JPH09257643A - Lens meter - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a lens meter. A lens meter according to the present invention includes a measurement light projecting system 10A for projecting a measurement light beam Pi onto a lens 6 to be measured.
And a measurement light receiving system 10B having a light receiving sensor 17b for receiving the measurement light beam Pi after passing through the lens to be inspected, and a measurement light beam P after passing through the lens to be inspected detected by the light receiving sensor 17b.
Measuring means for measuring the power distribution of the lens 6 to be measured by obtaining the power at each position of the surface of the lens 6 to be measured based on the displacement amount of i, the measuring light projecting system 10A and the measuring light receiving system 1
0B and at least one of the measurement optical paths 10C that can be inserted into and removed from the measurement optical path 10C, and have a known diopter and different diopters, and drive control for selecting the measurement auxiliary lenses 18 and inserting them into the measurement optical path 10C. And means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring light projecting system for projecting a measuring light beam onto a lens to be measured, and a measuring light receiving system for receiving a measuring light beam after passing through the lens to be tested, which is provided with a light receiving sensor. The present invention relates to an improvement of a lens meter that measures a power distribution by obtaining the power at each position on the surface of the lens to be measured based on the amount of displacement of the measurement light beam after passing through the lens to be detected detected by the light receiving sensor.

[0002]

2. Description of the Related Art Conventionally, an examiner sets a lens to be inspected on a lens receiver, causes a measurement light beam from a light source section of a measurement light projecting system to enter the lens to be inspected, and the measurement light beam after passing through the lens to be inspected. There is known a lens meter that detects the amount of displacement of a light receiving sensor and measures the diopter at that position on the surface of the lens to be tested based on the detection result. In recent years, progressive multifocal lenses and distance-use aspherical lenses have become widely used as spectacle lenses, and along with this, measuring the change in the power at each position of the surface of the lens to be tested, that is, the power distribution, Although it is desired to measure, in this conventional lens meter, the examiner manually moves the lens to be inspected one by one in a plane orthogonal to the optical axis to read the power at that position. There is also a lens meter of this type having a mechanism for driving a lens to be tested with respect to a lens receiver. Furthermore, a lens meter that measures a two-dimensional power distribution of the lens to be inspected by projecting a parallel light beam as a measurement light beam onto the lens to be inspected and observing moire fringes based on the displacement of the light beam transmitted through this lens is also known. Has been.

[0003]

However, the conventional lens meter in which the examiner manually moves the lens to be inspected to measure the dioptric power at each position of the surface is inexpensive, but the measurement is troublesome. There is. Further, the lens meter having a drive mechanism for automatically moving the lens to be inspected in a plane orthogonal to the optical axis has a problem that the mechanical structure is complicated and the cost is high. Further, in a lens meter that measures a frequency distribution by observing moire fringes, it takes time to analyze the moire fringes, and there is a problem that the frequency distribution cannot be measured quickly.

In order to solve the above-mentioned problems, the applicant of the present invention provides a measurement light projection system with a microlens array as an optical member for forming a large number of measurement light beams which are two-dimensionally arranged. I applied for a lens meter that is a light source and that does not require a mechanical drive unit and that can measure the power distribution of each position on the surface of the lens under test in a short time (see Japanese Patent Application No. 7-189289). .

In the case of a lens meter having a structure in which a large number of measuring light fluxes arranged two-dimensionally are arranged between the light source unit and the lens to be inspected, the lens to be inspected has a negative negative power. In the case where the measurement light beam has a part, a part of the measurement light beam may protrude from the light receiving area of the light receiving sensor. In such a case, a part of the power distribution of the lens under test may be missing, and an accurate power distribution cannot be obtained. There is an inconvenience. Further, when the lens to be inspected has a strong positive power, the measurement light fluxes cross each other, and in this case also, there is the inconvenience that an accurate power distribution cannot be measured.

In the invention disclosed in Japanese Patent Application No. 7-189289, in order to solve this inconvenience, a liquid crystal shutter having a measurement light flux transmission window formed of a transmission light shielding region is provided, and the measurement light flux transmission window is opened and closed in order. By this, the correspondence between the position of the measurement light beam on the light receiving sensor and the position on each surface of the lens to be inspected is given. The configuration of using this liquid crystal shutter to prevent the measurement light flux from protruding from the light receiving area of the light receiving sensor and avoiding the intersection of the measurement light flux has a problem that the control is complicated and the cost becomes high as a whole.

[0007] Therefore, the applicant of the present application has proposed a technique for inserting and removing a measurement auxiliary lens having a known dioptric power into and out of a measurement optical path in order to easily measure a lens to be inspected having a strong power on November 13, 1995. The date was filed as "Invention title: Lens meter (Japanese Patent Application No. 7-294436)".

However, the above-mentioned Japanese Patent Application No. 7-29443.
In the invention disclosed in No. 6, if the measurement auxiliary lens is manually inserted into and removed from the measurement optical path, it is necessary to prepare a plurality of measurement auxiliary lenses having different powers according to the power of the lens to be inspected. However, it is troublesome to insert and remove the measurement auxiliary lens into and from the measurement optical path, and the reliability of the measurement cannot be maintained unless the insertion position of the measurement auxiliary lens in the measurement optical path is substantially constant. Further, the measurement auxiliary lens, from the viewpoint of being able to perform the measurement of the test lens having a positive power of the intensity accompanied by the intersection of the measurement light beam,
From the viewpoint of enabling measurement of a lens to be inspected having a negative power of intensity by using a measurement auxiliary lens having a small diameter as much as possible, it is desirable to insert the lens into the measurement optical path as close as possible to the lens to be inspected.

Therefore, it is desirable that the measurement auxiliary lens is automatically inserted and removed, but under the above request, the glasses shown in FIGS. 1 (a) and 1 (b). Like the lens 1A, the lens 1C as the lens to be inspected, which is mounted on the frame 1B, is mounted on the frame 1B, and the measurement auxiliary lens is automatically selected and inserted into the measurement optical path in the commercially available lens meter. When the insertion / removal mechanism is adopted, the width of the measurement light path of the measurement light receiving system is a predetermined width W from the viewpoint of preventing the measurement light beam from being eclipsed by the chord 1D of the frame 1B.
Since the following is set, the insertion / removal space of the measurement auxiliary lens is restricted, and a plurality of measurement auxiliary lenses are arranged on the turret board and simply rotated to select the measurement auxiliary lens and automatically insert it into the measurement optical path. Is difficult to do.

Therefore, it is an object of the present invention to provide a lens meter in which a measurement auxiliary lens can be automatically inserted into and removed from a measurement optical path.

[0011]

A first aspect of the present invention.
The lens meter described in 1 above, in order to solve the above problems, a measurement light projecting system that projects a measurement light beam onto a lens to be inspected,
A measurement light receiving system including a light receiving sensor for receiving the measurement light beam after passing through the lens to be inspected, and a surface of the lens to be inspected based on a displacement amount of the measurement light beam after passing through the lens to be inspected detected by the light receiving sensor. Measuring means for measuring the power distribution of the lens to be measured by obtaining the power at each position of, and at least one of the measurement light projecting system and the measurement light receiving system is insertable / removable and has a known power. Moreover, it has a plurality of measurement auxiliary lenses having different dioptric powers, and drive control means for selecting the measurement auxiliary lenses and inserting them into the measurement optical path.

[0012] Preferably, the drive control means rotates the measurement auxiliary lens to select a measurement auxiliary lens to be inserted into the measurement optical path, and the selected measurement auxiliary lens to the measurement optical path. And an insertion / removal mechanism that reciprocates in a plane orthogonal to the insertion / removal mechanism.

The drive control means has a holding frame for holding the plurality of measurement auxiliary lenses, and the measurement auxiliary to be inserted into the measurement optical path by reciprocating the holding frame in a direction parallel to the measurement optical path. A reciprocating selection mechanism for selecting a lens and an insertion / removal mechanism for reciprocating and moving the selected measurement auxiliary lens in a plane orthogonal to the measurement optical path may be used.

[0014]

FIG. 2 is a perspective view showing a schematic structure of a lens meter 1 according to the present invention. On the front surface of the lens meter 1, a keyboard 2, a lens receiver 3, and a measuring light beam to be described later are provided. A guide unit 4, a monitor 5 and the like for deflecting and guiding the camera are provided. In this case, a base lens is set as the lens 6 to be inspected here, but any one lens 1C of the spectacle lenses 1A may be set as the lens 6 to be inspected in the lens receiver 3.

Inside the lens meter 1, a measuring optical system 10 shown in FIG. 3 is provided. The measuring optical system 10 comprises a measuring light projecting system 10A and a measuring light receiving system 10B, and FIG. 3 schematically shows the measuring optical system. The measurement light projecting system 10A includes a light source including a tungsten lamp 11, a diaphragm 12, a filter 13, and a collimator lens 1.
4 and the microlens array 15 are roughly configured. The microlens array 15 is composed of an assembly of a large number of minute lenses 15a arranged two-dimensionally as shown in FIG. The minute lens 15a is, for example, a spherical lens. Tungsten lamp 11, diaphragm 12,
The filter 13 and the collimator lens 14 form one light source unit. The filter 13 transmits light having a wavelength near the e-line and blocks light rays other than the e-line. The light flux emitted from the tungsten lamp 11 is collimated by the collimator lens 14 and guided to the microlens array 15. Each micro lens 15a of the micro lens array 15
Have substantially the same focal length, and each micro lens 15a
The number of microlens array 1 is about 1000.
Reference numeral 5 has a role as an optical member that generates a large number of two-dimensionally arranged measurement light beams Pi corresponding to the number of parallel light beams. The optical member may be a pinhole plate having a large number of pinholes instead of the microlens array 15. The lens 6 to be inspected is located near the rear focal position of the microarray lens 15.

The measuring light receiving system 10B includes a relay lens 16,
The CCD camera 17 is generally configured. The CCD camera 17 is composed of an image forming lens 17a and a light receiving sensor 17b, and 17c shows its light receiving area. This measurement light receiving system 10B is a lens meter 1 as shown in FIG.
Is provided in the lower portion of the lens receiver 3 and a measurement optical path 10C between the lens receiver 3 and the relay lens 16 is provided with an insertion / removal space for a measurement auxiliary lens 18 having a function to be described later, and between the relay lens 16 and the CCD camera 17. Is provided with a reflection mirror 20 for deflecting the measurement light beam Pi toward the CCD camera 17. Various types of measurement auxiliary lenses 18 having a known power and positive and negative powers are prepared from weak ones to strong ones. Here, four measurement auxiliary lenses 18 are used, and in FIG. 6, reference numeral 18a denotes a measurement auxiliary lens having a strong negative power, 18b a measurement auxiliary lens having a weak negative power, and 18c a weak measurement power. Reference numeral 18d denotes a measurement auxiliary lens having a positive power, and reference numeral 18d denotes a measurement auxiliary lens having a strong positive power. The measurement auxiliary lenses 18a to 18d are held by respective holding frames 20, and the respective holding frames 20 are supported by a rotary shaft 22 of a motor 21. The motor 21 is mounted and fixed on the slide table 23. A rack 24 is formed on the slide table 23, and a pinion 25 is engaged with the rack 24, and is moved forward and backward in the direction of arrow XX along a guide member (not shown). The motor 21 and the pinion 25 are controlled by the control unit 26, and the measurement auxiliary lens 18 to be inserted into the measurement optical path 10C by rotationally driving the motor 21 at the retracted position of the slide table 23.
Is selected, and then the slide table 23 is moved forward to insert the selected measurement auxiliary lens 18 into the measurement optical path 10C. That is, the measurement auxiliary lens 18
a to 18d are the same portions of the measurement optical path 10C (lens receiver 3
Is set at a predetermined distance from). 5 and 6
Shows the case where the slide table 23 is in the forward position and the measurement auxiliary lens 18a having a strong negative power is selected and inserted into the measurement optical path 10C.
Reference numeral 1 constitutes a rotation selection mechanism for rotating the measurement auxiliary lens 18 to select the measurement auxiliary lens 18 to be inserted into the measurement optical path 10C, and the slide table 23 and the pinion 25 connect the selected measurement auxiliary lens 18 to the measurement optical path 10C. A control unit 26 functions as a drive control means for these, which constitutes an insertion / removal mechanism that reciprocates in a plane orthogonal to the insertion / removal mechanism.

Here, in the measurement auxiliary lens 18, the lens 6 to be inspected is not set in the lens receiver 3 (the lens 6 to be inspected is not inserted in the measurement optical path 10C) and the measurement auxiliary lens 18 is not inserted in the measurement optical path 10C. At this time, the measurement light beam Pi is designed to be evenly distributed over the entire light receiving area 17c of the light receiving sensor 17b as shown in FIG. As shown in FIG. 8, the test lens 6 having a negative power is measured by the measurement optical path 10C.
When the measurement auxiliary lens 18 is not inserted in the measurement optical path 10C, the number and intervals of the light spots on the light receiving area of the measurement light beam Pi are first measured. Next, as shown in FIG. 9, the measurement auxiliary lens 18 having a strong negative power is used.
When a is inserted, the measurement light beam Pi that is refracted outward by passing through the lens 6 to be inspected is further refracted outward by passing through the measurement auxiliary lens 18a. Therefore, as shown in FIG. And the measuring light flux Pi
Of the measurement light beam Pi on the light receiving area 17c decreases. Further, the measurement light beam Pi on the light receiving area 17c
The distance between the light spots in the area also increases. Therefore, it can be determined that the lens 6 to be inspected has negative power by counting the number of light spots of the measurement light beam Pi on the light receiving area 17c and determining the interval between the light spots. Next, when the measurement auxiliary lens 18b having a weak negative power is inserted in the measurement optical path 10C, when the lens 6 under test has a negative power, the distance between the light spots of the measurement light beam Pi on the light receiving area 17c becomes small. It becomes narrower than when the measurement auxiliary lens 18a is inserted. In this case as well, the measurement light beam Pi refracted outward by passing through the lens 6 to be inspected has the measurement auxiliary lens 18b.
Since the light beam is refracted further outward by passing through, the number of measurement light beams Pi on the light receiving area 17c is smaller than that in the case where the measurement auxiliary lens 18 is not inserted, and the measurement light beams Pi are projected. Next, the measurement auxiliary lens 1
8b is removed from the measurement optical path 10C, and a measurement auxiliary lens 18c having a weak positive power is inserted into the measurement optical path 10C as shown in FIG. 11, and at this time, as shown in FIG. When is not protruding from the light receiving area 17c of the light receiving sensor 17b, the power distribution of the lens 6 to be tested is measured in the state shown in FIG. In this case, it is desirable that the points of the measurement light beam Pi are scattered all over the light receiving area 17c from the viewpoint of improving the measurement accuracy. That is, the provisional power distribution including the power distribution of the subject lens 6 and the known power is measured as a whole, and the known power is removed from the provisional power distribution to obtain the correct power distribution of the subject lens 6. The power distribution obtained by this measurement is the correct power distribution of the lens 6 under test. The measurement auxiliary lens 18c having a positive power of this weakness is used for the measurement optical path 1
Even if it is inserted in 0C, when it is determined that the measurement light beam Pi has overflowed, the measurement auxiliary lens 18d having a positive power of intensity is inserted, and the measurement auxiliary lens 1 is inserted.
When 8d is inserted, when all of the measuring light beam Pi does not protrude from the light receiving area 17c of the light receiving sensor 17b, and when the points of the measuring light beam Pi are scattered all over the light receiving area 17c, this measurement assistance is performed. Lens 1
Even if the power distribution of the lens 6 to be measured is measured with the 8d inserted and the measurement auxiliary lens 18d having a positive power of intensity is inserted, all of the measurement light beam Pi protrudes from the light receiving area 17c of the light receiving sensor 17b. If it is, the measurement is stopped because it exceeds the measurement range.

As shown in FIG. 13, when the lens 6 to be inspected having a positive power is set in the measurement optical path 10C, as shown in FIG. 13, there is no intersection in the measurement light beam Pi, and in FIG. It is considered that the measurement light flux Pi has an intersection as shown. If the measurement light beam Pi has no crossing and a measurement auxiliary lens 18a having a strong negative power is inserted as shown in FIG. 15, the measurement light beam Pi is expanded and the light spot of the measurement light beam Pi on the light receiving area 17c is expanded. The interval of is wider than when it is not inserted. In this case, the light receiving area 17
If the distance between the light spots of the measurement light beam Pi on c is the same as the case where the measurement light beam Pi is not inserted, it is considered that the measurement light beam Pi does not protrude, and therefore the power of the lens 6 to be inspected with the measurement auxiliary lens 18a inserted. Measure the distribution. As shown in FIG. 13, when the measurement light beam Pi does not intersect and the measurement auxiliary lens 18a is inserted in the measurement optical path 10c, the interval between the light spots of the measurement light beam Pi on the light receiving area 17c is not inserted. When it is decreased, it is determined that the measurement light beam Pi is squeezed out. Therefore, the weak measurement auxiliary lens 1 having negative power is used.
8b is inserted, and the protrusion of the measurement light beam Pi is set to the light receiving area 1
Judgment is made based on the number of light spots of the measurement light beam Pi on 7c, and when the measurement light beam Pi does not protrude, when the light points of the measurement light beam Pi are evenly scattered over the entire light receiving area 17c, this measurement is performed. The power distribution of the lens 6 to be measured is measured with the auxiliary lens 18b inserted. If three or more measurement auxiliary lenses 18 having a known power having a negative power from intensity are provided instead of two, the light points of the measurement light beam Pi are evenly received by appropriately selecting the measurement auxiliary lenses. The area 17c can be scattered over the entire area, which can be expected to improve the measurement accuracy. When the measurement auxiliary lens 18a is inserted in the measurement optical path 10C when the measurement light beam Pi has an intersection as shown in FIG.
It moves in the direction in which the interval between the light spots of the measurement light beam Pi on c is reduced. Therefore, it can be determined whether or not the measurement light beam Pi has an intersection depending on whether the light spots of the measurement light beam Pi are widened or narrowed.

Therefore, if the power distribution of the lens 6 to be measured is automatically measured by the following procedure, the measurement can be performed in a short time with simple control.

First, the lens 6 to be inspected is set in the measurement optical path 10C, and the measurement auxiliary lens 18 having a known diopter is attached to the measurement optical path 1C.
The number of the light spots of the measurement light beam Pi on the light receiving area 17c and the distance between the light spots are measured in a state where the measurement auxiliary lens 18a having a known negative power is inserted. Measurement beam Pi on the light receiving area 17c
The number of light spots and the distance between the light spots are measured, and when the distance between the light spots is narrowed, the measurement of the power distribution of the lens 6 to be inspected is stopped because the measurement light beams Pi intersect, and when the distance between the light spots is widened. , The projection of the light spot is judged, and when there is no projection of the light spot, the frequency distribution is measured assuming that the lens 6 to be tested has a positive power, and when there is a projection of the light spot, the next The measurement auxiliary lens 18b having negative power is inserted into the measurement optical path 10C, and when the light spot does not protrude, the measurement of the lens 6 to be inspected is similarly performed, and the measurement auxiliary lens 18b having negative power of the weakness is measured. When the light spot is projected even if it is inserted in the optical path 10C, it is considered that the lens 6 to be inspected has negative power. Therefore, the measurement auxiliary lens 18c having weak positive power is placed in the measurement optical path 10C. Insertion And, when there is no protrusion of the light spot is measured as the power distribution of the lens 6, measure the measurement auxiliary lens 18c with a positive power of the weaker optical path 10
If the light spot is projected even if it is inserted in C, the measurement auxiliary lens 18d having a positive power of intensity is used for the measurement optical path 10.
I will insert it in C. According to this measurement procedure, the power distribution can be automatically measured regardless of whether the power of the lens 6 to be tested is positive or negative.

The power distribution of the lens 6 to be tested can also be automatically measured by executing the procedure described below.

Even if the positive or negative of the power of the lens 6 to be inspected is unknown, for the time being, a positive measurement auxiliary lens 18c having a known degree of weakness is inserted into the measurement optical path 10C to receive light.
The distance between the light spots of the measuring light beam Pi on 7c is measured, and if the distance between the light spots becomes small, it is determined that the measuring light beam Pi does not intersect, and it is determined whether or not the light spot is protruding. When there is no light spot protrusion, the power distribution of the lens 6 to be inspected is measured as it is. If there is a light spot protrusion,
A positive measurement auxiliary lens 18d having a known power is inserted in the measurement optical path 10C, and the power distribution of the lens 6 to be measured is measured. A positive measurement auxiliary lens 18c having a known degree of weakness is inserted into the measurement optical path 10C, the distance between the light points of the measurement light beam Pi on the light receiving area 17c is measured, and when the distance between the light points is widened, , The measurement auxiliary lens 18b having a known negative power and a weak negative power is inserted into the measurement optical path 10C, and the measurement auxiliary lens 18 having a large negative power is inserted in order until the distance between the light spots increases. The power distribution of the lens 6 to be tested is measured by the negative measurement auxiliary lens 18 whose power is known immediately before the interval between the light spots is projected.

The measurement of the frequency distribution is based on the principle described below.

In FIG. 9, the chief ray Ps of the measurement light beam Pi from each microlens 15a incident on the lens 6 to be inspected is parallel to the optical axis O. The principal ray Ps is deflected after passing through the lens 6 to be inspected, and the degree of the deflection depends on the incident height h (the incident position of the principal ray Ps on the surface 6a of the lens 6 to be inspected) and the lens 6 to be inspected at the incident position. It depends on the frequency and.

The frequency S (unit: diopter) at each point on the surface 6a is S = tan θ / (10h) (1) where θ is the deflection angle of the principal ray Ps after transmission.

The height of the chief ray Ps due to each minute lens 15a is known, and the height on the light receiving area 17c is h.
i, the relay magnification is β, and the distance from the rear surface 6b of the lens 6 to be tested to the relay lens 16 is Z, the relational expression of θ = tan ⁻¹ {(h−βhi) / Z} (2) is Therefore, if the unknown height hi on the light receiving area 17c is obtained, the deflection angle θ is obtained, and thus the frequency S is finally obtained by the equation (1).

FIG. 16 shows a modification of the drive control means according to the present invention. In this modification, the measurement auxiliary lens 1 is used.
8 is configured to be inserted into and removed from the measurement optical path 10C between the reflection mirror 20 and the CCD camera 17, 27 is a motor for rotationally driving the measurement auxiliary lenses 18a to 18d, and 28 is the measurement auxiliary lens. It is a turret board for holding 18a to 18d. According to this modification, the measurement auxiliary lenses 18a to 18d can be inserted into and removed from the measurement optical path 10C only by rotating.

FIG. 17 shows still another modification of the drive control means according to the present invention. In this modification, the drive control means has a cylindrical holding frame 29 for holding a plurality of measurement auxiliary lenses 18a to 18d. And a reciprocating selection mechanism (not shown) for reciprocating the cylindrical holding frame 29 in a direction parallel to the measurement optical path 10C to select the measurement auxiliary lens to be inserted into the measurement optical path 10C, and the selected measurement auxiliary lens. And an inserting / removing mechanism (not shown) that reciprocates in a plane orthogonal to the measurement optical path to insert and remove.

As described above, in the embodiment of the invention, the measurement auxiliary lens 18 is provided in the measurement light receiving system 10B behind the lens 6 to be inspected, but in the measurement light projecting system 10A in front of the lens 6 to be inspected. It may be configured to be provided.

[0030]

Since the lens meter according to the present invention is constructed as described above, it is possible to easily measure the lens to be inspected having a strong power.

[Brief description of drawings]

1 shows a spectacle lens, (a) is a plan view, (b)
Is a side view.

FIG. 2 is an overall perspective view showing an example of a lens meter.

FIG. 3 is an optical diagram schematically showing a measurement light projecting system and a measurement light receiving system according to the present invention, in which a measurement auxiliary lens whose test lens is not set in the measurement optical path and whose frequency distribution is known. The state where it is not inserted in the measurement optical path is shown.

FIG. 4 is a plan view of a microlens array.

FIG. 5 is a side view showing the relationship between the measurement light receiving system and the drive control means according to the present invention.

FIG. 6 is a plan view showing the relationship between the measurement light receiving system and the drive control means according to the present invention.

FIG. 7: When the lens under test is not set in the measurement optical path and the measurement auxiliary lens with known power distribution is not inserted in the measurement optical path, the light spots of the measurement light beam are even over the entire light receiving area of the light receiving sensor. It is an explanatory view showing that it is distributed to.

FIG. 8 is an optical diagram showing a state in which a lens to be inspected having negative power is inserted in a measurement optical path.

FIG. 9 is an optical diagram showing a state in which a lens to be inspected having negative power is inserted in the measurement optical path and a measurement auxiliary lens having power of negative intensity with known power is inserted in the measurement optical path.

FIG. 10 is an explanatory diagram showing that part of the light spots of the measurement light beam is protruding from the light receiving area of the light receiving sensor.

FIG. 11 is an optical diagram showing a state where a lens to be inspected having negative power and a measurement auxiliary lens having power of positive weakness whose power distribution is known are inserted in the measurement optical path.

FIG. 12 shows a measurement light flux when a test lens having negative power and an unknown power distribution is set in the measurement optical path, and a measurement auxiliary lens having a known weak power distribution and having positive weak power is inserted into the measurement optical path. FIG. 8 is an explanatory diagram showing that the light spots of are evenly distributed to the light receiving area of the light receiving sensor.

FIG. 13 is an optical diagram showing that the measurement light flux does not intersect when a lens to be inspected having a positive and unknown power distribution is set on the lens receiver.

FIG. 14 is an optical diagram showing that the measurement light flux has an intersection when a lens to be inspected having a positive unknown power distribution is set on the lens receiver.

FIG. 15 shows a state in which a measurement auxiliary lens having a known power and having a negative power is inserted in the measurement optical path when a lens to be measured having a positive and unknown power distribution is set in the lens receiver and the measurement light flux does not intersect. FIG.

FIG. 16 is a diagram showing a modified example of the drive control means according to the present invention.

FIG. 17 is a conceptual diagram showing still another modified example of the drive control means according to the present invention.

[Explanation of symbols]

 3 ... Lens receiver 6 ... Test lens 10A ... Measuring light projecting system 10B ... Measuring light receiving system 10C ... Measuring optical path 17b ... Light receiving sensor 17c ... Light receiving area 18 ... Measuring auxiliary lens 21 ... Motor (rotation selection mechanism) 23 ... Slide Table (insertion / removal mechanism) 26 ... Control unit (drive control means) Pi ... Measurement luminous flux

Claims (3)

[Claims] 1. A measuring light projecting system for projecting a measuring light beam onto a lens to be inspected, a light receiving system for receiving a measuring light beam after passing through the lens to be inspected, and a light receiving sensor for detection. Measuring means for measuring the power distribution of the lens to be inspected by obtaining the power at each position of the surface of the lens to be inspected based on the amount of displacement of the measured light beam after passing through the inspected lens, A plurality of measurement auxiliary lenses that can be inserted into and removed from the measurement optical path of at least one of the system and the measurement light receiving system, have known diopters, and have different diopters, and select the measurement auxiliary lenses and insert them into the measurement optical path. A lens meter having drive control means for controlling. 2. The drive control means rotates the measurement auxiliary lens to select a measurement auxiliary lens to be inserted in the measurement optical path, and a rotation selection mechanism for selecting the selected measurement auxiliary lens in the measurement optical path. The lens meter according to claim 1, further comprising an insertion / removal mechanism that reciprocates in a plane orthogonal to the insertion / removal mechanism. 3. The drive control means has a holding frame for holding the plurality of measurement auxiliary lenses, and the holding frame should be reciprocated in a direction parallel to the measurement optical path to be inserted into the measurement optical path. It has a reciprocating selection mechanism for selecting a measurement auxiliary lens, and an insertion / removal mechanism for reciprocating and moving the selected measurement auxiliary lens in a plane orthogonal to the measurement optical path. The lens meter according to 1.