JP2014134449A - Measurement device for concave surface optical element, measurement device for concave surface diffraction grating, and measurement device for flat surface diffraction grating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement device capable of quantitatively measuring a stray light value of a concave surface optical element in the same condition as a mounting state.SOLUTION: A measurement device of a concave surface optical element 7 includes: a concave surface optical element; a rotation stage 6 that rotates the concave optical element; a laser device 1 that can change a distance to the rotation stage and is a light source irradiating the concave surface optical element with light; and a photodetector 8 that forms a predetermined angle with a line connecting the light source and the rotation stage, can change the distance to the rotation stage, and detects light reflected at a position other than a light focusing-point out of light reflected from the concave surface optical element.

Description

  The present invention relates to a concave optical element measuring device, a concave diffraction grating measuring device, and a planar diffraction grating measuring device, and in particular, stray light reflected at a position other than a condensing point in light reflected from the concave optical element or The present invention relates to a concave optical element measuring apparatus, a concave diffraction grating measuring apparatus, and a planar diffraction grating measuring apparatus suitable for measuring stray light other than diffracted light diffracted by a concave diffraction grating or a planar diffraction grating.

  In general, when evaluating whether or not a concave optical element is in accordance with specifications, conventionally, measurement of a concave optical element radius of curvature, surface accuracy, surface roughness, and the like has been performed. However, under the same conditions as when the concave optical element is mounted on the device, the stray light of the single concave optical element (from the position where the reflected light from the concave optical element is determined by the radius of curvature and angle from the deepest concave surface of the concave optical element) Measurement of shifted light) is not performed. Further, when the surface accuracy is poor or the surface roughness is large, stray light is expected to be large, but the amount of stray light has not been quantitatively grasped.

  Further, as in Patent Document 1, a measurement apparatus has been proposed for stray light measurement of a diffraction grating, which is one of planar elements, but the measurement target is limited to a planar element, such as a concave optical element. Measurement is not considered.

JP 2006-337284 A

  In general, the concave optical element is evaluated by measuring a radius of curvature, surface accuracy, surface roughness, and the like. However, the stray light of a single concave optical element has not been measured under the same conditions as when the concave optical element is mounted on the apparatus.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and its object is to provide a concave optical element measuring device and a concave diffraction grating measuring device capable of quantitatively measuring stray light values under the same conditions as in the mounted state. Another object of the present invention is to provide a planar diffraction grating measuring device.

  In order to achieve the above object, the concave optical element measuring apparatus of the present invention can change the distance between the concave optical element, a rotary stage that rotates the concave optical element, and the rotary stage, and the concave surface. A light source that irradiates light to the optical element, and a straight line connecting the light source and the rotary stage forms a predetermined angle, the distance from the rotary stage is changeable, and light that reflects the concave optical element Of these, a detector for detecting light other than the condensing point is provided.

  In order to achieve the above object, the concave diffraction grating measuring apparatus of the present invention includes a concave diffraction grating, a rotary stage that rotates the concave diffraction grating, a light source that irradiates light to the concave diffraction grating, A detector that detects a light other than the diffracted light that is diffracted by the concave diffraction grating and that forms a predetermined angle with a straight line connecting a light source and the rotary stage, can change a distance from the rotary stage. It is a characteristic.

  The light source is movable so that the distance between the laser device, an objective lens for condensing laser light emitted from the laser device at a focal position, and the rotation stage can be changed. It comprises a first linear motion stage installed, and a pinhole is installed at a position where the laser beam is condensed at a focal position.

  A second linear motion stage is installed at a predetermined angle with a straight line connecting the light source and the rotary stage, and the second linear motion stage has a distance between the detector and the rotary stage. It is characterized by being installed so that it can be changed.

  The detector may include an arc stage that moves in an arc shape together with the second linear motion stage.

  Further, by fixing the detector to the arc stage and rotating the concave optical element on the rotary stage, the light reflected by the concave optical element is reflected at a position other than the condensing point. The incoming light is detected by the detector.

  In addition, the detector is fixed to the arc stage, the rotating stage is rotated, the diffracted light is incident on the detector, and the rotation angle of the rotating stage is detected by the detector. The number of grooves of the diffraction grating is measured.

  Furthermore, in order to achieve the above object, the planar diffraction grating measuring apparatus of the present invention includes a planar diffraction grating, a rotating stage that rotates the planar diffraction grating, a light source that irradiates light to the planar diffraction grating, A detector that detects a light other than the diffracted light that is diffracted by the planar diffraction grating and that forms a predetermined angle with a straight line connecting a light source and the rotary stage and is capable of changing a distance from the rotary stage. The light source is a laser device, and a second linear motion stage is installed at a predetermined angle with a straight line connecting the laser device and the rotational stage, and the second linear motion stage includes the rotational stage. The detector is movably installed so that the distance between the detector and the second linear motion stage can be changed, and the detector further includes an arc stage that moves in an arc shape together with the second linear motion stage.

  In addition, the detector is fixed to the arc stage, the rotating stage is rotated, the diffracted light is incident on the detector, and the rotation angle of the rotating stage is detected by the detector. The number of grooves of the diffraction grating is measured.

  According to the present invention, there is an effect that the stray light value can be quantitatively obtained under the same conditions as the mounting state.

It is a schematic block diagram which shows the measuring apparatus of the concave optical element which is Example 1 of this invention. It is a schematic block diagram which shows the measuring apparatus of the concave optical element which is Example 2 of this invention. It is a schematic block diagram which shows the measuring apparatus of the planar optical element which is Example 4 of this invention.

  The concave optical element measuring apparatus, concave diffraction grating measuring apparatus, and planar diffraction grating measuring apparatus of the present invention will be described below based on the illustrated embodiments. In addition, in each Example, the same code | symbol is used for the same component.

  FIG. 1 shows a concave optical element measuring apparatus that is Embodiment 1 of the present invention.

  As shown in the figure, the concave optical element measuring apparatus of this embodiment includes a concave optical element 7, a rotating stage 6 that rotates the concave optical element 7, and a laser device 1 that irradiates the concave optical element 7 with light. The objective lens 3 for condensing the laser light emitted from the laser device 1 at the focal position, and the objective lens 3 are installed so as to be movable so that the distance from the rotary stage 6 can be changed. The linear movement stage 5, the pinhole 4 installed at a position where the laser beam from the laser apparatus 1 is focused at the focal position, and a straight line connecting the laser apparatus 1 and the rotary stage 6 form a predetermined angle θ. A light detector 8 that detects a light (stray light) reflected at a position other than the condensing point among the light reflected from the concave optical element 7 and the distance to the rotary stage 6 can be changed; and a laser device 1 and rotating stage A second linear motion stage 11 that is installed at a position that forms a predetermined angle θ with a straight line connecting the two, and that the photodetector 8 is movably installed so that the distance from the rotary stage 6 can be changed. The optical detector 8 is generally composed of an arc stage 9 that moves together with the second linear motion stage 11 in an arc shape.

  Reference numeral 2 denotes a laser power source for driving the laser device 1 with a constant output, 10 denotes a stage driving device for driving the first linear motion stage 5, the second linear motion stage 11 and the rotary stage 6, and 12 denotes light detection. The ammeter 13 of the device 8 processes data based on the current value of the ammeter 12, and issues a drive command for the first linear motion stage 5, the second linear motion stage 11, and the rotary stage 6 to the stage driving device 10. It is a stage control / data processing device to be controlled.

In this embodiment, the laser beam 15 a emitted from the laser device 1 is condensed by the objective lens 3 at the focal position of the objective lens 3. Collecting pinhole 4 is installed as a spatial filter to light spot, the laser beam 15b past the focal point becomes a spherical wave by spreading at a specific angle according to the focal length f ₀ of the objective lens 3, the rotary stage 6 Irradiated to the concave optical element 7 to be measured, which is installed above.

  At this time, while keeping the relative position of the objective lens 3 and the pinhole 4, both are moved by the linear motion stage 5, so that the curvature radius R of the concave optical element 7 and the curvature radius R of the laser beam 15b (spherical wave) are obtained. Can be matched.

When the radius of curvature of the concave optical element 7 is R and the focal length of the objective lens 3 is f ₀ , the distance between the focal point and the deepest concave surface of the concave optical element 7 is the radius of curvature of the objective lens 3 and the pinhole 4. What is necessary is just to install so that it may become R. This is equivalent to a spherical wave having a radius of curvature R entering the concave optical element 7.

  The spherical wave incident on the concave optical element 7 is reflected at an angle twice the angle (θ) of rotating the rotary stage 6 below the concave optical element 7, and the radius of curvature R from the deepest concave surface of the concave optical element 7 Since the light is condensed at a position D determined by the angle θ within a plane including the light beam, the photodetector 8 is installed at an angle θ of 90 ° or less with respect to the laser optical axis emitted from the laser device 1. Is moved from the deepest part of the concave surface of the concave optical element 7 to the position D. The position D at this time is calculated | required by the following Formula (1).

  Then, the stray light is detected by detecting the light (stray light) L reflected at a position other than the condensing point among the light reflected from the concave optical element 7 by the photodetector 8 while changing the angle θ by the arc stage 9. The value can be measured.

  Note that the origin positions of the first linear motion stage 5 and the second linear motion stage 11 are arbitrary positions where the detection surfaces of the pinhole 4 and the photodetector 8 are the same from the center position of the rotary stage 6. The origin position of the arc stage 9 is the same as the installation angle θ of the second linear motion stage 11 with respect to the laser optical axis emitted from the laser device 1.

  By setting it as such a present Example, the stray light value of the concave optical element 7 can be measured quantitatively on the same conditions as a mounting state.

  FIG. 2 shows a concave optical element measuring apparatus that is Embodiment 2 of the present invention.

  The concave optical element measuring apparatus of this embodiment shown in the figure reflects the concave optical element 7 by fixing the photodetector 8 to the arc stage 9 and rotating the concave optical element 7 on the rotary stage 6. The light (stray light) L reflected at a position other than the condensing point is detected by the photodetector 8.

  That is, in the configuration of the first embodiment shown in FIG. 1, the photodetector 8 is fixed at the origin without being moved by the arc stage 9. Then, the concave optical element 7 is rotated by the rotating stage 6, and the light (stray light) L reflected to a position other than the condensing point is detected by the photodetector 8 to measure the stray light value.

  Even with this configuration of the present embodiment, the same effects as those of the first embodiment can be obtained.

  An apparatus for measuring a concave diffraction grating, which is Embodiment 3 of the present invention, will be described below.

  Although the concave diffraction grating measuring apparatus of the present embodiment is not particularly illustrated, the concave optical element 7 is changed to a concave diffraction grating in the configurations of the first and second embodiments (reference numerals are those shown in FIGS. 1 and 2). The same reference numerals are used for the same components as in FIG.

  In other words, the concave diffraction grating measuring apparatus of the present embodiment includes a concave diffraction grating, a rotating stage 6 that rotates the concave diffraction grating, a laser device 1 that irradiates light to the concave diffraction grating, and an irradiation from the laser device 1. An objective lens 3 for condensing the laser beam 15a at a focal position, and a first linear motion stage 5 in which the objective lens 3 is movably installed so that the distance from the rotary stage 6 can be changed; The distance between the second linear motion stage 11 installed at a predetermined angle with the straight line connecting the laser device 1 and the rotary stage 6 and the rotary stage 6 installed on the second linear motion stage 11. And a photodetector 8 that detects light other than the diffracted light diffracted by the concave diffraction grating, and an arc stage 9 that moves the photodetector 8 together with the second linear motion stage 11 in an arc shape, Consists of To have.

  Then, the optical detector 8 is fixed at the origin position on the arc stage 9, the rotating stage 6 is rotated, the diffracted light is incident on the optical detector 8, and the rotational angle α of the rotating stage 6 is recorded, thereby concave diffraction. The number d of grooves in the lattice (see the following formula (2)) can be measured.

  At this time, if λ is the wavelength of light incident on the concave diffraction grating and β is the diffraction angle of the concave diffraction grating, the diffraction angle β of the concave diffraction grating is zero-order light (regular reflection light) incident on the photodetector 8. It is obtained at the angle of the rotary stage 6 at the time.

  Further, after measuring the number of grooves d of the concave diffraction grating, the stray light of the concave diffraction grating is measured by detecting light other than the diffracted light by the photodetector 8 while moving the photodetector 8 by the arc stage 9. be able to.

  By setting it as such a present Example, the groove number and stray light value of a concave-surface diffraction grating can be measured quantitatively on the same conditions as a mounting state.

  FIG. 3 shows a planar optical element measuring apparatus that is Embodiment 4 of the present invention.

  The planar optical element measuring apparatus of this example shown in the figure is the same as that of Example 3, except that the objective lens 3 and the pinhole 4 are eliminated and the concave diffraction grating is changed to a planar diffraction grating. That is, the planar optical element measuring apparatus of the present embodiment includes a planar diffraction grating 14, a rotating stage 6 that rotates the planar diffraction grating 14, a laser apparatus 1 that irradiates the planar diffraction grating 14 with light, and a laser apparatus 1. The second linear motion stage 11 installed at a predetermined angle with the straight line connecting the rotary stage 6 and the rotary stage 6 and the distance between the second linear motion stage 11 and the rotary stage 6 can be changed. And a photodetector 8 that detects light other than the diffracted light diffracted by the planar diffraction grating 14 and an arc stage 9 that moves the photodetector 8 together with the second linear motion stage 11 in an arc shape. It is configured.

  Reference numeral 2 denotes a laser power source for driving the laser device 1 with a constant output, 10 denotes a stage driving device for driving the first linear motion stage 5, the second linear motion stage 11 and the rotary stage 6, and 12 denotes light detection. The ammeter 13 of the device 8 processes data based on the current value of the ammeter 12, and issues a drive command for the first linear motion stage 5, the second linear motion stage 11, and the rotary stage 6 to the stage driving device 10. It is a stage control / data processing device to be controlled.

  In this embodiment, the photodetector 8 is fixed to the arc stage 9 and the rotating stage 8 is rotated so that the diffracted light irradiated from the laser device 1 and diffracted by the planar diffraction grating 14 is incident on the photodetector 8. Then, the number of grooves of the planar diffraction grating 14 is measured by detecting the rotation angle of the rotary stage 6 with the photodetector 8.

  In addition, after measuring the number of grooves of the planar diffraction grating 14, stray light of the planar diffraction grating is measured by detecting light other than the diffracted light by the photodetector 8 while moving the photodetector 8 by the arc stage 9. be able to.

  By setting it as such a present Example, the groove number and stray light value of a concave-surface diffraction grating can be measured quantitatively on the same conditions as a mounting state.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Laser apparatus, 2 ... Laser power supply, 3 ... Objective lens, 4 ... Pinhole, 5 ... 1st linear motion stage, 6 ... Rotary stage, 7 ... Concave optical element, 8 ... Photodetector, 9 ... Arc stage DESCRIPTION OF SYMBOLS 10 ... Stage drive device, 11 ... 2nd linear motion stage, 12 ... Ammeter, 13 ... Stage control and data processing device, 14 ... Planar diffraction grating, 15a, 15b ... Laser beam.

Claims (12)

  A concave optical element, a rotary stage that rotates the concave optical element, a distance between the rotary stage and the light source that irradiates light to the concave optical element, and the light source and the rotary stage are connected. A detector that forms a predetermined angle with a straight line and that can change a distance from the rotary stage and that detects light reflected from a position other than a condensing point among light reflected from the concave optical element; An apparatus for measuring a concave optical element, comprising: The concave optical element measuring apparatus according to claim 1,
The light source is installed such that a laser device, an objective lens for condensing laser light emitted from the laser device at a focal position, and the objective lens are movable so that a distance from the rotary stage can be changed. A concave optical element measuring apparatus comprising: a first linear motion stage, wherein a pinhole is installed at a position where the laser beam is focused at a focal position. The concave optical element measuring apparatus according to claim 2,
A second linear motion stage is installed at a predetermined angle with the straight line connecting the light source and the rotary stage, and the distance between the detector and the rotary stage is changed on the second linear motion stage. A concave optical element measuring device, wherein the measuring device is movably installed as possible. In the measuring device of the concave optical element according to claim 3,
The measuring device of a concave optical element, wherein the detector includes an arc stage that moves in an arc shape together with the second linear motion stage. The concave optical element measuring apparatus according to claim 4,
Light that is reflected at a position other than the condensing point among light reflected by the concave optical element by rotating the concave optical element on the rotary stage while fixing the detector to the arc stage. Is detected by the detector, and the concave optical element measuring apparatus.   A concave diffraction grating, a rotary stage that rotates the concave diffraction grating, a light source that irradiates light to the concave diffraction grating, a straight line connecting the light source and the rotary stage, and a predetermined angle. And a detector that detects light other than the diffracted light diffracted by the concave diffraction grating, and a concave diffraction grating measuring device. In the concave diffraction grating measuring apparatus according to claim 6,
The light source is installed such that a laser device, an objective lens for condensing laser light emitted from the laser device at a focal position, and the objective lens are movable so that a distance from the rotary stage can be changed. A concave diffraction grating measuring apparatus comprising: a first linear motion stage, wherein a pinhole is provided at a position where the laser beam is focused at a focal position. In the concave diffraction grating measuring apparatus according to claim 7,
A second linear motion stage is installed at a predetermined angle with the straight line connecting the light source and the rotary stage, and the distance between the detector and the rotary stage is changed on the second linear motion stage. An apparatus for measuring a concave diffraction grating, which is movably installed as possible. The concave diffraction grating measuring device according to claim 8,
The measuring apparatus for a concave diffraction grating, wherein the detector includes an arc stage that moves in an arc with the second linear motion stage. In the concave diffraction grating measuring device according to claim 9,
The concave diffraction grating is fixed by fixing the detector to the arc stage, rotating the rotary stage to make the diffracted light incident on the detector, and detecting the rotation angle of the rotary stage with the detector. An apparatus for measuring a concave diffraction grating, characterized in that the number of grooves of the concave diffraction grating is measured. A planar diffraction grating, a rotary stage that rotates the planar diffraction grating, a light source that irradiates light to the planar diffraction grating, a straight line connecting the light source and the rotary stage, and a predetermined angle, and the rotary stage; And a detector that detects light other than the diffracted light diffracted by the planar diffraction grating,
The light source is a laser device, and a second linear motion stage is installed at a predetermined angle with a straight line connecting the laser device and the rotary stage, and the second linear motion stage includes the rotary stage and The plane diffraction is characterized in that the detector is movably installed so that the distance can be changed, and the detector further includes an arc stage that moves in an arc with the second linear motion stage. Grating measuring device. The planar diffraction grating measuring device according to claim 11,
The planar diffraction grating is fixed by fixing the detector to the arc stage, rotating the rotary stage to make the diffracted light enter the detector, and detecting the rotation angle of the rotary stage with the detector. An apparatus for measuring a planar diffraction grating, characterized in that the number of grooves in the plane is measured.

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