JP2014202589A - Surface interval measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface interval measurement device capable of performing a surface interval measurement without eccentricity adjustment of a measurement target lens, and simultaneously measuring a plurality of measurement target lenses.SOLUTION: A surface interval measurement device 100 includes: a light source 2a; a collimator lens 3a for causing a light beam from the light source 2a to be a parallel light beam; a light beam division part for dividing the parallel light beam into a measurement light beam L1m and a reference light beam L1r; a lens holding base part 9 for holding a measurement target lens 14; an optical path length change part 7a for changing the optical path length of the reference light beam L1r; a light beam synthesis part for overlapping a reflection light beam L2m from the measurement target lens 14 with the reference light beam L1r to form a synthesized light beam L2c; a photoelectric detection part 8a for measuring the change in the light intensity distribution of the synthesized light beam L2c; and a calculation part for calculating information on the vertex positions of a first surface 14a and a second surface 14b on the basis of the temporal change in the light intensity distribution, and calculating a surface interval on the basis of the information on the vertex positions, and information on the curvature radiuses of the first surface 14a and the second surface 14b.

Description

  The present invention relates to a surface interval measuring apparatus.

Conventionally, as a surface distance measuring device that measures the surface distance of a lens in a non-contact manner, the surface distance is determined from the difference between these optical path lengths by measuring the optical path length of the reflected light from the lens surface using low coherence interference. The required device is known.
In such a surface interval measuring device, if the lens optical axis of the test lens is decentered with respect to the measurement reference axis, a measurement error occurs. Therefore, when the test lens is held by the device, the decentering adjustment of the test lens is performed. It was necessary to do.
For example, in Patent Document 1, the amount of eccentricity of the surface to be measured is measured from the position of the reflected spot on the surface to be measured, the lens optical axis of the lens to be measured is calculated, and then centering by an automatic stage is performed. A surface spacing measuring device is described.

JP 2005-147703 A

However, the conventional inter-surface distance measuring apparatus as described above has the following problems.
The conventional surface distance measuring apparatus using low coherence interference needs to adjust the decentration of the lens to be measured before measuring the surface distance, so that there is a problem that the time required for the measurement increases as a whole. .
In the surface distance measuring device described in Patent Document 1, although the eccentric adjustment is simplified using the automatic stage, the measurement of the eccentric amount and the movement by the automatic stage are the same as in the manual adjustment. There is a problem that it takes a measurement time in addition to the measurement of the surface interval.
In addition, since it is necessary to perform such decentration adjustment for each test lens, for example, it is difficult to measure a plurality of test lenses at the same time, and it is difficult to improve measurement efficiency in this respect as well. There is.

  The present invention has been made in view of the above-described problems, and can measure the surface separation without adjusting the eccentricity of the test lens, and can simultaneously measure a plurality of test lenses. An object of the present invention is to provide a surface distance measuring device.

  In order to solve the above-described problem, the surface distance measuring apparatus according to the first aspect of the present invention is a surface distance measuring apparatus for measuring the surface distance of a lens to be measured, which is a spherical lens, and generates low coherence light. A light source, a collimator lens that converts the light beam from the light source into a parallel light beam, a light beam splitting unit that divides the parallel light beam formed by the collimator lens into a measurement light beam and a reference light beam, and an optical path of the measurement light beam A lens holder that holds the test lens, an optical path length changing unit that changes an optical path length of the reference light beam, a reflected light beam reflected by the test lens among the measurement light beam, and the optical path A light beam combining unit that forms a combined light beam by superimposing the reference light beam whose optical path length has been changed by the length changing unit, and the interference due to interference associated with a change in the optical path length of the reference light beam by the optical path length changing unit. A photoelectric detector that measures the change in the light intensity distribution of the light beam, and the time variation of the light intensity distribution of the combined light beam measured by the photoelectric detector, and the top surface of the lens surface of the test lens where the interference has occurred A surface apex position calculating unit for calculating position information, information on the position of the surface apex calculated by the surface apex position calculating unit with respect to the two lens surfaces of the lens to be tested, and the two lenses acquired in advance A surface interval calculation unit that calculates a surface interval between the two lens surfaces in a direction along the lens optical axis of the lens to be tested based on information on the curvature radius of the surface.

  In the surface interval measuring apparatus, the lens holding base unit includes at least three reference position reference units that can be detected by the photoelectric detection unit, and the surface top position calculation unit is detected by the photoelectric detection unit. It is possible to calculate the information on the position of the top surface based on the position of the reference position reference unit.

  In the inter-surface distance measuring apparatus, the light source, the collimator lens, the light beam splitting unit, the optical path length changing unit, the light beam combining unit, and the interference measuring unit having the photoelectric detection unit sandwich the lens holding base unit. , A first interference measurement unit arranged to face one of the two lens surfaces of the test lens, and a second interference measurement arranged to face the other of the two lens surfaces of the test lens. The surface top position calculation unit is based on a temporal change in the light intensity distribution of the combined light beam measured by the photoelectric detection unit of each of the first interference measurement unit and the second interference measurement unit. It is possible to calculate information on the position of the top of one of the two lens surfaces where the interference has occurred and information on the position of the top of the other of the two lens surfaces.

In the inter-surface distance measuring apparatus, the lens holding base unit includes at least three reference position reference units that can be detected by the photoelectric detection units of the first interference measurement unit and the second interference measurement unit, respectively. , In each of the first interference measurement unit and the second interference measurement unit,
The top surface position calculation unit can calculate information on the top surface position based on the position of the reference position reference unit detected by the photoelectric detection unit.

  In the above-mentioned surface distance measuring device, the reference position reference unit can be configured by three reflecting spheres.

  In the inter-surface distance measuring apparatus, at least three of the first interference measurement unit and the second interference measurement unit are provided on the lens holding table and a moving unit that moves independently with respect to the lens holding table. A reference position reference unit provided and capable of detecting a position by the photoelectric detection unit of each of the first interference measurement unit and the second interference measurement unit; the first interference measurement unit and the second interference measurement; The operation of the moving unit is controlled based on the position of the reference position reference unit detected by the photoelectric detection unit of each of the units, and the first interference measuring unit and the second interference measuring unit A movement control unit that adjusts the position of the lens holding base unit.

  According to the surface distance measuring device of the present invention, the surface of the two lens surfaces of the lens to be measured is detected by detecting the peak generation position of the light intensity distribution based on the interference by the low coherence light and the generation timing of the light intensity peak. Two lens surfaces in the direction along the lens optical axis of the lens to be measured are acquired based on the information on the position of the top and the information on the radius of curvature of the two lens surfaces acquired in advance. Therefore, it is possible to measure the surface distance without adjusting the eccentricity of the lens to be measured, and it is possible to simultaneously measure a plurality of lens to be tested.

It is a typical block diagram which shows the structure of the surface distance measuring apparatus of the 1st Embodiment of this invention. It is the top view which shows the structure of the lens holding stand part of the surface distance measuring apparatus of the 1st Embodiment of this invention, and its AA sectional drawing. It is a block diagram which shows the structure of the control unit of the surface distance measuring apparatus of the 1st Embodiment of this invention. It is a flowchart which shows the measurement flow of the measurement operation | movement using the surface distance measuring apparatus of the 1st Embodiment of this invention. It is a schematic diagram explaining the measurement principle of the surface interval measuring apparatus of the 1st Embodiment of this invention. It is a typical graph explaining the light intensity signal acquired with the photoelectric detection part of the surface distance measuring apparatus of the 1st Embodiment of this invention. It is a schematic diagram explaining the light intensity distribution acquired by the photoelectric detection part of the surface distance measuring apparatus of the 1st Embodiment of this invention. It is a schematic diagram explaining the coordinate conversion of the surface distance measuring apparatus of the 1st Embodiment of this invention. It is a typical block diagram which shows the structure of the surface distance measuring apparatus of the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the control unit of the surface distance measuring apparatus of the 2nd Embodiment of this invention. It is a flowchart which shows the measurement flow of the measurement operation | movement using the surface distance measuring apparatus of the 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

[First Embodiment]
A surface interval measuring apparatus according to a first embodiment of the present invention will be described.
FIG. 1 is a schematic configuration diagram showing a configuration of a surface interval measuring apparatus according to a first embodiment of the present invention. FIG. 2A is a plan view showing the configuration of the lens holding base part of the surface interval measuring apparatus according to the first embodiment of the present invention. FIG.2 (b) is AA sectional drawing in Fig.2 (a). FIG. 3 is a block diagram showing the configuration of the control unit of the surface distance measuring apparatus according to the first embodiment of the present invention.

As shown in FIG. 1, the surface distance measuring apparatus 100 according to the present embodiment is an apparatus that measures the surface distance of a lens 14 to be tested, which is a spherical lens.
The test lens 14 is not particularly limited as long as the first surface 14a and the second surface 14b, which are lens surfaces, are spherical lenses each having a spherical surface. For example, a biconvex lens, a biconcave lens, a positive or negative meniscus lens is used. Can be adopted. Hereinafter, as an example, a description will be given of an example in which the test lens 14 is a biconvex lens.
The surface interval of the test lens 14 is defined by the distance between the first surface 14 a and the second surface 14 b along the lens optical axis of the test lens 14. Such a lens surface interval may be referred to as a lens thickness or a lens inner thickness.

  As shown in FIG. 1, the schematic configuration of the inter-surface distance measuring apparatus 100 includes a first interference measurement unit 1a (interference measurement unit), a lens holding base unit 9, a second interference measurement unit 1b (interference measurement unit), and a control. A unit 10, a display unit 11, and an operation unit 12 are provided.

  The first interference measuring unit 1a includes a light source 2a, a collimator lens 3a, a half mirror 4a (light beam splitting unit, light beam combining unit), an optical path length changing unit 7a, and a photoelectric detecting unit 8a in a housing not shown. They are positioned relative to each other.

  The light source 2a is a light source that generates a light beam La that is low-coherence light and emits it as divergent light. As the light source 2a, for example, a halogen light source, a super luminescent diode (SLD), a light emitting diode (LED), or the like can be employed. In the present embodiment, an SLD is employed as an example.

The collimator lens 3a is a lens or lens group to form a parallel light beam L1 which condenses the light beam La traveling along the optical axis O _1.

The half mirror 4a is disposed on the optical path of the parallel light beam L1, transmits a part of the parallel light beam L1 as the reference light beam L1r, and reflects the other of the parallel light beam L1 as the measurement light beam L1m, thereby converting the parallel light beam L1 into 2 pieces. Divide in the direction.
In the present embodiment, as an example, the optical axis O ₁ extends in the horizontal direction, and the half mirror 4 a is arranged in a positional relationship that reflects the optical axis O ₁ vertically downward. Therefore, measurement beams L1m is reflected downward along the optical axis O ₁ and the optical axis O ₂ parallel to the vertical axis perpendicular.

The optical path length changing unit 7a is a device portion that changes the optical path length of the reference light beam L1r, and is disposed on the optical path of the reference light beam L1r.
Optical path length changing unit 7a, a reference mirror 5a having a reflection plane of the reference light beam L1r toward the half mirror 4a is reflected in the direction along the optical axis O _1, the direction of the position along the optical axis O ₁ of the reference mirror 5a And a moving stage 6a to be changed.

  The reflection plane of the reference mirror 5a has high surface accuracy because the optical path length of the reference light beam L1r is uniformly changed regardless of the radial position of the light beam.

The specific configuration of the moving stage 6a is such that the optical path length of the reference light beam L1r corresponds to the distance necessary for searching the top position of the first surface 14a and the position of the top face of the reflecting sphere 13 described later. The moving mechanism is not particularly limited as long as it has a moving resolution capable of detecting a peak of a light intensity signal, which will be described later, due to interference of low-coherence light. For example, a single-axis stage using a piezo element, a stepping motor, a linear motor, or the like as a drive source can be employed.
Moreover, the moving stage 6a is provided with position detection sensors (not shown), such as an encoder, for example, and can detect a moving amount and a moving speed.
Such movement stage 6a is communicably connected to the control unit 10 to be described later, the moving operation is controlled along the optical axis O ₁ on the basis of a control signal from the control unit 10.
The movement amount and movement speed detected by a position detection sensor (not shown) are sent to the control unit 10 and can be used for control in the control unit 10.

The photoelectric detection unit 8a interferes with the half mirror 4a, photoelectrically converts the light image projected on the light receiving surface of the photoelectric detection unit 8a, and acquires two-dimensional image data in the irradiation range of the measurement light beam L1m. .
As a preferable configuration of the photoelectric detection unit 8a, for example, an imaging device such as a CCD or a CMOS sensor, an image detector, or the like can be given.
In the present embodiment, a CCD is employed as an example of the photoelectric detection unit 8a. For this reason, the photoelectric detection unit 8a has a large number of light receiving units arranged in a rectangular range in a grid pattern, and the accumulated light amount detected by each light receiving unit is read out at a constant time interval. The amount of received light at can be detected.
The center of the imaging surface of the photoelectric detector 8a is aligned with the optical axis O _2, thereby, it is possible to identify the position of each light receiving portion in the direction perpendicular to the optical axis O _2.

  The photoelectric detector 8a is communicably connected to a control unit 10 described later. For this reason, the image signal acquired by the photoelectric detection unit 8 a is sent to the control unit 10.

The lens holding base 9 is supported by a support member (not shown) and holds the lens 14 to be tested, and is disposed on the optical path of the measurement light beam L1m reflected by the half mirror 4a.
In the present embodiment, as shown in FIGS. 2A and 2B, the lens holding base portion 9 is made of a plate-like member, and three test lenses 14 are placed thereon. Three holding holes 9c made of circular holes having a smaller diameter than the outer diameter and penetrating in the thickness direction are provided.
Thereby, as shown in FIG. 2A, the test lens 14 is held from below by placing the test lens 14 with the second surface 14b facing downward from the upper side of each holding hole 9c. can do.
In the present embodiment, the test lenses 14A, 14B, and 14C manufactured under the same design conditions are held on the holding holes 9c.

In this holding state, the second surface 14b of each lens 14 is in contact with the inner peripheral edge of the holding hole 9c on the upper surface 9a side. Thereby, the test lens 14 is positioned in the radial direction and the axial direction of the holding hole 9c.
At this time, the first surface 14 a of the test lens 14 is located above the upper surface 9 a of the lens holding base 9. When the lens holding base 9 is viewed from the lower surface 9b side, the second surface 14b excluding the outer edge located above the upper surface 9a is exposed to the inside of the holding hole 9c facing downward.
In such a holding state, each of the test lenses 14 can rotate around the spherical center of the second surface 14b. Therefore, as shown in FIG. 2 (b), a lens optical axis O _L of the lens 14, but the central axis of the holding hole 9c which may have become non-parallel to each other, in this embodiment, as described below, it is possible to accurately measure even with different direction of the lens optical axis O _L of each test lens 14. Therefore, the holding mechanism and positioning mechanism for restricting the direction of the lens optical axis O _L of the lens 14 is not necessary.

  The number of holding holes 9c is an example. As long as the holding hole 9c is within the irradiation range of the measurement light beam L1m, an appropriate number can be provided according to the number of test lenses 14 to be measured at one time. Therefore, the holding holes 9c may be provided by 1 to 2, or 4 or more.

In addition, three reflecting spheres 13 (reference position reference portions) having a known diameter are provided on the lens holding base 9 from the outside of the lens holding base 9 on the upper surface 9a side and the lower surface 9b side. Embedded in an observable state.
The diameters of the reflecting spheres 13 may be different from each other as long as they are known, but in the present embodiment, they have the same dimensions as an example.
The reflective sphere 13 is not particularly limited in material and manufacturing method as long as the outer diameter of the surface is a smooth reflecting surface formed with high accuracy. For example, a polished glass sphere or a metal sphere is adopted. can do.

It is preferable that the arrangement positions of the reflection spheres 13 in plan view are separated from each other in the vicinity of the outer periphery of the lens holding base portion 9. In the present embodiment, as an example, they are arranged at three corners of a rectangular lens holding base 9. That is, when the three reflecting spheres 13 are the reflecting spheres 13A, 13B, and 13C, the reflecting spheres 13A and 13C are arranged at the corners in the diagonal direction of the lens holding base 9, and the reflecting sphere 13b intersects with this. It is arranged at one corner in the diagonal direction.
The arrangement positions of the reflecting spheres 13 in the thickness direction of the lens holding base 9 are the spherical centers C ₁ , C ₂ , and C ₃ of the reflecting spheres 13A, 13B, and 13C (however, in FIG. C ₃ is omitted), but is arranged at an equal distance from the upper surface 9 a of the lens holding base 9.

As shown in FIG. 1, the second interference measuring unit 1b includes a light source 2b, a collimator lens 3b, a half mirror 4b (light beam splitting unit, light beam combining unit), and an optical path length changing unit 7b in a housing (not shown). , And the photoelectric detector 8b are positioned and arranged with respect to each other.
Each configuration is exactly the same as the configuration of the light source 2a, the collimator lens 3a, the half mirror 4a, the optical path length changing unit 7a, and the photoelectric detecting unit 8a of the first interference measuring unit 1a, and the reflecting spheres 13A, 13B, It differs from the first interference measurement unit 1a in that it is arranged at a position that is substantially plane symmetric (including the case of plane symmetry) with respect to the plane defined by the 13C ball centers C ₁ , C ₂ , C ₃ .
The following briefly describes the difference from the first interference measurement unit 1a.

Light source 2b is a light beam Lb is a low-coherence light as a divergent light, it is emitted along the optical axis O ₃ that extends in the horizontal direction.
The collimator lens 3b is a half mirror 4b to form a parallel light beam L3 which condenses the light beam Lb travels along the optical axis O ₃ is disposed on the optical path of the collimated light beam L3, the reference beam part of the parallel beam L3 While transmitting as L3r and reflecting the other of the parallel light beam L3 as the measurement light beam L3m, the parallel light beam L3 is divided into two directions.
Half mirror 4b is disposed in a positional relationship that reflects the optical axis O ₃ vertically upward, measuring beam L3m is reflected upward along the optical axis parallel O ₄ a vertical axis orthogonal to the optical axis O ₃ Is done.
The optical path length changing unit 7b is a device part that changes the optical path length of the reference light beam L3r, and includes a reference mirror 5b and a moving stage 6b having the same configuration as the reference mirror 5a and the moving stage 6a of the optical path length changing unit 7a. It is arranged on the optical path of the reference light beam L3r.
Reference mirror 5b is reflected in the direction along the optical axis O ₃ toward the reference beam L3r the half mirror 4b.
Moving stage 6b changes the direction of the position along the optical axis O ₃ of the reference mirror 5b.
The photoelectric detector 8b photoelectrically converts an interference image formed as described later in the half mirror 4b, and acquires two-dimensional image data in the irradiation range of the measurement light beam L3m.

Such second interference measuring unit 1b by not shown supporting member, below the lens holder 9, the optical axis O ₄ is substantially aligned with the optical axis O ₂ of the first interference measurement unit 1a ( (Including when aligned).

  The control unit 10 controls the operation of the surface distance measuring device 100. As shown in FIG. 3, the measurement control unit 21, the image acquisition unit 20, and the calculation unit 22 (surface top position calculation unit, surface space calculation unit). And a storage unit 23.

The measurement control unit 21 controls the entire measurement operation of the surface distance measuring device 100 based on the operation input of the measurer. The measurement control unit 21 controls the operation unit 12, the optical path length changing units 7a and 7b, the light sources 2a and 2b, which will be described later. The image acquisition unit 20 and the calculation unit 22 are communicably connected.
The operation unit 12 is a device part for a measurer to perform operations and data input, and includes, for example, a mouse, a keyboard, operation buttons, and the like.
Examples of control performed by the measurement control unit 21 include control for changing the optical path length of the reference light beam L1r (L3r) by driving the moving stage 6a (6b) of the optical path length changing unit 7a (7b), and the light source 2a (2b). Examples include control of turning on / off the light, control of image acquisition operation by the image acquisition unit 20, and control of starting calculation processing by the calculation unit 22.

The image acquisition unit 20 is communicably connected to the measurement control unit 21, the photoelectric detection units 8a and 8b, and the storage unit 23, and is detected by the photoelectric detection units 8a and 8b based on a control signal from the measurement control unit 21. An image signal is acquired and converted into image data.
That is, when the control signal for starting the acquisition of the image signal is sent from the measurement control unit 21, the image acquisition unit 20 acquires the image signal from the photoelectric detection units 8a and 8b, performs A / D conversion, and is necessary. Accordingly, noise removal processing or the like is performed, and image data in units of frames in which light intensity data is stored corresponding to the arrangement position of each light receiving unit is generated.
This image data is sent to the storage unit 23 and stored in the storage unit 23.
The image acquisition unit 20 is electrically connected to the display unit 11 such as a monitor, and can display the acquired image data on the display unit 11 sequentially.

The storage unit 23 is communicably connected to the image acquisition unit 20 and the calculation unit 22 and stores image data transmitted from the image acquisition unit 20, parameters necessary for calculation of the calculation unit 22, and parameters of the calculation unit 22. The calculation result is stored.
Examples of parameters necessary for calculation by the calculation unit 22 include information on the radius of curvature of the first surface 14 a and the second surface 14 b of the lens 14 to be tested and information on the diameter of the reflecting sphere 13.

Based on the control signal from the measurement control unit 21 and the image data group stored in the storage unit 23, the calculation unit 22 is based on the positions of the top surfaces of the first surface 14a and the second surface 14b in the lens 14 to be examined. Further, based on the information on the position of the surface top and information on the radii of curvature of the first surface 14a and the second surface 14b stored in advance in the storage unit 23, the surface interval of the lens 14 to be measured is calculated. Is to be calculated.
These specific calculation methods will be described in detail in the operation description to be described later.

  The device configuration of the control unit 10 is composed of a computer including a CPU, a memory, an input / output interface, an external storage device, and the like, thereby executing a control program for performing the above-described control and a calculation program for performing a calculation as described below. It has come to be.

Next, operation | movement of the surface distance measuring apparatus 100 of this embodiment is demonstrated.
FIG. 4 is a flowchart showing a measurement flow of the measurement operation using the surface distance measuring apparatus according to the first embodiment of the present invention. FIGS. 5A and 5B are schematic views for explaining the measurement principle of the inter-surface distance measuring apparatus according to the first embodiment of the present invention. FIG. 6 is a schematic graph for explaining a light intensity signal acquired by the photoelectric detection unit of the inter-surface distance measurement apparatus according to the first embodiment of the present invention. The horizontal axis represents time and the position of the light receiving unit, and the vertical axis represents the light intensity. FIG. 7 is a schematic diagram illustrating the light intensity distribution acquired by the photoelectric detection unit of the inter-surface distance measurement apparatus according to the first embodiment of the present invention. FIGS. 8A and 8B are schematic views for explaining coordinate conversion of the inter-surface distance measuring apparatus according to the first embodiment of the present invention.

  In order to measure the lens surface interval by the surface interval measuring apparatus 100, steps S1 to S6 shown in FIG. 4 are executed according to the measurement flow shown in FIG.

Step S <b> 1 is a step of placing the test lens 14 on the lens holding base 9.
In the present embodiment, as shown in FIGS. 2A and 2B, the test lenses 14A, 14B, and 14C are placed on the holding holes 9c with the first surface 14a facing upward. . Here, the range of “state facing upward” means a range in which the first surface 14a has a surface top when the first surface 14a is viewed from the normal direction of the upper surface 9a. In other words, even if the lens optical axis O _L of the lens 14 is tilted with respect to the normal of the upper surface 9a, on the first surface 14a, the tangential plane parallel to the upper surface 9a of the lens holder portion 9 Means an existing state.
For example, if the size of the inner diameter of the holding hole 9c is set to an appropriate value close to the outer diameter of the lens 14 to be tested, the second surface 14b is in contact with the entire circumference of the inner peripheral edge of the holding hole 9c. The above-mentioned “upward-facing state” is satisfied only by mounting.
Thus, step S1 is completed.

Next, step S2 is performed. This step is a step of turning on the light sources 2a and 2b and irradiating the measurement light beams L1m and L3m to the first surface 14a and the second surface 14b, respectively, in the first interference measurement unit 1a and the second interference measurement unit 1b. is there.
That is, after the step S1, the measurement controller 21 turns on the light sources 2a and 2b when the measurer performs an operation input for starting the surface interval measurement through the operation unit 12.
However, in the present embodiment, since the measurement light beams L1m and L3m are irradiated to the range covering the lens holding base 9, the respective test lenses 14 and the respective reflecting spheres 13 are irradiated.

When the light source 2a (2b) is turned on, a light beam La (Lb) is generated. The light beam La (Lb) is incident on the collimator lens 3a (3b) as divergent light, is converted into a parallel light beam by the collimator lens 3a (3b), and is converted into a parallel light beam L1 (L3) on the optical axis O ₁ (O ₃ ). move on.
When the parallel light beam L1 (L3) reaches the half mirror 4a (4b), the reference light beam L1r (L3r) that travels along the optical axis O ₁ (O ₃ ) through the half mirror 4a (4b) and the half mirror The light beam is divided into measurement light beams L1m (L3m) that are reflected by 4a (4b) and travel downward (upward) along the optical axis O ₂ (O ₄ ).

The measurement light beam L1m (L3m) reaches the upper surface 9a (lower surface 9b) of the lens holding base 9, and the first surface 14a (second surface 14b) of each lens 14 to be exposed exposed on the upper surface 9a (lower surface 9b). The surface of each reflecting sphere 13 is irradiated.
As a result, the reflected light beam L2m (L4m) reflected by the upper surface 9a (lower surface 9b), the first surface 14a (second surface 14b), and the surface of each reflecting sphere 13 of the lens holder 9 is half mirror 4a (4b). ) Side, a part of which passes through the half mirror 4a (4b) and proceeds upward (downward) along the optical axis O ₁ (O ₃ ).
On the other hand, the reference light beam L1r (L3r) reaches the reference mirror 5a (5b), the optical axis is folded back by the respective reflection planes, and reaches the half mirror 4a (4b) along the optical axis O ₁ (O ₃ ). A part thereof is reflected by the half mirror 4a (4b) and proceeds upward (downward) along the optical axis O ₂ (O ₄ ).
Therefore, a combined light beam L2c (L4c) obtained by superimposing the reflected light beam L2m (L4m) and the reference light beam L1r (L3r) is incident on the photoelectric detection unit 8a (8b) by the half mirror 4a.
This is the end of step S2.

  Since the combined light beam L2c (L4c) causes interference according to the difference in optical path length between the reflected light beam L2m (L4m) and the reference light beam L1r (L3r), the difference in the optical path length is an integral multiple of the wavelength. It has a light intensity distribution that increases the light intensity. However, the light source 2a (2b) is a low coherence light source. For this reason, when the difference in optical path length becomes 0, the light intensity increases markedly compared to non-interfering light. However, even if the optical path length difference is an integral multiple of the wavelength, interference does not easily occur if the optical path length difference increases. Thus, the light intensity rapidly approaches the light intensity of the non-interfering light.

Here, since the first surface 14a (second surface 14b) is a spherical surface, as shown in FIG. 5A, it is the optical axis O ₂ (that causes interference to return to the half mirror 4a (4b). O ₄ ) (not shown in FIG. 5A), the top surface P _a (P _b ), that is, parallel to the optical axis O ₂ (O ₄ ) and the first surface 14a (second surface 14b). The straight line O ₂ ′ (O ₄ ′) passing through the spherical center C _14a (C _14b ) and the first surface 14a (second surface 14b) are only point-like portions.
For this reason, the image captured by the photoelectric detection unit 8a (8b) is an image in which a high-intensity reflection spot is generated at the position of the surface top P _a (P _b ) where the interference has occurred.
Similarly, since the surface 13a (13b) of each reflecting sphere 13 is a spherical surface, as shown in FIG. 5B, it is the optical axis O ₂ (that causes interference back to the half mirror 4a (4b). O ₄ ) (top not shown in FIG. 5A), the apex Q _a (Q _b ), that is, the sphere center C of the surface 13a (13b) parallel to the optical axis O ₂ (O ₄ ) It is only a point-like portion where the straight line O ₂ ″ (O ₄ ″) passing through and the surface 13a (13b) intersect.

5A and 5B, for the sake of simplicity, the plane S ₀ defined by the spherical centers C ₁ , C ₂ , and C _{3 of} the reflecting spheres 13A, 13B, and 13C and the optical axes O ₂ and O ₄ even when you are orthogonal illustrates an example in which the lens optical axis O _L of the lens 14 is inclined by an angle θ with respect to the optical axis O _2, O _4.

On the other hand, since the upper surface 9a (9b) is a flat surface, if interference occurs, the entire upper surface 9a (lower surface 9b) has high brightness.
However, in the present embodiment, the upper surface 9a (9b) is not manufactured as a reflective plane having the same level of surface accuracy as the reference mirror 5a (5b), and the optical axis O ₂ (O ₄ ) has an upper surface 9a ( Neither is it strictly adjusted to be the normal of 9b).
For this reason, interference between the reflected light beam L2m (L4m) and the reference light beam L1r (L3r) on the upper surface 9a (9b) does not substantially occur.

Next, step S3 is performed. This step is a step in which the optical path length changing units 7a and 7b change the optical path lengths of the reference light beams L1r and L3r, respectively, and acquire image data by the combined light beams L2c and L4c.
The measurement control unit 21 sends a control signal to the optical path length changing unit 7a (7b), moves the moving stage 6a (6b), and sets the optical path length of the reference beam L1r (L3r) within a preset change range. Change.
In the present embodiment, as an example, the reference mirror 5a (5b) starts to move from the optical path length where the optical path length of the reference light beam L1r (L3r) becomes the optical path length of the return light reflected by the upper surface 9a (9b). Moves at a constant speed in a direction approaching the half mirror 4a to shorten the optical path length.
In that case, the measurement control part 21 acquires an image signal from the photoelectric detection part 8a (8b) by the image acquisition part 20 with a fixed space | interval.
The image acquisition unit 20 performs A / D conversion on the acquired image signal, performs noise removal processing as necessary, and generates image data. The image data is stored in the storage unit 23 in units of frames together with the time from the start of the optical path length change, and is sent to the display unit 11 to be displayed on the display unit 11.
Step S3 is complete | finished above.

  This step can be performed in parallel by independently driving the photoelectric detection units 8a and 8b of the first interference measurement unit 1a and the second interference measurement unit 1b. However, if it cannot be performed in parallel due to data transfer time or the like, for example, after acquiring image data from the first interference measurement unit 1a, image data from the second interference measurement unit 1b is obtained. It is also possible to obtain.

The image data acquired in this step is an image in which a relatively high-intensity reflection spot appears at the site where interference has occurred.
If the elapsed time from the start of changing the optical path length is t, the image changes according to the time t. For example, as shown in FIG. 7A, at t = t ₁ , a reflection spot appears due to reflection at the top Q _2a of the first surface 14a of the reflection sphere 13B.
Reflective spheres 13A, 13B, @ 13 C is, is strictly positioned parallel to the upper surface 9a of the lens holder 9, and the optical axis _{O 2} of the first interference measurement part 1a is, if parallel to the normal of the upper surface 9a The height of each surface 13a of the reflecting spheres 13A, 13B, 13C measured from the upper surface 9a is equal. For this reason, reflection spots at the tops Q _1a and Q _2a of the reflecting spheres 13A and 13C should also appear.
However, when there is a manufacturing error of the lens holding base 9 or an alignment error with the first interference measuring unit 1a, the height of each surface 13a of the reflecting spheres 13A, 13B, and 13C varies. Appear in ascending order.
The same applies to the reflection spots due to reflection at the first surface 14a, for example, the t = _{t 4,} as shown in FIG. 7 (b), appear reflective spots due to reflection at the surface apex _{P 1a} of the lens 14A .

As can be seen from the description of steps S2 and S3, the half mirror 4a (4b) uses the parallel light beam L1 (L3) formed by the collimator lens 3a (3b) as the measurement light beam L1m (L3m) and the reference light beam L1r (L3r). The light beam splitting unit is configured to split into two.
The half mirror 4a (4b) has the optical path length changed by the reflected light beam L2m (L4m) reflected by the test lens 14 in the measurement light beam L1m (L3m) and the optical path length changing unit 7a (7b). A light beam combining unit that forms the combined light beam L2c (L4c) by superposing the reference light beam 1r (L3r) is configured.

Next, step S4 is performed. This step is a step of measuring the change in the light intensity distribution from each image data and detecting the peak generation position and generation timing of the light intensity due to interference.
In the following, for simplicity, an example based on image data acquired from the photoelectric detection unit 8a will be described. From the following description, the arithmetic processing based on the image data acquired from the photoelectric detection unit 8b can be easily understood.

When the change of the light intensity distribution appearing in the image data described above is plotted for each light receiving unit of the photoelectric detection unit 8a, for example, as shown in FIG. 6, there is a peak in a slight time width in which interference occurs. A graph of light intensity is obtained.
In the example of FIG. 6, at times t ₁ , t ₂ , and t ₃ (where t ₁ <t ₂ <t ₃ ) that have a slight time difference from each other, due to reflection of the tops Q _2a , Q _1a , and Q _3a , respectively. A peak corresponding to the reflected spot appears.
Further, at times t ₄ , t ₅ , and t ₆ (time t ₄ <t ₅ <t ₆ ) at which time has further elapsed than time t ₃ , the reflection is caused by reflection of the tops P _1a , P _2a , and P _3a , respectively. A peak corresponding to the reflected spot appears.
Here, the time at which the peak of the light intensity signal occurs (hereinafter referred to as peak occurrence time) corresponds to the change in the optical path length, corresponding to the timing at which the strongest interference occurs at each light receiving part position. This corresponds to an optical path length that is twice the amount of movement of the reference mirror 5a. Accordingly, the movement speed of the reference mirror 5a, the optical path length of each time difference, i.e., it is possible to calculate the distance between the vertex each other along the optical axis O _2.
The difference in peak occurrence time between the tops Q _1a , Q _2a , and Q _3a represents a relative position shift between the lens holding base 9 and the first interference measuring unit 1a, and the reflection spheres 13A, 13B, and 13C Since the arrangement position is known, it is possible to calculate the deviation of the relative position.

Therefore, the measurement control unit 21 sends a control signal to the calculation unit 22 so as to detect the light intensity peak generation position due to interference and the light intensity peak generation timing.
The calculation unit 22 detects the peak position of the light intensity from the data indicating the change in the light intensity distribution for each light receiving unit as shown in FIG. 6, and obtains t _{1 to} t ₆ as the occurrence timing of interference. At this time, the peak occurrence position in the direction orthogonal to the optical axis O ₂ is obtained by converting the arrangement of the light receiving parts into the actual dimensions on the upper surface 9a.
Above, step S4 is complete | finished.

Next, step S5 is performed. This step is a step of calculating information on the positions of the top surfaces of the first surface 14a and the second surface 14b from the peak generation position and generation timing detected in step S4.
For simplicity, it is assumed that information on the surface apex P _1a of the first surface 14a of the lens 14A to be measured is calculated, and the peak occurrence position obtained in step S4 is represented by (x, y), which is also the occurrence timing of interference. the height of the surface apex obtained from t ₄ and z '.

In this step, first, from the time t ₁ , t ₂ , t ₃ representing the occurrence timing of the peak of the light intensity based on the interference due to the reflection of each reflection sphere 13, the reflection spheres 13 A, 13 B, 13 C with respect to the optical axis O ₂ The inclination φ of the plane S ₀ defined by the sphere centers C ₁ , C ₂ , and C ₃ is calculated (see FIG. 8B).

For example, as shown in FIGS. 8A and 8B, the plane S ₀ is around the rotation axis R extending in the depth direction of the paper with respect to the plane S ₀ ′ assumed from the arrangement of the surface interval measuring device 100. Suppose that it is rotated by an angle φ.
In this case, for example, the height z ′ of the surface apex P _1a ′ determined from the time t ₄ representing the generation timing of the peak of the light intensity based on the interference due to the reflection of the first surface 14a of the lens 14A to be measured is the plane S ₀ ′. The height is against.
However, since the actual plane S ₀ is inclined by φ with respect to the plane S ₀ ′, the true plane apex P _1a where interference occurs is the plane apex P _1a determined from the arrangement of the inter-plane distance measuring device 100. It is a surface apex P _1a (x, y, z) different from '. Here, the coordinate (x, y) is a position obtained by converting the arrangement position of the light receiving unit of the photoelectric detection unit 8a into an actual dimension on the upper surface 9a. Further, z is a z 'according to the amount of rotation of the plane S ₀ phi, is obtained by converting the height from the plane S _0.
The origin of the position coordinates can be set as appropriate. For example, one of the reflecting spheres 13 can be set as the origin.
In this way, position coordinates (x, y, z) are obtained as information on the position of the surface apex P _1a .

Similarly, the position coordinates of the true surface apexes P _2b and P _3a at which interference occurs in the test lenses 14B and 14C are calculated from the peak generation position of the other first surface 14a and the generation timing.
Further, based on the image data acquired from the photoelectric detection unit 8b, the position coordinates of the surface apexes P _1b , P _2b , and P _3b where interference occurs on the second surface 14b are calculated.
At this time, the coordinate system is the same coordinate system as the coordinate system used to calculate the tops P _1a , P _2a , and P _3a .
This is the end of step S5.

In this way the step S5, the corrected inclination φ of the plane S _0, the first surface 14a of the test lens 14, the position coordinates of the vertex of the second surface 14b is described in a common coordinate system. That is, the position coordinates of each surface apex is to the plane S ₀ and xy plane, is described an axis perpendicular to the plane S ₀ in xyz coordinate system with z.
Therefore, for example, as shown in FIGS. 5 (a) and 5 (b), the position coordinates of the tops of the surfaces are determined by the first interference measuring unit 1a and the second interference measuring unit 1b and the lens holding base unit 9. It is converted into a measurement value similar to the measurement value when the position is accurately aligned in advance.
Accordingly, the following description will be given with reference to FIGS. 5A and 5B unless otherwise specified.

Next, step S6 is performed. In this step, the surface interval between the first surface 14a and the second surface 14b is calculated based on the information on the top positions of the first surface 14a and the second surface 14b and the information on the curvature radius of each surface. It is a process to do.
As shown in FIG. 5 (a), when the test lens 14 is inclined by an angle θ with respect to the plane S _0, a surface apex P _a interference _occurs, P _b is offset from the lens optical axis O _L .
In the following description, the position coordinates of the surface apexes P _a and P _b calculated in step S5 are (x _a , y _a , z _a ) and (x _b , y _b , z _b ), respectively, and the first surface 14a, Let the radius of curvature of the second surface 14b be R _a and R _b . However, the sign of each radius of curvature is determined according to the unevenness, and has a positive value when convex in the positive direction of the z axis and a negative value when concave in the positive direction of the z axis.
The lens optical axis _{O L} a first surface 14a, the point at which the second surface 14b intersect each point _{P 0a,} and _{P 0b.}

The surface interval d is calculated as a distance between these two points by calculating the position coordinates of the points P _0a and P _0b by the calculation unit 22. Hereinafter, an example of this calculation method will be described.
Coordinates of the spherical center _{C 14a} of the first surface 14a, by using the curvature radius _{R a} of the first surface _14a, is expressed as _{(x a, y a, z} a -R a).
Coordinates of the spherical center _{C 14b} of the second face 14b, by using the curvature radius _{R b} of the second face _14b, is expressed as _{(x b, y b, z} b -R b).
Accordingly, a straight line along the spherical center _{C 14a,} lens optical axis _{O L} through the _{C 14b,} using the parametric k, can be expressed by the following equation (1) to (5).
The curvature radius R _a of the first surface 14 _a and the curvature radius R _b of the second surface 14 _b are stored in the storage unit 23 in advance. For this reason, the calculating part 22 reads these curvature radii from the memory | storage part 23, and uses them for calculation.

x = (1-k) · x _a + x _b (1)
y = (1-k) .y _a + y _b (2)
z = (1-k) · z _a ′ + z _b ′ (3)
z _a ′ = z _a −R _a (4)
z _b ′ = z _b −R _b (5)

  The spherical equations of the first surface 14a and the second surface 14b can be expressed by the following equations (6) and (7).

^{_{(X-x a) 2 +}} (y-y a) 2 + (z-z a ') 2 = R a 2 ··· (6)
^{_{(X-x b) 2 +}} (y-y b) 2 + (z-z b ') 2 = R b 2 ··· (7)

Therefore, the position coordinates of the points P _0a and P _0b can be obtained by solving a quadratic equation relating to k obtained by substituting the equations (1) to (3) into the equations (6) and (7).
That is, when the expressions (1) to (3) are substituted into the expression (6), the following expressions (8), (9), (10), and (11) are obtained.

A · k ² + B · k + C = 0 (8)
A = x _a ² + y _a ² + z _a ′ ² (9)
B = −2 · (x _a · x _b + y _a · y _b + z _a '· z _a ') (10)
_{^{C = x b 2 + y b}} 2 + z b '2 -R a 2 ··· (11)

  Further, when Expressions (1) to (3) are substituted into Expression (7), the following Expressions (12), (13), (14), and (15) are obtained.

D · k ² + E · k + F = 0 (12)
D = x _a ² + y _a ² + z _a ′ ² (13)
E = −2 · (x _a ² + y _a ² + z _a ′ ² ) (14)
F = x _a ² + y _a ² + z _a ′ ² −R _b ² (15)

Solving equation (8) yields k ₁ and k ₂ shown in the following equations (16) and (17). Solving equation (12) solves k ₃ and k in equations (18) and (19) below. k ₄ is obtained.

k ₁ = {− B + √ (B ² −4 · A · C)} / 2 · A (16)
k ₂ = {− B−√ (B ² −4 · A · C)} / 2 · A (17)
k ₃ = {− E + √ (E ² −4 · D · F)} / 2 · D (18)
k ₄ = {− E−√ (E ² −4 · D · F)} / 2 · D (19)

Next, the above k ₁ and k ₂ are substituted into the above (1), (2), and (3) to obtain two position coordinates that are candidates for the point P _0a , and the above k ₃ and k ₄ are Substituting into the above (1), (2), and (3), two position coordinates that are candidates for the point P _0b are obtained.
Next, the distance between the two points is determined by using the two position coordinates that are candidates for the point P _{0a and} the two position coordinates that are candidates for the point P _0b , respectively, and the position where the distance between the two points is smaller. The combination of coordinates is the points P _0a and P _0b to be obtained. The distance between the two points is the surface interval d.
When the calculation unit 22 calculates the surface interval d in this manner, the calculation unit 22 stores the surface interval d in the storage unit 23.

When the calculation of the surface distance d of the test lens 14A is thus completed, the surface distance d of the test lenses 14B and 14C is calculated in the same manner and stored in the storage unit 23 in the same manner.
After calculating the surface distances of all the test lenses 14 on the lens holding base 9 in this way, the calculation unit 22 reads the calculated surface distances d of the respective test lenses 14 from the storage unit 23 and displays them. The data is sent to the unit 11 and displayed on the display unit 11.
Thus, step S6 is finished, and the face distance measurement by the face distance measuring apparatus 100 is finished.

Thus, in this embodiment, the calculating part 22 is the 1st surface 14a and 2nd surface which interference generate | occur | produced from the time change of the light intensity distribution of the synthetic light beams L2c and L4c measured by the photoelectric detection parts 8a and 8b. 14b surface apex P _a, it constitutes the surface apex position calculating unit that calculates information of position of P _b.
The arithmetic unit 22 includes a first surface 14a, a surface apex _P a was calculated by the vertex position calculation unit with respect to the second surface 14b, a data position _{P b,} the first surface 14a obtained in advance, the second the radius of curvature R _a of the surface _14b, on the basis of the information of R _b, constitutes the first face 14a in the direction along the lens optical axis O _L, a surface distance calculating unit that calculates the surface spacing between the second surface 14b ing.

As described above, according to the inter-surface distance measuring apparatus 100, the surface of the first surfaces 14a and 14b of the lens 14 to be measured is detected by detecting the occurrence position of the interference due to the low-coherence light and the generation timing of the peak of the light intensity. Gets top _P a, the positional information of the _{P b,} the surface apex _P a, the first surface 14a obtained in advance the position information of the _{P b,} 14b a curvature radius _R a of, based on the information of _{R b,} Since the surface distance d is calculated, the surface distance d can be measured without adjusting the eccentricity of the lens 14 to be examined.
Furthermore, a plurality of test lenses 14 can be placed on the lens holding base 9 and the surface distance d can be measured simultaneously.
Since the test lens 14 only needs to be placed on the lens holder 9, the test lens 14 can be quickly replaced. Thereby, measurement efficiency can be improved.

[Second Embodiment]
Next, a surface interval measuring apparatus according to a second embodiment of the present invention will be described.
FIG. 9 is a schematic configuration diagram showing the configuration of the inter-surface distance measuring apparatus according to the second embodiment of the present invention. FIG. 10 is a block diagram showing the configuration of the control unit of the surface distance measuring apparatus according to the second embodiment of the present invention.

As shown in FIG. 9, the surface distance measuring device 110 of this embodiment is a device that measures the surface space of the lens 14 to be measured in the same manner as the surface distance measuring device 100 of the first embodiment.
The surface interval measuring device 110 adds a first position adjusting unit 31a (moving unit) and a second position adjusting unit 31b (moving unit) to the surface interval measuring device 100 of the first embodiment, and measures the surface interval. A control unit 30 is provided instead of the control unit 10 of the apparatus 100.
Hereinafter, a description will be given centering on differences from the first embodiment.

The first position adjustment unit 31a (second position adjustment unit 31b) moves relative to the lens holding table 9 of the first interference measurement unit 1a (second interference measurement unit 1b), and the lens holding table. It is a moving part that adjusts the position and orientation relative to the part 9.
In the present embodiment, the first position adjustment unit 31a (second position adjustment unit 31b) moves the first interference measurement unit 1a (second interference measurement unit 1b) in the horizontal two-axis direction. It consists of a combination of a stage and a tilting stage that tilts the attitude of the first interference measuring unit 1a (second interference measuring unit 1b) with respect to the vertical axis.
The first position adjustment unit 31a (second position adjustment unit 31b) is communicably connected to the control unit 30, and based on a control signal from the control unit 30, the first interference measurement unit 1a (second position adjustment unit 31a). The interference measuring unit 1b) is moved.

  As shown in FIG. 10, the control unit 30 includes a movement control unit 42 added to the control unit 10 of the first embodiment, and includes a measurement control unit 41 instead of the measurement control unit 21.

The movement control unit 42 is a first position adjustment unit based on the positions of the respective reflecting spheres 13 detected by the photoelectric detection units 8a and 8b of the first interference measurement unit 1a and the second interference measurement unit 1b. The operation of 31a and the second position adjustment unit 31b is controlled to adjust the position of the first interference measurement unit 1a and the second interference measurement unit 1b with respect to the lens holding base unit 9.
For this reason, the movement control part 42 is connected so that communication is possible with the calculating part 22, the 1st position adjustment part 31a, and the 2nd position adjustment part 31b.

Similar to the measurement control unit 21 of the first embodiment, the measurement control unit 41 controls the entire measurement operation of the surface distance measurement device 110 based on the operation input of the measurer. However, prior to the measurement of the surface spacing, the position adjustment operation control for the lens holding base 9 of the first interference measuring unit 1a and the second interference measuring unit 1b is performed with reference to the position of the reflecting sphere 13 as a reference. This is different from the first embodiment.
The control performed by the measurement control unit 41 will be described in the explanation of the operation of the surface distance measuring device 110.

Next, operation | movement of the surface distance measuring apparatus 110 of this embodiment is demonstrated.
FIG. 11 is a flowchart showing a measurement flow of a measurement operation using the inter-surface distance measurement apparatus according to the second embodiment of the present invention.

  In order to measure the lens surface interval by the surface interval measuring device 110, steps S11 to S20 shown in FIG. 11 are executed according to the measurement flow shown in FIG.

  Step S11 is the same as step S1 in the first embodiment.

Next, step S12 is performed. In this step, the light sources 2a and 2b are turned on in the first interference measurement unit 1a and the second interference measurement unit 1b, and the measurement light beams L1m and L3m are applied to the surfaces 13a and 13b of the reflecting spheres 13, respectively. is there.
However, the first interference measurement unit 1a and the second interference measurement unit 1b in the surface distance measurement device 110 are separated from the lens holding base unit 9 by the first position adjustment unit 31a and the second position adjustment unit 31b. The only difference is that it is held movable.
For this reason, also in this step, if the light sources 2a and 2b are simply turned on, the surfaces 13a and 13b of the reflecting spheres 13 are also irradiated with the measurement light beams L1m and L3m.
Above, step S12 is complete | finished.

Next, step S13 is performed. In this step, the range in which the measurement control unit 41 changes the optical path lengths of the reference light beams L1r and L3r by the optical path length changing units 7a and 7b is a range in which all images of reflection spots of interference by only the reflecting spheres 13 are acquired. Except for this point, the steps are the same as step S3 of the first embodiment.
Next step S14 is performed. In this step, the measurement control unit 41 causes the calculation unit 22 to detect the light intensity peak generation position and the light intensity peak generation timing due to the interference between the reflected light beam and the reference light beam at each reflection sphere 13. Except for this, the steps are the same as step S4 of the first embodiment.

Next, step S15 is performed. In this step, the relative position between the interference measuring unit and the lens holder is determined from the light intensity peak generation position caused by the interference between the reflected light beam and the reference light beam at each reflecting sphere 13 and the light intensity peak generation timing. This is a step of calculating and aligning the first interference measuring unit 1 a and the second interference measuring unit 1 b with respect to the lens holding base unit 9.
In this step, similarly to step S5 of the first embodiment, the calculation unit 22 causes the light intensity peak generation position (x, y) and the light intensity peak based on the interference caused by the reflection of each reflecting sphere 13 to be detected. From the times t ₁ , t ₂ , and t ₃ representing the occurrence timing, the inclination φ of the plane S ₀ defined by the spherical centers C ₁ , C ₂ , and C ₃ of the reflecting spheres 13A, 13B, and 13C with respect to the optical axis O ₂ (See FIG. 8B), and the position coordinates of the ball centers C ₁ , C ₂ , C ₃ are calculated.
The calculation unit 22 sends the inclination φ of the surface S ₀ and the position coordinates of the sphere centers C ₁ , C ₂ , and C ₃ to the movement control unit 42.

In the movement control unit 42, a control signal for changing the postures of the first interference measurement unit 1a and the second interference measurement unit 1b so that the inclination φ of the plane S0 sent from the calculation unit 22 is set to ₀ , The data is sent to the first position adjusting unit 31a and the second position adjusting unit 31b.
Next, the movement control unit 42 uses lenses of the first interference measurement unit 1a and the second interference measurement unit 1b with reference to the position coordinates of the ball centers C ₁ , C ₂ and C ₃ sent from the calculation unit 22. A control signal for performing horizontal alignment with respect to the holding base 9 is sent to the first position adjusting unit 31a and the second position adjusting unit 31b.
Thus, the position and attitude with respect to the lens holder portion 9 of the first interference measurement part 1a and the second interference measurement unit 1b is adjusted, the plane S ₀ and the optical axis O _2, O ₄ are orthogonal photoelectric detector The positions of the light receiving portions in the horizontal direction in 8a and 8b are aligned with the positions facing each other.
Step S15 is complete | finished above.

Next, step S16 is performed. This step is a step of irradiating the first surface 14a and the second surface 14b with the measurement light beams L1m and L3m in the first interference measurement unit 1a and the second interference measurement unit 1b, respectively.
In the present embodiment, as in the first embodiment, the measurement light beams L1m and L3m are irradiated on the respective test lenses 14 together with the respective reflecting spheres 13, so that the light sources 2a and 2b are turned on even after the end of step S13. If it is lit, no new action is required.
If the light sources 2a and 2b are turned off before the start of this step, the light sources 2a and 2b are turned on by the measurement control unit 41 in this step.

Next, step S17 is performed. In this step, image data is acquired in substantially the same manner as in step S3 of the first embodiment, but the peak of the light intensity due to the interference of reflection on the first surface 14a and the second surface 14b of each lens 14 to be examined. The difference is that image data in a range in which detection of the image can be detected is obtained.
For example, since the position of each reflecting sphere 13 is measured in step S15, in this step, it is possible to acquire image data that masks an image outside the range where the lens 14 is arranged.
Further, the range in which the optical path length is changed by the optical path length changing units 7a and 7b can be changed only in the range where the top surfaces of the first surface 14a and the second surface 14b of each lens 14 are present.
Thus, in this step, since the amount of image data and the change range of the optical path length can be reduced as compared with the case where an image of interference due to reflection by each reflection sphere 13 is acquired, more rapid measurement can be performed. It becomes possible.

Next, step S18 is performed. This step is the above except that only the light intensity peak generation position and the light intensity peak generation timing due to the interference of reflection on the first surface 14a and the second surface 14b of each lens 14 are detected. This is the same as step S4 in the first embodiment.
Also in this step, the calculation time can be reduced as compared with the case where the peak generation position and generation timing of the light intensity due to the interference of reflection from each reflection sphere 13 is acquired, so that more rapid measurement is possible. .

Next, step S19 is performed. This step is a step of calculating information on the positions of the top surfaces of the first surface 14a and the second surface 14b from the peak generation position and generation timing detected in step S18.
In this embodiment, since the positions and postures of the first interference measurement unit 1a and the second interference measurement unit 1b with respect to the lens holding base unit 9 have been adjusted in step S15, the peak occurrence position detected in step S18 The height of the surface top based on the generation timing is the position coordinates (x, y, z) of the surface top as it is.

Next, step S20 is performed. This step is exactly the same as step S6 of the first embodiment.
Thereby, similarly to the first embodiment, the surface distance d of each lens 14 is calculated and displayed on the display unit 11.
Thus, step S20 is completed, and the measurement of the surface interval by the surface interval measuring device 110 ends.

According to the surface distance measuring device 110, as in the first embodiment, the surface distance can be measured without adjusting the decentering of the test lens, and a plurality of test lenses can be measured simultaneously. become.
In particular, in the surface distance measuring apparatus 110, the position adjustment of the first interference measuring unit 1a and the second interference measuring unit 1b with respect to the lens holding base unit 9 is performed by performing steps S12 to S15. For this reason, while the position adjusted in this way is maintained, the measurement can be continued by replacing another lens 14 without performing steps S12 to S15 again. Thereby, the measurement after the 2nd time only needs to perform step S11, S16-S20.
For this reason, measurement efficiency can be improved especially when measuring the surface interval of many test lenses 14 continuously.
Further, since the surface interval measuring device 110 automatically determines the position adjustment of the first interference measurement unit 1a and the second interference measurement unit 1b based on the position measurement of each reflecting sphere 13, the position adjustment is performed quickly. Therefore, it is possible to easily perform measurement with good measurement accuracy.

In the description of each of the above embodiments, the example in which the reference position reference unit includes the three reflecting spheres 13 has been described. However, if the reference position reference unit can specify the posture and position of the lens holding base unit 9, Four or more may be provided.
The shape of the reference position reference portion is not limited to a sphere, and a reflector having a shape such as a hemisphere, an ellipsoid, or a protrusion having a minute flat reflection surface at the tip may be used. The reflecting surface is not limited to a convex surface, and may be a concave surface.
If the positional relationship between the reflecting surface on the upper surface 9a side and the reflecting surface on the lower surface 9b side is known, each reflector may be arranged separately on the upper surface 9a and the lower surface 9b.

In the description of each of the above embodiments, an example in which the first interference measurement unit 1a and the second interference measurement unit 1b have the light sources 2a and 2b has been described. However, the light sources 2a and 2b have a single low coherence. It is also possible to use a configuration in which a light beam from a light source is branched by an optical fiber or the like.
In this case, the interval between each interference measurement unit is set so that the photoelectric detection unit does not detect an interference signal generated by superimposing the measurement beam irradiated from one of the interference measurement units and the measurement beam irradiated from the other of the interference measurement units. And the moving range of the reference mirror is set appropriately.

In the description of the first embodiment, the example in which the reflection sphere 13 is provided as the reference position reference unit has been described. However, the lens holding base unit 9, the first interference measurement unit 1a, and the second interference are previously described. If the alignment with the measurement unit 1b is performed with alignment accuracy that requires alignment, a configuration in which the reference position reference unit is deleted is also possible.
In this case, the surface distance measurement operation may be performed in this order in steps S11 and S16 to S20 in the second embodiment.

In the description of the second embodiment, the first position adjusting unit 31a and the second position adjusting unit 31b are respectively connected to the lens holding base unit 9 of the first interference measuring unit 1a and the second interference measuring unit 1b. Although the example in the case of adjusting the position and orientation has been described, the position adjustment mechanism only needs to include an adjustment mechanism in a direction that requires adjustment.
For example, when the inclination of the optical axis can be easily adjusted to the required accuracy by assembly adjustment, a configuration in which the posture adjustment mechanism is omitted and only the movement in the horizontal direction can be adopted.

In each of the above embodiments, the optical path length changing unit has been described as an example of changing the optical path length by changing the position of the reference mirror that reflects the reference light beam. However, if the optical path length can be changed, the optical path can be changed using other means. It is also possible to change the length.
For example, instead of the reference mirror, for example, a reflecting member other than a plane mirror such as a corner cube may be used.

In each of the above embodiments, the example in which two interference measurement units are arranged with the lens holding base 9 interposed therebetween has been described. However, by moving the interference measurement unit relative to the lens holding base 9, If the measurement on the 9a side and the measurement on the lower surface 9b side are sequentially performed by one interference measurement unit, a configuration having only one interference measurement unit is also possible.
In addition, when one surface of the lens 14 to be tested is a spherical lens having a flat surface, a lens plane is arranged on the lens holding base 9, and the position of the top of the spherical surface is measured with reference to the lens plane. Thus, it is possible to measure the surface spacing.

  In addition, all the components described in the above embodiments can be implemented by appropriately changing or deleting combinations within the scope of the technical idea of the present invention.

1a First interference measurement unit (interference measurement unit)
1b Second interference measurement unit (interference measurement unit)
2a, 2b Light source 3a, 3b Collimator lens 4a, 4b Half mirror (beam splitting unit, beam combining unit)
5a, 5b Reference mirrors 6a, 6b Moving stages 7a, 7b Optical path length changing units 8a, 8b Photoelectric detection unit 9 Lens holding base unit 10, 30 Control units 13, 13A, 13B, 13C Reflecting sphere (reference position reference unit)
14, 14A, 14B, 14C Test lens (spherical lens)
14a First surface (lens surface)
14b Second surface (lens surface)
20 Image acquisition unit 21, 41 Measurement control unit 22 Calculation unit (surface top position calculation unit, surface interval calculation unit)
23 Storage unit 31a First position adjustment unit 31b Second position adjustment unit 42 Movement control unit 100, 110 Inter-spacing measurement device L1, L3 Parallel beam L1m, L3m Measurement beam L1r, L3r Reference beam L2c, L4c Composite beam L2m, L4m Reflected light beam La, Lb Light beam (low coherence light)
O ₁ , O ₂ , O ₃ , O ₄ Optical axis OL Lens optical axis P _a , P _b , P _1a , P _2a , P _3a , Q _a , Q _b , Q _1a , Q _2a , Q _3a surface top R _a , R _b curvature radius S ₀ plane

Claims (7)

A surface interval measuring device for measuring a surface interval of a lens to be measured comprising a spherical lens,
A light source that generates low coherence light;
A collimator lens for converting the light beam from the light source into a parallel beam;
A light beam splitting unit that splits the parallel light beam formed by the collimator lens into a measurement light beam and a reference light beam;
A lens holder that is disposed on the optical path of the measurement light beam and holds the test lens;
An optical path length changing unit for changing an optical path length of the reference light beam;
A light beam combining unit that forms a combined light beam by superimposing a reflected light beam reflected by the test lens among the measurement light beam and the reference light beam whose optical path length has been changed by the optical path length changing unit;
A photoelectric detector that measures a change in light intensity distribution of the combined light beam due to interference caused by an optical path length change of the reference light beam by the optical path length changing unit;
A surface apex position calculation unit that calculates information on the position of the surface of the lens surface of the lens in which the interference has occurred, from the time change of the light intensity distribution of the combined light beam measured by the photoelectric detection unit;
Based on the information on the position of the surface apex calculated by the surface apex position calculation unit with respect to the two lens surfaces of the lens to be tested and the information on the radius of curvature of the two lens surfaces acquired in advance, A surface interval calculator that calculates a surface interval between the two lens surfaces in the direction along the lens optical axis of the lens;
A surface interval measuring device comprising: The lens holder is
Comprising at least three reference position reference parts detectable by the photoelectric detection part;
The surface top position calculation unit
2. The surface interval measuring device according to claim 1, wherein the information on the position of the top of the surface is calculated based on the position of the reference position reference unit detected by the photoelectric detection unit. The reference position reference unit is
The inter-surface distance measuring apparatus according to claim 2, comprising three reflecting spheres. The interference measurement unit having the light source, the collimator lens, the light beam splitting unit, the optical path length changing unit, the light beam combining unit, and the photoelectric detection unit,
A first interference measurement unit disposed opposite to one of the two lens surfaces of the test lens across the lens holding base, and opposite to the other of the two lens surfaces of the test lens A second interferometric measurement unit arranged,
The surface top position calculation unit
One of the two lens surfaces on which interference has occurred is obtained from a temporal change in the light intensity distribution of the combined light beam measured by the photoelectric detection unit of each of the first interference measurement unit and the second interference measurement unit. 2. The inter-surface distance measuring apparatus according to claim 1, wherein information on a position of a surface top and information on a position of the other surface top of the two lens surfaces are calculated. The lens holder is
Comprising at least three reference position reference units that can be detected by the photoelectric detection units of each of the first interference measurement unit and the second interference measurement unit;
In each of the first interference measurement unit and the second interference measurement unit,
5. The surface according to claim 4, wherein the surface top position calculation unit calculates information on the position of the surface top on the basis of the position of the reference position reference unit detected by the photoelectric detection unit. Distance measuring device. The reference position reference unit is
The inter-surface distance measuring device according to claim 5, comprising three reflective spheres. A moving unit that independently moves the first interference measuring unit and the second interference measuring unit with respect to the lens holding base;
A reference position reference unit that is provided in at least three of the lens holding base unit and can be detected by the photoelectric detection unit of each of the first interference measurement unit and the second interference measurement unit;
The operation of the moving unit is controlled based on the position of the reference position reference unit detected by the photoelectric detection unit of each of the first interference measurement unit and the second interference measurement unit, and the first interference measurement unit and the second interference measurement unit are controlled. A movement control unit for adjusting the position of the interference measurement unit and the second interference measurement unit with respect to the lens holding base unit;
The surface interval measuring device according to claim 4, comprising:

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