. The method of claim 11, wherein the reference position is closer to the second scanning mirror than to the first scanning mirror.

13. The method of claim 11 , further comprising adjusting a distance between the second scanning mirror and the object.

14. and changing a third position of the second scanning mirror. the second scanning mirror includes a plurality of mirrors having different sizes; The method of claim 11 , wherein the light beam is scanned by one of the plurality of mirrors by changing the third position.

15. 12. The light beam scanning method according to claim 11, further comprising: adjusting an optical path length of the light beam incident on the first scanning mirror using an optical path length adjuster arranged on an optical path of the light beam incident on the first scanning mirror so that the optical path length of the light beam from an incident end of the optical path length adjuster to the reference position is constant regardless of the first position of the first scanning mirror.

16. The light beam scanning method according to any one of claims 11 to 15, emitting said light beam from a light source; detecting the light beam that has been two-dimensionally scanned by the first scanning mirror and the second scanning mirror and that has passed through the object.

17. and causing either the first light beam or the second light beam to be incident on the first scanning mirror as the light beam; 17. The optical characteristic measuring method of claim 16, wherein the light source includes a first light source capable of emitting the first light beam having a first wavelength, and a second light source capable of emitting the second light beam having a second wavelength different from the first wavelength.

18. 17. The optical characteristic measuring method according to claim 16, wherein detecting the light beam comprises detecting a wavefront of the light beam that has passed through the object.

19. The optical characteristic measuring method according to claim 16, wherein the object is an fθ lens.

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