JPH0314445B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the radius of curvature of a curved surface, and more specifically, an off-salmometer for measuring the radius of curvature of the main meridian of the cornea of the human eye, and a device for measuring the radius of curvature of a contact lens. This invention relates to a curvature measuring device that can be applied to a radius meter.

In this specification, the principles and embodiments of the present invention will be explained with reference to an ophthalmometer, but the present invention is not limited thereto, and the present invention can be applied to a wide range of optically reflective spherical surfaces or toric curved surfaces. The present invention can also be applied to a device that measures the radius of curvature (hereinafter sometimes simply referred to as "radius of curvature").

The refractive power of the human cornea itself is approximately 80% of the total refractive power of the entire eye, or approximately 45 Diopter, and approximately 75% of astigmatic eyes have corneal astigmatism, that is, the anterior surface of the cornea is not spherical but has a torturous curved shape. This is due to what you are doing. Furthermore, when prescribing a contact lens, the base curve needs to be prescribed based on the radius of curvature of the principal axis of the anterior surface of the cornea of the eye in which the contact lens is to be worn. From these points of view, it is important to measure the radius of curvature of the principal axis of the anterior surface of the cornea.

In response to this requirement, various types of off-salmometers have been put into practical use as devices for measuring the radius of curvature of the anterior surface of the cornea of the human eye. Both types of off-salmometers project one or more visual targets onto the cornea to be examined, and observe the size of the projected image or the position of its reflected image at the focal plane of an observation telescope.
The radius of curvature of the cornea to be examined and the corneal astigmatism axis were measured from the amount of change in the size of the projected image or the amount of relative positional shift of the reflected image of the optotype.

In the ophthalmometer, especially when measuring the cornea of an astigmatic eye whose cornea has a toric curve shape, the first (strong principal meridian) and second principal meridian (weak principal meridian)
It is necessary to measure three measurable quantities: the radius of curvature of I needed it. However, the human eye is always accompanied by physiological eyeball vibrations, and longer measurement times result in vibrations in the projected image due to eyeball vibrations, which can lead to measurement errors and frequent alignment adjustment operations during measurements. There was a big problem that it was necessary.

As a device that solves the drawbacks of this conventional device,
For example, JP-A-56-18837, JP-A-56-66235
Publication or US Pat. No. 4,159,867 discloses that the reflected image of the projected image from the cornea is detected by a one-dimensional or two-dimensional position sensor, and the radius of curvature and the cornea of the eye to be examined are determined from the detected position. An apparatus for measuring major radius axis angles is disclosed.

However, like the conventional off-salmometers in practical use, these devices are of the type that uses a telescope to image the reflected image of the projection target from the cornea.
In order to improve measurement accuracy, the focal length of the telescope had to be increased, which had the disadvantage of increasing the size of the Ikioi device. Also, since it was an image-forming type, its focusing mechanism was essential. Furthermore, since the alignment between the device and the cornea to be examined is performed using this focusing telescope, the alignment is inaccurate and does not lead to shortening of measurement time or complete automation.

Using a non-imaging optical system, the refractive properties of the optical system,
U.S. Patent No. 3880525 is a device that mainly measures the spherical refractive power and cylindrical refractive power of eyeglass lenses and their axial angles.
It is disclosed in the specification of No. This device irradiates a parallel light beam onto the eyeglass lens to be examined, selects the light beam deflected by the refractive characteristics of the lens by using a mask means having a point aperture, and selects the light beam from a plane placed at a distance shorter than the focal length of the lens to be examined. type image detector
The configuration was such that the refractive characteristics of the lens to be tested were determined from the position of the projection point on the detector of the light beam that had passed through the point aperture and was projected onto the imaging surface of the TV camera.

However, this US patent specification only discloses the measurement of refractive properties in a refractive optical system, and does not disclose or suggest anything about measuring the radius of curvature of the reflective curved surface of a reflective optical system. moreover,
Since this device detects refractive characteristics using a point aperture, the above-mentioned flat image detector or TV camera must be used as the detection means, which not only makes the device expensive but also If dirt, dust, etc. adhere to the optical system or the detection surface of the device, the light beam that should pass through the point aperture is blocked by the dirt, dust, etc., which has the disadvantage that it may not be possible to measure the refractive characteristics of the test lens. Ta.

Therefore, the present invention solves the drawbacks of the conventional off-salmometers described above, and provides a curvature measurement device that can be applied to off-salmometers, radius meters, etc., and can perform automatic measurements using a non-imaging optical system. This is what I am trying to do.

Another object of the present invention is to use a non-imaging optical system to reduce the size of optical components that need to be observed and operated by an examiner, such as an imaging telescope. It is an object of the present invention to provide a curvature measuring device that can automatically measure the radius of curvature of the main radius of a spherical surface or a toric curve without having.

Yet another object of the present invention is to provide excellent operability and reduce measurement time by automatically outputting information for alignment between the curved surface to be inspected and the optical axis of the device, which was done by collimation in conventional devices. The object of the present invention is to provide an automatic curvature measurement device that can be used.

Still another object of the present invention is that by increasing the amount of information in the masking means, a detection means that is cheaper than a conventional ophthalmometer or an automatic lens meter can be used, and moreover, it is possible to prevent dust from entering the optical system or detection surface of the device. To provide a curvature measuring device capable of automatically measuring curvature, which is resistant to disturbance effects, highly accurate, and inexpensive, capable of measuring even in the presence of dust.

Incidentally, according to the present invention, there is provided an illumination optical system having a light source and a collimator means for converting the light from the light source into a parallel light beam; a mask means having a pattern of straight lines configured to substantially intersect at least two straight lines at at least one point on a substantial surface in order to select the reflected light; a detection optical system having a detection means for detecting; a calculation means for calculating a radius of curvature of the curved surface to be inspected from a straight line projection pattern corresponding to the straight line pattern of the reflected light detected by the detection means; A curvature measuring device is provided in which both the pattern and the detection means are respectively arranged on different planes that are optically conjugate with the light source.

Note that in the present invention, a "substantive intersection" includes both an actual intersection and a virtual intersection. Furthermore, "substantially on a surface" refers to a case where the detection means are actually arranged on one plane, and a case where the detection means located at different locations are arranged as if they were on a virtual plane, for example, by optical means. This includes both cases where

In the present invention, due to the above-mentioned structural features, compared to conventional curvature radius measuring devices, the device is smaller, the measurement time is shorter, it is resistant to disturbance effects, the measurement accuracy is higher, and it is less expensive. The radius of curvature of the curved surface to be tested can be automatically measured. Furthermore, since alignment information can be automatically output, it is possible to further shorten measurement time and improve measurement accuracy.

These advantages of the present invention are that, especially when the present invention is applied to an off-salmometer, the off-salmometer has high measurement accuracy that is not affected by eye vibration, has a short measurement time, is small, and enables automatic measurement at low cost. can be provided.

Furthermore, if the present invention is applied to a so-called radius meter that measures the radius of curvature of the base curve or front surface of a contact lens, the target image is focused twice on the surface of the contact lens and the center of curvature, and the objective lens is moved at that time. Based on the amount
Compared to conventional radius meters, which measure the radius of curvature of curves, etc., there is no need for a microscope optical system for target image observation and measurement, which conventional radius meters have, and therefore the measurement accuracy is improved. It is possible to provide a new type of radius meter that not only does not require any direct diopter adjustment, but also can perform automatic measurements without causing personal errors between operators, has high measurement accuracy, and has a short measurement time.

Furthermore, the present invention can increase the amount of information in the mask means, and can use a detection means that is cheaper than the conventional Orsa motor or automatic lens meter, and can measure even if there is dirt or dust on the optical system or detection surface of the device. It is possible to provide a curvature measurement device that is resistant to disturbance effects, is highly accurate, and can perform automatic measurements at low cost.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The measurement principle and embodiments in which the present invention is applied to an off-salmometer for measuring the radius of curvature of the cornea will be described below with reference to the drawings.

FIG. 1 is a perspective view for explaining the measurement principle of the present invention, and FIG. 2 is a plan view thereof.

In these figures, consider an X ₀ -Y ₀ orthogonal coordinate system having its origin at the device optical axis O ₁ . The cornea C is arranged with its optical center O _c shifted E _H in a direction parallel to the X ₀ axis and E _v in a direction parallel to the Y ₀ axis, and has a first principal axis (strong principal axis) with a radius of curvature γ ₁ . Assume that the radial line) is inclined by an angle θ _r1 with respect to an axis parallel to the X ₀ axis. Further, the radius of curvature of the second principal radial line (weak principal radial line) is assumed to be γ ₂ . The angle of the second principal meridian is θ+90°.

The cornea C to be examined is illuminated with a circular light beam having a radius of φ/ ₂ , as shown in FIG. The light is selectively transmitted through the formed linear apertures A, B, and C, and is projected onto a detection surface D that is separated from the mask M by a distance d. This straight opening A
and B intersect with each other at one point i, and the straight aperture C intersects with the straight aperture A at an intersection j and the straight aperture B at an intersection k, respectively. Linear opening A is at an angle θ ₁ with respect to the X ₀ axis
It is tilted, and the straight opening B is relative to the X ₀ axis,
Assume that it is inclined at an angle θ ₂ . Further, the intersecting angle of both straight apertures A and B is assumed to be θ. _{Let l A be the length of the straight aperture A, that is, the length between the intersections i and j, and l B be} the length of the straight aperture B, that is, the length between the intersections i and k. Further, the slope of the straight aperture A is tanθ ₁ =m _A , and the slope of the straight aperture B is tanθ ₂ =m _B.

Furthermore, the projection straight lines A', B', and C corresponding to the linear apertures A, B, and C, respectively, on the detection surface D are detected on the X axis and Y axis of the X-Y orthogonal coordinate system provided on the detection surface D. Although only the case of detecting the intersection of these projected straight lines at the axis will be described, it goes without saying that the entire detection plane D may be scanned and detected. Further, when detection is performed on a surface, only two straight apertures A and B are required to be formed in the mask M, and the above-mentioned intersections j and k are the end points of the straight apertures A and B in this case.

Now, the X axis and Y axis and the projection straight lines A', B' and
From the intersections xa ₁ , xa ₂ , xa ₃ and ya ₁ , ya ₂ , ya ₃ of C′, the equation of the straight line can be determined by determining any two points among them, so the projection from the detected points ya ₁ and xa ₃ The equation of the straight line A′ can be determined, and similarly the detection point xa ₁ and
The equation of the projection straight line B′ from ya ₂ is the detection point xa ₂ and ya ₃
The equation of the projection line C′ can be determined from the following.
The length of the projected straight line is lA′, the length of the projected straight line B′ is lB′,
Alternatively, the slope of the projection line A' is calculated as tan θ′ ₁ = m _A ′, and the slope of the projection line B′ is calculated as tan ₂ ′ = m _B ′, respectively, from the equation of the projection line. From this, the length of the linear aperture A of the mask M mentioned above is l _A , its slope m _A , the length of the linear aperture B is l _B , and its slope m _B , ψ _A・ψ _B (m _A −m _B ) (d/Z-+1) ² - [ψ _A (m _A -m _B ′) + ψ _B (m _A ′-m _B )] (d/Z+1) + (m _A ′-m _B ′) = 0... …The quadratic equation of equation (1) is obtained, where ψ _A and ψ _B are It is. The second roots Z ₁ and Z ₂ of this quadratic equation are the focal point F _r1 of the first principal axis of the cornea C from the mask M, respectively.
It shows the distance of the second principal meridian to the focal point F _r2 .
In general, the relationship between the focal length of a spherical reflective optical system and its radius of curvature R is R/2, so this two roots
The radii of curvature _{r 1 and} r _{2 of the first and second principal meridians of the cornea C from Z 1 and Z 2 are} r ₁ = 2 (Z ₁ - l) r ₂ = 2 (Z ₂ - l)... It can be determined by equation (2).

Here, the distance l may be a constant determined by a known working distance detection means, or a relay optical system may be used to set the mask M so that l=0.

The angle θ _r1 of the first principal radial line r ₁ is θ _r1 = tan ^-1 [m _A・ψ ₄ (1+d/Z ₁ )−m _A ′/ψ _A (
1+d/Z ₁ )-1]...(3).

FIG. 3 is a perspective view showing a second embodiment of the measurement principle described above. The embodiment of Fig. 3 is a projection straight line A′B′,
C' is the two Y axes on the X-Y plane of the detection surface D, i.e.
It is detected from the position intersecting the _Y1 axis and _Y2 axis.

As shown in Figure 3, the projected straight lines are y ₁ , y ₂ , y ₃
Intersects the Y ₁ axis at y ₄ , y ₅ , y ₆ and Y ₂
intersects the axis. Therefore, from y ₂ and y ₆ we get the equation of line B', and from y ₁ and y ₄ we get the equation of line A',
Also, the equation of the straight line C' can be obtained from ₃ and y ₅ , respectively. Then, based on these straight line equations, the straight line
The lengths of A′ and B′, l _A ′, l _B ′ and the slope m _A ′,
m _B ′ can be found, and the intersections of the straight lines i′, j′,
The coordinates of k′ can be found.

FIG. 4 is a perspective view showing only a portion of the detection surface D, showing a third aspect of the measurement principle. This is an example when considering an oblique coordinate system X'-Y' that intersects at an angle γ on the detection plane D. In this case, as shown in Fig. 5 _{, the projected} straight lines intersect at points X _{' 1} , _{X ' 2} , The equation of the straight line A′ from the point
The equation of straight line B' can be obtained from X' ₁ and y' ₁ , and the equation of straight line C' can be obtained from points X' ₂ and y' ₃ . Here, the oblique coordinate system X'-Y' and the orthogonal coordinate system X-
When there is a relationship as shown in Figure 6 between Y (or the orthogonal coordinate system X ₀ - Y ₀ on the mask surface), the conversion from the oblique coordinate system X'-Y' to the orthogonal coordinate system X-Y can be converted using the following equation x=X′ sinα+y′ sinβ+ξ y=−X′ cosα+y′ cosβ+η ...(4), and then calculated using equations (1) to (3) to obtain the corneal C to be examined. The shape characteristics of can be calculated.

Alternatively, when calculating the radius of curvature r ₁ of the first principal meridian, the radius of curvature r ₂ of the second principal meridian, and the principal meridian angle θ, measurements are made before irradiating the test cornea C with the illumination light beam. An illumination light flux is irradiated onto a reflective surface perpendicular to the optical axis of the device in the optical path, and the reflected light flux passes through the linear aperture A of the mask M,
Detect the projected straight lines A', B', and C' onto the detection surface D when selectively transmitted at B and C using the oblique X'-Y' coordinate system,
Calculate the lengths l _A and l _B and the slopes m _A and m _B , and use these values as initial values. Next, place the cornea C to be examined in the measurement optical path, detect the projection straight lines A', B', and C' in the same way, and calculate their lengths l _A ', l _B ' and slopes m _A ', m _B '. The initial values l _A , l _B , m _A , m _B and the newly calculated l _A ′, l _B ′,
From m _A ′ and m _B ′, the shape characteristics of the cornea to be examined, that is, the radii of curvature r ₁ , r ₂ , and the main meridian angle θ can be measured. In this way, the present invention is a device that is independent of how the coordinate system is determined, and as described in the following embodiments, when the linear position sensor is arranged along each axis of the X'-Y' coordinate system, This placement position is on the mask.
Since it can be arranged arbitrarily regardless of the X ₀ - Y ₀ coordinate system, this is an extremely advantageous feature in terms of device manufacturing and maintenance management.

Furthermore, the linear openings A, B, and C may have virtual intersections i, . . . instead of actual intersections on the mask M, as shown in FIG. This means that the present invention provides projection straight lines A', B',
Detect the intersection of C′ and each axis of the X′-Y′ coordinate system on the detection plane, find the equation of the projected straight line from this detection point, and use this equation to find the intersection i′, j′ ,
Since the position of k′ is calculated,
Intersections i, j, and k do not actually need to exist as a pattern. In addition, straight openings A, B,
As shown in FIG. 8, C can virtually form triangles i, j, and k by extending linear openings A, B, and C, respectively, which do not need to form triangles on mask M. Bye. Such linear apertures A, B, and C are also changed according to the shape characteristics of the cornea C to be examined, similar to the above-mentioned principle, to form projected straight lines A', B', and C' on the detection surface D. That is, as shown in FIG. 9, linear apertures A, B, and C that create virtual triangles i, j, and k in the _X0 - _Y0 coordinate system on the mask M are X'-Y' on the detection surface D. X′ ₁ , X′ ₂ , X′ ₃ and
are detected as y′ ₁ , y′ ₂ , y′ ₃ , and the equations of projection straight lines A′, B′, and C′ can be calculated respectively using the same principle as shown in FIG. ,
Virtual triangles i′, j′, and k′ can be calculated from the equations of B′ and C′. Then, from virtual triangles i, j, k and virtual triangles i′, j′, k′, lengths l _A , l _B , l _A ′, l _B ′ and slopes are obtained.
By obtaining m _A , m _B , m _A ′, and m _B ′, the radius of curvature r ₁ , r ₂ and the axis angle θ of the cornea to be examined can be similarly calculated using equations (1) to (3).

The alignment amounts α and β are calculated using the triangles i, j, and k formed by straight lines A, B, and C, as in equation (5).
Calculate and memorize ΔX=X _i +X _j +X _k ΔY=y _i +y _j +y _k ...(5) in advance, and from straight lines A′, B′, and C′, i′, j′
,
k′ and find ΔX′=X′ _i +X′ _j +X′ _k ΔY′=y′ _i +y′ _j +y′ _k ...(6), the horizontal and vertical alignment amounts α and β are as follows. It can be found as follows.

Here, A=X cosθ _r1 +Y sinθ _r1 B=X sinθ _r1 +Y cosθ _r1 ...(8) In the oblique coordinate system as shown in Figure 6, this becomes (4)
This shows that it is possible to obtain the alignment amounts α and β by converting the equations and calculating.

Detection points xa ₁ , xa ₂ , xa ₃ , ya ₁ , ya ₂ , ya ₃ of the projected straight line on the detection surface D corresponding to the straight aperture of the mask M
or y ₁ , y ₂ , y ₃ , y ₄ , y ₅ , y ₆ , or x ₁ ′, x ₂ ′,
In order to determine which linear aperture x ₃ ′, y ₁ ′, y ₂ ′, and y ₃ ′ correspond to, it is necessary to change the width of the linear aperture, or to use a linear aperture instead of one linear aperture. A method such as using a group of two or three straight apertures may be used. For example, as the linear openings on the mask, it is desirable to use an arrangement in which two sets of parallel linear openings are orthogonal to each other. If the projection of the intersection of the straight apertures is located on the coordinate axis, even if the widths of the straight apertures are different or a group of multiple straight apertures is used instead of one straight aperture, the Although it may be difficult to calculate the center position of the projected straight line, this problem can be solved by cutting one of the straight lines at the intersection of the straight lines in the straight line opening on the mask and providing an appropriate gap.

FIG. 10 is an optical layout diagram showing the first embodiment of the present invention. This embodiment is an off-salmometer that utilizes the measurement principle described above.

In this embodiment, one linear position sensor is used as a detector by combining an image rotator so that the optical conjugate images of the detector are obliquely crossed on the detection surface D, but in the present invention, It is clear from the above explanation of the principle that the detection is not limited to this, but can also be performed using a flat position sensor, two intersecting linear position sensors, or two parallel position sensors.

Two infrared light emitting diodes 30 and 31 having different emission wavelengths are used as light sources of the illumination optical system 1. Light from the light emitting diode 30 passes through the dichroic surface 32a of the dichroic prism surface 32 and enters the condenser lens 7. On the other hand, the light from the light emitting diode 31 is transmitted to the dichroic surface 32.
a is reflected and similarly enters the condenser lens 7.

The light emitted from the condenser lens 7 passes through the pinhole of the pinhole plate 10, is made into a parallel beam by the collimator lens 33 whose focal point is at this pinhole, and is then tilted onto the optical axis _O1 of the device. It is reflected by the provided micromirror 34, and the optical axis
The cornea C to be examined is irradiated parallel to O ₁ . The fixation optical system 3 uses a half mirror 20 tilted in the illumination optical system 1 to illuminate the fixation target image onto the subject's eye.

In the measurement optical system 2, a mask plate 35 is arranged behind the first relay lens 14. The mask plate 35 has a linear aperture group 2 in which thick linear apertures 25 and 26 are formed in parallel and three thin linear apertures perpendicular to the parallel linear apertures 25 and 26 are formed.
7 and 28 are formed parallel to each other. The intersection points i and l of the thick linear aperture of this mask plate 35 and the group of three thin linear apertures are on the X0 axis, and the intersection points j and k are on the _X0 axis.
Y is on the ₀ axis. As shown in FIG. 11b, the intersection points are such that the straight aperture group 27
It is shaped like a cut piece. Also, straight opening 2
6 and the linear aperture group 28 as well. A conjugate image of this mask plate 35 by the relay lens 14 is formed at a position M in the figure. Also mask board 3
A second relay lens group 36 is arranged behind the dichroic prism 3.
A dichroic mirror 37 having the same optical characteristics as 2 is tilted. By this dichroic mirror 37, the measurement optical path is changed to the first optical path 120.
and a twelfth optical path 121. First optical path 12
0 is mirror 122, dichroic mirror 12
3. It is composed of a third relay lens 124. On the other hand, the second optical path 121 includes an image rotator 125, a mirror 126, and a dichroic mirror 1.
23, and a third relay lens 124. A linear position sensor 38 is configured behind the third relay lens 124. This linear position sensor 38 includes a first relay lens 14, a second relay lens group 36, and a third relay lens group 36.
The relay lens 124 creates an optical conjugate image at position D in the figure, and the image rotator 125 of the second optical path 121 creates two virtual images that intersect at a predetermined angle γ on the conjugate detection surface D. Acts as a linear sensor.

The parallel light beam from the light emitting diode 30 or 31 that exits the collimator lens 33 is reflected by the cornea C, and the curved surface characteristics of the cornea C to be examined, that is, the radii of curvature γ ₁ and γ ₂ of the first and second principal meridians, and the principal meridian angle After being deflected according to θ, it passes through the relay lens 14 and passes through the mask plate 3.
The light is selectively transmitted through the linear apertures 25, 26, 27, and 28 of No. 5, and reaches the linear sensor 38 through the relay lens group 36, the first optical path 120, or the second optical path 121. At this time, the projection straight line is deformed according to the curved surface characteristics of the cornea C to be examined, and becomes, for example, as shown in FIG. 12. Here, the intersections of each projected straight line or group of projected straight lines with the coordinate axes X′, Y′ are X ₁ ′, X ₂ ′, X ₃ , X ₄ ′, y ₁ ′,
By determining y ₂ ′, y ₃ ′, and y ₄ ′ and performing necessary calculations according to equations (1) to (3) above, the curved surface characteristics of the cornea C to be examined can be obtained. In the illustrated embodiment, two light emitting diodes 30 with different emission wavelengths,
31 are blinked alternately, and the light from one light emitting diode 30 is transmitted from the illumination optical system 1 through the dichroic mirror 37 of the measurement optical system 2 to the first light emitting diode 30.
The light from the other light emitting diode 31 reaches the linear sensor 38 through the optical path 120 and performs detection, for example, on the X' axis. Second optical path 1 with theta 125
21 and reaches the linear sensor 38,
Detection is performed on the Y′ axis.

Next, referring to FIG. 13, a flip-flop 60 for driving the light emitting diodes 30 and 31 is connected to the light emitting diodes 30 and 31, and this flip-flop 60 is activated by a scan start pulse from a drive circuit 61. As the linear sensor 38,
For example, a CCD consisting of 1728 elements is used, and its output is amplified by an amplifier 62 and given to a sample and hold circuit 63. The output of the sample and hold circuit 63 is applied to a comparator 64, where it is compared with a reference value from a reference setter 65 and binarized to produce an output 701. Drive circuit 61 generates a scan start pulse 702 and a clock pulse 703, which are applied to sensor 38. FIG. 14 shows these pulses, where a shows the scan start pulse, b shows the clock pulse, c shows the output pulse of the sample hold circuit 63, and d shows the output 701 of the comparator 64.

In such a configuration, when scanning is performed by the sensor 38, it is necessary to detect which position on the sensor 38 each projected straight line of the linear aperture has reached. To do this, it is only necessary to detect on which sensing element of the sensor 38 the center of the output pulse corresponding to the width of the projected straight line is located.
The purpose is achieved by counting by clock pulses. A circuit for this purpose is shown in FIG.
In FIG. 15, output 701 from comparator 64
is applied to a rising edge detector 40a and a falling edge detector 40b, and a scan start pulse 702 and a clock pulse 703 are applied to a counter 41. Counter 4
1 is first cleared by a scan start pulse 702 and then counts clock pulses 703. The output of the counter 41 is supplied to a latch circuit 44, which latches the output of the counter 41 at the output 401 of the rising edge detector 40a. The output of the latch circuit 44 at this time is, for example, the 14th
It represents the position on the sensor 28 of the front end of the pulse L ₁ in the figure. The gate circuit 42 outputs an output pulse 70
1 is "1", a clock pulse is supplied to the counter 43, which has been cleared in advance by the scan start pulse 702. The output of the gate circuit 42 is indicated by g in FIG. Therefore, the output of the counter 43 indicates a value equal to the width of the projected straight line projected onto the sensor 38. If the counter 43 is a binary counter, the adder 47 adds the value obtained by discarding the least significant bit of the output of the gate circuit 42 and shifting it by one bit toward the lower bit, and the output of the latch circuit 44. The center position of the projected straight line projected onto the sensor 38 is determined. A delay circuit 46 delays the output 402 of the falling edge detector 40b by Δt. This state is shown as f in FIG. 16. The output of the delay circuit 46 is sent to the counter decoder 4
given to 8. This counter decoder 48 is
Latch the output of the adder 47 to the sequence serial1
This is for latching up to 91, 192...198. Note that the output of the delay circuit 46 is also used to reset the counter 43.

With the above circuit, when one scan of the sensor 38 is completed, the position of the center of the projection straight line that appears first on the sensor is displayed on the latch 191.
The center position of the second projection straight line is held respectively. For example, if sensor 38 is
When scanned along the Y' axis, sensor 38 has
Signals corresponding to eight projection straight lines appear as shown in c in FIG. 14. Therefore, the latch circuit has 191
8 circuits from 198 to 198 are required.

In FIG. 15, 45 is a digital comparator which compares the output of the reference value generator 50 and the output of the counter 43 and supplies a comparison output to the latches 191-198. This is to determine whether the data represents the position of the intersection on the sensor due to a thick projected straight line among the projected straight lines or a thin projected straight line. Therefore, the output of each latch is sent to the determination circuit 51 together with information on the position of the center of the projected straight line and information on the size of the line width. The reason why the linear aperture of the mask is composed of one thick linear aperture and three thin linear apertures is to facilitate the discrimination of the projected straight line projected onto the sensor 38, as described above. This will be explained in detail using FIG. 18. FIG. 18 is an enlarged view of the intersection of the projected straight lines. 25 is a thick projected straight line, and 27 is a thin projection line 3 that can be easily distinguished from 25.
This is a group of projected straight lines consisting of projected straight lines 27-1, 27-2, and 27-3 of the book.

Now, if the sensor 38 scans the pattern at position a or e, the center of the thick projection straight line 25 is determined to be the position of this projection straight line on the sensor, and the central projection straight line 27- 2 can be detected as the position of the projected straight line group 27. When the projection straight line is scanned at the position b, outputs from the projection straight lines 25, 27-2, 27-3 appear on the sensor 24, and at the position c, the outputs from the projection straight lines 27-1, 25,
At the position 27-3, d, the projection straight line 27-1, 2
7-2 and 25 are output in this order. Therefore, when only two thin projected straight lines are projected onto the sensor, the position of the center of each straight line and group of straight lines can be detected and determined by performing the following determination.

The center position of the sensor output based on the thick projection straight line is always the position of the projection straight line 25 detected on the sensor.

(2) When outputs from three thin projection straight lines appear in the sensor output, the position of the projection straight line group 27 detected on the central position sensor of the intermediate projection straight line is taken as the position.

(3) When only two thin projection straight lines are output, (a) If the order is thick, thin, thin, then the center of the first thin projection straight line, (b) Thin, thick, thin. (c) If the order is thin, thin, thick, the center of the second thin line is the position of the projected straight line group 27 detected on the sensor. shall be.

The above determination is made by the determination circuit 51 shown in FIG. Although it is possible to construct the determination circuit 51 using random logic, it is preferable that the subsequent data processing including the determination circuit be performed by a microprocessor. It will be easy for those skilled in the art to make the above determination using a microprocessor.

The above explanation is based on the projection straight line 25 and the projection straight line group 27.
Although this is about the intersection with
Needless to say. In addition, the sensor output is 4
The output corresponding to two intersections is output in one scan, but by dividing it into two sections at the center position of the sensor and making the above judgment for each section, y' ₁ as shown in Fig. 17 is obtained. , y′ ₂ , y′ ₃ , y′ ₄ on the sensor can be detected.

FIG. 19 shows an example of the overall configuration of an off-salmometer based on the measurement principle described above. In FIG. 19, 700 represents the circuit shown in FIG.
It consists of the optical system shown in the figure. 1000 is the first
The circuit consists of the circuit shown in FIG. 5, and inputs the position of each projection straight line of the mask 35 on the sensor to the microprocessor 52. Microprocessor 52
are the data memory section 53 and the program memory section 5.
4. Display interface unit 55, printer interface unit 57, and output register group 29 that outputs the results of calculations by the microprocessor.
1 to 295, but it is also easy to achieve such a configuration in the field of microprocessors.

With one scan of the first sensor, y′ ₁ , y′ ₂ , y′ ₃ , y′ ₄
Once the position is obtained, the light emitting diode illuminating the mask 35 is switched in the next scan. When the light emitting diode is switched, the emission wavelength is different, so the optical path by the optical system is switched, and equivalently, the sensor scans along the X' axis in FIG. 17.
Therefore, the positions of x′ ₁ , x′ ₂ , x′ ₃ , and x′ ₄ on the sensor are determined.

Once the position of the projection straight line on the sensor 38 is determined in this way, the curved surface characteristics of the cornea of the eye to be examined are calculated by the following calculation process.

() Projected straight lines 25, 26, projected straight lines 27,
Find the equation 28 and calculate the slope of the projected straight line group 27.
Let _m'A be the slope of the projection straight line 26 and be _m'B .

() Find the length of the projected straight line group 27 sandwiched between the projected straight lines 25 and 26, and let the length be l' _A .

() Find the length of the projected straight line 26 sandwiched between the projected straight line groups 27 and 28, and let the length be l' _B.

() Calculation of alignment amounts α and β is performed in the 17th
Let the coordinates of figures i, j, k, l be (x′ _i ,
x′ _i ), (x′ _j , y′ _j ), (x′ _k , y′ _k ), (x′ _l , y
' _l ), then the horizontal alignment amount α (X-axis direction) and the vertical alignment amount β (Y-axis direction) are expressed as ΔX by extending equations (5) and (6) to the case of four intersections. =x _i +x _j +x _k +x _l ΔY=y _i +y _j +y _k +y _l ...(5)', and from the intersection on the detection plane D, ΔX'=x' _i +x' _j +x' _k +x' _l ΔY′=y′ _i +y′ _j +y′ _k +y′ _l ...(6)′ is obtained, and by forming a straight line pattern on the mask in advance so that ΔX=ΔY=0, the above ( 7) Calculate with the denominator of the formula as "4".

(V) A microprocessor performs arithmetic processing based on the above-mentioned equations to obtain desired curved surface characteristics.

_The results _obtained in this manner are displayed on the display shown in FIG. 56, printer 58, output register 2
91-295. Furthermore, on the display 56,
By using a device capable of two-dimensional display (for example, a CRT display device, etc.), the alignment amounts α, β, and the main meridian angle θ can be displayed as a two-dimensional pattern. By doing this, there is an advantage that alignment between the cornea to be examined and the ophthalmometer can be easily and quickly performed.

Furthermore, if the alignment amount output register is connected to a movement mechanism that electrically and mechanically drives the off-salmometer housing to move it left, right, up and down, alignment can be automatically performed, as in the first embodiment described above. .

FIG. 20 is a partial optical arrangement diagram showing a second embodiment of the present invention. Components having the same functions as those in FIG. 10 are designated by the same reference numerals, and explanations thereof will be omitted. In this embodiment, instead of rotating the image using the image rotator 21 in FIG.
The parallel plane glass 301 is placed at an angle to the optical axis 302, and the parallel plane glass 301 is placed at a position of 301a and
By changing the position to b, the sensor 38 is moved in parallel to the position 38' on the conjugate detection surface D as shown in FIG. 21, or the two sensors 38 and 38' are arranged in parallel. It gives the same effect as .

When the sensor is at position 38, it detects points e ₁ to e ₄ , and when it is at position 38', it detects points e' ₁ to e' _4. From this, the equation of projection line 25 to 28 is obtained. The curved surface characteristics of the cornea C to be examined can be measured by calculations similar to those in the first embodiment.

FIG. 22 is an optical layout diagram showing a third embodiment of the present invention, in which the illumination optical system 1 and the fixation optical system 3 have the same configuration as in FIG. 10, so they are shown in a simplified manner. Components similar to those in FIG. 100 are given the same reference numerals and their explanations will be omitted. In this embodiment, the mask 35 is divided into two masks 35-1 and 35-.
2, the mask 35-1 is formed with linear apertures 25 and 26 shown in FIG. Combine them into one.
A dichroic mirror 37 is arranged behind the relay lens 14, and the optical path behind it is connected to the first optical path 1.
20 and a second optical path 121. The aforementioned mask 35-1 is placed in the first optical path, and the mask 35-2 is placed in the second optical path 121, respectively. mask 35
The light beam that has passed through -1 is further divided into two by a half mirror 303, and the reflected light beam enters the linear position sensor 38, and the transmitted light beam enters the linear position sensor 302. Similarly, mask 35
-2 is also reflected and transmitted by the half mirror 303, and the linear sensors 38 and 30 respectively
2. Here linear sensors 38 and 302
are arranged by the relay lens 14 so as to virtually intersect with each other within the conjugate detection plane D thereof. Due to the light emitted from the light emitting diode 30, the linear sensor 38 detects x' ₂ and x' ₃ shown in FIG. 17, and the linear sensor 302 detects y' ₂ and y' ₃ . Next, when the light emitting diode 31 emits light, the linear sensor 38
detects x′ ₁ and x′ ₄ , and the linear sensor 302 detects y′ ₂ and
Detect y′ ₃ . Thereafter, the curved surface characteristics of the cornea to be examined are obtained by the same procedure as in the first embodiment described above.

The first to third embodiments described above are flat type position sensors fixedly arranged as detectors,
Although one or more linear position sensors are used, the present invention is not limited to this, and at least one linear position sensor is used in parallel in a plane perpendicular to the optical axis O ₁ of the measurement optical system 1. It may be moved or rotated around the optical axis _O1 .
An example is shown in FIG. Linear sensor 38
The pulse motor drive circuit 31 is controlled by the microprocessor 100 with the optical axis _O1 as the rotation axis.
It is rotated by a pulse motor 311 which is rotated by a motor. The linear sensor 38 can be continuously rotated by this pulse motor 311 to have the same function as a flat sensor on the conjugate detection surface D, or can be rotated by a predetermined angle to have the same function as two intersecting linear sensors. Can be done.

FIG. 24 is an optical layout diagram showing an embodiment in which the measurement principle of the present invention is applied to a radius meter for measuring the base curve or front curve of a contact lens. Components similar to those in the first embodiment described above are designated by the same reference numerals, and explanations thereof will be omitted.

When measuring the base curve of the contact lens CL, hold the convex surface of the contact lens down and hold the cylindrical protrusion 60 of the contact lens holding means 600.
It is held at 1.

In this embodiment, the conjugate detection surface D by the relay lens 14 of the positional sensor 38 of the measurement system 2 is designed to be located inside the focal length f _CL of the rear surface of the contact lens to be measured.

Although the measurement principle explained above and the example in which the mask means of each embodiment has a linear aperture that selectively transmits the luminous flux is shown, a reflective linear pattern that selectively reflects the luminous flux may be used instead. Needless to say, the same functions and effects as those of the present invention can be obtained.

Furthermore, the circuit that scans and drives the light-emitting element or the light-receiving element and processes the detected data is not limited to the above-mentioned circuit, but any circuit that can obtain the necessary data and process the above-mentioned arithmetic expression may be used. It will be apparent to those skilled in the art that various circuits could be designed.

[Brief explanation of drawings]

Fig. 1 is a perspective view for explaining the measurement principle of the present invention, Fig. 2 is a plan view thereof, Fig. 3 is a perspective view for explaining another aspect of the measurement principle, and Fig. 4 is a detection Figure 5 is a diagram showing an oblique coordinate system on a plane, Figure 5 is a diagram of projected straight lines appearing in oblique coordinates, Figure 6 is a diagram showing the relationship between oblique coordinates and orthogonal coordinates, and Figure 7 is a diagram showing virtual intersection points. FIG. 8 is a diagram showing another straight aperture of the mask and a projected straight line; FIG. 9 is a diagram showing a straight aperture having a virtual intersection and its projected straight line appearing on oblique coordinates. , FIG. 11a is a diagram showing an example of a linear aperture in a mask, FIG. 10 is an optical layout diagram showing a first embodiment of the present invention, and FIG. 11b is a diagram showing an intersection of linear apertures in a mask. , FIG. 12 is a diagram showing the relationship between the obliquely arranged linear sensors and the projected straight line, FIG. 13 is a block diagram showing a part of the detection circuit of the first embodiment, FIG. 14 is a diagram showing the detection pulse train, 1
FIG. 5 is a block diagram showing the arithmetic processing circuit of the first embodiment, FIG. 16 is a diagram showing each output signal, FIG. 17 is a diagram showing the relationship between the projection straight line and sensor scanning of the first embodiment, and FIG. 19 is a block diagram showing the entire electrical circuit of the first embodiment, and FIG. 20 is a partially omitted optical diagram showing the second embodiment of the present invention. Layout diagram, Figure 21 is the second
22 is an optical layout diagram showing the third embodiment of the present invention, and FIG. 23 is a side view of the embodiment in which the linear position sensor is rotated. FIG. 24 is an optical layout diagram showing a fourth embodiment of the present invention. 10... Pinhole plate, 14, 36, 124...
...Relay lens, 38,302...Position sensor, 125...Image rotator, 33...
...Collimator lens, 301...Parallel plane glass.

Claims (1)

[Scope of Claims] 1. An illumination optical system having a light source and a collimator means for converting light from the light source into a parallel light beam; Selecting a light beam reflected by a curved surface to be inspected from the light beam from the illumination optical system. mask means having a straight line pattern configured to substantially intersect at least two straight lines at at least one point on a substantial surface in order to detect the reflected light selected by the mask means; a detection optical system having a detection means; a calculation means for calculating a radius of curvature of the curved surface to be inspected from a projected straight line pattern corresponding to the straight line pattern of the reflected light detected by the detection means; and a curvature measuring device, wherein each of the detection means is optically non-conjugate with the light source and arranged on substantially different surfaces. 2. The curvature measuring device according to claim 1, wherein the straight line pattern includes at least three straight lines that substantially intersect at at least three points. 3. The curvature measuring device according to claim 1 or 2, wherein the straight line patterns have different thicknesses or numbers of the straight lines or selectivity of the reflected light. . 4. The straight line pattern includes a first parallel straight line group each consisting of one mutually parallel straight line, and two straight line groups each consisting of three straight lines that substantially intersect the first parallel straight line group. A radius of curvature measuring device according to claim 2 or 3, characterized in that the device comprises a second group of parallel straight lines formed in parallel with each other. 5. According to any one of claims 1 to 4, wherein the linear pattern is constituted by an opening formed in the mask means to selectively transmit the reflected light. The curvature measuring device described. 6. The curvature measuring device according to any one of claims 1 to 5, wherein the straight line pattern is formed by forming all straight lines on one mask means. 7. The curvature measuring device according to any one of claims 1 to 6, wherein the irradiation light beam is infrared light. 8. The curvature measuring device according to any one of claims 1 to 7, wherein the detection means is a planar position sensor. 9. Claim 1, wherein the detection means is at least two linear position sensors that substantially intersect within the non-conjugate plane.
The curvature radius measuring device according to any one of Items 7 to 7. 10. Claim 1, wherein the detection means is at least two linear position sensors that are substantially parallel on the non-conjugate surface.
The curvature measuring device according to any one of Items 7 to 7. 11. The radius of curvature measurement according to any one of claims 1 to 7, wherein the detection means is at least one linear position sensor that rotates on the non-conjugate surface. Device. 12. The detection means is at least one linear position sensor, and is characterized in that it has a light flux rotation means for rotating the reflected light from the curved surface to be inspected about the optical axis of the device. A curvature radius measuring device according to any one of claims 1 to 7. 13. The curvature measuring device according to any one of claims 1 to 7, wherein the detection means is at least one linear position sensor that moves in parallel within the nonconjugate plane. . 14. The detection means is at least one linear position sensor, and has an image shift means for moving the reflected light in parallel within a plane perpendicular to the optical axis of the device. Range 1
The curvature measuring device according to any one of Items 7 to 7. 15. Claims 1 to 14, characterized in that the detection optical system includes a relay optical means for forming an image of at least one of the detection means and the mask means on the non-conjugate surface. The curvature measuring device according to any one of. 16. The detection optical system is characterized in that a reflection member having a reflection surface perpendicular to the illumination optical axis is insertably arranged between the detection surface and the mask means. The curvature measuring device according to any one of Items 1 to 15. 17. The curvature measuring device according to claim 15 or 16, characterized in that the optical axis of the relay optical means and the illumination optical axis are at least partially common.