JP2012026968A - Interface eccentricity measuring apparatus and interface eccentricity measuring method of optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an interface eccentricity measuring apparatus and an interface eccentricity measuring method having a compact installation configuration and capable of shortening tact time of measurement.SOLUTION: The interface eccentricity measuring apparatus 1 for an optical element includes: a lens fixing tool 2 for holding an aspheric lens; rotation means 3 for rotating and inverting the lens fixing tool 2; a self-aligning mechanism 4 for performing fine adjustment of a horizontal position and an inclination of the lens fixing tool 2; a displacement sensor 5 for detecting the horizontal position of the lens fixing tool 2; an optical flat 6 fixed on the lens fixing tool 2; an autocollimator for detecting the inclination of the lens fixing tool 2; a face deflection measuring sensor 8 for measuring face deflection of the aspheric lens; control means for allowing the displacement sensor 5 and the autocollimator 7 to measure the horizontal position and inclination of the lens fixing tool 2; and arithmetic means for calculating shift quantity and tilt quantity of the aspheric lens.

Description

  The present invention relates to an inter-surface eccentricity measuring apparatus and inter-surface eccentricity measuring method of an optical element, and more particularly to an inter-surface eccentricity measuring apparatus and surface capable of reducing the measurement time of the inter-surface eccentricity of one optical element with a compact apparatus configuration. The present invention relates to a method of measuring eccentricity.

  In the aspherical lens, the decentering and inclination of the upper and lower surfaces of the lens (hereinafter referred to as inter-surface decentering) influence the lens characteristics. In addition, for example, in lenses used in cameras, the required accuracy of decentering between lenses required for lenses is increasing with the increase in the number of aspheric lenses used due to recent improvements in camera body performance.

  In order to measure the inter-surface eccentricity with high accuracy, a three-dimensional measuring machine is used to measure the three-dimensional shape of the upper and lower surfaces of the lens. This is done by mounting a displacement sensor for measuring shake and measuring the shake of the lens surface when the lens is rotated by this displacement sensor (see, for example, Patent Documents 1 and 2).

Japanese Patent No. 4291849 Japanese Patent No. 3725817

  However, the measurement using a three-dimensional measuring machine requires a large amount of equipment and results in a long tact time of about 30 minutes / piece.

  In addition, the measurement using the reflection eccentricity measuring device (1) is not suitable for measuring a lens having a small aspheric coefficient, and (2) it is necessary to improve the measurement position accuracy of the displacement sensor in order to improve the measurement accuracy. After all, the equipment becomes large, (3) The shift measurement accuracy is poor in principle, (4) The lens position adjustment cannot be automated due to the measurement accompanied by the rotation of the lens, and the three-dimensional measuring machine. Even when compared, there were problems such as no merit in measurement tact time.

  In order to solve the above-described problems, an object of the present invention is to provide an inter-surface eccentricity measuring apparatus and an inter-surface eccentricity measuring method for an optical element that have a more compact equipment configuration and can shorten the measurement tact time.

  An inter-surface decentering measuring apparatus for an optical element according to the present invention includes a plate-like lens fixing jig having a lens holding part for holding an aspherical lens to be measured, and horizontal rotation and upper of the lens fixing jig. Rotating means for inverting the lower surface, a centering mechanism for adjusting the horizontal position and inclination of the lens fixing jig, a displacement sensor for detecting the horizontal position of the lens fixing jig, and the lens fixing jig A fixed optical flat, an autocollimator for detecting the inclination of the lens fixing jig, a surface shake measuring sensor for measuring the surface shake of the aspheric lens by rotating around a vertical axis, Based on the measurement result of the surface runout measurement sensor, the presence or absence of surface runout is determined.If it is determined that there is surface runout, the alignment mechanism is operated, and the surface runout is measured again and the presence or absence of surface runout is determined. Repeat, face If it is determined that there is no error, the lens fixing unit measured with respect to the upper surface of the aspherical lens and the control means for measuring the horizontal position and inclination of the lens fixing jig using the displacement sensor and the autocollimator. Computing means for calculating a shift amount and a tilt amount of the aspheric lens from the horizontal position and tilt of the jig for jig and the horizontal position and tilt of the lens fixing jig measured for the lower surface of the aspheric lens. It is characterized by that.

Further, the optical element decentering measurement method of the optical element of the present invention is a method of measuring the decentering between the optical elements using the apparatus for measuring decentering of the optical element, wherein the lens holding part of the lens fixing jig is subjected to measurement. A holding step for holding the aspheric lens, an upper surface run-out measurement for measuring surface run-out by the surface run-out measurement sensor with respect to one surface of the aspheric lens held by the lens fixing jig, and the upper surface A top surface alignment step for determining the aspherical axis by repeatedly performing top surface position adjustment for changing the horizontal position and inclination of the aspherical lens based on the result of the surface vibration measurement until the surface vibration of the aspherical lens is eliminated. ,
A first position determination step of measuring the horizontal position of the lens fixing jig when the aspherical axis is determined by a displacement sensor, and an inclination by an autocollimator, and the upper surface of the aspherical lens from which the surface shake is eliminated, A top surface rotating step of horizontally rotating the lens fixing jig 180 degrees around the determined aspheric axis, and a horizontal position of the lens fixing jig horizontally rotated by the top surface rotating step by a displacement sensor, A second position determining step for measuring the inclination with an autocollimator;
The reversing step of reversing the upper and lower surfaces of the lens fixing jig after the second position determining step, and the surface runout with respect to the other surface of the aspherical lens held by the reversed lens fixing jig The surface shake of the aspheric lens is measured by a bottom surface shake measurement for measuring a surface shake by a measurement sensor and a bottom surface position adjustment for changing a horizontal position and a tilt of the aspheric lens based on a result of the bottom surface shake measurement. A bottom alignment process that repeats until no longer exists and determines the aspherical axis;
A third position determining step of measuring the horizontal position of the lens fixing jig when the aspherical axis is determined by a displacement sensor and an inclination by an autocollimator, and the lower surface of the aspherical lens where the surface shake is eliminated, The lower surface rotating step for horizontally rotating the lens fixing jig 180 degrees around the determined aspheric axis, and the horizontal position of the lens fixing jig rotated 180 degrees by the lower surface rotating step is tilted by a displacement sensor. A fourth position determining step for measuring the position with an autocollimator;
Based on the horizontal position values obtained in the first to fourth position determining steps, the shift amount calculating step for calculating the shift amount of the aspherical lens, and the first to fourth position determining steps. And a tilt amount calculating step of calculating the tilt amount of the aspherical lens based on the tilt value.

  According to the inter-surface eccentricity measuring apparatus and inter-surface eccentricity measuring method of the present invention, the shift amount and tilt amount of the aspherical axes of the upper and lower surfaces of the optical element can be easily measured while the equipment configuration is compact. . The measurement by this apparatus and method can be applied to a lens having a small aspheric coefficient, the measurement accuracy is good, and the measurement time tact can be shortened.

It is a schematic block diagram of the inter-surface eccentricity measuring apparatus of the optical element which is one Embodiment of this invention. 2A is a side cross-sectional view and FIG. 2B is a plan view of a lens fixing jig used in the inter-surface decentering measuring apparatus for optical elements in FIG. 1. It is a figure explaining the operation | movement about process (A)-(C) in the inter-surface eccentricity measuring method using the inter-surface eccentricity measuring apparatus of the optical element of FIG. It is a figure explaining operation | movement about process (D)-(E) in the inter-surface eccentricity measuring method using the inter-surface eccentricity measuring apparatus of the optical element of FIG. It is a related figure for explaining shift amount calculation of an aspherical lens. It is a figure explaining the calculation method of the shift amount of an aspherical lens. It is a related figure for demonstrating the tilt amount calculation of an aspherical lens. It is a figure explaining the calculation method of the tilt amount of an aspherical lens.

  The present invention will be described below with reference to the drawings.

  1 is a lens fixing jig 2 for holding an aspherical lens 50, and a rotating means 3 for horizontally rotating the lens fixing jig 2 and inverting the upper and lower surfaces. , An alignment mechanism 4 for adjusting the horizontal position and inclination of the lens fixing jig 2, a displacement sensor 5 for detecting the horizontal position of the lens fixing jig 2, and an optical flat fixed to the lens fixing jig 2. 6, an autocollimator 7 that detects the tilt of the lens fixing jig 2, and a surface shake measurement sensor 8 that measures the surface shake of the aspherical lens 50.

  In the inter-surface eccentricity measuring apparatus 1 of the optical element, the surface shake measurement sensor 8 measures the surface shake of the aspherical lens 50 by rotating around the vertical axis. The presence or absence of surface shake is determined. When it is determined that there is surface shake, the alignment mechanism 4 is operated. When it is determined that there is no surface shake, the displacement sensor 5 and the autocollimator 7 are used to fix the lens 2. Control means for measuring the horizontal position and inclination of the. Further, the inter-surface decentering measuring device 1 of the optical element is configured to include a calculation unit that calculates the shift amount and the tilt amount of the aspherical lens 50 from the obtained plurality of horizontal positions and tilts. Here, the surface shake means that when the distance between the sensor and the lens is measured by the face shake measuring sensor 8, the measurement distance is not constant. At this time, the measured aspheric axis of the aspheric lens and the surface shake measurement are measured. The rotational axis of the sensor 8 is shifted.

  The lens fixing jig 2 is a plate-shaped jig having a lens holding portion 2a for holding and fixing the aspherical lens to be measured at the center as shown in FIG. is there. The aspheric lens 50 to be measured is fixed by a lens fixing bracket 2b disposed in the center of the lens fixing jig 2 so as not to contact the optical surface. The lens fixing bracket 2b uniformly holds a plurality of locations on the outer periphery of the lens so that the aspherical lens 50 can be stably fixed. In order to stably hold the lens, it is preferable to hold the lens at least at the outer periphery of the lens at equal intervals in the circumferential direction at three locations, preferably at four or more locations.

  The side surface 2c of the lens fixing jig 2 is smoothly mirror-finished, and the lens fixing jig 2 is obtained by irradiating the mirror surface portion with laser light from a displacement sensor 5 described later and measuring the light receiving time of the reflected light. The position of can be measured accurately.

  The rotating means 3 can independently control the horizontal rotation of the lens fixing jig 2 and the inversion of the upper and lower surfaces of the lens fixing jig 2. In the case of horizontal rotation, the lens fixing jig 2 is rotated 180 degrees (on a horizontal plane) by a vertical axis. In order to reverse the upper and lower surfaces, the lens fixing jig 2 is once moved from the inter-surface eccentricity measuring device 1 to the outside, and is rotated 180 degrees by a horizontal rotation axis to invert the upper and lower surfaces.

  This rotating means 3 can be achieved by, for example, a rotating arm as shown in FIG. The rotating arm can hold and move the lens fixing jig 2 with the hand portion 3a while maintaining the tilted state. When the held lens fixing jig 2 is rotated horizontally, the aspherical lens to be measured is not moved. Horizontal rotation is possible around the spherical axis. Further, the rotating arm holds and moves the lens fixing jig 2 with the hand portion 3a while maintaining the tilted state, and then rotates the hand portion 3a by 180 degrees around the arm portion 3b. The upper and lower surfaces can be reversed.

  The alignment mechanism 4 finely adjusts the horizontal position and inclination of the lens fixing jig 2. This alignment mechanism is composed of a horizontal moving means 4a that can finely adjust the horizontal position and an inclination angle adjusting means 4b that can finely adjust the inclination.

  The horizontal moving means 4a has an inclination angle adjusting means 4b placed on the top thereof, and can further fix the lens fixing jig 2 on the top thereof. Therefore, the horizontal position of the lens fixing jig 2 can be changed by moving the horizontal moving means 4a. Here, examples of the horizontal moving means 4a include a piezo element and an XY axis fine movement stage.

  In configuring the tilt angle adjusting means 4b, it is preferable to combine a coarse adjustment type having a large adjustment angle with a fine adjustment type having a small adjustment angle. At this time, for example, the adjustment angle for coarse adjustment is adjusted continuously or stepwise with an accuracy of ± 0.1 degrees or less, and the adjustment angle for fine adjustment is an accuracy of ± 0.001 degrees or less. It can be adjusted continuously or stepwise.

  As the tilt angle adjusting means 4b, a piezo element, a tilt stage, a gonio stage, or the like can be used. The adjustment angle may be in a range up to ± 10 degrees with respect to the horizontal plane.

  The upper part of the inclination angle adjusting means 4b can hold and fix the lens fixing jig 2, and the inclination of the lens fixing jig 2 can be finely adjusted by the inclination angle adjusting means 4b. This tilt angle can be achieved by adjusting the tilt angle in both the X-axis direction and the Y-axis direction to achieve any tilt angle with respect to the horizontal plane.

  The displacement sensor 5 detects the horizontal position of the lens fixing jig 2. As this displacement sensor 5, for example, a reflection type laser displacement meter, an optical triangulation distance displacement sensor, a laser focus displacement sensor, an ultrasonic displacement sensor, an overcurrent displacement sensor, or the like can be used. When a displacement meter is used, a laser beam is irradiated horizontally on the mirror-finished side surface of the lens fixing jig 2, and the time for receiving the reflected light is measured to determine whether the lens fixing jig 2 and the displacement sensor 5 Is required.

  In FIG. 1, the displacement sensor 5 is described only so as to measure the position in the X direction on the XY plane by irradiating from the left side of the lens fixing jig 2. A displacement sensor 5 is provided so as to irradiate laser light from the front of the figure to the back so that the position can also be measured. At this time, it is preferable that at least two displacement sensors are provided in each of the X direction and the Y direction so that the distance can be accurately measured.

  The optical flat 6 is fixed to the lens fixing jig 2 and determines the reference inclination of the lens fixing jig 2. The optical flat 6 is used to measure the inclination of the lens fixing jig 2 and is provided at a position for receiving laser light from an autocollimator 7 described later. Specifically, as shown in FIG. 2, it is preferable that the lens fixing jig 2 is provided in an annular shape on the outer periphery of the lens fixing portion 2 a. In order to maintain the optical flat surface accuracy, it is desirable that the inner circumference is as small as possible and the thickness is as thick as possible.

  The autocollimator 7 detects the inclination of the lens fixing jig 2. The autocollimator 7 irradiates the optical flat 6 with laser light and detects the inclination of the lens fixing jig 2 from the angle of the reflected light.

  The surface shake measurement sensor 8 rotates about the vertical axis to measure the surface shake of the aspherical lens. The surface shake measurement sensor 8 is disposed obliquely above the measurement surface of the lens to be measured, and rotates about the rotation axis close to the aspherical axis of the lens while rotating between the measurement surface of the lens and the sensor. Measure distance. When the deflection of the distance between the sensor and the lens is measured, it can be seen that the aspherical axis and the rotation axis 8a of the sensor do not match. When the deflection is not measured, the aspherical axis and the rotation axis 8a of the sensor are You can see that they match.

  The surface shake measurement sensor 8 may not be able to be measured depending on the irradiation angle of the laser beam to the aspheric lens that is the measurement target. Therefore, the sensor angle, vertical position, and horizontal position of the sensor may be adjusted. It is preferable to be able to stably measure the surface shake of an aspheric lens.

  Although not shown in the figure, the control means determines the presence or absence of surface shake by measurement of the surface shake measurement sensor 8. When it is determined that there is surface vibration, the horizontal position and inclination of the lens fixing jig 2 are changed by operating the alignment mechanism 4, and the surface vibration is measured again by the surface vibration measuring sensor 8, Again, the presence or absence of runout is determined.

  On the other hand, if it is determined that there is no surface runout, it can be seen that the aspherical axis of the measurement surface and the sensor rotation axis 8a of the surface runout measurement sensor 8 coincide with each other. Causes the displacement sensor 5 and the autocollimator 7 to measure the horizontal position and inclination of the lens fixing jig 2 at this position.

  At this time, the measurement values obtained by the displacement sensor 5 and the autocollimator 7 are stored by the storage means. The measured value stored here is used by the calculation means described later. Examples of the storage means used at this time include known storage means such as a semiconductor memory and an HDD.

  The computing means also calculates the shift amount and tilt amount of the aspheric lens that is the measurement target. Here, the shift amount and the tilt amount will be described more specifically. The shift amount is a deviation in the relative position in the horizontal direction between the aspherical axis on the upper surface of the aspherical lens and the aspherical axis on the lower surface, and the tilt amount is the difference between the aspherical axis on the upper surface of the aspherical lens and the lower surface. The angle between the aspherical axis and the angle, and how much the angle deviates from 180 degrees.

  Therefore, the determination of the aspherical axis and the measurement of the position and inclination of the lens fixing jig 2 at that time are performed on both the upper and lower surfaces of the aspherical lens 50 and the respective data are stored in the storage means. Remembered. Then, the horizontal position and inclination of the lens fixing jig 2 when the stored aspherical axis of the upper surface is determined, and the horizontal position and inclination of the lens fixing jig 2 when the aspherical axis of the lower surface is determined. Based on the above, a shift amount and a tilt amount between the aspheric axis on the upper surface and the aspheric axis on the lower surface of the aspheric lens 50 are calculated. A specific calculation method will be described in the inter-plane eccentricity measurement method described later.

  Next, a method for measuring the inter-surface eccentricity of the optical element using the inter-surface eccentricity measuring apparatus 1 for the optical element will be described. FIG. 3 is a diagram for explaining the operations for the following steps (A) to (C) of the method for measuring the decentering of the optical element, and FIG. 4 is a diagram for explaining the operations for the following steps (D) to (E). .

(A) Holding Step First, the lens fixing jig 2 is removed from the inter-surface decentering measuring device 1 of the optical element, and the aspheric lens 50 to be measured is fixed to the lens holding portion 2a as shown in FIG. And hold it (FIG. 3A). The lens fixing jig 2 holding the aspheric lens 50 is set in the inter-plane eccentricity measuring device 1 and adjusted to the reference position. The reference position is a horizontal position where the tilt is applied to the optical flat 6 so that the jig center of the lens fixing jig 2 is at the same position on the plane of the sensor rotation shaft 8a. The locus of the laser light and the reflected light is the same position.

(B) Upper surface aligning step Next, the upper surface aligning step with respect to one surface of the aspherical lens 50 held by the set lens fixing jig 2 (hereinafter, this surface is referred to as "the upper surface"). I do. In this top alignment process, (B-1) top surface shake measurement and (B-2) top surface position adjustment, which will be described below, are repeated until the surface shake of the aspherical lens 50 is eliminated. A spherical axis is determined.

  (B-1) Upper surface vibration measurement is an operation of measuring surface vibration by the surface vibration measurement sensor 8 on the upper surface of the aspheric lens 50 held by the lens fixing jig 2. At this time, the surface shake measurement sensor 8 is rotated around the sensor rotation axis 8a in the vertical direction to measure the surface shake of the aspherical lens (FIG. 3B). By this rotation, the surface shake measuring sensor 8 continuously measures the distance to the lens and confirms the state of fluctuation of the measured distance. When the measurement distance fluctuates, it is determined that there is a runout, and it can be seen that the aspherical axis 50a and the sensor rotation axis 8a do not match.

  (B-2) When there is a surface runout by the above-described top face runout measurement, the top face position is adjusted. This top surface position adjustment is an operation of changing the horizontal position or inclination of the aspheric lens 50 to move the aspheric surface axis 50a in a direction that coincides with the sensor rotation axis 8a.

  At this time, the horizontal position is adjusted by moving the horizontal position together with the lens fixing jig 2 holding the aspherical lens 50 by the horizontal moving means 4a. Similarly, the tilt is adjusted by changing the tilt angle for each lens fixing jig 2 holding the aspherical lens 50 using the tilt angle adjusting means 4b.

  If the surface runout is large as a result of the above-mentioned top face runout measurement, the horizontal position is first changed by the horizontal adjustment means 4a to adjust the position. This horizontal position adjustment is performed so that the difference between the maximum value and the minimum value is minimized based on the size and position data of the maximum value and the minimum value obtained by the upper surface deflection measurement. Specifically, it is horizontally moved in the direction of the maximum value by a distance of (maximum value−minimum value) / 2.

  After the horizontal movement, the upper surface runout measurement is performed again to determine whether the runout has been improved. If the surface runout is improved, the tilt is adjusted by changing the tilt angle adjusting means 4b. The adjustment of the tilt angle is performed so that the difference between the maximum value and the minimum value is minimized based on the size and position data of the maximum value and the minimum value obtained by the upper surface deflection measurement. Specifically, it is inclined in the direction of the maximum value by an angle corresponding to a distance of (maximum value−minimum value) / 2. Here, the angle corresponding to the distance of (maximum value−minimum value) / 2 is calculated by calculating the relationship between the angle and the distance from the slope of the tangent of the position of the aspherical lens for which the surface shake is being measured, and converting the distance to the angle. Convert it.

  After tilting, the top surface runout measurement is performed again to determine whether the runout has been improved. If the surface runout is improved, the horizontal position adjustment and the inclination angle adjustment are repeated as described above. In addition, after the adjustment operation is performed, if the surface runout is not improved, the state before the adjustment operation may be temporarily returned to continue the adjustment operation for adjusting the other element.

  When the operations (B-1) and (B-2) are repeated and the surface shake is not measured, that is, the distance from the lens upper surface measured by the surface shake measurement sensor is constant, the aspheric axis When 50a and the sensor rotation shaft 8a coincide with each other, the upper surface alignment process is ended (FIG. 3C).

  By the way, since it is very difficult to match the aspherical axis 50a and the sensor rotation axis 8a, in practice, the amount of surface runout is sufficiently small with respect to the required inter-surface eccentricity measurement accuracy. Also when it is determined, the top surface alignment process is terminated in the same manner as the case of matching axes. Here, the determination that the amount of surface shake has become sufficiently small is based on the size and shape of the aspherical lens to be measured. (1) A predetermined reference value is provided, and the “maximum value−minimum” When the “value” falls within the reference value, (2) the “maximum value−minimum value” of the runout is almost zero in the difference between the nth and n + 1 times of the runout measurement and the difference between the n + 1 and n + 2 times. (Or below the reference value) (3) The state of the most improved runout when the magnitude of runout due to runout measurement changes from “large → medium → small → medium” (“ When the “small” part) is determined, these may be performed singly or in combination according to the criteria such as.

(C) 1st position determination process If it can confirm that the aspherical surface axis 50a and the sensor rotating shaft 8a corresponded by the said alignment process, the horizontal position and inclination of the lens fixing jig | tool 2 in the state which corresponded A first position determination step is performed to measure.

  (C-1) The horizontal position in the first position determination step is performed by using the displacement sensor 5 that is fixed to the apparatus so as to be separated from the outer periphery of the lens fixing jig 2. The outer peripheral side surface 2 c related to the measurement of the lens fixing jig 2 is mirror-finished, and laser light is irradiated from the displacement sensor 5 to the mirror surface portion. The distance from the displacement sensor 5 to the lens fixing jig 2 is measured by measuring the detection time of the reflected light from the irradiation of the laser light. In order to determine the horizontal position of the lens fixing jig 2, the displacement sensor 5 is provided in the apparatus so as to measure the distance in two directions of the X-axis direction and the Y-axis direction (FIG. 3 (d)). When the lens fixing jig 2 is tilted in the X-axis and Y-axis directions by calculating the average value by providing two or more sensors in both the X-axis direction and the Y-axis direction. In addition, the position of the aspherical axis of the lens can be calculated reliably.

  (C-2) The inclination in the first position determination step is performed by using the autocollimator 7 that is fixed to the apparatus so as to be spaced above the lens fixing jig 2. An optical flat 6 is embedded in the lens fixing jig 2, and laser light is emitted from an autocollimator 7. By detecting the inclination of the reflected light of the laser beam, the inclination of the lens fixing jig 2 can be measured (FIG. 3D).

  The position information consisting of the horizontal position and the inclination measured here is stored in the storage means and used in the subsequent steps.

(D) Upper surface rotation process After the first position determination is completed, an upper surface rotation process is performed. The rotation of the upper surface horizontally rotates the lens fixing jig 2 180 degrees about the aspherical axis 50a (sensor rotation axis 8a) as a rotation axis (FIG. 4A; before rotation). That is, in this rotation, the lens fixing jig 2 is rotated while maintaining its inclination and with the upper surface of the aspherical lens 50 facing upward. Further, this rotation does not change the state in which the aspherical axis 50a coincides with the sensor rotation axis 8a (FIG. 4B; after rotation).

  After the rotation, the horizontal position and the inclination are also rotated by 180 degrees, so that the horizontal position of the horizontal moving means 4a and the inclination of the inclination angle adjusting means 4b are also rotated by 180 degrees about the sensor rotation shaft 8a. And adjusted.

(E) Second position determining step A second position determining step for determining a horizontal position and an inclination is performed on the lens fixing jig 2 rotated 180 degrees horizontally. In the second position determination step, the horizontal position and the inclination are determined by the displacement sensor 5 and the autocollimator 7 in the same manner as in the first position determination step (C) (FIG. 4C).

  As in the first position determination step, the position information including the horizontal position and the inclination measured here is stored in the storage means and used in the subsequent steps.

(F) Inversion Step After the second position determination is completed, the upper and lower surfaces of the lens fixing jig 2 are then inverted by the rotating means 3. By this inversion, the upper surface and the lower surface of the aspheric lens 50 are interchanged, and preparation for measurement of the lower surface is completed. At this time, it is preferable that the horizontal position and inclination of the alignment mechanism are returned to the reference position, and the lens fixing jig 2 is placed at the reference position.

(G) Lower surface aligning step Next, an aligning step is performed on the other surface of the aspheric lens 50 held by the lens fixing jig 2 (hereinafter, this surface is referred to as a “lower surface”). In this lower surface alignment process, as in the upper surface alignment process, the lower surface vibration measurement and the lower surface position adjustment are repeatedly performed until the surface vibration of the aspherical lens 50 is eliminated, thereby determining the aspherical axis. .

  (G-1) The lower surface vibration measurement is an operation for measuring surface vibration by the surface vibration measurement sensor 8 on the lower surface of the aspheric lens 50 held by the lens fixing jig 2. At this time, the surface shake measurement sensor 8 is rotated about the sensor rotation axis 8a in the vertical direction to measure the surface shake of the aspherical lens. Due to this rotation, the surface shake measurement sensor 8 continuously measures the distance to the lens, and confirms the state in which the measurement distance fluctuates. When the measurement distance fluctuates, it is determined that there is runout, and it can be seen that the aspherical axis 50b and the sensor rotation axis 8a do not match.

  (G-2) If there is a surface run-out by the measurement of the run-out of the lower surface, the lower surface position is adjusted. This bottom surface position adjustment is an operation of changing the horizontal position or inclination of the aspheric lens 50 to move the aspheric surface axis 50b in a direction coinciding with the sensor rotation axis 8a.

  When the operations of (G-1) and (G-2) are repeated and the surface shake is not measured, that is, the distance from the lower surface of the lens measured by the surface shake measurement sensor is constant, the aspheric axis When 50b and the sensor rotating shaft 8a coincide with each other, the lower surface alignment process is ended. Similarly to the upper surface alignment step (B), the lower surface alignment step is also terminated when it is determined that the amount of surface runout has become sufficiently small relative to the required inter-surface eccentricity measurement accuracy.

(H) Third position determination step When the lower surface alignment step is performed and it is confirmed that the aspherical surface shaft 50b and the sensor rotation shaft 8a are aligned, the lens fixing jig 2 in the aligned state is confirmed. A third position determining step for measuring the horizontal position and the inclination is performed. In the measurement, the horizontal position and the inclination are determined by the displacement sensor 5 and the autocollimator 7 in the same manner as in the first position determination step (C). Note that the optical flat 6 embedded in the lens fixing jig 2 is provided with an opening in the lens fixing jig 2 at the measurement position so that the optical flat 6 can be measured from the lower surface.

  The position information consisting of the horizontal position and the inclination measured here is stored in the storage means and used in the subsequent steps.

(I) Lower surface rotation process After the third position determination is completed, a lower surface rotation process is performed. In this lower surface rotation, the lens fixing jig 2 is horizontally rotated 180 degrees about the aspherical axis 50b (sensor rotation axis 8a) as a rotation axis. That is, in this rotation, the lens fixing jig 2 is rotated while maintaining its inclination and with the lower surface of the aspherical lens 50 facing upward. Further, this rotation does not change the state in which the aspherical axis 50b coincides with the sensor rotation axis 8a.

  After the rotation, the horizontal position and the inclination are also rotated by 180 degrees, so that the horizontal position of the horizontal moving means 4a and the inclination of the inclination angle adjusting means 4b are also rotated by 180 degrees about the sensor rotation shaft 8a. And adjusted.

(J) Fourth Position Determination Step A fourth position determination step for determining the horizontal position and the tilt is performed on the lens fixing jig 2 rotated horizontally by 180 degrees. In the fourth position determination step, the horizontal position and the inclination are determined by the displacement sensor 5 and the autocollimator 7 in the same manner as the above (H) first position determination step.

  As in the first position determination step, the position information including the horizontal position and the inclination measured here is stored in the storage means and used in the subsequent steps.

(K) Shift amount calculation step When the fourth position determination step is completed, the shift amount of the aspheric lens 50 to be measured is calculated. The shift amount is calculated using the horizontal position information obtained in the first to fourth position determination steps.

  First, the jig center line O of the lens fixing jig 2 is used as a reference, and this reference is the origin on the plane of the lens fixing jig 2. At this time, the coordinates of the aspherical axis of the upper surface of the aspherical lens 50 existing with a deviation from the origin are A (ax, ay), and the coordinates of the aspherical axis of the lower surface are B (bx, by). At this time, the deviation in the X-axis direction as seen from the side cross section of the lens fixing jig 2 is shown in FIG.

  At this time, the X component of the coordinate A is the horizontal position information in the X-axis direction (hereinafter referred to as X1) obtained in the first position determining step shown in FIG. 6A and shown in FIG. 6B. It is calculated by taking the difference from the horizontal position information in the X-axis direction (hereinafter referred to as X2) obtained in the second position determination step. Specifically, the difference (X1−X2) obtained from X1 and X2 is always twice the distance between the jig center line O and the X component of the coordinate A of the aspheric axis on the upper surface. The X component of the coordinate A can be calculated by a calculation formula of ax = (X1−X2) / 2.

  Since the above relationship can also be applied to the Y-axis direction, the horizontal position information in the Y-axis direction (hereinafter referred to as Y1) obtained in the first position determination step and the second position determination step are obtained in exactly the same way. Further, using the horizontal position information in the Y-axis direction (hereinafter referred to as Y2), the Y component of the coordinate A can be calculated by the equation: ay = (Y1-Y2) / 2.

  If the X component and the Y component are calculated as described above, the coordinate A with respect to the jig center line O can be obtained.

  Next, with respect to the coordinate B as well as the coordinate A, horizontal position information in the X-axis direction (hereinafter referred to as X3) obtained in the third position determination step shown in FIG. 6C and FIG. Using the horizontal position information in the X-axis direction (hereinafter referred to as X4) obtained in the fourth position determination step shown in FIG. 4, the X component of the coordinate B can be calculated by the formula bx = (X3−X4) / 2. Further, horizontal position information in the Y-axis direction (hereinafter referred to as Y3) obtained in the third position determination step and horizontal position information in the Y-axis direction (hereinafter referred to as Y4) obtained in the fourth position determination step. , The Y component of the coordinate B can be calculated by a calculation formula of by = (Y3−Y4) / 2.

  If the X component and the Y component are calculated as described above, the coordinate B with respect to the jig center line O can be obtained.

  If the coordinates A and B are known in this way, the shift amount in the aspherical lens can be easily calculated by taking the difference between the coordinates (coordinate A−coordinate B).

(L) Tilt Amount Calculation Step When the fourth position determination step is completed, the tilt amount of the aspheric lens 50 to be measured is calculated. The tilt amount is calculated using information on the tilt of the lens fixing jig 2 obtained in the first to fourth position determining steps.

  First, the normal line of the upper and lower surfaces of the optical flat fixed to the lens fixing jig 2 is used as a reference (reference line). At this time, the inclination of the aspherical axis on the upper surface of the aspherical lens 50 with respect to the reference line is γ, and the inclination of the aspherical axis on the lower surface is φ (FIG. 7).

  At this time, when the laser beam from the autocollimator 7 has an angle θ with respect to the sensor rotation axis, the tilt information obtained in the first position determination step as shown in FIG. (Θ + γ) is obtained as the inclination of the reflected light. Further, as shown in FIG. 8B, the inclination information obtained in the second position determination step is (θ−γ). Taking the difference between these pieces of inclination information, (θ + γ) − (θ−γ) = 2γ is obtained, and the value of γ can be determined.

  Next, the same applies to the lower surface. At this time, the laser beam from the autocollimator 7 with respect to the sensor rotation axis does not change at the angle θ. Therefore, as shown in FIG. 8C, the inclination information obtained in the third position determination step is 2 × (θ + φ) as the inclination of the reflected light. Further, as shown in FIG. 8D, the inclination information obtained in the fourth position determination step is (θ−φ). Taking the difference between the tilt information, (θ + φ) − (θ−φ) = 2φ is obtained, and the value of φ can be determined.

  Both γ and φ obtained as described above have an X-axis component and a Y-axis component, and these are separated to calculate the tilt amount in the X-axis direction and the tilt amount in the Y-axis direction, respectively. As a result, the tilt amount of the aspherical lens 50 can be calculated.

  As described above, according to the inter-surface eccentricity measuring apparatus and method of the present invention, the shift amount and tilt amount of the aspherical lens 50 can be easily measured while having a compact equipment configuration. Furthermore, according to this measuring apparatus and method, it is possible to deal with a lens having a small aspheric coefficient, good measurement accuracy, and shorten the measurement tact time.

  The inter-surface decentration measuring apparatus and inter-surface decentration measuring method of the present invention can be used for measuring the shift amount and tilt amount of the upper and lower surfaces of an aspheric lens obtained by press molding.

DESCRIPTION OF SYMBOLS 1 ... Optical element inter-surface eccentricity measuring apparatus, 2 ... Lens fixing jig, 3 ... Rotating means, 4 ... Alignment mechanism, 5 ... Displacement sensor, 6 ... Optical flat, 7 ... Auto collimator, 8 ... Surface shake measurement Sensor, 8a ... sensor rotation axis, 50 ... aspheric lens, 50a, 50b ... aspheric axis,

Claims (4)

A plate-like lens fixing jig having a lens holding part for holding the aspherical lens to be measured;
Rotating means for reversing the horizontal rotation and the upper and lower surfaces of the lens fixing jig;
An alignment mechanism for adjusting the horizontal position and inclination of the lens fixing jig;
A displacement sensor for detecting a horizontal position of the lens fixing jig;
An optical flat fixed to the lens fixing jig;
An autocollimator for detecting the inclination of the lens fixing jig;
A surface shake measurement sensor that rotates about a vertical axis and measures the surface shake of the aspheric lens;
Based on the measurement result of the surface shake measurement sensor, the presence or absence of surface shake is determined. When it is determined that there is a surface shake, the alignment mechanism is operated to measure the surface shake again and determine the presence or absence of the surface shake. When it is determined that there is no surface shake, the control means for measuring the horizontal position and inclination of the lens fixing jig by the displacement sensor and the autocollimator,
Shift of the aspheric lens from the horizontal position and inclination of the lens fixing jig measured for the upper surface of the aspheric lens and the horizontal position and inclination of the lens fixing jig measured for the lower surface of the aspheric lens Calculating means for calculating the amount and the tilt amount;
An inter-surface decentering measuring apparatus for an optical element, comprising:   The inter-surface eccentricity measuring apparatus according to claim 1, wherein an outer peripheral side surface of the lens fixing jig is mirror-finished, and the displacement sensor is a reflection type laser displacement meter.   The inter-plane eccentricity measuring apparatus according to claim 1 or 2, wherein the tilt angle adjusting means of the aligning mechanism includes a piezo element. An inter-plane eccentricity measuring method using the inter-surface eccentricity measuring device for an optical element according to any one of claims 1 to 3,
A holding step of holding the aspherical lens to be measured in the lens holding portion of the lens fixing jig;
Based on the result of the upper surface deflection measurement and the upper surface deflection measurement, the aspherical surface is measured on the one surface of the aspheric lens held by the lens fixing jig by the surface deflection measurement sensor. An upper surface position adjustment for changing the position and inclination of the lens, and an upper surface alignment step for repeatedly determining the aspherical axis until the surface vibration of the aspherical lens is eliminated,
A first position determining step of measuring a horizontal position of the lens fixing jig when the aspherical axis is determined by a displacement sensor and an inclination by an autocollimator;
An upper surface rotating step for horizontally rotating the lens fixing jig 180 degrees around the determined aspheric axis with respect to the upper surface of the aspheric lens in which the surface shake has been eliminated;
A second position determining step of measuring a horizontal position of the lens fixing jig horizontally rotated by the upper surface rotating step by a displacement sensor and an inclination by an autocollimator;
An inversion step of inverting the upper and lower surfaces of the lens fixing jig after the second position determination step;
Based on the result of the lower surface shake measurement, which measures the surface shake by the surface shake measurement sensor, with respect to the other surface of the aspherical lens held by the inverted lens fixing jig, A bottom surface alignment step for determining the aspherical axis by repeatedly performing bottom surface position adjustment for changing the horizontal position and inclination of the aspherical lens, until the surface vibration of the aspherical lens is eliminated, and
A third position determining step of measuring a horizontal position of the lens fixing jig when the aspherical axis is determined by a displacement sensor and an inclination by an autocollimator;
A lower surface rotating step of horizontally rotating the lens fixing jig 180 degrees around the determined aspheric axis with respect to the lower surface of the aspheric lens with no surface shake;
A fourth position determining step of measuring the horizontal position of the lens fixing jig rotated 180 degrees by the lower surface rotating step by a displacement sensor and the inclination by an autocollimator;
A shift amount calculating step of calculating a shift amount of the aspherical lens based on the horizontal position value obtained by the first to fourth position determining steps;
A tilt amount calculating step of calculating a tilt amount of the aspherical lens based on the tilt value obtained by the first to fourth position determining steps;
A decentering measurement method for an optical element, comprising:

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