JP6629706B2 - Shape measuring device, shape measuring method and shape measuring program - Google Patents

Description

  The present invention relates to a shape measuring device, a shape measuring method, and a shape measuring program for measuring a shape of a measurement target such as an aspherical lens.

  As a device for measuring the shape of a substantially spherical member such as an aspherical lens, a shape measuring device as disclosed in Patent Document 1 is known. In the shape measuring device of Patent Document 1, the relative position between the measuring element and the measuring object is moved while the measuring element is in contact with the surface of the measuring object such as a substantially spherical member, and the surface of the measuring object is moved by the measuring element. Scanning. The shape measurement value of the surface of the measurement target is acquired by scanning with the tracing stylus, and the shape error of the measurement target is calculated by aligning the acquired shape measurement value with the design value.

  Further, in the shape measurement device of Patent Document 2, before calculating the shape error of the measurement target, the arrangement state of the measurement target such as the inclination of the measurement target is acquired. Then, the design value is corrected according to the acquired arrangement state of the measurement target, and the shape error of the measurement target is calculated from the corrected design value and the shape measurement value.

JP 2009-299299 A JP 2009-150822 A

  In recent years, lenses having a variety of different shapes have been used for optical-related products. For example, as a projection lens for a projector, a D-cut lens in which a part of an outer periphery is cut has been used. By adopting the D-cut lens in the projector device, it is possible to reduce the size and weight of the projector device. On the other hand, the D-cut lens has a rotationally asymmetric shape for the most part, and therefore has optical characteristics different from those of a conventional lens having a rotationally symmetric shape.

  For example, the D-cut lens shown in FIG. 2 has a shape error in the X direction and a shape error in the Y direction as shown in FIG. The shape error in the X direction of the D-cut lens is rotationally asymmetric with respect to the Z axis, and the shape error in the X direction increases as the distance from the origin indicating the optical axis center CL increases. (See "X plus side error E1" and "X minus side error E2.") Further, since the shape of the D-cut lens in the Y direction is interrupted on the way due to partial cutting of the outer periphery, there is no shape error corresponding to the interrupted portion.

  Since the D-cut lens has the above optical characteristics, the arrangement state of the measurement target S, such as the deviation from the optical axis center and the inclination, is accurately calculated at the time of shape measurement, as in Patent Document 2. It is difficult. Therefore, the shape measurement value may be aligned with the design value without correcting the design value according to the arrangement state of the measurement target S. For example, when a shape measurement value in the X direction is obtained by simply aligning the shape measurement value with a design value, the inclination correction and the recognition of the optical axis center are erroneously performed. Different erroneous measurement results may occur (see FIG. 10 (original shape error) and FIG. 12 (shape error when shape measurement value is simply aligned with design value)). In addition, when the shape measurement value in the Y direction is obtained by simply aligning the shape measurement value with the design value, it is not possible to determine whether the measurement target S is deviated from the optical axis center CL or has fallen, and is largely different from the actual one. Different erroneous measurement results may occur (see FIG. 11 (original shape error) and FIG. 13 (shape error when shape measurement value is simply aligned with design value)).

  From the above, with respect to a rotationally asymmetric shape to be measured such as a D-cut lens, a conventional shape measuring apparatus as disclosed in Patent Literatures 1 and 2 can accurately calculate an arrangement state such as a deviation or an inclination from the optical axis center. As a result, the shape error could not be accurately calculated.

  An object of the present invention is to provide a shape measuring device, a shape measuring method, and a shape measuring program that can accurately calculate a shape error of a rotationally asymmetric measurement target such as a D-cut lens.

  The present invention relates to a shape measuring apparatus for measuring the shape of a rotationally asymmetric measurement target including a rotationally symmetric portion that is rotationally symmetric with respect to the optical axis center. By changing the relative position of the object and scanning the surface of the object to be measured at a specific measurement pitch with the measuring element, the shape measuring unit for acquiring the shape measurement value of the measuring object and the rotationally symmetric part are scanned by the measuring element. A rotationally symmetric part scanning sequence for acquiring a shape measurement value of a rotationally symmetric part, a scanning sequence control unit for performing a measurement scanning sequence for scanning a measurement object with a tracing stylus and acquiring a shape measurement value of the measurement object, An arrangement state acquisition unit that acquires an arrangement state of a measurement target from a shape measurement value of a unit, and an error calculation that calculates an error between a design value for measurement of the measurement object and a shape measurement value of the measurement object in the arrangement state of the measurement object Provided with a door.

  It is preferable that the arrangement state acquisition unit compares the shape measurement value of the rotationally symmetric part with a predetermined initial design value of the rotationally symmetric part, and acquires the arrangement state of the measurement target from the comparison result. The scanning sequence control unit scans a plurality of scan lines provided at different positions in the rotationally symmetric part, acquires a shape measurement value of the rotationally symmetric part for each scan line, and the arrangement state acquisition unit performs It is preferable to acquire the arrangement state of the measurement target based on a plurality of comparison results obtained by comparing the shape measurement value of the rotationally symmetric part and the initial design value of the rotationally symmetric part. The arrangement state of the measurement target preferably includes a deviation from the center of the optical axis and a tilt of the measurement target.

  The measurement scanning sequence includes an offset portion scanning sequence for scanning the offset portion of the measurement target offset from the optical axis center by the distance D with a tracing stylus to obtain a shape measurement value of the offset portion. It is preferable to calculate an error between the design value for measurement of the offset portion and the shape measurement value of the offset portion in the arrangement state of the measurement target. The offset section scanning sequence preferably includes a sequence for positioning the tracing stylus at the offset section by changing the relative position.

  A design value setting unit configured to set a design value for measurement of the offset unit in the arrangement state of the measurement target from a preset initial design value of the measurement object and the arrangement state of the measurement object, and the error calculation unit performs measurement of the offset unit. It is preferable to calculate an error between the design value for use and the measured shape value of the offset portion. The design value for measurement of the offset portion is composed of a plurality of point groups for design value, and the number of the plurality of point groups for design value is the same as the number of the plurality of measurement point groups based on scanning of the tracing stylus or the number of the plurality of measurement points. Preferably, the number is equal to or greater than the number of groups. It is preferable that the number of the plurality of design value point groups is determined to be 50 or more, or according to a specific measurement pitch.

  It is preferable that the scanning sequence control unit includes a gradient calculating unit that calculates the gradient of the measurement target from the plurality of design value point clouds, and causes the tracing stylus to scan at a scanning speed set according to the gradient of the measurement target. It is preferable that the measurement target has a circumference in the first direction passing through the center of the optical axis larger than a circumference in the second direction passing through the center of the optical axis and orthogonal to the first direction. In the rotationally symmetric scanning sequence, it is preferable that the scanning distance in the first direction by the tracing stylus is longer than the scanning distance in the second direction. The measurement target is preferably a D-cut lens.

  The present invention is a shape measuring method for measuring the shape of a rotationally asymmetric measurement target including a rotationally symmetric portion that is rotationally symmetric with respect to the optical axis center, wherein the shape measuring unit is in a state in which the measuring element is in contact with the measurement target. Scanning the surface of the measurement object at a specific measurement pitch with the measurement element while changing the relative position of the measurement element and the measurement object, thereby obtaining a shape measurement value of the measurement object; and A rotationally symmetrical part scanning sequence for scanning a symmetrical part with a tracing stylus to obtain a shape measurement value of a rotationally symmetrical part, and a measuring scanning sequence for scanning a measurement target with a tracing stylus and acquiring a shape measurement value of the measurement target. Performing the step, the arrangement state acquiring unit acquiring the arrangement state of the measurement target from the shape measurement value of the rotationally symmetric part, and the error calculation unit performing the measurement design of the measurement object in the arrangement state of the measurement object. And a step of calculating an error between the shape measured values of the measurement target.

  The present invention is a shape measuring program for measuring the shape of a rotationally asymmetric measurement target including a rotationally symmetric portion that is rotationally symmetric with respect to the optical axis center, wherein the computer causes the shape measuring unit to contact the measuring element with the measurement target. Scanning the surface of the measurement object at a specific measurement pitch with the measurement element while changing the relative position of the measurement element and the measurement object in a state where However, the rotationally symmetric portion is scanned by the tracing stylus, and the rotationally symmetric portion scanning sequence for acquiring the shape measurement value of the rotationally symmetric portion, and the measurement object is scanned by the tracing stylus to obtain the shape measurement value of the measurement object. A step of performing a measurement scanning sequence; a step in which the arrangement state acquisition unit acquires an arrangement state of the measurement target from the shape measurement value of the rotationally symmetric part; And a step of calculating an error between the measurement design value of definitive measurement target shape measurement value of the measurement object.

  According to the present invention, it is possible to measure the shape of a rotationally asymmetric measurement target such as a D-cut lens.

It is an external view of a shape measuring device. FIG. 3 is a plan view of a D-cut lens in which an optical axis center CL corresponds to an origin of XY coordinates. It is a top view of an XY movable stage. FIG. 9 is an explanatory diagram of a rotationally symmetric scanning sequence. FIG. 9 is an explanatory diagram of a non-offset portion scanning sequence. FIG. 4 is an explanatory diagram of an offset section scanning sequence. FIG. 3 is a block diagram illustrating functions of an arithmetic processing unit. FIG. 4 is an explanatory diagram illustrating a method of calculating a tilt amount and a shift amount of a measurement target S. It is explanatory drawing which shows the point group for design values, and a measurement point group. It is explanatory drawing which shows the shape error of the X direction of the measuring object S at the time of calculating the shape error using the design value for measurement. It is explanatory drawing which shows the shape error of the Y direction of the measuring object S at the time of calculating a shape error using the design value for a measurement. It is explanatory drawing which shows the shape error of the X direction of the measuring object S at the time of calculating a shape error with an initial design value. FIG. 9 is an explanatory diagram illustrating a shape error in the Y direction of a measurement target S when a shape error is calculated with an initial design value. 9 is a flowchart illustrating a series of steps for calculating a shape error of a measurement target S. FIG. 4 is an explanatory diagram showing scanning of a plurality of scanning lines by a tracing stylus P. FIG. 3 is a block diagram illustrating functions of an arithmetic processing unit having a scanning speed setting function according to a gradient of a measurement target S. FIG. 9 is an explanatory diagram illustrating a method of setting a scanning speed according to a gradient of a measurement target S. FIG. 9 is an explanatory diagram showing that the scanning distance in the X direction and the scanning distance in the Y direction are different in the rotationally symmetric portion. It is explanatory drawing which shows the shape error of the X direction of a D cut lens, and the shape error of a Y direction.

  As shown in FIG. 1, the shape measuring device 10 measures the shape of the measurement target S. In the present embodiment, a shape measurement of a measurement target S having a rotationally asymmetric shape such as an aspherical D-cut lens will be described as the measurement target S. As shown in FIG. 2, the measurement target S has a rotationally symmetric portion Sa that is rotationally symmetric with respect to the optical axis center CL in a central range within a certain range in the radial direction from the optical axis center CL. Is rotationally asymmetric about the optical axis center CL. In addition, the measurement target S has a circumference Lx in the X direction (first direction) passing through the optical axis center CL longer than a circumference Ly in the Y direction (second direction) passing through the optical axis center CL. Has become.

  As shown in FIG. 1, a shape measuring apparatus 10 includes a base 12, an XY movable stage 14 provided on the base 12, and a shape of a surface of a measurement target S mounted on the XY movable stage 14. A shape measuring unit 16 for measuring the distance, an operation unit 18 for operating these, a scanning sequence control unit 20, and an arithmetic processing unit 22 are provided.

  As shown in FIG. 3, the XY movable stage 14 is a mechanism for changing the relative position between the tracing stylus P and the measuring object S in a state where the tracing stylus P is in contact with the measuring object S. It comprises a Y movable stage 14b. The X movable stage 14a is movable on the base 12 in the X direction, and the Y movable stage 14b is movable on the X movable stage 14a in the Y direction orthogonal to the X direction. The driving of the X movable stage 14a and the Y movable stage 14b is controlled by the scanning sequence control unit 20. When driving the X movable stage 14a or the Y movable stage 14b, the scanning sequence control unit 20 outputs the X coordinate data in the X direction or the Y coordinate data in the Y direction of the measurement target S to the shape measuring unit 16. The XY movable stage 14 includes a posture adjustment unit (not shown) for adjusting the posture of the measurement target S.

  As shown in FIG. 1, the shape measurement unit 16 acquires a shape measurement value of the measurement target S by scanning the measurement target S with the tracing stylus P in accordance with the movement of the XY movable stage 14. The shape measuring unit 16 is attached to a substantially rectangular parallelepiped column 23 provided on the base 12 so as to be movable in the vertical Z direction. The shape measuring section 16 includes an arm 24 that can advance and retreat in the X direction, and a tracing stylus P is attached to the arm 24. The tracing stylus P can be displaced in the Z direction, and the displacement of the tracing stylus P in the Z direction is detected by a displacement detection sensor (not shown) provided on the tracing stylus P.

  The displacement detection sensor outputs Z-direction displacement data in accordance with the detection of the displacement of the tracing stylus P. The shape measurement unit 16 generates a shape measurement value by associating the Z-direction displacement data output from the displacement detection sensor with the X-coordinate data or the Y-coordinate data when the Z-direction displacement data is acquired. The generated shape measurement value is output to the arithmetic processing unit 22.

  The scanning sequence control unit 20 controls the XY movable stage 14 according to a predetermined scanning sequence. The scanning sequence performed by the scanning sequence controller 20 includes an initialization sequence, a rotationally symmetric scanning sequence, a non-offset scanning sequence, and an offset scanning sequence. The initial scanning sequence is a sequence performed before the measurement of the measurement target S. The XY movable stage 14 is moved in the XY directions or the shape measuring unit 16 is moved in the Z direction, and the tracing stylus P is placed on the XY movable stage 14. The measurement object S is brought into contact with the surface at the initial position. The initial position is a position on the surface of the rotationally symmetric portion Sa in the measurement target S. This completes the initial sequence. The “measurement scan sequence” of the present invention includes the above “non-offset portion scan sequence” and “offset portion scan sequence”.

  The rotationally symmetric part scanning sequence is a sequence in which the rotationally symmetric part Sa is scanned by the tracing stylus P in order to detect the arrangement state of the measurement target S. In this rotationally symmetric scanning sequence, the measurement target S is moved in the X direction by moving the X movable stage 14a at a predetermined measurement pitch W (specific measurement pitch). Due to the movement of the measurement target S in the X direction, the tracing stylus P scans the surface of the rotationally symmetric portion Sa at the measurement pitch W as shown in FIG. By the scanning of the tracing stylus P, the displacement of the measuring object S in the Z direction at a predetermined position in the X direction is measured. The measurement result is output from the shape measurement unit 16 as a shape measurement value of the rotationally symmetric portion Sa in the X direction.

  In the rotationally symmetrical part scanning sequence, the Y movable stage 14b is moved at the measurement pitch W in the same manner as described above, and the rotationally symmetrical part Sa is scanned in the Y direction by the tracing stylus P. By the scanning of the tracing stylus P in the Y direction, the shape measuring section 16 outputs a measured value of the rotationally symmetric portion Sa in the Y direction. Note that the distance LSx for scanning the rotationally symmetric portion Sa in the X direction by the tracing stylus P is the same as the distance LSy for scanning in the Y direction.

  As shown in FIG. 5, the non-offset portion scanning sequence is performed to obtain a shape measurement value in the X direction or the Y direction of the non-offset portion 30 passing through the optical axis center CL of the measurement target S. This is a sequence in which the whole is scanned by the tracing stylus P. In the non-offset portion scanning sequence, by moving the measurement target S in the X direction or the Y direction, the tracing stylus P scans the surface of the measurement target S in the X direction or the Y direction at the measurement pitch W. By the scanning of the tracing stylus P in the X direction or the Y direction, the shape measuring section 16 outputs a shape measurement value of the non-offset portion 30 in the X direction or the Y direction. For example, in the case of FIG. 5, the shape measurement unit 16 outputs a shape measurement value in the X direction of the cross section 30 a in the non-offset portion 30.

  As shown in FIG. 6, the offset unit scanning sequence is performed by changing the surface of the offset unit 32 in order to acquire a shape measurement value in the X direction or the Y direction of the offset unit 32 that does not pass through the optical axis center CL of the measurement target S. This is a sequence for scanning with the tracing stylus P. In the offset section scanning sequence, first, a sequence is performed in which the position of the tracing stylus P is offset from the optical axis center CL by the distance D in the X direction or the Y direction by moving the measurement target S in the X direction or the Y direction. For example, in the case of FIG. 6, the tracing stylus P is offset from the optical axis center CL by a distance D in the Y direction.

  After the offset of the tracing stylus P is completed, by moving the measuring object S in the X or Y direction, the tracing stylus P scans the surface of the offset portion 32 at the measuring pitch W in the X or Y direction. For example, in the case of FIG. 6, a portion separated by a distance D from the X axis becomes a scan line of the offset unit 32 scanned by the tracing stylus P. By scanning the tracing stylus P in the X direction or the Y direction, the shape measurement unit 16 outputs a shape measurement value of the offset unit 32 in the X direction or the Y direction. For example, in the case of FIG. 6, the shape measuring unit 16 outputs a measured value of the shape of the cross section 32 a in the X direction in the offset unit 32.

  As shown in FIG. 7, the arithmetic processing unit 22 includes an arrangement state acquisition unit 40, a design value setting unit 42, and an error calculation unit 44. The arrangement state acquisition unit 40 acquires the arrangement state of the measurement target S based on the shape measurement value of the rotationally symmetric part Sa obtained in the rotationally symmetric part scanning sequence. The arrangement state acquisition unit 40 compares a predetermined initial design value relating to the shape of the measurement target S with the shape measurement value of the rotationally symmetric part, and acquires the arrangement state of the measurement target S obtained from the comparison result. Since the rotationally symmetric portion Sa is a region near the optical axis center CL, the shape error is small. Therefore, while the shape measurement value of the rotationally symmetric portion Sa hardly includes a shape error, a lot of information on the arrangement state of the measurement target S such as the inclination of the measurement target S and the deviation from the optical axis center CL is included. Have been. Therefore, by subtracting the initial design value from the shape measurement value of the rotationally symmetric portion Sa, it is possible to separate and acquire information on the arrangement state of the measurement target S.

  As the arrangement state of the measurement target S, the inclination amount of the measurement target S in the X direction, the inclination amount of the measurement target S in the Y direction, the inclination amounts of the two-dimensional inclined surfaces in the X direction and the Y direction of the measurement target S, the measurement target S It is preferable to determine the amount of deviation of the rotation center of the optical axis or the optical axis center CL. When the amount of inclination of the measurement target S in the X direction is obtained, the amount of inclination in the X direction is obtained from the initial design value and the shape measurement value in the X direction at the rotationally symmetric portion. For example, as shown in FIG. 8, when the initial design value in the X direction of the rotationally symmetric portion is represented by a curve 50 and the measured shape value of the rotationally symmetric portion in the X direction is represented by a curve 52, the measurement target S Is obtained by dividing the difference dz in the Z direction between the curve 50 and the curve 52 by the distance Lax of the X coordinate of the part where the difference dz is obtained. In the same manner as above, the inclination amount of the measurement target S in the Y direction can be obtained.

  In addition, when obtaining the amount of inclination of the two-dimensional inclined surface in the X direction and the Y direction in the measurement target S, the initial design value and the shape measurement value in the X direction in the rotationally symmetric portion and the initial value in the Y direction in the rotationally symmetric portion are obtained. From the design value and the shape measurement value, the amount of inclination of the two-dimensional inclined surface can be obtained. The rotation center of the measurement target S can also be obtained from the initial design value and shape measurement value in the X direction at the rotationally symmetric part and the initial design value and shape measured value in the Y direction at the rotationally symmetric part. Regarding the displacement amount of the optical axis center CL, for example, as shown in FIG. 8, the difference dx in the X direction between the curves 50 and 52 is the displacement amount of the optical axis center CL of the measurement target S.

  The design value setting unit 42 changes the design value for measurement of the non-offset part based on the arrangement state of the measurement target S in order to calculate the shape error of the non-offset part. In addition, the design value setting unit 42 changes the measurement design value of the offset unit based on the arrangement state of the measurement target S in order to calculate the shape error of the offset unit. In the design value setting unit 42, in addition to the case where the arrangement state of the measurement target S is the inclination amount of the measurement object in the X direction or the Y direction, the arrangement state of the measurement object S is determined by the inclination amount of the inclined surface in the measurement object. Even in a certain case, it is possible to change (correct) the measurement design value of the non-offset portion or the measurement design value of the offset portion according to the amount of inclination of the inclined surface.

ただし、（式１）においてｈ²は「ｘ²＋ｙ²」を表しており、「ｘ」はＸ方向の座標を、「ｙ」はＹ方向の座標を表している。「ｚ」はＺ方向の座標を表している。「ｃ」、「ｋ」はパラメータであり、「Ａ_k」は非球面係数である。 The design value setting unit 42 previously stores an initial design value represented by a function represented by the following equation (1), and sets the offset value of the offset unit according to the function of the initial design value of (equation 1) and the arrangement state of the measurement target S. Set the design value for measurement and the design value for measurement of the non-offset part. Specifically, the design value setting unit 42 adds an adjustment amount corresponding to the arrangement state of the measurement target S to the function of the initial design value in (Equation 1), and adds this adjustment amount (Equation 1). The measurement design value of the offset portion and the measurement design value of the non-offset portion are set in accordance with the following function.

However, in Equation 1, h ² represents “x ² + y ² ”, “x” represents coordinates in the X direction, and “y” represents coordinates in the Y direction. “Z” indicates coordinates in the Z direction. “C” and “k” are parameters, and “A _k ” is an aspheric coefficient.

  For example, when the measurement target S is tilted by a specific tilt amount and deviates from the optical axis center CL by a specific deviation amount, in order to adjust the design value to the tilt of the measurement target S, , An adjustment amount in the Z direction corresponding to the specific inclination amount is added. Further, in order to match the design value with the specific deviation amount of the measurement target, an adjustment amount corresponding to the specific deviation amount is added to “x” in (Equation 1). Then, the design value for measurement of the non-offset portion and the design value for measurement of the offset portion are set according to the function of (Equation 1) to which the above two adjustment amounts are added.

  In addition, it is preferable that the design value for measurement of the non-offset part or the design value for measurement of the offset part is a plurality of design value point groups or an aspherical form of the plurality of design value point groups. . As shown in FIG. 9, when the measurement design value is composed of a plurality of design value point groups, a plurality of design value point groups K1 to Ki (i is a natural number between 2 and I (I is 3 The number of the above natural numbers)) is the same as or a plurality of the plurality of measurement point groups M1 to Mj (j is a natural number between 2 and J (J is a natural number of 3 or more)) based on the scanning of the tracing stylus P. Is preferably equal to or more than the number of the measurement point groups M1 to Mj. For example, the number of the plurality of design value point groups K1 to Ki is preferably set to 50 or more, or to be determined according to the measurement pitch W.

  The error calculator 44 calculates the shape error of the non-offset part from the design value for measurement of the non-offset part set by the design value setting unit 42 and the shape measurement value of the non-offset part. The shape error of the non-offset portion is obtained by a difference process between the shape measurement value of the non-offset portion and the design value for measurement of the non-offset portion. The error calculator 44 calculates a shape error of the offset portion from the design value for measurement of the offset portion set by the design value setting portion 42 and the shape measurement value of the offset portion. The method of calculating the shape error of the offset portion is the same as the method of calculating the shape error of the non-offset portion. In calculating these shape errors, as described above, the design values for measurement in which the initial design values are adjusted in accordance with the arrangement state of the measurement target are used, and thus the shape has a rotationally asymmetric shape like the measurement target S. Even in this case, the shape error can be accurately calculated.

  In the case of the D-cut lens shown in FIG. 2, as to the shape error in the X direction of the non-offset portion, as shown in FIG. A rotationally asymmetric shape error that is not symmetric with respect to is obtained. Further, as for the shape error in the Y direction of the non-offset portion, as shown in FIG. 11, a partially cut shape error is obtained.

  Here, when the shape error is obtained with the initial design value, not the measurement design value set by the design value setting unit 42, without adjusting to the arrangement state of the measurement target S, the non-design error shown in FIG. As for the shape error of the offset portion in the X direction, the shape error may be reduced as shown in FIG. In addition, as for the shape error in the Y direction of the non-offset portion shown in FIG. 11, as shown in FIG. 13, the arrangement state of the measurement target S and the shape error may be mixed and the original correct shape error may not be obtained. .

  Next, a series of flows for calculating the shape error of the measurement target S will be described with reference to the flowchart shown in FIG. First, an initialization sequence is performed. The scanning sequence control unit 20 moves the XY movable stage 14 in the XY direction or the shape measuring unit 16 in the Z direction so that the tracing stylus P is located at the initial position on the surface of the rotationally symmetric portion Sa according to the initial setting sequence. Move. When the tracing stylus P comes into contact with the initial position, the initial setting sequence is completed.

  Next, a rotationally symmetric scanning sequence is performed. The scanning sequence control unit 20 moves the XY movable stage 14 so that the tracing stylus P scans the surface of the rotationally symmetric portion Sa at the measurement pitch W in accordance with the rotationally symmetrical portion scanning sequence. In accordance with the scanning of the rotationally symmetric portion Sa by the tracing stylus P, the shape measurement value of the rotationally symmetric portion Sa is output from the shape measuring portion 16. Since the scanning of the tracing stylus P is performed in the X direction and the Y direction, the shape measurement unit 16 calculates the shape measurement value in the X direction of the rotationally symmetric portion Sa and the shape measured value in the Y direction of the rotationally symmetric portion Sa from the arithmetic processing unit 22. Is output to

  After the completion of the rotationally symmetric part measurement sequence, an arrangement state acquisition step is performed. The arrangement state acquisition unit 40 compares an initial design value relating to a predetermined shape of the measurement target S with a shape measurement value of the rotationally symmetric part Sa, and acquires the arrangement state of the measurement target S obtained from the comparison result. .

  After the arrangement state obtaining step is completed, a non-offset portion scanning sequence is performed. The scanning sequence control unit 20 moves the XY movable stage 14 so that the tracing stylus P scans the surface of the non-offset portion of the measurement target S at the measurement pitch W in accordance with the non-offset portion scanning sequence. In accordance with the scanning of the non-offset portion by the tracing stylus P, the shape measurement unit 16 outputs a shape measurement value of the non-offset portion. Since the scanning of the tracing stylus P is performed in the X direction and the Y direction, the shape measurement unit 16 obtains the shape measurement value of the non-offset part in the X direction and the shape measurement value of the non-offset part in the Y direction. Is output to

  After the non-offset part scanning sequence is completed, a non-offset part shape error calculation step is performed. The design value setting unit 42 sets a design value for measurement of the non-offset part in the arrangement state of the measurement target S based on the initial setting value relating to the shape of the measurement target S and the arrangement state of the measurement target S. Next, the error calculator 44 calculates the shape error of the non-offset portion from the design value for measurement of the non-offset portion and the shape measurement value of the non-offset portion. The calculated result is displayed on the monitor 60 by a graph or the like.

  After the step of calculating the shape error of the non-offset portion is completed, an offset portion scanning sequence is performed. The scanning sequence control unit 20 first moves the XY movable stage 14 according to the offset unit scanning sequence so that the tracing stylus P is offset by the distance D from the optical axis center CL. Next, the scanning sequence control unit 20 moves the XY movable stage 14 so that the tracing stylus P scans the surface of the offset portion of the measurement target S at the measurement pitch W. In accordance with the scanning of the offset portion by the tracing stylus P, a shape measurement value of the offset portion is output from the shape measuring portion 16. Since the scanning of the tracing stylus P is performed in the X direction and the Y direction, the shape measurement unit 16 outputs a shape measurement value of the offset unit in the X direction and a shape measurement value of the offset unit in the Y direction to the arithmetic processing unit 22. Is done.

  After the offset portion scanning sequence is completed, a step of calculating a shape error of the offset portion is performed. The design value setting unit 42 sets the design value for measurement of the offset unit in the arrangement state of the measurement target S based on the initial setting value relating to the shape of the measurement target S and the arrangement state of the measurement target S. Next, the error calculator 44 calculates a shape error of the offset portion from the design value for measurement of the offset portion and the shape measurement value of the offset portion. The calculated result is displayed on the monitor 60 by a graph or the like. A series of steps for calculating the shape error of the measurement target S as shown in FIG. 14 described above is performed as a shape measurement program executable by the arithmetic processing unit 22 in a storage unit such as a hard disk in the arithmetic processing unit 22. It is remembered.

  In the above embodiment, the arrangement state of the measurement target S is calculated from the shape measurement value of the rotationally symmetric part Sa. However, in order to improve the calculation accuracy of the arrangement state, the rotationally symmetric part scanning sequence is as follows. May be performed. For example, as shown in FIG. 15, when scanning the rotationally symmetric portion Sa with the tracing stylus P, not only the first scan line Sc1 passing through the optical axis center CL, but also a distance D1 in the Y plus direction from the optical axis center CL. The tracing stylus P is scanned by a total of three lines of the second scanning line Sc2 and the third scanning line Sc3 offset by the distance D2 in the Y minus direction from the optical axis center CL, and a shape measurement value is acquired in each scanning line.

  Then, by comparing the shape measurement value of the first scan line Sc1 with the initial design value, a temporary first arrangement state of the measurement target S is obtained, and the shape measurement value of the second scan line Sc2 is compared with the initial design value. As a result, the temporary second arrangement state of the measurement target S is acquired, and the provisional third arrangement state of the measurement object is acquired by comparing the shape measurement value of the third scan line Sc3 with the initial design value. Then, by averaging the provisional first to third arrangement states, the arrangement state of the measurement target S is obtained. For example, as for the tilt amount, which is one of the arrangement states, a temporary tilt amount β1 is obtained for the first scan line Sc1, a temporary tilt amount β2 is obtained for the second scan line Sc2, and a temporary tilt amount β2 is obtained for the third scan line Sc3. The temporary inclination amount β3 is obtained. Then, the temporary inclination amounts β1, β2, and β3 are averaged to formally determine the inclination amount β of the measurement target S. Although shape measurement values are acquired from three scanning lines, it is preferable to scan three or more scanning lines and acquire three or more shape measurement values in order to increase the calculation accuracy of the arrangement state. .

  In the above-described embodiment, the tracing stylus P scans the measurement target S at a constant scanning speed. However, the shape of the measurement target S has a steep or gentle gradient. The scanning speed of the tracing stylus P may be changed. In this case, as shown in FIG. 16, the arithmetic processing unit 22 calculates a gradient calculating unit 70 for calculating the gradient of the shape of the measurement target S, and sets the scanning speed of the tracing stylus P according to the gradient calculated by the gradient calculating unit 70. A scanning speed setting unit 72 for setting is provided.

  The gradient calculation unit 70 acquires a plurality of design point groups from the measurement design value of the non-offset part or the measurement design value of the offset part set in the above. Then, the gradient calculation unit 70 calculates the gradient of the measurement target S from the plurality of design point clouds. The scanning speed setting unit 72 sets the scanning speed of the tracing stylus P differently according to the gradient of the measurement target S. For example, as shown in FIG. 17, the scanning speed is increased when the gradient of the measurement target S is gentle, while the scanning speed is decreased when the gradient of the measurement target S is sharp. The scanning sequence control unit 20 moves the XY movable stage 14 according to the scanning speed set by the scanning speed setting unit 72. Thereby, the tracing stylus P scans the measuring object S at the measuring speed set according to the gradient of the measuring object S.

  In the above embodiment, the distance LSx for scanning the rotationally symmetric portion Sa in the X direction and the distance LSy for scanning in the Y direction with the tracing stylus P in the rotationally symmetrical portion scanning sequence are the same (see FIG. 4). Since the length Lx of the measurement target S in the X direction is larger than the length Ly in the Y direction, as shown in FIG. 18, even if the distance LSx for scanning in the X direction is longer than the distance LSy for scanning in the Y direction. Good. However, in this case, it is preferable that the range scanned in the X direction falls within the rotationally symmetric portion Sa.

  In the above embodiment, a hardware structure of a processing unit (processing unit) that executes various types of processing in the arithmetic processing unit 22 such as the arrangement state acquisition unit 40, the design value setting unit 42, and the error calculation unit 44 is described below. These are various processors. For various processors, the circuit configuration is changed after the production of CPUs (Central Processing Units) and FPGAs (Field Programmable Gate Arrays), which are general-purpose processors that execute software (programs) and function as various processing units. It includes a programmable logic device (PLD) that is a possible processor, a dedicated electric circuit that is a processor having a circuit configuration specifically designed to execute various processes, and the like.

  One processing unit may be configured by one of these various processors, or configured by a combination of two or more processors of the same type or different types (for example, a plurality of FPGAs or a combination of a CPU and an FPGA). May be done. Further, a plurality of processing units may be configured by one processor. As an example of configuring a plurality of processing units with one processor, first, as represented by a computer such as a client or a server, one processor is configured by a combination of one or more CPUs and software; There is a form in which this processor functions as a plurality of processing units. Second, as represented by a system-on-chip (System On Chip: SoC), a form using a processor that realizes the functions of the entire system including a plurality of processing units with one IC (Integrated Circuit) chip. is there. As described above, the various processing units are configured using one or more of the various processors described above as a hardware structure.

  Furthermore, the hardware structure of these various processors is more specifically an electric circuit (circuitry) in which circuit elements such as semiconductor elements are combined.

Reference Signs List 10 Shape measuring device 12 Base 14 XY movable stage 14a X movable stage 14b Y movable stage 16 Shape measuring unit 18 Operating unit 20 Scanning sequence control unit 22 Operation processing unit 23 Column 24 Arm 30 Non-offset unit 30a Cross section 32 Offset unit 32a Cross section 40 arrangement state acquisition unit 42 design value setting unit 44 error calculation unit 50 curve 52 curve 60 monitor 70 gradient calculation unit 72 scanning speed setting unit

Claims (15)

A shape measuring device that measures the shape of a rotationally asymmetric measurement target including a rotationally symmetric portion that is rotationally symmetric with respect to the optical axis center,
In a state where the measuring element is in contact with the measuring object, the surface of the measuring object is scanned at a specific measuring pitch by the measuring element while changing the relative position of the measuring element and the measuring object, whereby the measuring object A shape measurement unit that obtains a shape measurement value of
Scanning the rotationally symmetric portion with the tracing stylus, a rotationally symmetric portion scanning sequence to obtain a shape measurement value of the rotationally symmetric portion, and scanning the measurement object with the tracing stylus, the shape measurement value of the measurement object A scanning sequence control unit that performs a measurement scanning sequence to obtain
From the shape measurement value of the rotationally symmetric part, an arrangement state acquisition unit that acquires the arrangement state of the measurement target,
A shape measuring apparatus comprising: an error calculating unit that calculates an error between a measurement design value of the measurement target and a shape measurement value of the measurement target in an arrangement state of the measurement target.   The arrangement state acquisition unit compares a shape measurement value of the rotationally symmetrical part with a predetermined initial design value of the rotationally symmetrical part, and acquires the arrangement state of the measurement target from a result of the comparison. The shape measuring device according to the above. The scanning sequence control unit scans a plurality of scan lines provided at different positions in the rotationally symmetric part, to obtain a shape measurement value of the rotationally symmetric part for each scan line,
The arrangement state acquisition unit acquires the arrangement state of the measurement target based on a plurality of comparison results obtained by comparing a shape measurement value of the rotationally symmetric part in each scan line and an initial design value of the rotationally symmetric part. The shape measuring device according to claim 2.   The shape measuring apparatus according to claim 2, wherein the arrangement state of the measurement target includes a deviation from the optical axis center and an inclination of the measurement target. The measurement scanning sequence includes an offset section scanning sequence of scanning the offset section of the measurement target offset from the optical axis center by a distance D with the tracing stylus to obtain a shape measurement value of the offset section. ,
The shape measurement device according to claim 1, wherein the error calculation unit calculates an error between a design value for measurement of the offset unit and a shape measurement value of the offset unit in the arrangement state of the measurement target.   The shape measuring apparatus according to claim 5, wherein the offset section scanning sequence includes a sequence of positioning the tracing stylus at the offset section by changing the relative position. From a preset initial design value of the measurement target and the arrangement state of the measurement target, a design value setting unit that sets a measurement design value of the offset unit in the arrangement state of the measurement target,
The shape measurement device according to claim 5, wherein the error calculation unit calculates an error between a design value for measurement of the offset unit and a shape measurement value of the offset unit.   The design value for measurement of the offset unit is composed of a plurality of point groups for design value, and the number of the plurality of point groups for design value is the same as or the same as the number of the plurality of measurement point groups based on scanning of the tracing stylus. The shape measuring apparatus according to claim 7, wherein the number is equal to or larger than the number of the plurality of measurement point groups.   The shape measuring apparatus according to claim 8, wherein the number of the plurality of design value point groups is determined to be 50 or more or according to the specific measurement pitch. A gradient calculating unit that calculates a gradient of the measurement target from the plurality of design value point clouds,
The shape measuring apparatus according to claim 8, wherein the scanning sequence control unit causes the tracing stylus to scan at a scanning speed set according to a gradient of the measurement target.   The object to be measured has a circumference in a first direction passing through the center of the optical axis, which is longer than a length in a second direction passing through the center of the optical axis and orthogonal to the first direction. 10. The shape measuring device according to any one of 10 above.   12. The shape measuring apparatus according to claim 11, wherein in the rotationally symmetric scanning sequence, a scanning distance of the tracing stylus in the first direction is longer than a scanning distance of the tracing stylus in the second direction.   The shape measuring apparatus according to claim 1, wherein the measurement target is a D-cut lens. A shape measurement method for measuring the shape of a rotationally asymmetric measurement target including a rotationally symmetric portion that is rotationally symmetric with respect to the optical axis center,
The shape measuring unit scans the surface of the measurement object at a specific measurement pitch with the measurement element while changing the relative position of the measurement element and the measurement object while the measurement element is in contact with the measurement object. By acquiring a shape measurement value of the measurement object,
A scanning sequence control unit scans the rotationally symmetrical part with the tracing stylus, and a rotationally symmetrical part scanning sequence for acquiring a shape measurement value of the rotationally symmetrical part, and scans the measurement target with the tracing stylus, Performing a measurement scan sequence to obtain a shape measurement value of the measurement target;
An arrangement state acquiring unit, from the shape measurement value of the rotationally symmetric part, acquiring the arrangement state of the measurement target,
An error calculating unit that calculates an error between a design value for measurement of the measurement target and a shape measurement value of the measurement target in an arrangement state of the measurement target. A shape measurement program for measuring the shape of a rotationally asymmetric measurement target including a rotationally symmetric portion that is rotationally symmetric with respect to the optical axis center,
On the computer,
The shape measuring unit scans the surface of the measurement object at a specific measurement pitch with the measurement element while changing the relative position of the measurement element and the measurement object while the measurement element is in contact with the measurement object. By acquiring a shape measurement value of the measurement object,
A scanning sequence control unit scans the rotationally symmetrical part with the tracing stylus, and a rotationally symmetrical part scanning sequence for acquiring a shape measurement value of the rotationally symmetrical part, and scans the measurement target with the tracing stylus, Performing a measurement scan sequence to obtain a shape measurement value of the measurement target;
An arrangement state acquiring unit, from the shape measurement value of the rotationally symmetric part, acquiring the arrangement state of the measurement target,
A shape measurement program for causing an error calculation unit to execute an error calculation step between a measurement design value of the measurement target and a shape measurement value of the measurement target in an arrangement state of the measurement target.

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