JP6882651B2 - Measurement preparation of surface shape measuring device Alignment method and surface shape measuring device - Google Patents

Description

The present invention relates to a measurement preparation alignment method of a surface shape measuring device and a surface shape measuring device, and particularly in a surface shape measuring device using a scanning white interferometer, focus adjustment and inclination angle adjustment of a surface to be measured of a measurement object are adjusted. The present invention relates to a measurement preparation alignment method and a surface shape measuring device in a surface shape measuring device that prepares for measurement.

The surface shape measuring device is a device that measures the three-dimensional shape of the surface to be measured of the object to be measured, and is known to use a scanning white interferometer.

As described in Patent Document 1, the scanning white interferometer uses white light having a wide wavelength width (low coherence light with low coherence) as a light source, and an interferometer such as a Michaelson type or a Millow type is used. The three-dimensional shape of the surface to be measured of the object to be measured is measured by non-contact.

As described in Patent Document 1, the Michelson-type scanning white interferometer illuminates the measured surface with the Michelson-type interferometer arranged so as to face the surface to be measured of the object (sample) to be measured. It includes a white light source that emits white light, a CCD camera that captures the interference light generated by the Michelson type interferometer, and the like.

The Michaelson type interferometer has an objective lens as a component of an optical microscope, a beam splitter arranged between the objective lens and the surface to be measured, and a reference mirror. The white light incident on the Michelson interferometer from the white light source passes through the objective lens and is split into the measurement light and the reference light by the beam splitter, the measurement light is applied to the surface to be measured, and the reference light is applied to the reference mirror. Will be done. Then, the measurement light returning from the surface to be measured and the reference light returning from the reference mirror are superposed to generate interference light, and the interference light passes through the objective lens and is emitted from the Michelson interferometer to the CCD camera.

As a result, an interference fringe image is formed on the image pickup surface of the CCD camera, and the interference fringe image is acquired by the image sensor of the CCD camera as interference fringes. Then, the interference fringes are acquired while the Michaelson type interferometer is displaced with respect to the surface to be measured in the height direction, and the amount of displacement when the brightness value shows the maximum value for each pixel of the interference fringes is detected. The relative height of each point on the measurement surface is measured.

By the way, in the scanning white interferometer as described above, as the measurement preparation alignment which is the preparatory work before the measurement, the focus adjustment and the tilt angle adjustment are performed after the measurement object is placed on the stage.

Focus adjustment is an alignment that drives the measurement scanning axis so that the measurement target surface of the measurement object comes to the focus position of the optical system where interference fringes can be observed, and tilt angle adjustment is the alignment in which the measurement target surface of the measurement object is horizontal. That is, it is an alignment that adjusts the tilt angle of the stage so as to be orthogonal to the measurement optical axis.

Then, in order to speed up the surface shape measurement, it is necessary to perform this measurement preparation alignment in the shortest possible time.

However, conventionally, such measurement preparation alignment is performed while the operator visually confirms the state of the interference fringes acquired by the CCD camera. For this reason, there is a problem that the time required for adjustment and the accuracy of alignment vary depending on the proficiency level of the operator.

For this reason, Patent Document 2 proposes, for example, a method of separately installing a dedicated camera for adjusting the tilt angle in addition to the camera that images the interference fringes, as a countermeasure against variations in the tilt angle adjustment.

Japanese Unexamined Patent Publication No. 2013-19767 Japanese Unexamined Patent Publication No. 2016-136091

However, the method of separately installing a dedicated camera for adjusting the tilt angle leads to an increase in equipment cost, and is not a good idea.

In addition, when performing measurement preparation alignment in a short time in order to speed up surface shape measurement, it is necessary to widen the image acquisition interval (image sampling interval) in the optical unit, but if the image acquisition interval is widened, interference fringes will occur. Searching becomes difficult. In particular, there is a problem that it is difficult to search for interference fringes when the surface to be measured of the object to be measured before the measurement preparation alignment has a minute inclination angle with respect to the horizontal plane orthogonal to the measurement optical axis. Therefore, in particular, in a device that implements a function (autofocus) for automatically adjusting the focus adjustment, interference occurs when the surface to be measured has a minute inclination angle with respect to the horizontal plane orthogonal to the measurement optical axis. It was difficult to detect the focus position using the stripes.

The present invention has been made in view of such circumstances, and can easily, quickly, and accurately measure focus adjustment and tilt angle adjustment regardless of the proficiency level of the operator and without increasing the equipment cost. It is an object of the present invention to provide a measurement preparatory alignment method and a surface shape measuring device of a surface shape measuring device which can perform preparatory alignment and are particularly effective in a device equipped with an autofocus mechanism.

In the measurement preparation alignment method of the surface shape measuring device according to one aspect of the present invention, in order to achieve the object, the support portion that supports the object to be measured, the light source portion that emits white light, and the white light from the light source portion are measured. The measurement light is divided into light and reference light, and the measurement light is irradiated to the measured surface of the object to be measured, and the reference light is irradiated to the reference surface, so that the measurement light returning from the measurement surface and the reference light returning from the reference surface interfere with each other. An interference unit that generates interference light, and an optical unit that has an interference fringe acquisition unit that acquires interference fringes from the brightness information of the interference light between the measurement light and the reference light applied to each point on the surface to be measured. The position of the interference fringes in the measurement optical axis direction of each point on the measurement surface is determined based on the interference fringes acquired by the interference fringe acquisition unit while changing the optical path length of the measurement light applied to each point on the measurement surface. This is a measurement preparation alignment method of a surface shape measuring device that measures the surface shape of an object to be measured by detecting it, and intentionally tilts the tilt angle of the surface to be measured with respect to the measurement optical axis to a preset tilt angle. The intentional tilting step, the interference fringe search step of searching for interference fringes by the interference fringe acquisition unit while changing the optical path length of the measurement light applied to each point of the surface to be measured tilted to the set tilt angle, and the search. The present invention includes an interference fringe position detecting step of detecting the interference fringe position from the interference fringes thus obtained, and a focus adjusting step of adjusting the focus position of the optical unit to match the detected interference fringe position.

According to the aspect of the present invention, in the intentional tilting step, the tilted angle of the surface to be measured with respect to the measurement optical axis is intentionally tilted to a preset tilting angle, and the surface to be measured is tilted in the interference fringe search step. The interference fringes are searched while changing the optical path length of the measurement light applied to each point. This makes it possible to easily, quickly and accurately search for the interference fringes and detect the position of the interference fringes required for focus adjustment. In particular, even when the surface to be measured of the object to be measured before the measurement preparation alignment has a minute inclination angle with respect to the measurement optical axis, the interference fringes required for focus adjustment can be easily, quickly and accurately. Can be found in. As a result, the focus adjustment can be performed in a short time.

Further, in the measurement preparation alignment method of the surface shape measuring device according to another aspect of the present invention, in order to achieve the object, a support portion that supports the object to be measured, a light source portion that emits white light, and white light from the light source portion. Is divided into a measurement light and a reference light, and the measurement light is applied to the measured surface of the object to be measured, and the reference light is irradiated to the reference surface. An interference unit that generates interference light that interferes with each other, and an optical unit that has an interference fringe acquisition unit that acquires interference fringes from the brightness information of the interference light between the measurement light and the reference light applied to each point on the surface to be measured. , And the interference fringes in the measurement optical axis direction of each point on the measurement surface based on the interference fringes acquired by the interference fringe acquisition unit while changing the optical path length of the measurement light applied to each point on the measurement surface. This is a measurement preparation alignment method of a surface shape measuring device that measures the surface shape of an object to be measured by detecting the position, and intentionally sets the tilt angle of the surface to be measured with respect to the measurement optical axis to a preset tilt angle. An intentional tilting step of tilting, an interference fringe search step of searching for interference fringes by an interference fringe acquisition unit while changing the optical path length of the measurement light applied to each point of the surface to be measured tilted to a set tilt angle. The interference fringe position detection step of detecting the interference fringe position from the interference fringes obtained by searching, and the correction angle for calibrating the surface to be measured with respect to the measurement optical axis from the detected interference fringe position are obtained and obtained. It has an inclination angle adjusting step of adjusting the inclination angle of the surface to be measured based on the angle.

According to the aspect of the present invention, in the intentional tilting step, the tilted angle of the surface to be measured with respect to the measurement optical axis is intentionally tilted to a preset tilting angle, and the surface to be measured is tilted in the interference fringe search step. The interference fringes are searched while changing the optical path length of the measurement light applied to each point. This makes it possible to easily, quickly, and accurately search for the interference fringes and detect the movement (change in position) of the interference fringe position required for adjusting the tilt angle. In particular, even when the surface to be measured of the object to be measured before the measurement preparation alignment has a minute inclination angle with respect to the measurement optical axis, the movement of the interference fringe position can be detected. As a result, the tilt angle can be adjusted in a short time.

Further, in the measurement preparation alignment method of the surface shape measuring device according to another aspect of the present invention, in order to achieve the object, a support portion that supports the object to be measured, a light source portion that emits white light, and white light from the light source portion. Is divided into a measurement light and a reference light, and the measurement light is irradiated to the measured surface of the object to be measured, and the reference light is irradiated to the reference surface. An interference unit that generates interference light that interferes with each other, and an optical unit that has an interference fringe acquisition unit that acquires interference fringes from the brightness information of the interference light between the measurement light and the reference light applied to each point on the surface to be measured. The interference fringe position in the measurement optical axis direction of each point on the measurement surface is based on the interference fringe acquired by the interference fringe acquisition unit while changing the optical path length of the measurement light applied to each point on the measurement surface. This is a measurement preparation alignment method of a surface shape measuring device that measures the surface shape of an object to be measured by detecting, and intentionally tilts the tilt angle of the surface to be measured with respect to the measurement optical axis to a preset tilt angle. The intentional inclination step and the interference fringe search step of searching for interference fringes by the interference fringe acquisition unit while changing the optical path length of the measurement light applied to each point of the surface to be measured inclined to the set inclination angle. The interference fringe position detection step of detecting the interference fringe position from the obtained interference fringes, the focus adjustment step of adjusting the focus position of the optical unit to the detected interference fringe position, and the measurement to be performed from the detected interference fringe position. It has an inclination angle adjusting step of obtaining a correction angle for calibrating the surface with respect to the measurement optical axis and adjusting the inclination angle of the surface to be measured based on the obtained correction angle.

According to the aspect of the present invention, in the intentional tilting step, the tilted angle of the surface to be measured with respect to the measurement optical axis is intentionally tilted to a preset tilting angle, and the surface to be measured is tilted in the interference fringe search step. The interference fringes are searched while changing the optical path length of the measurement light applied to each point. Thereby, the interference fringes can be easily, quickly and accurately searched, and the movement (change in position) of the interference fringe position required for focus adjustment and the interference fringe position required for tilt angle adjustment can be detected. In particular, even when the surface to be measured before the measurement preparation alignment has a minute inclination angle with respect to the measurement optical axis, it can be easily, quickly, and accurately found. As a result, the focus adjustment and the tilt angle adjustment can be performed in a short time.

As another aspect of the present invention, it is preferable to obtain the set tilt angle from the equation of tan (θ2) = N * λ / L. However, θ2: set tilt angle, N: number of interference fringes to be observed on the imaging surface, λ: center wavelength of the measurement light, L: viewing length in the x-axis direction (or y-axis direction) of the imaging surface,
Further, as another aspect of the present invention, in the intentional tilting step, the tilting angle of the surface to be measured with respect to the x-axis direction is intentionally tilted to a preset tilting angle, from the interference fringe search step to the tilting angle adjusting step. The x-axis tilt angle adjustment and the y-axis tilt angle from the interference fringe search step to the tilt angle adjustment step by intentionally tilting the tilt angle of the surface to be measured with respect to the y-axis direction to a preset set tilt angle. It is preferable to include at least one of the adjustments.

Further, as another aspect of the present invention, in the intentional tilting step, a preset tilt angle with respect to the bisection axis that divides the right angle formed by the x-axis and the y-axis of the surface to be measured into two equal parts is set in advance. It is preferable to perform the x-axis tilt angle adjustment and the y-axis tilt angle adjustment at the same time by intentionally tilting the vehicle from the interference fringe search step to the tilt angle adjustment step.

Since the x-axis tilt angle adjustment and the y-axis tilt angle adjustment can be performed at the same time in this way, the time required for the measurement preparation alignment can be further shortened.

Further, as another aspect of the present invention, in the intentional tilting step, a preset tilt angle with respect to the bisection axis that divides the right angle formed by the x-axis and the y-axis of the surface to be measured into two equal parts is set in advance. It is preferable that the focus adjustment, the x-axis tilt angle adjustment, and the y-axis tilt angle adjustment are performed at the same time by intentionally tilting the vehicle from the interference fringe search step to the tilt angle adjustment step.

Since the focus adjustment, the x-axis tilt angle adjustment, and the y-axis tilt angle adjustment can be performed at the same time in this way, the time required for the measurement preparation alignment can be further shortened.

Further, in the surface shape measuring device according to one aspect of the present invention, in order to achieve the object, the support portion that supports the object to be measured, the light source portion that emits white light, and the white light from the light source portion are referred to as measurement light. It is divided into light and the measurement light is irradiated to the measured surface of the measurement object and the reference light is irradiated to the reference surface so that the measurement light returning from the measured surface and the reference light returning from the reference surface interfere with each other. An optical unit having an interference unit that generates interference light, an interference fringe acquisition unit that acquires interference fringes from the brightness information of the interference light between the measurement light and the reference light applied to each point on the surface to be measured, and the measurement light. It is provided with a tilting means for tilting the surface to be measured relative to the measurement optical axis of the above, and is acquired by the interference fringe acquisition unit while changing the optical path length of the measurement light applied to each point of the surface to be measured. A surface shape measuring device that measures the surface shape of an object to be measured by detecting the position of the interference fringes in the measurement optical axis direction at each point on the surface to be measured based on the interference fringes. Interference fringe acquisition while changing the optical path length of the measurement light that is applied to each point of the surface to be measured that is tilted to the set tilt angle and the intentional tilt operation that intentionally tilts the tilt angle to the preset tilt angle. The interference fringe search operation for searching for interference fringes by the unit, the interference fringe position detection operation for detecting the interference fringe position from the interference fringes obtained by the search, and the focus position of the optical unit so as to match the detected interference fringe position. The focus adjustment operation to be adjusted and the correction angle for calibrating the surface to be measured with respect to the measurement optical axis are obtained from the detected interference fringe position. It has a tilt angle adjusting operation to be adjusted and a measurement preparation control unit for controlling a measurement preparation operation program.

According to the aspect of the present invention, a measurement preparation operation program of intentional tilt operation, interference fringe search operation, cross fringe position detection operation, focus adjustment operation, correction angle calculation operation, and inclination angle adjustment operation is performed. A measurement preparation control unit for control was provided. Thereby, the interference fringes can be easily, quickly and accurately searched, and the movement (change in position) of the interference fringe position required for focus adjustment and the interference fringe position required for tilt angle adjustment can be detected. Therefore, the focus adjustment and the tilt angle adjustment can be performed in a short time. In particular, even when the surface to be measured before the measurement preparation alignment has a minute inclination angle with respect to the measurement optical axis, it can be easily, quickly, and accurately found.

According to the measurement preparation alignment method and the surface shape measuring device of the surface shape measuring device of the present invention, focus adjustment and focusing can be easily, quickly and accurately performed regardless of the proficiency level of the operator and without increasing the device cost. Measurement preparation alignment for tilt angle adjustment can be performed.

This is particularly effective in a surface shape measuring device equipped with an autofocus mechanism.

Overall configuration diagram of the surface shape measuring device (scanning white interferometer) according to the embodiment of the present invention. The figure which showed the pixel array of the interference fringes on the xy coordinate of the image pickup surface of an image sensor The figure which illustrated the relationship between the z position of the interference part and the luminance value, and the interference fringe curve. A diagram illustrating the relationship between different z-coordinate values at different points on the surface to be measured and the interference fringe curve. A diagram showing the difficulty of searching for interference fringes when the surface to be measured is tilted at a small angle with respect to the measurement optical axis. Flow chart explaining the processing procedure of measurement preparation alignment Schematic diagram illustrating measurement preparation alignment It is a figure which showed the pixel array of the interference fringes on the xy coordinate of the image pickup surface of an image sensor, and is the figure which showed the setting example of the reference region. Explanatory drawing of how to set the intentional tilt angle of the surface to be measured in the measurement preparation alignment Explanatory drawing explaining the difference in the interference fringe search between the case where the surface to be measured is intentionally tilted to the set tilt angle and the case where it is not tilted in the focus adjustment of the measurement preparation alignment. The figure which showed the display example of the interference fringe curve of a selected pixel It is a figure which showed the pixel array in the interference fringe on the xy coordinate of the image pickup surface of an image sensor, and is the figure which showed the setting example of the x-axis leveling adjustment area. Explanatory drawing explaining the difference in the interference fringe search between the case where the surface to be measured is intentionally tilted to the set tilt angle and the case where it is not tilted in the tilt angle adjustment of the measurement preparation alignment. The figure which showed the display example of the interference fringe curve of the selected pixel in the x-axis leveling adjustment. It is a figure which showed the pixel array of the interference fringe on the xy coordinate of the image pickup surface of an image sensor, and is the figure which showed the setting example of the y-axis leveling adjustment area. The figure which showed the display example of the interference fringe curve of the selected pixel in the y-axis leveling adjustment. The figure which showed the display example of the interference fringe curve of the selected pixel after performing the x-axis leveling adjustment and the y-axis leveling adjustment. Explanatory drawing explaining the setting method of the setting tilt angle at the time of performing the x-axis leveling adjustment and the y-axis leveling adjustment at the same time. Flow chart explaining the overall processing procedure of surface shape measurement

Hereinafter, a measurement preparation alignment method of the surface shape measuring device of the present invention and a preferred embodiment of the surface shape measuring device will be described with reference to the accompanying drawings.

The present invention will be described in the following preferred embodiments. Changes can be made by many methods without departing from the scope of the present invention, and other embodiments other than the present embodiment can be used. Therefore, all modifications within the scope of the present invention are included in the claims.

Here, in the figure, the parts indicated by the same symbols are similar elements having the same functions. Further, in the present specification, when the numerical range is expressed by using "~", the numerical values of the upper limit and the lower limit indicated by "~" are also included in the numerical range.

[Surface shape measuring device]
FIG. 1 is a configuration diagram showing the overall configuration of the surface shape measuring device according to the embodiment of the present invention.

The surface shape measuring device 1 in the figure is a so-called Michaelson type scanning white interferometer (microscope) that measures the surface shape of the object P to be measured three-dimensionally by non-contact using a Michaelson type interferometer. Yes, there is an optical unit 2 that acquires the interference fringes (interference image) of the object to be measured P, a stage 10 on which the object to be measured P is placed, various controls of the optical unit 2, and interference fringes acquired by the optical unit 2. A processing unit 18 or the like including an arithmetic processing device such as a personal computer that performs various arithmetic processes based on an image is provided.

In the present embodiment, the example of the Michelson type scanning white interferometer will be described, but a well-known Millow type scanning white interferometer may be used. Further, in the measurement space where the measurement object P is arranged, the two horizontal coordinate axes orthogonal to each other are set as the x-axis (axis parallel to the paper surface) and the y-axis (axis orthogonal to the paper surface), and the x-axis and y-axis are defined. The coordinate axis in the vertical direction orthogonal to is defined as the z-axis (measurement optical axis direction). The z-axis is parallel to the measurement optical axis Z-0 described later.

The stage 10 is a flat surface substantially parallel to the x-axis and the y-axis, and has a stage surface 10S on which the measurement object P is placed. Further, the stage 10 includes a tilting means 35 for changing the tilt angle (tilt angle with respect to the z-axis) of the stage surface 10S with respect to the horizontal plane, and the stage surface 10S (stage 10) is parallel to the x-axis by the tilting means 35. It is rotatably provided around the x-rotation axis 30 and around the y-rotation axis 32 parallel to the y-axis.

Then, the stage surface 10S rotates around the x-rotation axis 30 by driving the x-actuator 34, and rotates around the y-rotation axis 32 by driving the y-actuator 36. The inclination angle of the surface S to be measured, which is the upper surface of the object P to be measured, is adjusted by the rotation of the stage surface 10S around the x rotation axis 30 and the rotation around the y rotation axis 32, as will be described later.

In addition, when the term "actuator" is used in the present specification as in the case of the x-actuator 34 and the y-actuator 36, it means an arbitrary driving device such as a piezo actuator or a motor.

Further, the stage 10 is a support portion that supports the measurement object P so that the surface S to be measured of the measurement object P can be calibrated with respect to the z axis (usually orthogonal to the z axis), and is with respect to the z axis. Any form may be used as long as it is provided with the tilting means 35 for changing the tilt angle of the surface S to be measured. As an example, a tilting means 35 in which two 1-axis goniometer (swivel) stages are stacked can be considered, but a 2-axis tilt table having the same rotation center is preferable (for example, GOHTA-120B manufactured by Sigma Kogyo). .. In the present embodiment, the stage 10 will be described in the case where the surface S to be measured of the object to be measured P is supported so as to be orthogonal to the z-axis.

An optical unit 2 integrally housed and held by a housing (not shown) is arranged at a position facing the stage surface 10S, that is, on the upper side of the stage 10.

The optical unit 2 includes a light source unit 12 having an optical axis Z-1 parallel to the x-axis, an interference unit 14 having an optical axis Z-0 parallel to the z-axis (hereinafter referred to as a measurement optical axis Z-0), and an interference unit 14. It has a photographing unit 16. The optical axis Z-1 of the light source unit 12 is orthogonal to the measurement optical axis Z-0 of the interference unit 14 and the imaging unit 16, and intersects the measurement optical axis Z-0 between the interference unit 14 and the imaging unit 16. To do. The optical axis Z-1 does not necessarily have to be parallel to the x-axis.

The light source unit 12 emits white light having a wide wavelength width (low coherence light with little coherence) as illumination light for illuminating the object P to be measured, and illumination light diffused from the light source 40 and emitted. It has a collector lens 42 that converts light into a substantially parallel light source. The central axes of the light source 40 and the collector lens 42 are coaxially arranged as the optical axis Z-1 of the light source unit 12.

Further, as the light source 40, any kind of light emitting body such as a light emitting diode, a semiconductor laser, a halogen lamp, and a high-intensity discharge lamp can be used.

The illumination light emitted from the light source unit 12 is arranged between the interference unit 14 and the photographing unit 16, and is a half mirror or the like arranged at a position where the optical axis Z-1 and the measurement optical axis Z-0 intersect. It is incident on the beam splitter 44 of the above. Then, the illumination light reflected by the beam splitter 44 (the flat light dividing surface (reflecting surface) of the beam splitter 44) travels along the optical axis Z-0 and is incident on the interference portion 14.

The interference unit 14 is composed of a Michelson type interferometer, and divides the illumination light incident from the light source unit 12 into measurement light and reference light. Then, the measurement object P is irradiated with the measurement light and the reference light is irradiated to the reference mirror 52 to generate interference light in which the measurement light returning from the measurement object P and the reference light returning from the reference mirror 52 interfere with each other.

The interference unit 14 includes an objective lens 50 having a condensing action, a reference mirror 52 having a reference surface for reflecting light and having a flat reflecting surface, and a beam splitter 54 having a flat light dividing surface for dividing light. Have. The central axes of the objective lens 50, the reference mirror 52, and the beam splitter 54 are coaxially arranged as the measurement optical axis Z-0 of the interference unit 14. The reflecting surface of the reference mirror 52 is arranged at a lateral position of the beam splitter 54 in parallel with the measurement optical axis Z-0.

The illumination light incident on the interference unit 14 from the light source unit 12 is focused by the objective lens 50 and then incident on the beam splitter 54.

The beam splitter 54 is, for example, a half mirror, and the illumination light incident on the beam splitter 54 is split into a measurement light that passes through the beam splitter 54 and a reference light that is reflected by the light splitting surface of the beam splitter 54.

The measurement light transmitted through the beam splitter 54 is applied to the surface S to be measured of the object P to be measured, then returns from the surface S to be measured to the interference portion 14, and is incident on the beam splitter 54 again. Then, the measurement light transmitted through the beam splitter 54 is incident on the objective lens 50.

On the other hand, the reference light reflected by the beam splitter 54 is reflected by the light reflecting surface of the reference mirror 52 and then incidents on the beam splitter 54 again. Then, the reference light reflected by the beam splitter 54 is incident on the objective lens 50.

As a result, interference light is generated in which the measurement light irradiated from the interference unit 14 to the surface S of the object to be measured P and returned to the interference unit 14 and the reference light reflected by the reference mirror 52 are superimposed. After the interference light is focused by the objective lens 50, it is emitted from the interference unit 14 toward the photographing unit 16.

Further, after the illumination light is divided into the measurement light and the reference light, the optical path of the optical path through which each of the measurement light and the reference light passes until the measurement light and the reference light are superimposed is determined by the optical path of the measurement light. The length and the optical path length of the reference light are referred to, and the difference between them is referred to as the optical path length difference between the measurement light and the reference light.

Further, the interference unit 14 is provided in the optical unit 2 so as to be linearly movable in the z-axis direction. Then, the interference unit 14 moves in the z-axis direction by driving the interference unit actuator 56. As a result, the position (height) of the focal plane of the objective lens 50 moves in the z-axis direction, and the distance between the surface S to be measured and the beam splitter 54 changes, so that the optical path length of the measurement light changes, and the measurement is performed. The optical path length difference between the light and the reference light changes.

The photographing unit 16 is an interference fringe acquisition unit that acquires interference fringes from the brightness information of the interference light due to the measurement light irradiated to each point of the measured surface S of the measurement object P and the reference light, for example, a CCD (CCD). It corresponds to a Charge Coupled Device) camera and has a CCD type image pickup element 60 and an imaging lens 62. The central axes of the image sensor 60 and the image lens 62 are coaxially arranged as the measurement optical axis Z-0 of the photographing unit 16. As the image sensor 60, any imaging means such as a CMOS (Complementary Metal Oxide Semiconductor) type solid-state image sensor can be used.

The interference light emitted from the interference unit 14 is incident on the beam splitter 44 described above, and the interference light transmitted through the beam splitter 44 is incident on the imaging unit 16.

The interference light incident on the photographing unit 16 forms an interference fringe image on the image pickup surface 60S of the image pickup element 60 by the image pickup lens 62. Here, the imaging lens 62 magnifies the interference fringe image with respect to the region around the measurement optical axis Z-0 of the measurement surface S of the measurement object P at a high magnification and forms an image on the image pickup surface 60S of the image pickup element 60. ..

Further, the imaging lens 62 forms an image of a point on the focal plane of the objective lens 50 of the interference unit 14 as an image point on the imaging surface of the image pickup device 60. That is, the photographing unit 16 is designed so that the position of the focal plane of the objective lens 50 is in focus (focused).

In the following, the position of the focal plane of the object P to be measured in the z-axis direction is simply referred to as the "focus position" or the "focus position of the photographing unit 16".

The interference fringe image formed on the image pickup surface 60S of the image pickup element 60 is converted into an electric signal by the image pickup element 60 and acquired as interference fringes. Then, the interference fringes are given to the processing unit 18.

As described above, the optical unit 2 including the light source unit 12, the interference unit 14, the photographing unit 16, and the like is provided as an integral body so as to be movable in the z-axis direction in a straight line. For example, the optical unit 2 is supported by a z-axis guide unit (not shown) erected along the z-axis direction so as to be movable in a straight line. Then, the entire optical unit 2 moves linearly in the Z-axis direction by driving the z-actuator 70. As a result, the focus position of the imaging unit 16 can be moved more in the z-axis direction than when the interference unit 14 is moved in the z-axis direction. For example, the imaging unit can be moved according to the thickness of the measurement object P or the like. The focus position of 16 can be adjusted to an appropriate position.

When measuring the surface shape of the surface S to be measured of the object P to be measured, the processing unit 18 controls the interference unit actuator 56 to move the interference unit 14 of the optical unit 2 in the z-axis direction, while the processing unit 18 of the imaging unit 16 Interference fringes are sequentially acquired from the image sensor 60. Then, based on the acquired interference fringes, the three-dimensional shape data of the surface S to be measured is acquired as data indicating the surface shape of the surface S to be measured.

Here, a process in which the processing unit 18 acquires the three-dimensional shape data of the surface S to be measured based on the interference fringes will be described.

The image sensor 60 of the photographing unit 16 is composed of a large number of light receiving elements (pixels) two-dimensionally arranged along the xy plane (horizontal plane F) composed of the x-axis and the y-axis. Then, the brightness value of the interference fringes received by each pixel, that is, the brightness value of each pixel of the interference fringes acquired by the image pickup element 60 is the measurement light reflected at each point of the surface S to be measured corresponding to each pixel. The intensity (luminance information) of the interference light according to the difference in the optical path length between the light and the reference light is shown.

Here, as shown in FIG. 2, the pixels in the m-th column and the n-th row in the interference fringes on the xy coordinates of the image pickup surface 60S of the image pickup device 60 are assumed to represent (m, n). Then, the x-coordinate value indicating the position of the pixel (m, n) in the x-axis direction (hereinafter, the position in the x-axis direction is referred to as “x position”) is expressed as x (m, n). Then, the y coordinate value indicating the position in the y-axis direction (hereinafter, referred to as the position “y position” in the y-axis direction) is expressed as y (m, n).

Further, the x-coordinate value indicating the x-position of the point on the measured surface S of the measurement object P corresponding to the pixel (m, n) is represented by X (m, n), and the y-coordinate value indicating the y-position is Y. It shall be expressed as (m, n), and the point shall be expressed as (X (m, n), Y (m, n)) by the xy coordinate value. The point on the measured surface S corresponding to the pixel (m, n) is the point on the measured surface S on which the image point is formed at the position of the pixel (m, n) in the focused state. Means a point.

At this time, the brightness values of the pixels (m, n) of the interference fringes acquired by the image sensor 60 are the points (X (m, n), Y (X (m, n), Y ( The magnitude corresponding to the optical path length difference between the measurement light and the reference light irradiated to m, n)) is shown.

That is, the interference unit 14 is moved in the z-axis direction by the interference unit actuator 56 in FIG. 1, and the position of the interference unit 14 relative to the optical unit 2 (photographing unit 16) in the z-axis direction (hereinafter referred to as “z position”). ) Is displaced, the focus position of the photographing unit 16 (the focal plane of the objective lens 50) also moves in the z-axis direction, and the focus position is also displaced by the same displacement amount as that of the interference unit 14. Further, when the focus position is displaced, the optical path length of the measurement light applied to each point of the surface S to be measured also changes.

Then, while moving the interference unit 14 in the z-axis direction to displace the focus position, that is, while changing the optical path length of the measurement light, the interference fringes are sequentially acquired from the image sensor 60 and any pixel of the interference fringes ( The brightness value of m, n) is detected.

Here, the processing unit 18 can detect the displacement amount of the interference unit 14 from a predetermined reference position (z position of the interference unit 14) by a detection signal from a position detecting means (not shown) such as a potentiometer or an encoder. it can. Alternatively, when controlling the z position of the interference unit 14 without using the position detecting means, for example, when moving the interference unit 14 by a constant displacement amount by a drive signal given to the interference unit actuator 56, the total displacement amount. Can be detected by.

Then, the z position of the focus position when the interference unit 14 is the reference position is set as the reference position (origin position) of the z coordinate in the measurement space, and the displacement amount of the interference unit 14 from the reference position is the z coordinate value of the focus position. Can be obtained as. The z coordinate value has a positive side at a position higher than the origin position (a position closer to the photographing unit 16) and a negative side at a lower position (a position closer to the stage surface 10S). Further, the reference position of the interference unit 14, that is, the origin position of the z coordinate can be set or changed to an arbitrary z position.

3 (A) to 3 (C) show are when an image is acquired from the image sensor 60 of the photographing unit 16 while raising the interference unit 14 from a position close to the measured surface S of the measurement object P in the z-axis direction. It is a figure which showed the relationship between the z position of the interference part 14 and a luminance value.

As shown in FIG. 3A, when the optical path length L1 of the measurement light is smaller than the optical path length L2 of the reference light, the interference is small and the brightness value is substantially constant. Then, as shown in FIG. 3B, when the optical path length L1 of the measurement light and the optical path length L2 of the reference light are the same, that is, when the optical path length difference becomes 0, the interference becomes large and the maximum luminance value is shown. .. Further, as shown in FIG. 3C, when the optical path length L1 of the measurement light is larger than the optical path length L2 of the reference light, the interference becomes small again and the luminance value becomes substantially constant. As a result, the luminance value along the interference fringe curve Q shown in FIG. 3D can be obtained.

That is, the interference fringe curve Q at an arbitrary pixel (m, n) is located at a point (X (m, n), Y (m, n)) on the surface to be measured S corresponding to the pixel (m, n). When the optical path length difference between the irradiated measurement light and the reference light is larger than the predetermined value, a substantially constant luminance value is shown, and when the optical path length difference is smaller than the predetermined value, the luminance value increases as the optical path length difference decreases. As it vibrates, its amplitude increases.

Therefore, as shown in FIG. 3D, the interference fringe curve Q shows the maximum value when the optical path lengths of the measurement light and the reference light match (when the optical path length difference is 0), and the maximum value thereof is shown. The maximum value in the envelope of the interference fringe curve Q is shown.

Further, the optical path length between the measurement light and the reference light applied to the points (X (m, n), Y (m, n)) on the measurement surface S is such that the focus position of the photographing unit 16 is the measurement surface S. It matches when it matches the z position of the upper point (X (m, n), Y (m, n)).

Therefore, when the interference fringe curve Q shows the maximum value (or when the envelope of the interference fringe curve Q shows the maximum value), the focus position is the point (X (m, n), Y ( It matches the z-position of m, n)), and the z-coordinate value of the focus position at that time is the z-coordinate of the point (X (m, n), Y (m, n)) on the surface S to be measured. Indicates a value.

From the above, the processing unit 18 moves the interference unit 14 in the z-axis direction by the interference unit actuator 56 to move the focus position in the z-axis direction (while changing the optical path length of the measurement light), while the image sensor Interference fringes are sequentially acquired from 60, and the luminance value of each pixel (m, n) is acquired in association with the z-coordinate value of the focus position. That is, the brightness values of each pixel (m, n) of the interference fringes are acquired while scanning the focus position in the z-axis direction. Then, for each pixel (m, n), the z coordinate value (interference fringe position) of the focus position when the brightness value of the interference fringe curve Q as shown in FIG. 3D shows the maximum value is set to each pixel (m). , N) is detected as the z-coordinate value Z (m, n) of the point (X (m, n), Y (m, n)) on the surface S to be measured.

Note that Z (m, n) indicates the z coordinate value of the point (X (m, n), Y (m, n)) on the measured surface S corresponding to the pixel (m, n).

Further, a method for detecting the z-coordinate value of the focus position when the luminance value of the interference fringe curve Q indicates the maximum value is well known, and any method may be adopted. For example, by acquiring the interference fringes at the z-coordinate values for each minute interval of the focus position, it is possible to actually draw the interference fringe curve Q as shown in FIG. 3 (D) for each pixel (m, n). The brightness value can be obtained to some extent. Then, by detecting the z-coordinate value of the focus position when the acquired luminance value indicates the maximum value, the z-coordinate value of the focus position when the luminance value of the interference fringe curve Q indicates the maximum value can be detected. it can.

Alternatively, the interference fringe curve Q is estimated by the least squares method or the like based on the luminance value acquired at each z coordinate value of the focus position, or the envelope of the interference fringe curve Q is estimated. Then, by detecting the z-coordinate value of the focus position when the luminance value shows the maximum value based on the estimated interference fringe curve Q or the envelope, when the luminance value of the interference fringe curve Q shows the maximum value. The z-coordinate value of the focus position can be detected.

As described above, the processing unit 18 has each point (X (m, n), Y) on the measured surface S corresponding to each pixel (m, n) of the interference fringe (imaging surface 60S of the image sensor 60). By detecting the z-coordinate value z (m, n) of (m, n)), the relative height of each point (X (m, n), Y (m, n)) on the surface to be measured S is Can be detected.

Then, the x-coordinate values X (m, n), y-coordinate values Y (m, n), and z-coordinate values Z (m, n) of each point on the measured surface S are the three-dimensional shapes of the measured surface S. It can be acquired as data (data indicating the surface shape).

For example, as shown in FIG. 4, when the z-coordinate values Z1, Z2, and Z3 at three points on the measured surface S corresponding to the three pixels arranged in the x-axis direction are different, the focus position is scanned in the z-axis direction. While acquiring the brightness values of those pixels of the interference fringes. As a result, the interference fringe curves Q1, Q2, and Q3 showing the maximum luminance value when the focus position is the z coordinate values Z1, Z2, and Z3 for each of those pixels are acquired. Therefore, by detecting the z-coordinate value of the focus position when the luminance values of the interference fringe curves Q1, Q2, and Q3 show the maximum values, z at three points on the measured surface S corresponding to those pixels The coordinate values Z1, Z2, and Z3 can be detected. In this way, the surface shape of the object P to be measured is measured by acquiring the three-dimensional shape data of the surface S to be measured.

When measuring the surface shape of the object P to be measured as described above, measurement preparatory alignment is performed as a preparatory work before measurement. That is, in the processing unit 18, the measurement object P is orthogonal to the focus adjustment and measurement optical axis Z-0 for aligning the focus of the entire optical unit 2 to a position where interference fringes can be observed in preparation for measurement. Adjust the tilt angle so that the angle is adjusted.

By adjusting the angle so that the object P to be measured is orthogonal to the measurement optical axis Z-0, it is possible to reduce the measurement scanning range in which the interference portion 14 is measured and scanned in the z-axis direction when measuring the surface shape. Since it can be done, it contributes to shortening the measurement time. Furthermore, since the S / N ratio can be improved by improving the reflectance of the measurement light, high-precision measurement becomes possible.

It is preferable to perform this measurement preparation alignment in the shortest possible time in order to improve the measurement efficiency of the surface shape.

However, in order to prepare for measurement in a short time in order to improve the measurement efficiency of the surface shape, it is necessary to widen the image acquisition interval (image sampling interval) in the optical unit 2, but if the image acquisition interval is widened, interference occurs. Searching for fringes becomes difficult. In particular, when the surface S to be measured of the object to be measured P before the measurement preparation has a minute inclination angle θ1 with respect to the horizontal plane orthogonal to the measurement optical axis Z-0 (accidentally with respect to the measurement optical axis Z-0). Therefore, it is difficult to search for interference fringes when the surface S to be measured of the object to be measured P is orthogonal, that is, the inclination angle θ1 is zero).

In FIG. 5A, the interference portion 14 is measured when the surface S to be measured of the object P to be measured has a minute inclination angle θ1 with respect to the horizontal plane F orthogonal to the measurement optical axis Z-0. Four images (B) to (E) are captured while ascending and scanning along the z-axis direction (scanning axis direction) from a position close to the surface S to be measured of the object P. As can be seen from these four images, interference is observed in (C), but no interference is observed in (B), (D), and (E). This is because in the case of a white interferometer, the range in the z-axis direction in focus is very small (for example, about 3 μm), and when the image acquisition interval (image sampling interval) is widened, the z-axis position where interference fringes appear is This is because it is extremely difficult to search for interference fringes because of the limitation.

Therefore, the processing unit 18 of the surface shape measuring device 1 according to the embodiment of the present invention has a set tilt angle in which the tilt angle of the surface S to be measured of the object P to be measured with respect to the measurement optical axis Z-0 is preset by the tilting means 35. The interference fringes are searched by the photographing unit 16 while changing the optical path length of the measurement light applied to each point of the measured surface S inclined to the set inclination angle θ2 and the intentional inclination operation to intentionally incline the angle θ2. Interference fringe search operation, interference fringe position detection operation that detects the interference fringe position from the interference fringes obtained by searching, and focus adjustment operation that adjusts the focus position of the optical unit 2 to the detected interference fringe position. Then, the correction angle for the surface to be measured to be orthogonal to the measurement optical axis is obtained from the detected interference fringe position, and the tilt angle adjustment operation for adjusting the tilt angle of the surface to be measured is driven by the correction angle obtained by the tilting means 35. The measurement preparation control unit 18A for controlling the measurement preparation operation program is built-in.

[Measurement preparation alignment method]
Next, the measurement preparation alignment method of the surface shape measuring device 1 will be described.

In the following, a form of automatic alignment in which the basic work of measurement preparation alignment is automatically performed by the processing unit 18 will be described. However, it is also possible to manually perform a part or all of the basic alignment work, which will be described as appropriate in the following description.

FIG. 6 is a flowchart showing the processing procedure of the measurement preparation alignment of the focus adjustment and the tilt angle adjustment by the measurement preparation control unit 18A of the processing unit 18, but the alignment of the focus adjustment will be described first. Further, FIG. 7 is a schematic view showing a main part of the alignment of the focus adjustment and the tilt angle adjustment.

As shown in FIG. 7A, the surface S to be measured of the measurement object P before the focus adjustment alignment has a minute inclination angle θ1 with respect to the horizontal plane F orthogonal to the optical axis Z-0. Suppose you have. Further, FIG. 7D is a diagram for explaining the alignment of the tilt angle adjustment, and is not used for the explanation in the alignment of the focus adjustment.

(Focus adjustment alignment)
As shown in FIG. 8, the measurement preparation control unit 18A presets a reference region 100 as a reference for focusing alignment in the interference fringes on the xy coordinates of the image pickup surface 60S of the image pickup element 60. That is, the region of the surface S to be measured that is in focus when the focus position is set at the center position of the scanning range in the z-axis direction of the focus position due to the movement of the interference unit 14 with respect to the optical unit 2 in the z-axis direction. The region of the interference fringe corresponding to is set as the reference region 100. This reference region 100 is also used in the case of alignment for tilt angle adjustment, which will be described later.

In the case of the present embodiment, the reference area is a predetermined area before the focus adjustment. However, the operator designates the measurement preparation control unit 18A by the input unit 22 while referring to the image of the pixel arrangement on the interference fringe (imaging surface 60S of the image pickup device 60) as shown in FIG. 8 displayed on the display unit 20 of FIG. You may try to do it. Further, the reference area may be fixed to a predetermined shape and size, for example, an area including four pixels of 2 rows and 2 columns, or may have an arbitrary shape and size when specified by the operator. It may be possible to specify a size area. Further, it may be an area including only one pixel.

The reference region, the x-axis leveling adjustment region and the y-axis leveling adjustment region in the alignment of the tilt angle adjustment described later are set for the interference fringes as adjustment regions for adjusting the tilt angle of the surface S to be measured. However, it corresponds to setting the region on the measured surface S corresponding to the adjustment region, that is, the region including the point on the measured surface S corresponding to the pixels included in the adjustment region as the adjustment region.

Next, the measurement preparation control unit 18A performs an intentional tilting step of intentionally tilting the measurement object P (measured surface S) to the set tilt angle θ2 (step S10). That is, when the measurement object P is placed on the stage surface 10S of the stage 10, and for example, when the input unit 22 of FIG. 1 instructs the start of the measurement preparation, the measurement preparation control unit 18A has the measurement preparation control unit 18A (B) of FIG. As shown in the above, the stage 10 on which the measurement object P is placed so that the measurement surface S of the measurement object P has a set inclination angle θ2 with respect to the horizontal plane F orthogonal to the measurement optical axis Z-0. Is intentionally tilted by the tilting means 35. This set tilt angle θ2 is larger than the above-mentioned minute tilt angle θ1.

The set tilt angle θ2 can be obtained by the following equation 1 as shown in FIG.

tan (θ2) = N * λ / L …… Equation 1
However, θ2: set tilt angle,
N: It is preferable that 5 to 10 interference fringes can be observed with the number of interference fringes to be observed on the image pickup surface 60S of the image pickup device 60.

λ: Center wavelength of measurement light,
L: Field-of-view length of the imaging surface 60S in the x-axis direction (or y-axis direction),
Next, an interference fringe search step of starting scanning drive of the interference unit 14 in a predetermined range in the z-axis direction is started (step S12). That is, as shown in FIG. 7C, the measurement preparation control unit 18A maintains the measured surface S of the measurement object P at the set inclination angle θ2 with respect to the measurement optical axis Z-0, and the interference unit actuator. The interference unit 14 of the optical unit 2 is started to be scanned and driven in the z-axis direction by the 56. In FIG. 7C, the vehicle is driven upward in the z-axis direction. As a result, a search for detecting interference fringes for focus adjustment is started.

Here, the defined range refers to the scanning range of the focus position in the z-axis direction due to the movement of the interference unit 14 with respect to the optical unit 2 in the z-axis direction.

Next, an interference fringe search step of searching for interference fringes during scanning drive of the interference unit 14 is performed (step S14). That is, the measurement preparation control unit 18A moves the interference unit 14 in the z-axis direction by the interference unit actuator 56 and scans the focus position in the z-axis direction (that is, while changing the optical path length of the measurement light). Interference fringes are sequentially acquired from 60, and the brightness value of each pixel is acquired in association with the z-coordinate value of the focus position. It should be noted that only the brightness value of the pixel in the reference region may be acquired.

FIG. 10 shows interference in step S14 between the case where the step S10 for intentionally tilting the measurement object P to the set tilt angle θ2 and the case where the step S10 is not performed (the minute tilt angle θ1 remains). It is a schematic diagram comparing how the ease of searching for fringes differs.

The figure (A) on the left side of FIG. 10 shows a case where the surface S to be measured of the measurement object P has a minute inclination angle θ1 with respect to the measurement optical axis Z-0 without performing step S10. Yes, it is the same as FIG. 5 illustrated above. On the other hand, in the figure (B) on the right side of FIG. 10, step S10 is performed, and the measured surface S of the measurement object P is larger than the inclination angle θ1 with respect to the horizontal plane F orthogonal to the measurement optical axis Z-0. This is the case when the set inclination angle θ2 is provided.

In both (A) and (B) of FIG. 10, the same four zs are scanned while the interference portion 14 is ascended and scanned along the z-axis direction (measurement scanning axis direction) from a position close to the measured surface S of the measurement object P. Images (4 images in total) are imaged on the image pickup surface 60S of the image pickup element 60 at the axial positions.

As can be seen from the comparison between (A) and (B) of FIG. 10, when step S10 is not performed, if the image acquisition interval is widened, an image in which interference fringes can be observed as shown in (A) of FIG. 10 (unclear). (One image of interference fringes) is extremely reduced.

On the other hand, when step S10 is performed, interference fringes can be observed in all four images as shown in FIG. 10B.

Therefore, by performing step S10 in which the surface S to be measured of the object P to be measured is tilted to the set tilt angle θ2 with respect to the horizontal plane F orthogonal to the measurement optical axis Z-0, the image is prepared for measurement in a short time. Even when the acquisition interval (image sampling interval) is widened, the interference fringes can be easily searched and the interference fringe positions required for focus adjustment can be detected.

Next, an interference fringe position detection step of detecting the interference fringe position of the interference fringes obtained by searching is performed (step S16). If the interference fringe position is not detected, the process returns to step S14 to continue the detection of the interference fringe position. That is, the measurement preparation control unit 18A creates an interference fringe curve as shown in FIG. 3D based on the luminance value associated with the z-coordinate value of the focus position for each of the pixels included in the reference region. get. Further, the measurement preparation control unit 18A determines the z-coordinate value of the focus position when the luminance value shows the maximum value (maximum value of the envelope) based on the interference fringe curve acquired for each of the pixels included in the reference region. Ask. That is, the z-coordinate value of each point on the measured surface S corresponding to each pixel in the reference region is obtained. Then, one pixel having the largest z-coordinate value (the most prominent position) is selected. As a result, when the surface S to be measured has a dent such as a scratch, the pixel corresponding to the dent portion can be prevented from being selected.

Subsequently, the measurement preparation control unit 18A displays the selected pixels (hereinafter, referred to as “selected pixels”) and the interference fringe curve of the selected pixels on the display unit 20. For example, as shown in FIG. 8, an image of a pixel array in which the selected pixels 102 in the reference region 100 are arranged so as to be distinguishable from other pixels is displayed on the display unit 20. Further, as shown in FIG. 11, an image in which the interference fringe curve for the selected pixel is drawn on a graph showing the relationship between the z coordinate value and the brightness value is displayed on the display unit 20. In addition, the z-coordinate value Zs of the focus position when the luminance value shows the maximum value in the interference fringe curve and the z-coordinate value Zc which is the center position of the scanning range of the focus position should be displayed so as to be easily grasped. Is desirable.

In the case of a device equipped with an autofocus mechanism, that is, automatic alignment, it is not always necessary to display the selected pixels and the interference fringe curve of the selected pixels on the display unit 20.

Then, the measurement preparation control unit 18A stops the scanning drive of the interference unit 14 when the interference fringe position is detected or the movement of the interference unit 14 reaches the specified range (step S18).

Next, a focus adjustment step of adjusting the focus position of the optical unit 2 to the detected interference fringe position is performed (step S20). That is, the measurement preparation control unit 18A scans the focus position by driving the interference unit actuator 56 so that the z coordinate value Zs of the focus position when the brightness value shows the maximum value in the interference fringe curve of the selected pixel 102 in the reference region 100 The z actuator 70 of FIG. 1 is driven to move the entire optical unit 2 in the z-axis direction so as to match the z coordinate value Zc which is the center position of the range. In other words, the z position (z coordinate value Zc), which is the center position of the scanning range of the focus position, and the z position (z coordinate value) of the point on the measured surface S corresponding to the selected pixel match. The position of the entire optical unit 2 in the z-axis direction is adjusted.

Note that step S20 can be manually performed by the operator with reference to the display of the interference fringe curve as shown in FIG. 11 displayed on the display unit 20 in step S16. For example, the operator instructs the measurement preparation control unit 18A to move the optical unit 2 from the input unit 22 and drives the interference unit actuator 56 to move the optical unit 2 by a desired amount, or the interference unit. The optical unit 2 is directly and manually moved without driving the actuator 56 to match the z-coordinate value Zs with the z-coordinate value Zc.

This completes the focus adjustment alignment, which is one of the measurement preparation alignments. By performing step S10 in which the measurement object P is intentionally tilted to the set tilt angle θ2 in this way, the alignment of the focus adjustment is not dependent on the proficiency level of the operator and does not cause an increase in the device cost. It can be done easily, quickly and accurately.

Further, in the case of automatic alignment, it is important that the interference portion 14 can clearly and surely detect the interference fringes during scanning drive along the z-axis direction (scanning axis direction), and in particular, a device equipped with an autofocus mechanism. The present invention is effective in.

(Alignment for tilt angle adjustment)
Next, the alignment of the tilt angle adjustment will be described with reference to the flowchart of FIG. In the alignment of the tilt angle adjustment, as shown in FIG. 7A, the surface S to be measured of the measurement object P before the alignment of the tilt angle adjustment is the horizontal plane F orthogonal to the optical axis Z-0. It is assumed that the tilt angle θ1 is very small.

The alignment of the tilt angle adjustment eliminates the tilt of the surface S to be measured with respect to the x-axis direction (tilt around the y-axis) and the tilt of the surface S to be measured with respect to the y-axis direction (tilt around the x-axis). This is an alignment that adjusts the leveling of the x-axis and the y-axis so that the surface S to be measured is parallel to the x-axis and the y-axis.

As an explanation of the alignment of the inclination angle adjustment, a case where the x-axis leveling adjustment is first performed and then the y-axis leveling adjustment is performed will be described.

As shown in FIG. 12, the measurement preparation control unit 18A is an x-axis leveling adjustment region 110 that is a reference for x-axis leveling adjustment in the interference fringes on the xy coordinates of the image pickup surface 60S of the image pickup element 60, and is used for focus adjustment. The x-axis leveling adjustment area 110 whose y-coordinate value is the same as the center of the set reference area 100 and whose x-coordinate value is different from that of the reference area 100 is set in advance.

However, the center of the reference region 100 and the center of the x-axis leveling adjustment region 110 do not necessarily have to completely coincide with each other, and some deviation is allowed. That is, the y-coordinate values between the center of the reference region 100 and the center of the x-axis leveling adjustment region 110 may be a difference of a predetermined value or less that can be regarded as matching.

This x-axis leveling adjustment region may be a predetermined region, or an interference fringe on the xy coordinate of the image pickup surface 60S of the image pickup element 60 displayed on the display unit 20 by the measurement preparation control unit 18A as shown in FIG. The operator may specify by the input unit 22 while referring to the image of the pixel array in. Further, the x-axis leveling adjustment region may be a region having the same shape and size as the reference region, or may have a predetermined shape and size such as a region including four pixels in 2 rows and 2 columns. It may be fixed, or a region having an arbitrary shape and size may be specified when the operator specifies it. Further, it may be an area including only one pixel.

Next, the measurement preparation control unit 18A performs steps S10 to S18 in FIG. 6 as in the case of focus adjustment alignment. In the x-axis leveling adjustment, in step S10, the surface S to be measured of the object to be measured P is a horizontal plane F orthogonal to the measurement optical axis Z-0, and the inclination with respect to the x-axis direction (inclination around the y-axis) is predetermined. It is tilted so that the angle tilt is θ2.

Also in such x-axis leveling adjustment, the optical unit 2 performs step S10 in which the surface S to be measured of the object to be measured P is tilted to the set tilt angle θ2 with respect to the horizontal plane F orthogonal to the measurement optical axis Z-0. Interference fringes can be easily searched even when the image acquisition interval (image sampling interval) is widened.

FIG. 13 compares how the ease of grasping the movement (change in position) of the interference fringe position required for adjusting the tilt angle differs between the case where step S10 is performed and the case where step S10 is not performed. It is a schematic diagram.

The figure (A) on the left of FIG. 13 has a minute inclination angle θ1 with respect to the horizontal plane F in which the surface S to be measured of the object to be measured P is orthogonal to the measurement optical axis Z-0 without performing step S10. If you are. On the other hand, in the figure (B) on the right side of FIG. 13, step S10 is performed, and the measured surface S of the measurement object P is larger than the inclination angle θ1 with respect to the horizontal plane F orthogonal to the measurement optical axis Z-0. This is the case when the set inclination angle θ2 is provided.

In both FIGS. 13A and 13B, the same four z-axis positions are scanned while the interference portion 14 is ascended along the z-axis direction (scanning axis direction) from a position close to the measured surface S of the measurement object P. Each image (4 images in total) was imaged on the image pickup surface 60S of the image pickup element 60.

As can be seen from the comparison of (A) and (B) of FIG. 13, the surface S to be measured of the object to be measured P has a minute inclination angle θ1 with respect to the horizontal plane F orthogonal to the measurement optical axis Z-0. If the image acquisition interval is widened, it is difficult to grasp the movement (change in position) of the interference fringe position required for adjusting the tilt angle from the four images as shown in FIG. 12A.

On the other hand, when step S10 is performed and the surface S to be measured of the object P to be measured has a set inclination angle θ2 larger than the inclination angle θ1 with respect to the horizontal plane F orthogonal to the measurement optical axis Z-0. As shown in FIG. 13B, the movement (change in position) of the interference fringe position required for adjusting the tilt angle can be easily grasped from the four images.

Therefore, by performing step S10, interference fringes can be easily, quickly, and accurately searched even when the image acquisition interval (image sampling interval) in the optical unit 2 is widened in order to adjust the tilt angle in a short time. It is possible to detect the movement (change in position) of the interference fringe position required for adjusting the tilt angle.

Next, an inclination angle adjusting step of adjusting the measured surface S of the object to be measured P so as to be orthogonal to the z-axis direction from the detected interference fringe position is performed (step S20). That is, the measurement preparation control unit 18A has, for each of the pixels included in the reference region and each of the pixels included in the x-axis leveling adjustment region, based on the luminance value associated with the z-coordinate value of the focus position. The interference fringe curve as shown in FIG. 3D is acquired. Next, the measurement preparation control unit 18A has a maximum luminance value (maximum envelope) based on the interference fringe curve acquired for each of the pixels included in the reference region and each of the pixels in the x-axis leveling adjustment region. The z-coordinate value of the focus position when indicating the value) is obtained. That is, the z-coordinate value of each point on the measured surface S corresponding to each pixel of the reference region 100 and each pixel of the x-axis leveling adjustment region 110 is obtained. Then, one pixel having the largest z-coordinate value (which is the most protruding position) in the reference region 100 and the one pixel having the largest z-coordinate value (which is the most protruding position) in the x-axis leveling adjustment region 110. One pixel is elected as the elected pixel.

Next, the measurement preparation control unit 18A displays the selected pixels selected from the reference region 100, the selected pixels selected from the x-axis leveling adjustment region 110, and the interference fringe curves of those selected pixels on the display unit 20. For example, as shown in FIG. 12, an image of a pixel array in which the selected pixels 102 in the reference region 100 and the selected pixels 112 in the x-axis leveling adjustment region 110 are arranged so as to be distinguishable from other pixels is displayed on the display unit 20. Further, as shown in FIG. 14, the interference fringe curve for the selected pixel 102 in the reference region 100 and the interference fringe curve for the selected pixel 112 in the x-axis leveling adjustment region 110 are shown on a graph showing the relationship between the z coordinate value and the brightness value. The image drawn in 1 is displayed on the display unit 20. Further, in those interference fringe curves, the z-coordinate values Zs and Zs1 of the focus position when the luminance value shows the maximum value and the z-coordinate value Zc which is the center position of the scanning range of the focus position can be easily grasped. It is desirable to display.

In the case of automatic alignment, it is not always necessary to display the selected pixels and the interference fringe curve of the selected pixels on the display unit 20.

Next, the measurement preparation control unit 18A determines the z-coordinate value Zs of the focus position when the luminance value shows the maximum value in the interference fringe curve of the selected pixel 102 of the reference region 100, and the selected pixel 112 of the x-axis leveling adjustment region 110. The y-operator 36 of FIG. 1 is driven to move the stage surface 10S of the stage 10 to the y-rotation axis 32 so that the z-coordinate value Zs1 of the focus position when the luminance value shows the maximum value in the interference fringe curve of FIG. Rotate around. That is, the z position (z coordinate value Zs) of the point on the measured surface S corresponding to the selected pixel 102 in the reference region 100 and the point on the measured surface S corresponding to the selected pixel 112 in the x-axis leveling adjustment region 110. The stage surface 10S is rotated around the y rotation axis 32 so as to coincide with the z position (z coordinate value Zs1) of (see FIG. 7D).

Here, the difference between the z-coordinate value Zs and the z-coordinate value Zs1 and the distance in the x-axis direction from each of the selected pixels 102 in the reference region 100 and the selected pixels 112 in the x-axis leveling adjustment region 110 to the y-rotation axis 32. By adjusting the amount of rotation of the stage surface 10S around the y-rotation axis 32 based on the above, the z-coordinate value Zs and the z-coordinate value Zs1 can be matched. As a result, the surface S to be measured becomes parallel to the x-axis, and the x-axis leveling adjustment is completed.

Note that step S20 can be manually performed by the operator in the same manner as described above with reference to the display of the interference fringe curve as shown in FIG. 14 displayed on the display unit 20.

Subsequently, the y-axis leveling adjustment will be described.

As shown in FIG. 15, the measurement preparation control unit 18A is a y-axis leveling adjustment region 120 as a reference for y-axis leveling adjustment in the interference fringe (imaging surface of the image sensor 60), and is the center of the set reference region 100. And the y-axis leveling adjustment region 120 having a center whose y-coordinate value is at least different from the center of the x-axis leveling adjustment region set above are set. This y-axis leveling adjustment region may be a predetermined region, for example, a region in which the center of the reference region, the center of the x-axis leveling adjustment region, and the center of the y-axis leveling adjustment region are the vertices of an equilateral triangle. Alternatively, the operator may specify by the input unit 22 while referring to the image of the pixel arrangement on the interference fringes (imaging surface of the imaging element 60) displayed on the display unit 20 by the measurement preparation control unit 18A as shown in FIG. You may. Further, the y-axis leveling adjustment region may be a region having the same shape and size as the reference region, or may have a predetermined shape and size such as a region including four pixels in 2 rows and 2 columns. It may be fixed, or a region having an arbitrary shape and size may be specified when the operator specifies it. Further, it may be an area including only one pixel.

Next, the measurement preparation control unit 18A performs steps S10 to S18 in FIG. 6 as in the case of the x-axis leveling adjustment. In the y-axis leveling adjustment, in step S10, the surface S to be measured of the object to be measured P is a horizontal plane F orthogonal to the measurement optical axis Z-0, and the inclination with respect to the y-axis direction (inclination around the x-axis) is predetermined. It is tilted so that the angle tilt is θ2.

In the y-axis leveling adjustment as well, as in the case of the x-axis leveling adjustment shown in FIG. 13, the set inclination angle θ2 is set with respect to the horizontal plane F orthogonal to the measurement optical axis Z-0 with respect to the surface S to be measured of the measurement object P. By performing step S10 inclining to, the interference fringes can be easily searched and the movement of the interference fringe position can be clearly grasped even when the image acquisition interval (image sampling interval) in the optical unit 2 is widened.

Next, an inclination angle adjusting step of adjusting the measured surface S of the object to be measured P so as to be orthogonal to the z-axis direction from the detected interference fringe position is performed (step S20). That is, the measurement preparation control unit 18A has the z-coordinate value of the focus position for each of the pixels included in the reference region, each of the pixels included in the x-axis leveling adjustment region, and each of the pixels included in the y-axis leveling adjustment region. Based on the luminance value associated with, the interference fringe curve as shown in FIG. 3D is acquired.

Next, the measurement preparation control unit 18A is based on the interference fringe curve acquired for each of the pixels included in the reference region, each of the pixels in the x-axis leveling adjustment region, and each of the pixels in the y-axis leveling adjustment region. The z-coordinate value of the focus position when the luminance value indicates the maximum value (maximum value of the envelope) is obtained. That is, the z-coordinate value of each point on the measured surface S corresponding to each pixel in the reference region, each pixel in the x-axis leveling adjustment region, and each pixel in the y-axis leveling adjustment region is obtained.

Then, one pixel having the largest z-coordinate value (the most prominent position) in the reference region and one pixel having the largest z-coordinate value (the most prominent position) in the x-axis leveling adjustment region. A pixel and one pixel having the largest z-coordinate value (the most prominent position) in the y-axis leveling adjustment region are selected as selected pixels.

Next, the measurement preparation control unit 18A includes selected pixels selected from the reference region, selected pixels selected from the x-axis leveling adjustment region, selected pixels selected from the y-axis leveling adjustment region, and interference fringes of those selected pixels. The curve is displayed on the display unit 20. For example, as shown in FIG. 15, the selected pixels 102 in the reference area 100, the selected pixels 112 in the x-axis leveling adjustment area 110, and the selected pixels 122 in the y-axis leveling adjustment area 120 are colored so as to be distinguishable from other pixels. The image of the pixel arrangement is displayed on the display unit 20. Further, as shown in FIG. 16, the z-coordinate value of the interference fringe curve for the selected pixel in the reference region, the interference fringe curve for the selected pixel in the x-axis leveling adjustment region, and the interference fringe curve for the selected pixel in the y-axis leveling adjustment region are The image drawn on the graph showing the relationship between the brightness value and the brightness value is displayed on the display unit 20. Further, the z-coordinate values Zs, Zs1 and Zs2 of the focus position when the luminance value shows the maximum value in those interference fringe curves and the z-coordinate value Zc which is the center position of the scanning range of the focus position can be easily grasped. It is desirable to display as.

In the case of automatic alignment, it is not always necessary to display the selected pixels and the interference fringe curve of the selected pixels on the display unit 20.

Next, as shown in FIG. 17, the measurement preparation control unit 18A adjusts the z-coordinate value Zs of the focus position when the brightness value shows the maximum value in the interference fringe curve of the selected pixel in the reference region, or the x-axis leveling adjustment. The z-coordinate value Zs1 of the focus position when the brightness value shows the maximum value in the interference fringe curve of the selected pixel in the area, and the focus when the brightness value shows the maximum value in the interference fringe curve of the selected pixel in the y-axis leveling adjustment area. The x actuator 34 of FIG. 1 is driven to rotate the stage surface 10S of the stage 10 around the x rotation axis 30 so that the z coordinate value Zs2 of the position matches (see (D) of FIG. 7).

That is, the z position (z coordinate value Zs) of the point on the measured surface S corresponding to the selected pixel in the reference region and the z position of the point on the measured surface S corresponding to the selected pixel in the y-axis leveling adjustment region (z position). The stage surface 10S is rotated around the x rotation axis 30 so as to coincide with the z coordinate value Zs2).

Here, x from each of the difference between the z-coordinate value Zs or the z-coordinate value Zs1 and the z-coordinate value Zs2, the selected pixel in the reference region, the selected pixel in the x-axis leveling adjustment region, and the selected pixel in the y-axis leveling adjustment region. By adjusting the amount of rotation of the stage surface 10S around the x-rotation axis 30 based on the distance to the rotation axis 30 in the y-axis direction, the z-coordinate value Zs or the z-coordinate value Zs1 and the z-coordinate value Zs2 are made to match. be able to. As a result, the surface S to be measured becomes parallel to the y-axis, and the y-axis leveling adjustment is completed.

In the case of automatic alignment, it is not always necessary to display the selected pixels and the interference fringe curve of the selected pixels on the display unit 20.

By performing step S10 in which the measurement object P is intentionally tilted to the set tilt angle θ2 in this way, the tilt angle adjustment can be easily performed regardless of the proficiency level of the operator and without increasing the device cost. Can be done quickly and accurately.

Further, in the case of automatic alignment, it is important that the interference portion 14 can clearly and surely detect the interference fringes during scanning along the z-axis direction (scanning axis direction), especially in a device equipped with an autofocus mechanism. The present invention is valid.

In the above-mentioned alignment of the tilt angle adjustment, in each of the x-axis tilt angle adjustment and the y-axis tilt angle adjustment, the measured surface S of the measurement object P is relative to the horizontal plane F orthogonal to the measurement optical axis Z-0. It was tilted so that the set tilt angle θ2 was obtained. That is, in the x-axis tilt angle adjustment and the y-axis tilt angle adjustment, step S10 was performed individually.

However, in the x-axis tilt angle adjustment and the y-axis tilt angle adjustment, it takes time to perform step S10 individually. Further, it is possible to perform step S10 only in the x-axis direction (or y-axis direction) and obtain the correction inclination angle in the y-axis direction (x-axis direction) by calculation, but the calculation becomes difficult.

In order to prevent these, in the intentional tilting step, the tilt angle with respect to the bisector axis that divides the right angle formed by the x-axis and the y-axis of the surface S to be measured of the measurement object P into two equal parts is set in advance. It is preferable to intentionally incline the set inclination angle and perform the interference fringe search step S14 to the inclination angle adjustment step S20.

FIG. 18 shows interference fringes imaged on the image pickup surface 60S of the image pickup device 60 when the interference portion 14 is moved in the z-axis direction by inclining the inclination angle with respect to the bisector axis to the set inclination angle θ2. Is. Reference numeral N in FIG. 18 indicates a bisector.

As shown in FIG. 18, since the interference fringes are formed orthogonal to the bisection axis N and the interference fringe position moves along the bisection axis N, the x-axis leveling adjustment and the y-axis leveling adjustment can be performed. As in the case, the movement (change in position) of the interference fringe position required for adjusting the tilt angle can be clearly grasped. Therefore, the x-axis leveling adjustment and the y-axis leveling adjustment are performed by performing an inclination angle adjusting step (step S20) for adjusting the measured surface S of the object to be measured P so as to be orthogonal to the z-axis direction from the detected interference fringe position. And can be done at once.

Further, as can be seen from FIG. 6, in the focus adjustment and the tilt angle adjustment, steps S10 to S18 are the same steps, and the focus adjustment and the tilt angle adjustment in step S20 can be performed in parallel. Therefore, by performing step S10 on the bisector axis N and performing the x-axis tilt angle adjustment and the y-axis tilt angle adjustment at the same time, the focus adjustment and the tilt angle adjustment are aligned in parallel. Can be done.

If the tilting means 35 provided in the stage 10 tilts the measured surface S of the measurement object P relative to the z-axis to change the tilt angle of the measured surface S with respect to the z-axis. Often, it is not limited to the case where the tilting means 35 for tilting the stage 10 is provided as described above. For example, instead of tilting the stage 10, the optical unit 2 may be tilted with respect to the stage 10 to tilt the z-axis and adjust the tilt angle of the surface S to be measured with respect to the z-axis.

As described above, in the above embodiment, the reference area, the x-axis leveling adjustment area, and the y-axis leveling adjustment area are set at different timings, but the x-axis leveling adjustment area and the y-axis leveling adjustment are performed when the reference area is set. The area may also be set.

Further, in the above embodiment, one pixel is selected as a selected pixel from each of the reference region, the x-axis leveling adjustment region, and the y-axis leveling adjustment region, and a point on the measured surface S corresponding to the selected pixel is selected. The z-coordinate value of the region on the measured surface S corresponding to each region is used as the z-coordinate value of the region on the measured surface S, but the z-coordinate value of the region on the measured surface S may be obtained by another method. For example, the average value of the z-coordinate values of all the points on the measured surface S corresponding to all the pixels in each region can be set as the z-coordinate value of the region on the measured surface S corresponding to each region.

Further, in the above embodiment, three adjustment regions of a reference region, an x-axis leveling adjustment region, and a y-axis leveling adjustment region are set for the interference fringes according to specific conditions, and the adjustment regions correspond to those adjustment regions. The inclination angle of the surface to be measured S (stage surface 10S) is adjusted so that the z positions of the regions on the surface to be measured S match, but the present invention is not limited to this. That is, in the present invention, at least three regions (three or more locations) are set as adjustment regions with respect to the interference fringes, and the z-coordinate value of the region on the measured surface S corresponding to those adjustment regions is set as described above. It is detected by scanning the focus position as in the form. Then, the tilt angle of the measured surface S (stage surface 10S) is adjusted so that the z-coordinate values of the regions on the measured surface S corresponding to those adjustment regions match. Setting the adjustment area for the interference fringes is equivalent to setting the adjustment area on the surface S to be measured corresponding to the area.

[Overall flow of surface shape measurement]
FIG. 19 is an example of the overall flow of surface shape measurement including the measurement preparation alignment step described above.

As shown in FIG. 19, first, the object to be measured is placed on the stage 10 (step S100).

Next, the measurement preparation control unit 18A of the processing unit 18 carries out the measurement preparation alignment (step S200) of the focus adjustment and the tilt angle adjustment described in steps S10 to S20 above.

Next, the processing unit 18 adjusts the amount of measured light and the like so that the brightness values of the interference fringe curves acquired for all the pixels of the interference fringes (imaging surface of the image sensor 60) have an appropriate magnitude (step S300). ). That is, the strength of the light source 40 of the light source unit 12, the speed of the electronic shutter in the image sensor 60 (the length of the charge accumulation time), the gain for the image signal obtained by the image sensor 60, and the like are adjusted.

When the above adjustment process is completed, the processing unit 18 can start measuring the surface shape of the measurement object P placed on the stage 10. However, in order to speed up the surface shape measurement, the measurement scanning range is set before the start of measurement so as to shorten the measurement scanning range (the range in which the interference portion 14 is moved in the z-axis direction) to the minimum necessary. It is preferable to perform the step (step S400) of (preliminary measurement). In this step, the measurement scanning range is shortened to the minimum necessary by grasping the outline of the surface shape of the object to be measured in advance. For example, a method of separately providing a camera as described in Japanese Patent Application Laid-Open No. 2016-136091. Etc. can be adopted.

When these processes are completed, the process unit 18 starts measuring the surface shape of the object P to be measured (step S500). As a method for measuring the surface shape, the measured surface S is measured based on the interference fringes acquired by the photographing unit 16 while changing the optical path length of the measurement light applied to each point of the measured surface S of the measurement object P. Any method may be used as long as it is a method of measuring the surface shape of the object P to be measured by detecting the position of the interference fringes in the z-axis direction of each point.

When these processes are completed, the process unit 18 starts measuring the surface shape of the object P to be measured (step S600).

Finally, the processing unit 18 outputs the measurement result of the surface shape to the display unit 20 and the like.

P ... Measurement target, Q, Q1, Q2, Q3 ... Interference fringe curve, S ... Measured surface, Z-0, Z-1 ... Optical axis, 1 ... Surface shape measuring device, 2 ... Optical unit, 10 ... Stage 10, S ... Stage surface, 12 ... Light source unit, 14 ... Interference unit, 16 ... Imaging unit, 18 ... Processing unit, 18A ... Measurement preparation control unit, 20 ... Display unit, 22 ... Input unit, 30 ... x rotation axis, 32 ... y rotation axis, 34 ... x actuator, 35 ... tilting means, 36 ... y actuator, 40 ... light source, 42 ... collector lens, 44, 54 ... beam splitter, 50 ... objective lens, 52 ... reference mirror, 56 ... interference unit Actuator, 60 ... imaging element, 60S ... imaging surface, 62 ... imaging lens, 70 ... z actuator, 100 ... reference region, 102, 112, 122 ... selected pixels, 110 ... x-axis leveling adjustment region, 120 ... y-axis leveling Adjustment area, N ... bisected axis, F ... horizontal plane

Claims (7)

A support portion that supports the object to be measured and has a flat surface on which the object to be measured is placed, and a support portion.
The light source unit that emits white light, the white light from the light source unit is divided into measurement light and reference light, and the measurement light is irradiated to the measured surface of the measurement object along the measurement optical axis, and the reference is also made. The reference surface was irradiated with light, and the interference portion that generated the interference light in which the measurement light returning from the measured surface and the reference light returning from the reference surface interfered with each other, and each point of the measured surface were irradiated. and an optical unit having a luminance signal acquisition unit that acquires the luminance signal of the interference light between the measurement light and the reference light,
On the basis of the luminance signal of each point of the surface to be measured acquired by the luminance signal acquisition unit while changing the optical path length of the measuring light applied to each point of the surface to be measured, each of the surface to be measured It is a measurement preparation alignment method of a surface shape measuring device that measures the surface shape of the object to be measured by detecting the position in the optical axis direction, which is the position of the point in the measurement optical axis direction.
And said flat surface by tilting from the horizontal posture parallel to the horizontal plane, inclined swash step of inclination obliquely to the preset set tilt angle the tilt angle of the surface to be measured with respect to the horizontal plane,
The brightness of acquiring the luminance signal at each point of the surface to be measured by the luminance signal acquisition unit while changing the optical path length of the measurement light applied to each point of the surface to be measured inclined to the set inclination angle. Signal acquisition process and
An optical axis direction position detection step of detecting the optical axis direction position of each point of the measured surface from the luminance signal of each point of the measured surface acquired in the luminance signal acquisition step.
Based on the detection result of the optical axis direction position detection step, a correction angle for calibrating the surface to be measured with respect to the measurement optical axis is obtained, and the inclination angle of the surface to be measured is adjusted based on the obtained correction angle. An inclination angle adjusting step, and a measurement preparation alignment method for a surface shape measuring device. A support portion that supports the object to be measured and has a flat surface on which the object to be measured is placed, and a support portion.
The light source unit that emits white light, the white light from the light source unit is divided into measurement light and reference light, and the measurement light is irradiated to the measured surface of the measurement object along the measurement optical axis, and the reference is also made. The reference surface was irradiated with light, and the interference portion that generated the interference light in which the measurement light returning from the measured surface and the reference light returning from the reference surface interfered with each other, and each point of the measured surface were irradiated. and an optical unit having a luminance signal acquisition unit that acquires the luminance signal of the interference light between the measurement light and the reference light,
On the basis of the luminance signal of each point of the surface to be measured acquired by the luminance signal acquisition unit while changing the optical path length of the measuring light applied to each point of the surface to be measured, each of the surface to be measured It is a measurement preparation alignment method of a surface shape measuring device that measures the surface shape of the object to be measured by detecting the position in the optical axis direction, which is the position of the point in the measurement optical axis direction.
And said flat surface by tilting from the horizontal posture parallel to the horizontal plane, inclined swash step of inclination obliquely to the preset set tilt angle the tilt angle of the surface to be measured with respect to the horizontal plane,
The brightness of acquiring the luminance signal at each point of the surface to be measured by the luminance signal acquisition unit while changing the optical path length of the measurement light applied to each point of the surface to be measured inclined to the set inclination angle. Signal acquisition process and
From the luminance signal of each point of the surface to be measured acquired in the luminance signal acquisition step, the position in the optical axis direction of each point in the reference region and the leveling adjustment region preset in the surface to be measured is determined. Optical axis direction position detection process to be detected and
Based on the detection result of the optical axis direction position detection step, a focus adjustment step of adjusting the focus position of the optical unit to the optical axis direction position in the reference region, and a focus adjustment step.
Based on the detection result of the optical axis direction position of each point in the reference region detected by the optical axis direction position detection step and the detection result of the optical axis direction position of each point in the leveling adjustment region, the said A surface shape measuring device having an inclination angle adjusting step of obtaining a correction angle for calibrating the surface to be measured with respect to the measurement optical axis and adjusting the inclination angle of the surface to be measured based on the obtained correction angle. Measurement preparation alignment method. When the axes parallel to the horizontal plane and orthogonal to each other are the x-axis and the y-axis,
The tilting step is
When viewed from the y-axis direction, x-axis tilt angle of performing is tilted to a preset angle of inclination angle of inclination from said luminance signal acquisition step to the tilt angle adjustment step for the x-axis direction of the measurement surface Adjustment and
when viewed from the x-axis direction, y-axis tilt angle of performing is tilted to a preset angle of inclination angle of inclination from said luminance signal acquisition step to the tilt angle adjustment step for the y-axis direction of the measurement surface The measurement preparation alignment method of the surface shape measuring apparatus according to claim 1 or 2 , which comprises at least one of adjustment. The axes parallel to the horizontal plane and orthogonal to each other are defined as the x-axis and the y-axis, and the axis formed by the x-axis and the y-axis is divided into two equal parts. When the axis perpendicular to the bisection axis is defined as the vertical axis , the flat surface is tilted around the axis of the vertical axis in the tilting step, and the surface to be measured is tilted with respect to the bisection axis of the surface to be measured. to a preset tilt angle the tilt angle on an angle,
The measurement preparation alignment method of the surface shape measuring apparatus according to claim 1, wherein the x-axis tilt angle adjustment and the y-axis tilt angle adjustment are performed at the same time by performing the brightness signal acquisition step to the tilt angle adjusting step. The axes parallel to the horizontal plane and orthogonal to each other are defined as the x-axis and the y-axis, and the axis formed by the x-axis and the y-axis is divided into two equal parts. When the axis perpendicular to the bisection axis is defined as the vertical axis , the flat surface is tilted around the axis of the vertical axis in the tilting step, and the surface to be measured is tilted with respect to the bisection axis of the surface to be measured. to a preset tilt angle the tilt angle on an angle,
The measurement preparation alignment method of the surface shape measuring apparatus according to claim 2, wherein the focus adjustment, the x-axis tilt angle adjustment, and the y-axis tilt angle adjustment are simultaneously performed by performing the luminance signal acquisition step to the tilt angle adjustment step. .. The measurement preparation alignment method of the surface shape measuring apparatus according to any one of claims 1 to 5 , wherein the set inclination angle is obtained from the equation of tan (θ2) = N * λ / L.
However, θ2: set tilt angle, N: number of interference fringes to be observed on the imaging surface, λ: center wavelength of measurement light, L: viewing length in the x-axis direction (or y-axis direction) of the imaging surface. A support portion that supports the object to be measured and has a flat surface on which the object to be measured is placed, and a support portion that supports the object to be measured.
The light source unit that emits white light, the white light from the light source unit is divided into measurement light and reference light, and the measurement light is irradiated to the measured surface of the measurement object along the measurement optical axis, and the reference is also made. The reference surface was irradiated with light, and the interference portion that generated the interference light in which the measurement light returning from the measured surface and the reference light returning from the reference surface interfered with each other, and each point of the measured surface were irradiated. an optical portion having a luminance signal acquisition unit that acquires the luminance signal of the interference light between the measurement light and the reference light,
A tilting means for tilting the flat surface relative to the horizontal plane is provided.
Each point of the surface to be measured is based on the brightness signal of each point of the surface to be measured acquired by the luminance signal acquisition unit while changing the optical path length of the measurement light applied to each point of the surface to be measured. A surface shape measuring device that measures the surface shape of the object to be measured by detecting the position in the optical axis direction, which is the position in the measurement optical axis direction.
The tilting means, said planar surface by tilting from the horizontal posture parallel to the horizontal plane, the tilting to be inclined obliquely to the setting angle of inclination which is set in advance the inclination angle of the surface to be measured with respect to the horizontal plane,
Brightness for acquiring the luminance signal at each point on the surface to be measured by the luminance signal acquisition unit while changing the optical path length of the measurement light applied to each point on the surface to be measured inclined to the set tilt angle. Signal acquisition operation and
From the luminance signal of each point of the surface to be measured acquired by the luminance signal acquisition operation, the position in the optical axis direction of each point in the reference region and the leveling adjustment region preset in the surface to be measured is determined. With the optical axis position detection operation to be detected
Based on the detection result of the optical axis direction position detection operation, a focus adjustment operation for adjusting the focus position of the optical unit to the optical axis direction position in the reference region, and a focus adjustment operation.
Based on the detection result of the optical axis direction position of each point in the reference region detected by the optical axis direction position detection operation and the detection result of the optical axis direction position of each point in the leveling adjustment region, the said An inclination angle adjusting operation of obtaining a correction angle for calibrating the surface to be measured with respect to the measurement optical axis and driving the tilting means by the obtained correction angle to adjust the inclination angle of the surface to be measured. A surface shape measuring device having a measurement preparation control unit that controls a measurement preparation operation program.

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