JP2005104093A - Method for producing diffractive optical element, and the diffractive optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a diffractive optical element having high shape accuracy by effectively correcting the shape of a molding die. <P>SOLUTION: In the step 3 to 6, an error of the base face shape of the die is obtained by measuring the three-dimensional shape of the die for molding a diffraction optical element, obtaining the base face shape from which a diffraction lattice shape is removed and comparing it with a design value. On the basis of the error of the base face shape thus obtained, mold machining condition is changed and a return to the step 2 is made for remachining the die. The steps 3 to 6 are repeated. If the error of the base face shape of the die is within a tolerance of specification, the diffraction optical element is molded by using the die, and in the steps 9 to 11, the same steps as described above are executed to extract an error of the base face shape of a molded product. If necessary, the machining shape of the die is corrected in the step 15, and a return to the step 2 and the die is reprocessed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a diffractive optical element for manufacturing a diffractive optical element used as an optical component of a measuring optical system of a semiconductor measuring apparatus, a camera, a laser beam printer, a copying machine, a head-mounted display, a liquid crystal projector, etc. The present invention relates to an element manufacturing method and a diffractive optical element.

  In a diffractive optical element manufacturing method in which a flat, spherical, or aspherical surface is used as a base surface shape, and a diffraction grating (relief) shape defined by a phase function is formed on the base surface shape, a conventional continuous surface shape is used. Similar to the manufacturing method of various optical elements such as lenses, the shape of the diffractive optical element can be evaluated by measuring the three-dimensional shape of the mold after the mold is manufactured. It has been broken. Further, the three-dimensional shape measurement is performed on the diffractive optical element manufactured by the molding process using the mold, and the shape evaluation is performed on the shape of the diffractive optical element.

  If the measurement shape evaluation of the mold or its molded product does not satisfy the specifications such as tolerance standards, rework the mold by changing the machining conditions, etc., and use the reworked mold. Thus, the molding process is performed again. In addition, when the measurement shape of the optical element manufactured by molding using the mold does not satisfy the specification, even though the mold shape satisfies the specification of the three-dimensional shape measurement result, A method is employed in which molding is performed again by changing molding conditions using the same mold.

Here, as a method for measuring a three-dimensional shape of a mold or an optical element in a manufacturing process of a diffractive optical element according to the conventional technique, for example, a measuring method disclosed in Patent Document 1 below can be cited. That is, as shown in FIG. 10, the shape of the diffraction grating is measured by tracing the stylus with respect to the surface shape of the diffractive optical element with a stylus type three-dimensional shape measuring device, and the cross-sectional measurement shape obtained by the trace For R100, first, a fitting process is performed on the base surface design shape R101 using a least square method or the like, and calculation of diffraction efficiency and the like is performed based on the residual shape R102 obtained by removing the base surface design shape R101 from the cross-section measurement shape R100. The shape of the diffractive optical element that is the object to be measured was evaluated.
Japanese Patent Laid-Open No. 11-167013

  In the method of manufacturing a diffractive optical element according to the above-described prior art, it is only necessary to measure and evaluate the processing shape of a mold for molding the diffractive optical element and the surface shape of the diffractive optical element formed by the mold. It is difficult to efficiently manufacture a diffractive optical element having a high shape evaluation of the diffraction grating shape. The reason is as follows.

  For the measurement shape traced by the stylus (probe) of the stylus type three-dimensional shape measuring device, in the above conventional example, a fitting process is performed on the base surface design shape formed by a flat surface, a spherical surface, or an aspherical surface. The diffraction grating shape is obtained by subtracting the designed base surface shape from the measurement shape. That is, the removed shape obtained by subtracting the base surface design shape from the shape of the diffractive optical element or the mold for molding the element to be measured is handled as the diffraction grating shape. However, when such a measurement shape evaluation method according to the prior art is adopted, when a shape error R103 as shown in FIG. 10B exists in the shape of the base surface of the object to be measured, this shape error R103. Is included in the diffraction grating shape derived from the measurement shape.

  As a result, shape evaluation for the diffraction grating measurement shape, such as diffraction efficiency evaluation based on the diffraction grating measurement shape according to the prior art, becomes unreliable due to the shape error of the base surface included in the measurement shape. There was a trend.

  Incidentally, in a manufacturing method for creating a shape of an optical element such as a lens, which is generally formed of a flat, spherical, or aspherical continuous surface, by molding using a mold, the mold shape or molding is performed. A method of manufacturing a desired optical element that satisfies the tolerance standard of the design shape by measuring the three-dimensional shape of the measured optical element shape, deriving the shape error of the measured shape with respect to the design shape, and correcting the shape of the mold However, in a method of manufacturing a diffractive optical element in which a plane, spherical surface, or aspherical surface is a base surface shape, and a diffraction grating shape defined by a phase function is formed to overlap the base surface shape, The shape correction of the mold used in the above-described method for manufacturing an optical element having a continuous surface shape is not performed. Even in the above-described conventional example, the three-dimensional shape measurement is performed on the diffractive optical element which is a molded product. Only carry out the shape evaluation by performing.

  The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and the diffractive optics molded by extracting the base surface shape error of the diffraction grating and correcting the mold shape. An object of the present invention is to provide a diffractive optical element manufacturing method and a diffractive optical element that can improve the shape accuracy of the element and obtain stable and high optical performance.

  The method of manufacturing a diffractive optical element according to the present invention is a method of manufacturing a diffractive optical element in which a planar, spherical, or aspherical continuous surface shape is a base surface shape, and a diffraction grating shape is formed on the base surface shape. The process of obtaining the 3D shape data of the mold by measuring the 3D shape of the mold used for molding the optical element, and the base surface shape error of the mold based on the obtained 3D shape data of the mold A step of calculating, a step of correcting the shape of the mold based on the calculated base surface shape error of the mold, and a step of molding the diffractive optical element using the mold subjected to the shape correction. It is characterized by that.

  In addition, in a method for manufacturing a diffractive optical element in which a planar, spherical or aspherical continuous surface shape is a base surface shape and a diffraction grating shape is formed on the base surface shape, a mold used for molding the diffractive optical element Measuring the three-dimensional shape of the mold to obtain three-dimensional shape data of the mold, calculating the base surface shape error of the mold based on the obtained three-dimensional shape data of the mold, and the calculated mold A step of correcting the shape of the mold based on the shape error of the base surface of the mold, a step of molding the diffractive optical element using the mold subjected to the shape correction, and the three-dimensional shape of the molded diffractive optical element To obtain the three-dimensional shape data of the molded product by measuring the shape, the step of calculating the base surface shape error of the molded product based on the obtained three-dimensional shape data of the molded product, and the calculated base surface of the molded product Based on shape error And performing mold shape correction Te, or in the manufacturing method of the diffractive optical element and a step of molding the diffractive optical element using a mold subjected to shape correction, a.

  Further, in a method of manufacturing a diffractive optical element in which a flat, spherical, or aspherical continuous surface shape is a base surface shape and a diffraction grating shape is formed on the base surface shape, a diffraction formed by using a mold is used. The step of obtaining the three-dimensional shape data of the molded product by measuring the three-dimensional shape of the optical element, the step of calculating the base surface shape error of the molded product based on the three-dimensional shape data of the obtained molded product, A diffractive optical system, comprising: a step of correcting a shape of a mold based on a shape error of a base surface of a molded product; and a step of molding a diffractive optical element using the mold subjected to the shape correction. An element manufacturing method may be used.

  The three-dimensional shape of the mold and / or the diffractive optical element may be measured by a three-dimensional shape measuring apparatus having a contact or non-contact type probe.

  For the residual shape obtained by subtracting the base surface design shape from the measured three-dimensional shape data of the mold or molded product, the base surface shape error may be calculated by removing the diffraction grating shape defined by the phase function.

  Measures the three-dimensional shape of the mold and the diffractive optical element that is the molded product, and calculates the base surface shape error by subtracting the base surface design shape and the diffraction grating shape defined by the phase function to correct the shape of the mold. Do. A diffractive optical element with extremely high shape accuracy can be manufactured by molding a diffractive optical element using a mold that has been subjected to shape correction for such a base surface shape.

  FIG. 1 is a process diagram for explaining a method of manufacturing a diffractive optical element according to an embodiment, in which a continuous surface of a plane, a sphere, or an aspheric surface is a base surface shape, and is defined by a phase function. The manufacturing process of the diffractive optical element in which the grating (relief) shape is formed on the base surface includes steps 2 to 7 which are steps for correcting the base surface shape of the mold.

  That is, in Step 2, which is the first process after the start of manufacture in Step 1, a mold for forming a diffractive optical element is manufactured. Next, in step 3, using the three-dimensional shape measuring apparatus provided with the contact-type or non-contact-type probe shown in FIG. By scanning, the three-dimensional shape of the mold is measured.

  In step 4, the base surface shape extraction calculation process is performed on the measurement shape data which is the three-dimensional shape data of the mold obtained in the mold shape measurement step 3. That is, similarly to the conventional technique, a calculation process for removing the base surface design shape of the mold from the measured shape data is performed. Next, in step 5, a mold base surface shape error extraction process is performed. That is, the base surface shape error of the mold is extracted by performing arithmetic processing described later on the residual shape calculated by removing the base surface design shape of the mold in Step 4.

  In step 6, shape evaluation is performed on the measurement shape data based on the base surface shape error of the mold extracted in step 5. Here, it is determined whether the base surface shape error satisfies the standard against the tolerance standard defined as the design value for the base surface shape. When the base surface shape error extracted from the measurement shape data of the mold is smaller than a tolerance standard (for example, PV value of the shape error) related to the shape error, the process proceeds to the diffractive optical element forming step in Step 8. On the other hand, if the above condition is not satisfied, the machining conditions of the mold are corrected in step 7.

  Needless to say, in the process of evaluating the tolerance standard regarding the base surface shape error, the measurement shape evaluation for the diffraction grating shape other than the base surface shape error is also performed as the processing shape evaluation of the mold. For example, even when the base surface shape error satisfies the tolerance standard, if there is a processing error in the diffraction grating shape and the desired shape is not obtained, the process proceeds to the step of forming the diffractive optical element in step 8. First, the process proceeds to the machining condition correcting step in step 7.

  After the modification of the machining conditions, the process returns to the above-described mold machining in step 2 and the mold is reworked. After the mold reworking, the mold shape measurement in step 3, the mold base surface design shape removal in step 4, and the mold base surface shape error extraction in step 5 are performed in order, and in step 6 the mold base is again performed. The surface shape error is evaluated with respect to the tolerance standard, and the measurement shape evaluation with respect to another shape tolerance standard as described above is performed to determine whether or not to proceed to the diffractive optical element molding step in Step 8.

  In the diffractive optical element molding step of Step 8, the diffractive optical element is molded by using a mold that satisfies the tolerance standard for the mold base surface shape error in the previous process. At this time, the molding material may be any material that can be molded by a mold, such as a plastic resin material or a glass material. Next, in step 9, as in the shape measurement for the mold in step 3, the shape measurement of the molded product is performed using the three-dimensional shape measurement apparatus provided with the contact type or non-contact type probe shown in FIG. .

  For the measurement shape data, which is the three-dimensional shape data of the molded product obtained by the measurement of the molded product shape in step 9, the base surface shape extraction calculation process of the molded product is performed in step 10 in the same manner as in the mold shape measurement. That is, the base surface design shape removal processing of the molded product is performed from the measured shape data of the molded product obtained in step 9. Next, in step 11, the base surface shape error of the molded product is extracted by performing arithmetic processing described later on the residual shape calculated in the base surface design shape removing process in step 10.

  Thereafter, in step 12, the shape evaluation is performed on the measured shape data of the molded product based on the base surface shape error of the molded product extracted in step 11. When the base surface shape error extracted from the measured shape data of the molded product satisfies the tolerance standard related to the shape error, the process ends in step 14 and a diffraction grating shape that satisfies the design optical performance is created. The diffractive optical element is obtained as a molded product. On the other hand, if the above condition is not satisfied, in step 13, the die machining shape is corrected using the base surface shape error of the molded product. After the mold machining shape correction, the process returns to the mold machining in step 2 and the mold is reworked. For the subsequent steps, the above-described steps are repeated in the same manner.

  By repeating the mold machining shape correction in step 13 one or more times, it is possible to obtain a diffractive optical element molded product that satisfies the conditions in the measurement shape evaluation related to the base surface shape error of the molded product in step 12. In other words, compared to the manufacturing method of the diffractive optical element according to the prior art, since the shape correction is performed on the base surface shape defined by the continuous surface of either a flat surface, a spherical surface, or an aspherical surface, the design shape is further improved. A diffractive optical element having a nearly highly accurate diffraction grating shape can be manufactured.

  FIG. 2 is a schematic diagram showing a three-dimensional shape measuring apparatus, in which the probe 1 is supported so as to be in perpendicular contact with the surface of the workpiece W held on the stage 2, and the stage 2 is supported by the stage controller 3. Scanning in the X-axis direction and feeding in the Y-axis direction are performed. The probe 1 is moved in the Z-axis direction by the probe control device 4 in accordance with the surface shape of the workpiece W. The arithmetic device 5 calculates the three-dimensional shape data of the object W to be measured based on the outputs of the stage control device 3 and the probe control device 4, and the hard disk drive 6 uses a computer to calculate the diffraction grating shape and the like. Is recorded, and the base surface shape error or the like is obtained by comparison with the design data input by the keyboard 7. The calculation result is displayed on the display 8. The same applies when a non-contact type probe is used instead of the contact type probe 1.

  The three-dimensional shape measuring apparatus shown in FIG. 2 is an example in the present invention, and the configuration of the apparatus is not limited to this. For example, the stage 2 and the stage control device 3 shown in FIG. 2 are not equipped, but the three-dimensional shape measuring device (not shown) of the type in which the probe 1 follows the surface shape of the workpiece W fixed to the three-dimensional shape measuring device. It may be. In this case, the probe 1 is moved on the workpiece W by a driving device in the XYZ axial directions. Further, the probe 1 is provided with a sensor for detecting a three-dimensional coordinate in the three-dimensional shape measuring apparatus, and calculates three-dimensional shape data based on the output of the sensor. The coordinate detection sensor is specifically a laser length measuring device or a linear scale, and may be other sensors.

  Similarly, in the three-dimensional shape measuring apparatus shown in FIG. 2, not based on the outputs of the stage control device 3 and the probe control device 4 but based on the output signal of the sensor for detecting the coordinates provided in the probe 1 (not shown), The apparatus structure which calculates the three-dimensional shape data of the to-be-measured object W may be sufficient.

  FIGS. 3 and 4 show the mold base surface shape error extraction method in the mold shape measurement step 3, the mold base surface design shape removal step 4 and the mold base surface shape error extraction step 5, and the molded product. The method of extracting the base surface shape error of the diffractive optical element molded product in the molded product shape measurement step 9, the molded product base surface design shape removal step 10 and the molded product base surface shape error extraction step 11 will be described. The X-axis is a probe scan when shape measurement is performed on a die for diffractive optical element molding or a molded product thereof by a three-dimensional shape measuring apparatus including the contact type or non-contact type probe shown in FIG. This is the coordinate axis set for the direction. That is, when the cross-sectional shape measurement is performed by scanning only one line of the probe on the mold or the diffractive optical element molded product, the scanning direction of the probe and the X axis indicate the same direction. . Further, when surface shape measurement is performed by scanning a plurality of lines of the probe with respect to the object to be measured, the X axis is set in the probe scanning direction when one of the plurality of lines scanned by the probe is taken out. The direction of is the same. The other coordinate axis is a Z axis set in a direction orthogonal to the X axis.

  In the coordinate system defined by the coordinate axes X and Z, as shown in FIG. 4, the measurement shape R of the mold or the diffractive optical element as the workpiece W is obtained by adding the base surface design shape R1 and the diffraction grating shape R2. It has a shape. The base surface design shape R1 is fitted to the measurement shape R by using the least square method or the like, and the base surface design shape R1 is removed from the measurement shape R after the fitting to obtain the result shown in FIG. When such a diffraction grating shape R2 is calculated as a residual shape, a base surface shape error R3 as shown in FIG. 4C is included. In view of this, the base surface shape error R3 is extracted from the measurement shape data obtained by the three-dimensional shape measurement apparatus by removing the diffraction grating shape R2 by the method shown in FIG. 5 or FIG.

FIG. 5 illustrates a first calculation processing method for separating the diffraction grating shape R2 from the measurement shape R of the diffractive optical element. The measurement shape R is continuously measured by the three-dimensional shape measuring apparatus shown in FIG. Is represented as point cloud data R4. Each measurement point coordinate of the point group data R4 is represented by arbitrary point coordinate data p ₁ defined by the coordinate axis X and a coordinate value (coordinate data) (not shown) defined by the coordinate axis Z.

Here, in the X and Z coordinate systems shown in the drawing, the diffraction grating design shape R0 has a height ΔZ in the coordinate axis Z direction at the same position relative to the point coordinate data p ₁ defined by the coordinate axis X, and the phase function of the diffraction grating. Uniquely obtained from Thus, when the base surface shape error is zero, the diffraction grating design shape R0 is obtained by performing this calculation on all point group data R4 that is continuously measured by the three-dimensional shape measuring apparatus.

As described above, since the measurement shape R of the diffractive optical element always includes the base surface shape error R3, the point cloud data R4 of the measurement shape R is calculated with the base surface shape error being zero, the diffraction grating design shape R0. Do not ride on the line. Here, for all measurement point coordinate values defined by the coordinate axis X, the height ΔZ in the coordinate axis Z direction calculated based on the phase function is obtained for each measurement point, and this value is measured by the coordinate axis Z. An arithmetic process is performed to subtract from the point coordinate value. That is, in the point coordinate data p ₁ defined by the coordinate axis X, the measurement point Z1 including the base surface shape error R3 is obtained by subtracting the height ΔZ in the coordinate axis Z direction from the measurement point coordinate value similarly defined by the coordinate axis Z. Is required. By performing the same calculation process for all measurement points, the base surface shape error R3 with respect to the measurement shape R of the diffractive optical element is extracted as point group data.

  FIG. 6 shows another calculation method, and the measurement shape R of the diffractive optical element is represented as point cloud data R4 measured by the three-dimensional shape measurement apparatus of FIG. 2 as in the case of FIG. In determining the diffraction grating design shape (base surface shape error zero) R0 defined by the phase function based on the measurement point coordinate value defined by the coordinate axis X for this measurement shape R, each annular shape Every time, the point cloud data R4 of the measurement shape R is subjected to a calculation process for fitting the diffraction grating design shape using the least square method or the like, and the position and orientation error of the measurement shape R with respect to the design shape is obtained as coordinate conversion information. Based on the coordinate transformation information, the diffraction grating design shape R0 is obtained by performing the inverse transformation of the coordinate transformation on the design shape. Similarly, the base surface shape R5 after the coordinate conversion is obtained by performing the inverse conversion of the coordinate conversion for the base surface shape. By executing this calculation process for all the measured shapes (all annular shapes) for each annular shape, the entire base surface shape is calculated.

  In this way, the entire base surface shape that has been subjected to coordinate transformation based on the fitting calculation processing represents the shape error of the same measured shape with respect to the diffraction grating design shape (shape error caused by position and orientation errors). Therefore, the base surface shape error R3 is represented. As described above, in the measurement shape R of the diffractive optical element, the base surface shape error R3 can be extracted by performing the fitting calculation process on the diffraction grating design shape in the annular zone unit.

  Instead of performing the above-described fitting process for each annular zone shape, the fitting process may be performed for a plurality of adjacent annular zone units, and the base surface shape error may be extracted by the above-described coordinate transformation calculation. Good. At this time, since the calculated base surface shape R5 is performed for each of the plurality of annular zones while shifting the fitting calculation target by one annular zone, overlapping portions are formed. In this case, the average shape is calculated for each annular zone shape for the overlapping portion, and the base surface shape error R3 is extracted by arranging the averaged base surface shape errors for all the annular zone shapes.

  In the base surface shape error extraction method described with reference to FIGS. 5 and 6, the above-described arithmetic processing is similarly performed on all cross-sectional measurement shapes obtained as measurement data by three-dimensional shape measurement, thereby obtaining a surface shape. Needless to say, the base surface shape error can be calculated. That is, the illustrated base surface shape error is two-dimensional data defined by an orthogonal two-axis coordinate system, but in actual measurement shape processing, the base surface shape error data can be extracted as three-dimensional data. The mold shape is corrected based on the three-dimensional data.

  FIG. 7 is a process diagram for explaining a specific implementation method of the die machining shape correction step 13 of FIG. With respect to the base surface shape error data of the molded product extracted by the method of FIG. 5 or FIG. 6, in step 17, positive / negative inversion calculation processing (shape error data positive / negative inversion) is performed in the coordinate axis Z direction of FIG. Next, in step 18, a calculation process for expanding the shape shrinkage rate of the molded product with respect to the mold shape (enlargement process for the molded product shrinkage rate) is performed on the data obtained in step 17. In step 19, the mold shape correction data calculated in the calculation process in step 18 and the mold design shape data are added (added with the mold design shape data). The shape data calculated as a result of performing the arithmetic processing in step 19 is handled as mold shape correction processed shape data in step 20. That is, the die shape correction machining shape data in step 20 is input to the machining apparatus as machining shape data at the time of shape correction, and the die shape is corrected by reworking the die in step 2 in FIG. To do.

  FIG. 8 shows a partial modification of the mold shape correction process of FIG. For the base surface shape error extracted by the method of FIG. 5 or FIG. 6, step 17 for performing positive / negative reversal calculation processing (shape error data positive / negative reversal) on the base surface shape error data of the molded product in step 16, and molding for the mold shape The process up to step 18 for performing the calculation process for expanding the shape shrinkage rate of the product (enlargement process for the molded product shrinkage rate) is the same as in FIG. In step 21, step 22 is performed for the base surface shape error data of the mold obtained as a result of the measurement of the processing shape for the mold, in the same manner as the positive / negative inversion processing 17 for the base surface shape error data of the molded product. Provide. That is, in the method of FIG. 7, the mold shape correction data is derived by adding the shape correction data calculated based on the base surface shape error data of the molded product to the mold design shape data. In the method shown in FIG. 8, the shape correction data calculated based on the die base surface shape error data in step 21 is also added to simultaneously correct the shape error of the machining shape of the die. . This method is particularly effective when the die machining shape error is large with respect to the tolerance standard.

  FIG. 9 shows a modification. This is a polyhedral diffractive optical element having an optically effective surface R6 whose shape is a continuous surface in addition to the optically effective surface on which the diffraction grating shape R2 is formed. In this case, the shape correction method is as follows: It is as follows.

  First, the base surface shape error R3 is extracted for the base surface design shape R1 as described above. In addition, the three-dimensional shape measurement is also performed on the optically effective surface R6 whose shape is created by the continuous surface, and the shape error of the measured shape with respect to the design shape is derived. Since it is well known that the shape error deriving method on the optical effective surface R6 at this time is obtained by performing a surface shape fitting process using a least square method or the like, the details are omitted here. .

  Next, based on the base surface shape error R3 related to the base surface design shape R1 and the shape error of the optical effective surface R6, shape correction is performed on the shape of the optical effective surface R6 in which the shape of the diffraction grating is not created. Here, when calculating the shape correction amount, the shape correction is not performed for the base surface shape error R3, and only the optical effective surface R6 in which the shape of the diffraction grating is not created is corrected.

  This satisfies the optical performance of the entire diffractive optical element rather than the optical performance of each surface alone. That is, the shape of the optical effective surface R6 having the performance of eliminating the influence of the base surface shape error R3 on the optical performance of the optical element in FIG. 9 is obtained by optical analysis, and only the mold of the optical effective surface R6 is reprocessed. Perform shape correction. Thereby, in the element shape different from the initial design shape, the optical performance theoretically defined from the design shape is obtained with respect to the optical performance.

  This method achieves the desired optical element performance without reworking the optically effective surface having a diffraction grating, which requires much manufacturing tact and cost, as compared with the optically effective surface whose shape is created by a continuous surface. Has the advantage of being low cost.

It is process drawing explaining the manufacturing method of the diffractive optical element by one embodiment. It is a figure explaining the three-dimensional shape measuring apparatus used for the manufacturing method of the diffractive optical element of FIG. It is a figure explaining a diffractive optical element shape. It is a figure explaining a base surface shape error. It is a figure explaining the specific method of extracting a base surface shape error. It is a figure explaining another specific method of extracting a base surface shape error. It is process drawing explaining the specific method of correct | amending the process shape of the metal mold | die for diffractive optical element shaping | molding. It is process drawing explaining another specific method of correct | amending the process shape of the metal mold | die for diffractive optical element shaping | molding. It is a figure explaining the diffractive optical element by one modification. It is a figure explaining a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Probe 2 Stage 3 Stage control device 4 Probe control device 5 Arithmetic device 6 Hard disk drive R Measurement shape R1 Base surface design shape R2 Grating shape R3 Base surface shape error

Claims (6)

In the method of manufacturing a diffractive optical element in which a plane, spherical or aspherical continuous surface shape is a base surface shape, and a diffraction grating shape is formed on the base surface shape,
Measuring the three-dimensional shape of the mold used to mold the diffractive optical element to obtain the three-dimensional shape data of the mold; and
Calculating the base surface shape error of the mold based on the obtained three-dimensional shape data of the mold;
A step of performing mold shape correction based on the calculated mold base surface shape error;
And a step of molding the diffractive optical element using a mold whose shape has been corrected. In the method of manufacturing a diffractive optical element in which a plane, spherical or aspherical continuous surface shape is a base surface shape, and a diffraction grating shape is formed on the base surface shape,
Measuring the three-dimensional shape of the mold used for molding the diffractive optical element to obtain the three-dimensional shape data of the mold; and
Calculating the base surface shape error of the mold based on the obtained three-dimensional shape data of the mold;
A step of performing mold shape correction based on the calculated mold base surface shape error;
A step of molding a diffractive optical element using a mold subjected to shape correction;
Measuring the three-dimensional shape of the molded diffractive optical element to obtain three-dimensional shape data of the molded product;
A step of calculating a base surface shape error of the molded product based on the three-dimensional shape data of the obtained molded product;
Correcting the mold shape based on the calculated base surface shape error of the molded product;
And a step of molding the diffractive optical element using a mold whose shape has been corrected, and a method for producing the diffractive optical element. In the method of manufacturing a diffractive optical element in which a plane, spherical or aspherical continuous surface shape is a base surface shape, and a diffraction grating shape is formed on the base surface shape,
Measuring the three-dimensional shape of the diffractive optical element molded using a mold to obtain three-dimensional shape data of the molded product;
A step of calculating a base surface shape error of the molded product based on the three-dimensional shape data of the obtained molded product;
Correcting the mold shape based on the calculated base surface shape error of the molded product;
And a step of molding the diffractive optical element using a mold whose shape has been corrected.   4. The diffractive optical system according to claim 1, wherein the three-dimensional shape of the mold and / or the diffractive optical element is measured by a three-dimensional shape measuring apparatus having a contact type or non-contact type probe. Device manufacturing method.   The base surface shape error is calculated by removing the diffraction grating shape defined by the phase function for the residual shape obtained by subtracting the base surface design shape from the measured 3D shape data of the mold or molded product. A method for manufacturing a diffractive optical element according to any one of claims 1 to 4.   6. A diffractive optical element manufactured by the method for manufacturing a diffractive optical element according to claim 1.

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