JP4830837B2 - Lens measuring device - Google Patents

Description

  The present invention relates to a technique for measuring characteristics of a lens used for reading and writing information on an optical disk type high-density information recording medium such as a DVD (Digital Versatile Disc) and a BD (Blu-ray Disc).

  In order to read information from an optical disk type high-density information recording medium and write information to this high-density information recording medium, an optical system for irradiating light emitted from a light source to a target location with high accuracy is required. It is. Among the optical systems, the objective lens, in particular, requires a wavefront aberration accuracy of about 1/100 of the laser wavelength of the light source for its own characteristics. Therefore, it is necessary to perform strict measurement in the characteristic inspection of the objective lens. Therefore, as a lens inspection method represented by this objective lens, a method of inspecting the lens based on the aberration detected by the interference measurement (diffraction interference method) has been proposed (see Patent Document 1).

  This diffraction interference method will be briefly described. Hereinafter, the same components are denoted by the same reference numerals and description thereof is omitted.

  FIG. 7 is a schematic diagram of a conventional lens measuring apparatus. In FIG. 7, a laser light source 1 as a light source emits laser light 2. The emitted laser light 2 is magnified by the beam expander 3 into substantially parallel light, then reflected by the half mirror 4, and enters the objective lens 6 held on the holding table 5. The objective lens 6 has a flat edge surface 8 around the lens spherical surface 7. In the conventional lens measuring apparatus, light is incident not only on the lens spherical surface 7 but also on the edge surface 8.

  The light incident on the edge surface 8 is reflected by the edge surface 8, passes through the half mirror 4, and then forms an image on the image sensor 10 by the imaging lens 9. The image sensor 10 transmits a signal corresponding to the received image to the display device 11. The display device 11 processes a signal from the image sensor 10 and displays an image of the edge surface 8. Therefore, by looking at the image displayed on the display device 11, it can be determined whether or not the objective lens 6 is accurately arranged with respect to the optical axis 12. When the objective lens 6 is not correctly positioned with respect to the optical axis 12, the holding table 5 is moved in the direction of the optical axis 12 or a direction orthogonal thereto using a holding table moving mechanism. At the same time, if necessary, the holding table 5 is rotated about the optical axis 12. Thereby, the inclination of the objective lens 6 with respect to the optical axis 12 is adjusted.

  Here, the lens spherical surface 7 of the objective lens 6 has a region that cannot be used for measurement. In this region, a portion of the lens spherical surface 7 close to the edge surface 8 is a surface discontinuous with the edge surface 8. In general, a lens used for a high-density information recording medium such as a DVD is produced by molding an aspherical surface, but it is difficult to process a discontinuous surface in this molding. Therefore, it is necessary to make the size of the lens spherical surface 7 of the objective lens 6 larger than the radius at which light is actually incident, and also in the lens inspection, it is necessary to determine the size of the lens opening. Therefore, there is a device in which an aperture is installed under the objective lens.

  FIG. 8 is a schematic diagram of a lens measuring apparatus using a conventional aperture. In FIG. 8, the aperture 13 is installed under the objective lens 6 (laser light source 1 side). This aperture 13 limits the area of light incident on the objective lens 6. Here, in FIG. 8, the transmitted light from the objective lens 6 is branched by the half mirror 14 in the middle of the measurement system, and is imaged on the image sensor 16 by the imaging lens 15. The image sensor 16 transmits a signal corresponding to the received image to the display device 17. The display device 17 processes a signal from the image sensor 16 and displays a spot image by the objective lens 6. Therefore, by looking at the image displayed on the display device 17, it can be determined whether or not the objective lens 6 is accurately arranged with respect to the optical axis 12. If the objective lens 6 is not correctly positioned with respect to the optical axis 12, the holding table 5 is moved and adjusted by the same means as described above. The aperture 13 is positioned based on the validity of the measurement data obtained by the light transmitted through the objective lens 6, and when observing the image of the edge surface 8, for example, a position where the aperture 13 is removed from the optical path using a cylinder or the like Move to.

  The light transmitted through the objective lens 6 enters the transmission type diffraction grating 30. Here, the diffraction grating 30 has a function of emitting incident light as transmitted light and diffracted light to the side opposite to the incident side across the diffraction grating 30. The diffraction grating 30 is supported so as to be movable by a diffraction grating moving mechanism 31 such as a piezo element.

The diffracted light from the diffraction grating 30 passes through the condensing lens 32 and the imaging lens 33 facing each other, and then forms an image on the imaging element 34. The image sensor 34 is installed at the focal position of the imaging lens 33. Data obtained by the image sensor 34 is sent to the processing device 35 and processed. Based on the processed data, the characteristics of the objective lens 20 are evaluated and displayed on the display device 36.
JP 2000-329648 A

  However, in the conventional configuration shown in FIG. 7, it is necessary to provide a play (gap) for inserting and removing the objective lens between the holding table and the objective lens. For this reason, the relative positional relationship between the objective lens and the aperture fluctuates by the amount of play for each measurement, and the measurement data varies due to the fluctuation, so high-precision measurement cannot be performed.

  Further, in the conventional configuration shown in FIG. 8, it is not necessary to provide play (gap) between the holding table and the objective lens. However, in order to align the aperture and the optical axis, the relative position between the aperture and the optical axis. It is necessary to evaluate the validity of the measured data, but it takes a lot of time to acquire the data. And even if the positional relationship between the two occurs due to a sudden factor or a change over time, there is a problem that it is difficult to notice the deviation.

The present invention is intended to solve the conventional problems, and providing a lens measuring equipment capable of managing relative position of the aperture and the objective lens with high accuracy.

To achieve the above object, the lens measuring apparatus comprising a light source for emitting light, an aperture having a groove and are formed to constitute at least part of said opening concentric circle with the opening, A diffraction grating that collects light emitted from the light source and transmitted through the groove, an image sensor that captures a shearing interference image formed by diffracted light of different orders diffracted by the diffraction grating, and emitted from the light source Adjustment means for moving the aperture in a direction perpendicular to the optical axis of the light, measurement means for measuring a lens based on the sharing interference image, and an auxiliary aperture between the aperture and the light source. The opening diameter of the auxiliary aperture is larger than the opening diameter of the aperture and smaller than the innermost diameter of the groove .

Further, an invention according to claim 2, wherein a lens measuring apparatus according to claim 1, wherein the groove, characterized in Rukoto formed in the opening concentrically.

Further, an invention according to claim 3, wherein a lens measuring device according to claim 1 or 2, the wavelength of the light emitted from the light source and lambda, the width of the groove in a radius r _n and p _n (n Is a natural number), and when the distance from the diffraction grating to the aperture is L, the groove of the aperture satisfies a predetermined condition.

The invention according to claim 4 is the lens measuring device according to claim 1 , wherein when the effective radius of the lens is Ra and the radius of the auxiliary aperture is Rb, the radius of the innermost peripheral portion of the groove of the aperture r ₁ satisfies a predetermined condition.

  As described above, according to the present invention, it is possible to provide a lens measurement device and a lens measurement aperture capable of managing the relative positional relationship between a lens and an aperture with high accuracy. In addition, since it is not necessary to spend a great deal of time in aperture management, it is possible to easily perform measurement that is resistant to deterioration over time when measuring continuously.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the present invention, the same components are denoted by the same reference numerals and description thereof is omitted.

(Embodiment 1)
FIG. 1 is a schematic diagram of a lens measuring apparatus according to Embodiment 1 of the present invention. In FIG. 1, a laser emission source 18 emits a coherent and substantially parallel laser beam 19. The wavelength of the coherent laser beam 19 is desirably about the same as the wavelength when the objective lens 20 (test lens) to be inspected is actually used. The beam expander 21 has a function of emitting substantially parallel light incident from the laser emission source 18 as substantially parallel light having an enlarged diameter.

  The substantially parallel light expanded by the beam expander 21 passes through the half mirror 22 and then enters the auxiliary aperture 23. The substantially parallel light whose diameter is limited by the auxiliary aperture 23 then enters the aperture 24. Here, the auxiliary aperture 23 is configured to limit light outside the effective diameter of the aperture 24. The auxiliary aperture 23 is supported so as to be movable by the auxiliary aperture moving mechanism 25.

  The aperture 24 is configured to limit the incident light on the objective lens 20 to only the effective diameter of the objective lens 20. Here, the aperture 24 is created by performing vapor deposition on a region outside the aperture diameter on a parallel plate formed of optical glass. In the aperture 24, a peripheral pattern 26 that transmits light is formed in a region outside the effective diameter (opening diameter) of the aperture 24. For example, the peripheral pattern 26 is formed by a plurality of grooves having different diameters with the opening diameter of the aperture 24 as the center. The aperture 24 is supported by an aperture moving mechanism 27 so that the auxiliary aperture 23 can be moved simultaneously.

  The light limited by the auxiliary aperture 23 and the aperture 24 is incident on the objective lens 20 held by the holding table 28. Here, the holding table 28 has an opening (hole) that is larger than the effective diameter of the objective lens 20 and smaller than the lens outer shape of the objective lens 20 and a gripping mechanism (not shown) that grips the objective lens 20 from the left and right. . The holding base 28 fixes the objective lens 20 by a gripping mechanism after the objective lens 20 is arranged so that the lens spherical surface side of the objective lens 20 comes to the opening. The holding table 28 is supported by a holding table moving mechanism 29 so that the objective lens 20 can be moved simultaneously.

  The light transmitted through the objective lens 20 is incident on the transmission type diffraction grating 30. Here, the diffraction grating 30 has a function of emitting incident light as transmitted light and diffracted light to the side opposite to the incident side across the diffraction grating 30. The diffraction grating 30 is supported so as to be movable by a diffraction grating moving mechanism 31 such as a piezo element.

  The diffracted light from the diffraction grating 30 passes through the condensing lens 32 and the imaging lens 33 facing each other, and then forms an image on the imaging element 34. The image sensor 34 is installed at the focal position of the imaging lens 33. Data obtained by the image sensor 34 is sent to the processing device 35 and processed. Based on the processed data, the characteristics of the objective lens 20 are evaluated and displayed on the display device 36.

  These constituent elements described above are arranged with reference to the optical axis 37.

  Further, in order to observe the image on the diffraction grating 30, an optical system branched by the half mirror 38 is used. The light transmitted through the diffraction grating 30 is reflected by the half mirror 38 and then imaged on the image sensor 40 by the imaging lens 39. The image sensor 40 transmits a signal corresponding to the received image to the display device 41. The display device 41 processes a signal from the image sensor 40 and displays an image from the surrounding pattern 26 imaged on the diffraction grating 30. Thereby, the position of the aperture 24 in the optical system can be confirmed.

  Further, in order to adjust the relative position of the objective lens 20 with respect to the optical axis 37, the light reflected by the edge surface of the objective lens 20 is reflected by the half mirror 22 and then imaged by the imaging lens 42 on the image sensor 43. . The image sensor 43 transmits a signal corresponding to the received image to the display device 44. The display device 44 processes a signal from the image sensor 43 and displays an edge image of the objective lens 20. By looking at the image displayed on the display device 44, it can be determined whether or not the objective lens 20 is accurately arranged with respect to the optical axis 37.

Here, the surrounding pattern 26 is provided at a position of a radius r _n (n is a natural number) from the effective diameter center of the aperture 24. Assuming that the effective radius of the objective lens 20 is Ra and the width of the region through which light is transmitted at the position of the radius r _n is p _n (n is a natural number), the radius is defined in order from the inside as shown in the number (1). The Here, _pn is defined as the number (2). Here, λ is the wavelength of the laser beam 19 from the laser emission source 18, and L is the distance between the aperture 24 and the diffraction grating 30.

The radius r ₁ of the innermost peripheral portion of the peripheral pattern 26 is set to r ₁ = 1.1 Ra in consideration of the adjustment margin of the auxiliary aperture 23. That is, when the adjustment margin of the auxiliary aperture 23 is taken into consideration, the radius of the surrounding pattern 26 needs to be expressed by Expression (3).

  In addition, if the diameter of the surrounding pattern 26 is excessively widened, extra light is transmitted. Therefore, it is necessary to make it as small as possible. However, if the diameter is too small, a sufficient amount of light cannot be obtained to obtain an image. Thus, as a result of studying various conditions by the authors of the present invention, it was found that sufficient light quantity can be obtained by satisfying Expression (4).

  Next, the configuration of the aperture 24 and the surrounding pattern 26 will be described in detail. In general, a Fresnel zone pattern is well known as a means for condensing light by diffraction. The Fresnel zone pattern is configured such that, in a region where the radius is defined by Equation (5), an odd-numbered pattern in the natural number m is a transmissive region, and an even-numbered pattern in the natural number m is a non-transmissive region (this The same effect can be obtained when the odd-numbered portion is the non-transmissive region and the even-numbered portion is the transmissive region). However, this Fresnel zone pattern is conditional on the focal length L being greater than the concentric radius r. Therefore, for example, in the case of λ = 405 nm, L = 2.5 mm, and r = 1.1 mm, which can be considered as an example of conditions at the time of measurement of the BD objective lens, the condition of the Fresnel zone pattern is not satisfied. Therefore, this Fresnel zone pattern cannot be used in the peripheral pattern 26 of the present embodiment.

Therefore, the authors of the present invention, through trial and error, the position of the radius r _n of the aperture 24, have devised a configuration in which the transmission area of the pitch of the formula (2) (ambient pattern 26). The peripheral pattern 26 condenses the first-order diffracted light from each transmission part in the peripheral pattern 26, and condenses incident light at a position substantially equivalent to the condensing position of the objective lens 20 at the time of measurement in the optical axis direction. be able to. Thereby, the surrounding pattern 26 can be set to form an image at a position substantially equivalent to the objective lens 20 in the optical axis direction. In addition, since the auxiliary aperture 23 can be installed at a position very close to the aperture 24 in the optical axis direction, the influence of diffraction due to the edge of the auxiliary aperture 23 can be almost ignored. Accordingly, in consideration of the adjustment margin of the relative positional relationship between the auxiliary aperture 23 and the aperture 24, the adjustment can be easily performed by eliminating the loss of the aperture transmitted light obtained on the image sensor 34 by the scanning of the auxiliary aperture 23. It becomes possible to do.

  FIG. 2A is a diagram showing the relative positions of the objective lens 20, the aperture 24, and the auxiliary aperture 23 in the first embodiment, and FIG. 2B is a diagram showing the surrounding pattern 26 in the first embodiment. It is.

In FIG. 2A, when the effective radius of the objective lens 20 is Ra, the radius of the auxiliary aperture 23 is Rb, and the radius of the innermost periphery of the peripheral pattern 26 is r ₁ , Equation (6) is obtained from the above description. By satisfying this, it is possible to prevent substantially parallel light from entering the surrounding pattern 26 and prevent the surrounding pattern 26 from affecting the aberration measurement of the objective lens 20. Moreover, since the diameter of substantially parallel light becomes smaller than the inner diameter of the edge by satisfying Expression (6), stray light is not included in the light emitted from the objective lens 20.

  Next, a flow for measuring lens characteristics using this apparatus will be described.

  In the present embodiment, in order to measure the position of the aperture 24 with higher accuracy, first, the position of the aperture 24 in the optical system is confirmed. Next, the position and orientation of the objective lens 20 are adjusted. Thereafter, the position of the aperture 24 and the position of the objective lens 20 are compared, and the position of the objective lens 20 is further prepared as necessary. In this way, after adjusting the position and orientation of the objective lens 20, the characteristics of the objective lens 20 are inspected. Thereby, the characteristic inspection of the objective lens 20 can be performed with higher accuracy.

  FIG. 3 is a flowchart for adjusting the position and orientation of the lens in the first embodiment.

  In FIG. 3, first, in steps S1 to S3, the position of the aperture 24 in the optical system is confirmed.

  First, the aperture 24 is inserted into the optical system. At this time, each is arranged so that substantially parallel light from the beam expander 21 is incident on the surrounding pattern 26 formed in the aperture 24. Here, the surrounding pattern 26 is configured to satisfy the expressions (3) and (4) (step S1).

  Next, the light transmitted through the surrounding pattern 26 is imaged on the diffraction grating 30. Here, the surrounding pattern 26 is arranged so as to be condensed on the diffraction grating 30 (step S2).

  Next, the light transmitted through the diffraction grating 30 is branched by the half mirror 38, and the position of the aperture 24 in the optical system is confirmed by using the branched optical system. Specifically, the light reflected by the half mirror 38 is imaged on the image sensor 40 by the imaging lens 39. An image from the formed peripheral pattern 26 is displayed on the display device 41, and the position of the aperture 24 in the optical system is confirmed (step S3).

  Subsequently, in steps S4 to S7, the position and orientation of the objective lens 20 are adjusted.

  After step S3 is completed, the objective lens 20 is thrown into the optical system (step S4).

  Next, the aperture 24 is retracted from the optical path from the laser emission source 18 by the aperture moving mechanism 27 (step S5).

  Next, substantially parallel light from the laser emission source 18 is incident on the edge surface of the objective lens 20. Thereafter, the light reflected by the edge surface is imaged on the image sensor 43. It is determined whether or not the objective lens 20 is disposed at an accurate position with respect to the optical axis 37 based on information on the reflected light from the edge surface that has been imaged (step S6).

  Here, when the objective lens 20 is not disposed at an accurate position with respect to the optical axis 37, the position of the objective lens 20 with respect to the optical axis 37 is adjusted together with the holding base 28 using the holding base moving mechanism 29 (step). S7).

  Subsequently, in steps S8 to S11, the position and orientation of the objective lens 20 are further adjusted.

  In step S 6, when it is confirmed that the objective lens 20 is accurately positioned with respect to the optical axis 37, the aperture 24 is inserted by the aperture moving mechanism 27 and the auxiliary aperture 23 is inserted by the auxiliary aperture moving mechanism 25 in the optical path. To do. Here, the aperture 24, the auxiliary aperture 23, and the objective lens 20 are arranged so as to satisfy the relationship of Expression (6). Thereby, substantially parallel light can be prevented from entering the surrounding pattern 26, and the surrounding pattern 26 does not affect the characteristic inspection (particularly, aberration measurement) of the objective lens 20 (step S8).

  Next, the light transmitted through the auxiliary aperture 23, the aperture 24, and the objective lens 20 is condensed on the diffraction grating 30, and the condensing point collected on the diffraction grating 30 is detected by the image sensor 40. Thereby, the position in the optical system of the objective lens 20 can be confirmed (step S9).

  If the objective lens 20 is not placed at an accurate position in step S9, the position of the objective lens 20 is adjusted using the holding table moving mechanism 29 (step S10).

  Thereafter, the position of the aperture 24 in step S3 and the position of the objective lens 20 in step S9 are relatively compared, and steps S9 and S10 are repeated so as to obtain an accurate relative position, thereby adjusting the position of the objective lens 20. Is performed (step S11).

  With the above configuration, the condensing position by the surrounding pattern 26 and the condensing position of the objective lens 20 can be observed with the same optical system. Then, by adjusting the position of the objective lens 20 so as to match the condensing position, the relative positional relationship between the objective lens 20 and the aperture 24 can be managed with high accuracy at any time.

  Here, the influence of the positional deviation of the aperture center with respect to the lens center will be described.

  4A is a diagram showing a lens transmission wavefront when the aperture center and the lens center coincide with each other, and FIG. 4B is a diagram showing a lens transmission wavefront when the aperture center and the lens center are misaligned. It is.

  As shown in FIGS. 4A and 4B, when the relative positional relationship between the center of the aperture 45 and the center of the objective lens 20 is different, a difference occurs in the transmitted wavefront 46 from the objective lens 20.

  In this embodiment, for example, when measuring the objective lens of a BD pickup, if the aperture center is shifted by 5 μm from the lens center, an error of 1/100 or more of the wavelength may occur. This is a significant influence when performing highly accurate lens measurement. Furthermore, considering that a wavefront aberration of about 1 / 100th of the laser wavelength is required for aberration measurement of the BD objective lens, it is desirable to manage the relative positional relationship between the lens and the aperture in submicron units. . In the present embodiment, an optical system that can see the positional relationship between the center of the objective lens 20 and the center of the aperture 24 is provided, and the relative position between the center of the objective lens 20 and the center of the aperture 24 is provided. The relationship can be evaluated in submicron units. Therefore, highly accurate measurement is possible by adjusting the positional relationship between the objective lens 20 and the aperture 24 according to the present embodiment.

  In the present embodiment, substantially flat light from the laser emission source 18 is used as substantially parallel light having a larger diameter by the beam expander 21, but if the diameter is large due to substantially parallel light that is coherent, Other configurations may be used for both the generation source and the enlargement mechanism.

  In the present embodiment, the aberration measurement of the objective lens 20 by the evaluation method using shearing interference by the diffraction grating 30 has been described. However, the present invention can be applied to other aberration measurement methods.

  In the present embodiment, the surrounding pattern 26 is a set of concentric circles, but other configurations can be realized as long as Expression (4) is satisfied. FIG. 5 is a diagram illustrating an example of the aperture 24 and the surrounding pattern 26. For example, as shown in FIG. 5, a configuration in which a pattern is formed in part instead of concentric circles may be used. This should just have a condensing effect | action in the position equivalent to the objective lens 20 in an optical axis direction.

  In the present embodiment, the material of the aperture 24 is optical glass. However, the material is not limited to optical glass, but can be realized by a material that can transmit incident light and can be deposited on the surface.

  In this embodiment, the means of vapor deposition is used to limit the transmitted light of the optical glass. However, it can be realized by a means capable of limiting the transmitted light.

  In this embodiment, vapor deposition is used to limit the light transmitted through the optical glass. However, the surrounding pattern 26 is a part of the pattern as shown in FIG. 5, and the material of the aperture 24 does not transmit light. It is also possible to use a material and create the aperture 24 and the surrounding pattern 26 by removing the material.

  In the embodiment of the present invention, a configuration in which a liquid crystal pattern is used for the aperture 24 is also possible. In this case, a configuration without the auxiliary aperture 23 is also possible.

  In the embodiment of the present invention, the surrounding pattern 26 is collected almost equally in the optical axis direction and the condensing position of the incident light by the objective lens 20, but this is not always necessary, and the pattern itself In addition to the light collecting action, light collecting means using other optical elements may be used.

  In the embodiment of the present invention, the position of the objective lens 20 is adjusted so that the focus position of the surrounding pattern 26 and the focus position of the objective lens 20 are matched. May be adjusted.

  In the embodiment of the present invention, the focusing position by the surrounding pattern 26 and the focusing position of the objective lens 20 are adjusted so as to coincide with each other. May be given a certain distance.

(Embodiment 2)
FIG. 6 is a schematic diagram of the lens measuring apparatus according to the second embodiment.

  In FIG. 6, the configuration of the second embodiment is obtained by omitting the auxiliary aperture 23 from the first embodiment. In this configuration, when the leakage light of the surrounding pattern 26 cannot be ignored, the accuracy of aberration measurement of the objective lens 20 is reduced. However, when the leakage light from the surrounding pattern 26 can be ignored, the process can be simplified. The device configuration can be simplified.

  According to the lens measuring method and the lens measuring apparatus of the present invention, it is possible to perform lens measurement with higher accuracy, and therefore, it can be applied to inspection of lenses used for reading and writing of a high-density information recording medium such as BD.

Schematic diagram of lens measuring apparatus in Embodiment 1 (A) The figure which shows the relative position of the objective lens 20 in Embodiment 1, and the aperture 24 and the auxiliary aperture 23, (b) The figure which shows the surrounding pattern 26 in Embodiment 1. FIG. The figure which shows the flow of the lens position and attitude | position adjustment in Embodiment 1. (A) A diagram showing a lens transmission wavefront when the aperture center and the lens center coincide with each other, (b) A diagram showing a lens transmission wavefront when the aperture center and the lens center are misaligned. The figure which shows an example of the aperture 24 and the surrounding pattern 26 Schematic of the lens measuring device in the second embodiment Schematic diagram of a conventional lens measuring device Schematic diagram of a conventional lens measurement device using an aperture

Explanation of symbols

DESCRIPTION OF SYMBOLS 18 Laser emission source 19 Laser beam 20 Objective lens 21 Beam expander 22 Half mirror 23 Auxiliary aperture 24 Aperture 25 Auxiliary aperture moving mechanism 26 Peripheral pattern 27 Aperture moving mechanism 28 Holding stand 29 Holding stand moving mechanism 30 Diffraction grating 31 Diffraction grating moving mechanism 32 Condensing lens 33 Imaging lens 34 Imaging device 35 Processing device 36 Display device 37 Optical axis 38 Half mirror 39 Imaging lens 40 Imaging device 41 Display device 42 Imaging lens 43 Imaging device 44 Display device

Claims (4)

A light source that emits light;
The aperture and grooves constituting an opening at least a part of said opening concentric circles are formed,
A diffraction grating that condenses light emitted from the light source and transmitted through the groove;
An image sensor that captures a shearing interference image formed by diffracted light of different orders diffracted by the diffraction grating;
Adjusting means for moving the aperture in a direction perpendicular to the optical axis of the light emitted from the light source;
Measuring means for measuring a lens based on the sharing interference image;
An auxiliary aperture between the aperture and the light source,
The lens measuring device , wherein an opening diameter of the auxiliary aperture is larger than an opening diameter of the aperture and smaller than a diameter of an innermost circumference of the groove . The lens measuring device according to claim 1 , wherein the groove is formed concentrically with the opening . And the wavelength of the light emitted from the light source lambda, the width of the groove in a radius r _n and p _n (n is a natural number), the distance from the diffraction grating to said aperture when is L, the said aperture grooves lens measuring apparatus according to claim 1 or 2, characterized by satisfying the following formula (1).

The effective radius of the lens is Ra, the radius of the auxiliary aperture when the Rb, claim 1, radius r ₁ of the innermost portion of the groove of the aperture is characterized by satisfying the following formula (2) The lens measuring device described.

Images