JPH0325165B2 - - 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, it can be applied to an off-salmometer that measures the radius of curvature of the cornea of a human eye and a radius meter that measures the radius of curvature of a contact lens. This invention relates to a curvature measuring device. In this specification, the principles and embodiments of the present invention will be mainly explained with respect to an ophthalmometer, but the present invention is not limited thereto, and the main diameter of a curved surface of a spherical surface or a toric curved surface having light reflectivity can be broadly described. The present invention can also be applied to a device that measures the radius of curvature of a line. The refractive power of the human cornea itself is approximately 45 Diopter, which is approximately 80% of the total refractive power of the entire eye, and approximately 75% of astigmatic eyes have corneal astigmatism, that is, the anterior surface of the cornea is not spherical but has a toric surface 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 viewpoints, measuring the radius of curvature of the anterior surface of the cornea has important significance. In response to this demand, 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 optotypes 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 where the cornea has a toric surface 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 and the angle in at least one main radial direction, and the conventional off-salmometer described above requires three stages of measurement to obtain these three measured values. It was. 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 leads to measurement errors and the need for frequent alignment adjustment operations during measurement. A big problem arose. As a device that solves the drawbacks of this conventional device,
For example, JP-A-56-18837, JP-A-56-18837,
66235 or US Pat. No. 4,159,867, the reflected image of the projected image from the cornea is detected by a one-dimensional or two-dimensional position sensor,
An apparatus is disclosed that measures the radius of curvature and main meridian angle of the cornea of an eye to be examined from the detected position. However, these devices, like the conventional off-salmometers in practical use, 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. Furthermore, since it is an imaging type, a focusing mechanism is required. Furthermore, the alignment between the device and the cornea to be examined and the alignment performed using this focusing telescope are inaccurate, and do 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 refractive characteristics of the lens to be tested are determined from the position of the projection point on the detector of the optical axis that has passed through the point aperture and is 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., and the refractive characteristics of the lens to be tested may not be measured. Therefore, the present invention solves the above-mentioned drawbacks of the conventional off-salmometers, and provides a curvature measurement device that can be applied to off-salmometers and radius meters, and is capable of automatic measurement using a non-imaging optical system. That is. 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 inspected 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 without having any. 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. Yet another object of the present invention is to provide a radius of curvature measuring device that does not require the installation or adjustment of a position sensor, has low assembly and adjustment costs, and is easy to maintain. According to the present invention, 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; In order to a detection optical system having a detection means for detecting reflected light; calculating the radius of the curved surface of the curved surface to be inspected from changes in the slope and pitch of a projected linear pattern corresponding to the linear pattern of the reflected light detected by the detection means; There is provided a curvature measuring device, wherein both the masking means and the detecting means are optically non-conjugate with the light source and are respectively arranged on different planes. In the present invention, "substantially within a plane" refers to a case where the straight line pattern (or detecting means) is actually arranged within one plane, and a case where the straight line pattern (or detecting means) is located at different locations, for example. This includes both cases in which it is constructed as if it were in one virtual plane by optical means. In the present invention, due to the above structural features,
Compared to conventional radius of curvature measuring devices, the device is smaller, takes less time to measure, is more resistant to external disturbances, has higher measurement accuracy, is more inexpensive, and can automatically measure the radius of curvature of the curved surface being tested. . Furthermore, since alignment information can be automatically output, measurement time can be further shortened and measurement accuracy can be improved. These advantages of the present invention are that, especially when the present invention is applied to an ophthalmometer, the ophthalmometer has high measurement accuracy that is not affected by eye vibration, is compact with a short measurement time, and enables automatic measurement at low cost. meter 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 back surface of the contact lens and the center of curvature, and the objective lens at that time is Compared to conventional radius meters that measure the radius of curvature of base curves, etc. from the amount of movement, there is no need for a microscope optical system for target image observation and measurement using conventional radius meters. To provide a new type of radius meter that not only does not require any diopter adjustment that directly affects measurement accuracy, but also allows automatic measurement without personal errors between operators, has high measurement accuracy, and short measurement time. be able to. 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 an origin O ₀ on the optical axis O ₁ of the device. This X ₀ −Y ₀
It is assumed that the cornea C is placed a distance l in front of the plane including the coordinate system. This cornea C is its optical center
_OC is shifted by E _H in the direction parallel to the X ₀ axis and _EV in the direction parallel to the Y ₀ axis, and the curve radius is
It is assumed that the first principal radial line (strong principal radial line) of R ₁ is inclined by an angle θ with respect to an axis parallel to the X ₀ axis. Further, the radius of curvature of the second principal meridian (weak principal meridian) is R ₂ . The first main radius line and the second main radius line are orthogonal. Now, a mask MA, which will be described later, is placed within the plane created by this X ₀ - Y ₀ coordinate system, and is placed on the optical axis O ₁ of the device at a distance d from the mask MA along the optical axis O ₁ of the device. Assume that an X-Y orthogonal coordinate system having an origin O is assumed, and a detection plane D is placed on this X-Y coordinate plane. The master MA has a straight aperture 0 L ₁ consisting of two parallel straight lines with a slope of ₀ m 1 and a pitch of ₀ P ₁ , and a straight line opening ₀ L ₁ with a slope of 0 m ₂ and a pitch of ₀ P 1.
It has a linear aperture ₀ L ₂ composed of two parallel straight line groups with a pitch ₀ P ₂ . As shown in FIG. 2, the cornea C to be examined is illuminated with a circular light beam having a radius of φ/2. The light reflected by the cornea C of this illumination light beam is
It is selectively transmitted through a _linear aperture consisting of a group of parallel straight lines ₀ L ₁ , ₀ L ₂ formed on a master MA that is separated by a distance l from the corneal apex OC, and is projected onto a detection surface D that is separated by a distance d from the master MA. Ru. The beam of light selected by the master MA reflected by the cornea C to be examined is projected on the detection surface D by a group of two projected parallel straight lines ₀ L ₁ ′ with an inclination of ₀ m _{1 ′ and a pitch of 0 P 1 ′ ;} It becomes a group of two projected parallel straight lines ₀ L ₂ ′ with pitch ₀ m ₂ ′ and pitch ₀ P ₂ ′. By detecting the projected parallel straight line groups ₀ L ₁ ′ and ₀ L ₂ ′ on the detection plane D, the pitch of the projected parallel straight line group ₀ L ₁ ′ is ₀ P ₁ ′,
If the slope changes to ₀ m ₁ ′, the pitch of the group of projected parallel straight lines ₀ L ₂ ′ changes to ₀ P ₂ ′, and the slope changes to ₀ m ₂ ′, then the slope ₀ m ′ for each of these changes is given by the following formula. holds true. ₀ m′=[A(l)sin ² θ+B(l)cos ² θ]+[A(l)
)-B(l)] sinθ・cosθ/ ₀ m[A(l)-B(l)
] sin θ・cos θ + [A(l) cos ² θ + B(l) sin ² θ]
…(1) Also, the amount of change in pitch P′ is ₀ P′/ ₀ P=A ² (l) sin ² θ+B ² (l) cos ² θ+A ² (l)
+B ² (l) / ₀ m ² +1 [cos2θ+ ₀ msin2θ]…(2), where [A(l)=1+2(l-d)/R ₁ /2l/R ₁ B(l )=1+2(ld)/ _R2 /2l/ _R2 ]. In this measurement principle, the parallel light beam reflected by the cornea C is selected by the linear aperture of the master MA, and this selected light beam is detected by the detection surface D. It is necessary to set the device so that the distance l, that is, the working distance, becomes a predetermined constant using a known working distance detecting device. Preferably, it is set so that l=O. Two sets of equations (1) and (2) are obtained from the two sets of projected parallel straight lines ₀ L ₁ ′ and ₀ L ₂ ′, a total of 4 equations, so the unknown number θ (the th 1 main radial line angle), R ₁ (curvature radius of the 1st main radial line), and R ₂ (curvature radius of the 2nd main radial line) can be determined. Solving the quadratic equations (1) and (2)
If determining R ₁ , R ₂ , and θ is complicated in terms of arithmetic processing and increases the cost of the processing mechanism and increases the processing time, the following intermediate arithmetic processing may be performed. FIG. 3a shows a group of parallel straight lines L ₁ and L ₂ formed by the linear light source of FIG. 2. FIG. The slope of L ₁ is m ₁ and the pitch is P ₁ , and the slope of L ₂ is m ₂ and the pitch is P ₂ as in FIG. 2. Now, consider a parallel line extending from one of _the parallel straight lines _L11 to a distance _eP1 that is e times the pitch _P1 , and a parallel line at a distance _fP1 . Also, the distance gP ₂ from one of the parallel straight lines L ₂ L ₂₁
Consider parallel lines with distance hP 2 and parallel lines with distance hP ₂ .
A reference virtual parallelogram UVWQ is formed from these parallel lines, and these four vertices
The virtual coordinates of the x ₀ −y ₀ coordinate system are U ( ₀ x ₁ , ₀ y ₁ ), V
( ₀ x ₂ , ₀ y ₂ ), W ( ₀ x ₃ , ₀ y ₃ ), and Q ( ₀ x ₄ , ₀ y ₄ ). Figure 3b shows that the luminous flux reflected by the cornea C is
This is a diagram showing a projected parallel straight line group ₀ L _{1 ′} , ₀ L ₂ ′ that is selectively transmitted by the parallel straight line group ₀ L ₁ , ₀ L ₂ shown in the figure and projected onto the detection surface D, and this ₀ L ₁ ′ is ₀ m ₁ , pitch ₀ P ₁ ′,
As in Fig. 1, L ₂ ′ changes to a slope of ₀ m ₂ ′ and a pitch of P ₂ ′. This projected parallel straight line group ₀ L ₁ ′,
₀ L ₂ ' may be detected by a flat position sensor placed on the detection surface D, but now suppose that the distance is ξ in the X-axis direction and η in the Y-axis direction from the origin O of the X-Y coordinates. Assuming that detection is performed by linear position sensors S ₁ and S ₂ that intersect at an intersection angle γ with the origin O′ at the moved point, linear position sensor S ₁ projects at detection points A, B, C, and D. A group of parallel straight lines is detected, and the linear position sensor S ₂ detects a group of projected parallel straight lines at detection points E, H, G, and J. And detection point b,
The equation of one of the projected parallel straight lines L ₁₁ ' is calculated from F, and the equation of L ₂₁ ' is calculated from the detection points C and T. Similarly, the equations of the other one of the projected parallel straight lines L ₁₂ ′ from the detection points A and E, and the equations of L ₂₂ ′ from the detection points N and J can be calculated as L ₁₁ ′,
The pitch P ₁ ′ of L ₁₂ ′ and the pitch P ₂ ′ of L ₂₁ ′ and L ₂₂ ′ can be calculated. Then, from L ₁₁ ′, the pitch P ₁ ′ can be multiplied by the same magnification e as in Fig. 3a, and we can consider the parallel line ′′ of the pitch of eP ₁ ′, and similarly, the parallel line ′ of the pitch of fP ₁ ′ ′, L ₂₁ ′ to gP ₂ ′ Pitch parallel line ′′ hP ₂ ′ Pitch parallel line ′′ can be considered, and these parallel lines ′′, ′′, ′′,
The first projected virtual parallelogram ``'''' can be found from U'Q'. The virtual coordinates of the four vertices of this virtual parallelogram in the X-Y coordinate system are defined as U′(x <sub>1</sub> ,
y <sub>1</sub> ), V′ (x <sub>2</sub> , y <sub>2</sub> ), W′ (x <sub>3</sub> , y <sub>3</sub> ), Q′ (x <sub>4</sub> , y <sub>4</sub> )
Then, the reference virtual parallelogram UVWQ in Fig. 3a
and the first projected virtual parallelogram in Fig. 3b.
U′V′W′Q′ corresponds, and this change is precisely related to the curved surface characteristics of the cornea to be examined. Now, the following coefficients and equations are defined for the four virtual points. A <sub>ij</sub> = ( <sub>0</sub> x <sub>i</sub> − x <sub>i</sub> ) − ( <sub>0</sub> x <sub>j</sub> − x <sub>j</sub> ) A <sub>ik</sub> = ( <sub>0</sub> x <sub>i</sub> − x <sub>i</sub> ) − ( <sub>0</sub> x <sub>k</sub> − x <sub>k</sub> ) B <sub>ij</sub> = ( <sub>0</sub> y <sub>i</sub> − y <sub>i</sub> ) − ( <sub>0</sub> y <sub>j</sub> y <sub>j</sub> ) B <sub>ik</sub> = ( <sub>0</sub> y <sub>i</sub> − y <sub>i</sub> ) − ( <sub>0</sub> y <sub>k</sub> − y <sub>k</sub> ) C <sub>ij</sub> = <sub>0</sub> x <sub>i</sub> − <sub>0</sub> x <sub>j</sub> C <sub>ik</sub> = <sub>0</sub> x <sub>i</sub> − <sub>0</sub> x <sub>k</sub> D <sub>ij</sub> = <sub>0</sub> y <sub>i</sub> − <sub>0</sub> y <sub>j</sub> C <sub>ik</sub> = <sub>0</sub> y <sub>i</sub> − <sub>0</sub> y <sub>k</sub> Equation (3a) Here, i, j, and k are assumed to be j or k with i as a reference. From the four virtual points, 12 combinations are possible. Using the above equation (3a), R <sub>1</sub> and R <sub>2</sub> regarding the radii of the two main system lines can be expressed by the following quadratic equation. 4(C <sub>ij</sub> D <sub>ij</sub> −C <sub>ij</sub> D <sub>ik</sub> )(l/R) <sup>2</sup> −2(A <sub>ij</sub> D <sub>ik</sub> +B <sub>ik</sub> C
−A <sub>ik</sub> D <sub>ij</sub> −B <sub>ij</sub> C <sub>ik</sub> ) (l/R) + (A <sub>ik</sub> B <sub>ij</sub> −A <sub>ij</sub> B <sub>ik</sub> )=
0...Equation (3b) Here, the Katsuko equation of the above coefficient is defined as follows. [p, q]≡p <sub>ij</sub> q <sub>ik</sub> −q <sub>ij</sub> p <sub>ik</sub> [p, q]=−[q, p] Here, if p and q are each A, B, C, or D, Equation (3b) is 4[C,D](l/R) <sup>2</sup> −{[B,C]−[A,D
]} (l/R)+[A,B]=0...It is expressed as equation (3c). l is the test cornea C and the master cornea as shown in Figure 1.
Refers to the distance between MAs. Therefore, as shown in Figure 1, two sets of projected parallel straight lines
The pitch of <sub>0</sub> L <sub>1</sub> ′, <sub>0</sub> L <sub>2</sub> ′ <sub>is 0</sub> P <sub>1</sub> ′, <sub>0</sub> P <sub>2</sub> ′ and the slope <sub>is 0</sub> m <sub>1</sub> ′, <sub>0</sub> m <sub>2</sub> ′
, and create a projected virtual projection quadrilateral as shown in Figure 3b. From the four vertices forming the parallelogram, (3c)
By solving the quadratic equation of the equation, let the two roots be λ <sub>1</sub> and λ <sub>2</sub> , λ <sub>1</sub> = l/R <sub>1</sub> , λ <sub>2</sub> = l/R <sub>2</sub> ...(4a) As a result, the first principal meridian and the first The radii of curvature R <sub>1</sub> and R <sub>2</sub> of each of the two principal meridians are It can be found as Also, the angle θ that the first principal axis makes with the axis parallel to the X <sub>0</sub> axis is θ = 1/2tan <sup>-1</sup> {[B, D] - [A, C] / [A,
D]+[B,C]}+90°...(5) In FIGS. 3a, 3b, and 3c, pitches 0 P 1 , <sub>0</sub> P <sub>1</sub> ,
<sub>0</sub> P <sub>2</sub> , <sub>0</sub> P <sub>1</sub> ′, and <sub>0</sub> P <sub>2</sub> ′ with arbitrary magnifications e, f, g,
h respectively, but in reality, e=1, g=1, and the virtual parallelogram U <sub>0</sub> V <sub>0</sub> W <sub>0</sub> Q, and
The processing can be simplified by using U <sub>0</sub> ′V <sub>0</sub> ′W <sub>0</sub> ′Q′. Also, the coordinates of each vertex of the virtual parallelogram are X <sub>0</sub> −
The explanation has been made using the <sub>Y0</sub> orthogonal coordinate system and the X-Y orthogonal coordinate system, but if we consider the oblique coordinate system X'-Y' coordinate system along with the arrangement of the linear sensors <sub>S1</sub> and <sub>S2</sub> , The coordinate transformation between the coordinate system and the X'-Y' oblique coordinate system is as shown in Figure 4, where the X axis and the
The axis and the Y' axis intersect at an angle β, and the origin O <sub>2</sub> of the X'-Y' coordinate system is offset from the origin O <sub>1</sub> of the X-Y drift system by ξ in the X-axis direction and η in the Y-axis direction. . At this time, X′−
<sub>The coordinate</sub> transformation from the Y <sub>′</sub> coordinate system to the X-Y coordinate system <sub>is</sub> −( <sub>0</sub> x <sub>j</sub> −x <sub>j</sub> ) Substituting equation (6) into this, A <sub>ij</sub> = {( <sub>0</sub> x′ <sub>i</sub> sinα+ <sub>0</sub> y′ <sub>j</sub> sinβ+ξ) −(x′ <sub>i</sub> sinα+y′sinβ+ξ)} −{( <sub>0</sub> x ′ <sub>j</sub> sinα+ <sub>0</sub> y′ <sub>j</sub> sinβ+ξ) −(x′ <sub>j</sub> sinα−y′ <sub>j</sub> sinβ+ξ)} = sinα{( <sub>0</sub> x′ <sub>i</sub> −x′ <sub>i</sub> )−( <sub>0</sub> x′ <sub>j</sub> −x′ <sub>j</sub> )} + sinβ{ <sub>0</sub> y′ <sub>i</sub> −y′ <sub>i</sub> ) − ( <sub>0</sub> y′ <sub>j</sub> −y′ <sub>j</sub> )} = A′ <sub>ij</sub> sinα+β′ <sub>ij</sub> sinβ …(7a) (Here, the ``′” indicates the X′−Y′ oblique It means coordinate values or operators based on the orthogonal coordinate system, the same applies hereinafter.) Also, B _ij = ( ₀ y _i − y _i ) − ( ₀ y _j − y _i ), and in the same calculation as above, B _ij = cos β { ( ₀ y′ _i −y′ _i ) −( ₀ y′ _j −y′ _j )} −cosα {( ₀ x′ _i −x′ _i ) −( ₀ x′ _j −x′ _j )} = B′ _ij cosβ−A′ _ij cosα…(7b) Similarly, C _ij =C′ _ij sinα+D′ _ij sinβ…(7c) D _ij =D′ _ij cosβ+C′ _ij cosα…(7c). Here, [C, D], [B, C], [A, D], [A,
B], from equations (7a) to (7d), [C, D]=C _ij D _ik −D _ij C _ik = (C′ _ij sinα+D′ _ij sinβ) (D′ _ik cosβ−C′ _ik cosα ) −(D′ _ij cosβ−C′ _ij cosα) (C′ _ik sinα+D′ _ik sinβ) = (sinαsinβ+cosαsinβ) [C′, D′] Similarly, [B, C] = (sinαsinβ+sinβcosα) [A′, B′ ] [A, D]=sinαcogβ[A′,D′] −sinαcosα[A′,C′] +sinβcosβ[B′,D′] −sinβcosα[β′,C′] [A,B]=(sinαcosβ+cosαsinβ) [A', B'] Also, [B, C] - [A, D] = sin α cos β + cos α sin β) {[B', C'] - [A', D']} Therefore, equation (3c) is sin (α + β) ×{4[C′,D′] (l/R) ² −2([B′,C′]−[A′,D′]) (l/R)+[A′,B′]}= 0 ...(8), and the inside { } of this equation (8) is a quadratic equation with the same form as equation (3c). From this, the quadratic equation of equation (3c) is independent of how the coordinate system is taken. It can be seen that it is an invariant equation. This shows that the degree of freedom in the arrangement of the two linear sensors as detectors is very large. In other words, as in the past, two linear sensors are
It is not necessary to place it on the orthogonal coordinate axes to the coordinate system;
This means that it can be used in the Y′ coordinate system,
The orthogonality accuracy and optical axis alignment of the linear sensor can be made irrelevant to the measurement accuracy without much consideration. During measurement, instead of setting the linear apertures ₀ L ₁ and ₀ L ₂ of the master MA in advance with respect to the oblique coordinate system Temporarily installed perpendicular to the axis O ₁ , the proof light beam reflected by this plane reflecting mirror is transmitted and selected by the linear apertures ₀ L ₁ and ₀ L ₂ of the master MA, and the projection parallel straight line group ₀ L ₁ on the conjugate detection plane D is transmitted. ′, ₀ L ₂ ′ are detected by linear sensors S ₁ and S ₂ placed on the X′ and Y′ axes of the oblique coordinate system X′-Y′ coordinates, and a virtual parallelogram is created from this detection. Let U, V, W, and Q be a reference projection virtual parallelogram, remove the plane reflecting mirror, and irradiate the test cornea C with an illumination light beam to create the projection virtual parallelogram U′V′W′Q′. The curved surface characteristics of the cornea to be examined can be determined from these reference projected virtual parallelogram and projected virtual parallelogram. In this case, the biparallelogram has an oblique coordinate system that can be selected arbitrarily.
This means that the coordinate system is considered only for the X'-Y' coordinate system, and this oblique coordinate system According to the present invention, the arrangement of the linear sensors S ₁ and S ₂ does not require any adjustment in terms of assembly or maintenance, which is an unrelated invariant equation with respect to the quadratic equation for calculation of . It has a very beneficial effect. The axial direction of the cornea to be examined is given by equation (5). Equation (5) is based on the orthogonal coordinate system, but the oblique coordinate system
When sensors S ₁ and S ₂ are located at X'-Y', the results obtained in the oblique coordinate system can be calculated using the following equation as the axial direction when using the orthogonal coordinate system. θ=1/2tan ^-1 X{ocs2β[B′,D′]−cos(α−β)・([A′,D
′]+[B′,C′]cog2α[A′,C′]/sin2α[B′
,D′]+sin(α+β)([A′,D′]+[B′+C′]
)−sin2α[A′,C′]}…(9) Next, the principle of measuring the amount of deviation in the horizontal and vertical directions (hereinafter referred to as alignment amount) between the vertex of the cornea and the optical axis _O1 of the device is based on Fig. 5. Explain. X ₀ - Y ₀ , the calculation of the alignment amount using the X _- Y orthogonal coordinate system is a group of parallel straight lines 0 L 1 of pitch ₀ P ₁ and pitch 0 L ₁ arranged symmetrically at the same angle γ with respect to the Y ₀ axis.
Similarly, any one straight line L ₁₁ , the straight line from L ₂₁ to e′P _{1 of} the parallel straight line group ₀ L ₂ of ₀ P 2,
f′P ₁ , gP ₂ , h′P ₂ , Q
, and the four vertices of the virtual parallelogram are X ₀
Axis, Y Take it to match the ₀ axis. That is, if the virtual parallelogram is made symmetrically with respect to the measurement optical axis O ₁ , the center of this virtual parallelogram will coincide with the measurement optical axis O ₁ . Next, measure the cornea to be examined, detect a group of parallel projection straight lines L′ ₁ and L′ ₂ , and draw straight lines ′ and ′ at e′P′ ₁ from the parallel projection straight line L′ ₁₁ .
Similarly, the straight line ′′ at f′P′ ₁ , ′′ at g′P ₂ ′, h
′P′ ₂
Subtract ′′ from the first projected virtual parallelogram ′′
Create W' Q '. The four vertices of this first projected virtual parallelogram are in the X-Y coordinate system '(x ₁ , y ₁ ), '(x ₂ ,
y ₂ ), ′(x ₃ , y ₃ ), ′(x ₄ , y ₄ ), and from the coordinates of these four vertices, the horizontal alignment amount α and the vertical alignment amount β can be calculated between the mask MA and the detection surface D. The distance d is involved and is expressed by the following equation. _{When measuring in the oblique coordinate system 2} ) ( ₀ x ₃ , ₀ y ₃ ) ( ₀ x ₄ , _0
y4 )
Then, set the virtual point so that ₀ x ₁ + ₀ x ₂ + _{0 x 3} + ₀ x ₄ = 0 ₀ y ₁ + 0 y ₂ + ₀ y ₃ + ₀ y ₄ = 0...(12) Bye. Since the horizontal alignment amount α and the vertical alignment amount β are each given by equation (10), if we convert equation (12) using equation (6), So, if we convert equation (10) using equation (6) in the same way, we get becomes. The amount of alignment is calculated using the coordinates ( ₀ x′ _i , ₀ y′ _i ) of the initial virtual point ( ₀ x _i , ₀ y _i ) in the oblique coordinate system when the test cornea is not measured and the test cornea in the measurement system. The coordinates (x′ _i ,
y′ _i ), the following equation can be obtained from equations (13) and (14). This formula represents the amount of alignment. As described above, with this measurement principle, the radius of curvature of the tested cornea can be calculated using an invariant equation that is independent of the coordinate system, but oblique-orthogonal coordinate transformation is required in the axial direction and alignment amount. Then,
It is necessary to convert equations (12) and (15), but if the calculation mechanism is complicated, the measurement coordinates (x′,
After performing orthogonal coordinate transformation from y′) using equation (6), the axial direction and alignment amount may be calculated using equations (5) and (10) using the orthogonal coordinate system. In this way, in the present invention, the group of parallel straight lines L ₁ ,
If we create a symmetrical virtual parallelogram from L ₂ to the optical axis O, then insert the cornea to be examined into the measurement optical system and create a similar projected virtual parallelogram from the projected parallel straight line images. , the amount of alignment can be calculated, and when calculating this amount of alignment, it means that the curved surface characteristics of the cornea to be examined, that is, the radius of curvature of the first and second principal meridians and their inclination angles can be measured independently without knowing anything. There is. With conventional off-salmometers, there is no way to calculate the amount of alignment numerically. First, while observing the cornea to be measured with a measuring telescope, This is very advantageous considering that the alignment was done by visual measurement, and the step of calculating the curved surface characteristics of the cornea to be examined and the step of calculating the amount of alignment can be performed as numerical calculations independently or in parallel. Automatic alignment is also possible by electrically inputting it to the , and the calculation time can be shortened. Also, when creating a virtual parallelogram, a straight line
A virtual parallelogram was created by multiplying the pitch of the straight line group to which these straight lines belong to L ₁₁ and L ₂₁ by n and drawing a virtual straight line parallel to the slope of the straight lines L ₁₁ and L ₂₁ .
The method of creating a virtual parallelogram is not limited to this, but as shown in Figure 3C, for straight line L ₁₁ ,
An imaginary straight line l ₁₁ with an inclination of angle β, and a straight line
Needless to say, it is also possible to create a virtual straight line l ₂₁ having an inclination of angle α with respect to L ₂₁ and create a virtual parallelogram uvwq based on _the created virtual straight lines l 11 and l ₂₁ . Therefore, the measurement principle of the present application is not changed. Examples of the present invention will be described below. FIG. 6 is an optical layout diagram showing an embodiment of the present invention. This embodiment is an off-salmometer that utilizes the measurement principle described above. Furthermore, in this embodiment, two linear position sensors are used as detectors in combination with a half mirror so as to intersect obliquely within the conjugate detection plane D, but the present invention is not limited to this. Furthermore, it is clear from the above explanation of the principle that detection can be performed using a planar position sensor or two intersecting linear position sensors. As light sources for the illumination optical system 1, two infrared light emitting diodes 70 and 71 having different emission wavelengths are used. Light from the light emitting diode 70 passes through the dichroic surface 72a of the dichroic prism 32 and enters the condenser lens 7. On the other hand, the light from the light emitting diode 71 is transmitted to the dichroic surface 7.
2a is reflected and similarly enters the condenser lens 7. The light emitted from the condenser lens 7 passes through a pinhole in the pinhole plate 10, is made into a parallel beam by a collimator lens 73 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 84 tilted in the illumination optical system 1 to illuminate the fixation target image onto the subject's eye. A dichroic mirror 86 is arranged behind the relay lens 14 and divides the optical path behind it into a first optical path 120 and a second optical path 121. A mask 13a is provided in the first optical path, and a mask 13a is provided in the second optical path 121.
Masks 13b are arranged respectively. The light beam that has passed through the mask 13a is further divided into two by a half mirror 303, and the reflected light beam enters the linear position sensor 15 and the transmitted light beam enters the linear position sensor 16. Similarly, the light flux that has passed through the mask 13b is also reflected and transmitted by the half mirror 303, and enters the linear sensors 15 and 16, respectively. Here, the linear sensors 15 and 16 are arranged by the relay lens 14 so as to intersect with each other within the conjugate detection surface D thereof. In addition, the masks 13a and 13b are connected to the relay lens 14.
Therefore, each conjugate image is formed at the position MA in the figure. These conjugate planes MA and D are in an optically non-conjugate relationship with the pinhole 10, respectively. FIGS. 7a and 7b are diagrams showing mask patterns of the aforementioned light flux limiting masks 13a and 13b, respectively. The mask 13a has a parallel straight line group 20 consisting of a plurality of straight line patterns with a slope _m2 and a pitch p. Furthermore, at least one of the parallel straight line groups 20 has a reference straight line pattern 22 having a different thickness so as to be distinguishable from other straight line patterns. Similarly, the mask 13b has a reference straight line pattern 23 with a slope m ₁ ,
It has a group of parallel straight lines 21 with pitch p. Here, in this embodiment, the reference straight line pattern 22,
No. 23 was distinguished from other straight line patterns by having a difference in thickness, but the present invention is not limited to this, and it may also be distinguished by having a difference in light transmittance or transmission wavelength characteristics. Alternatively, all straight lines may be the same, and the pitch at a specific location may be changed to serve as a reference straight line. Parallel straight lines 20 and 21 of the masks 13a and 13b each have an intersection angle of θ on the common conjugate plane MA of the masks 13a and 13b formed by the relay lens 14 in FIG. 6, and their bisector 24 is It is configured such that the angle at which it intersects with a certain reference axis 25 is ε. In this embodiment, θ=90° and ε=90. Note that the pitches of the groups of parallel straight lines 20 and 21 are selected to be the same value P, which is different from the mask 13.
This is only to facilitate the production of a and 13b.
Groups of parallel straight lines with different pitches may be used, and the pitches of the straight line patterns in one group of parallel straight lines do not need to be the same. Further, the angles θ and ε can also be arbitrarily selected. FIG. 8 is a diagram showing the projection relationship of the mask pattern image onto the linear sensor when the linear sensor detects the mask pattern image. As shown in FIG. 8, the linear sensors 15 and 16 shown in FIG. 6 are arranged by means of a relay lens 14 such that they have a crossing angle γ on a common conjugate plane, that is, a detection plane D. And this linear sensor 15, 16
Due to the cornea C to be examined above, the light beam having the curved surface characteristic information passes through masks 13a, 13b, and the parallel straight line group 20 of the mask 13a projects straight line patterns 20'a, 20'b, 20'b, 22'...2
Projected as 0'h. Similarly, the parallel straight line group 21 of the mask 13b is the projected straight line pattern 21'a, 2
1'b...23'...21'i. These projected straight line patterns are projected at pitches p' and p'' due to the curved surface characteristics of the cornea C to be examined, their intersection angle is at θ', and their bisector 24' is at the reference axis 2.
The angle intersecting 5' is changed to ε'. During measurement, first, the first light is emitted by the light source 70.
A measurement optical path is formed, and projected linear patterns 20'a, 20'b...22'...20'h are formed by the mask 13a.
is projected onto the linear sensors 15 and 16. Here, the projected linear patterns 20'a, 20'b...20'h are detected by the linear sensor 15 as detection points _e11 , _e12 ... _e17 , respectively. At the same time, the linear sensor 16 also detects the detection points f ₁₁ , f ₁₂ , . . . f ₁₉ . Next, when the light source 71 is made to emit light, a second measurement optical path is formed, and the linear patterns 21'a, 21'b...23'...21'i projected by the mask 13b are projected onto the linear sensors 15 and 16. . Here, the linear sensor 15 projects straight line patterns 21'a,
21'b...23'...21'i are the detection points e ₂₁ and
Detected as e ₂₂ ...e ₂₉ , e ₂₀ . Similarly, the detection points f ₂₁ , f ₂₂ , . . . f ₂₆ are detected by the linear sensor 16 as well. 9A to 9M are timing charts showing the linear sensor output and subsequent calculations when the linear sensor detects the projected linear pattern. (A)
is a pulse train for reading and driving the detection output of the linear sensor, and when this pulse is input to the linear sensor, the linear sensor sequentially outputs the detection output accordingly. (B) shows linear patterns 20'a, 20'b...22'...2 projected onto the linear sensor 15.
It shows the detection output waveform (envelope) from the linear sensor 15 when 0'h is projected. This (B)
The output waveform has a rise in the output level corresponding to the detection points e ₁₁ , e ₁₂ . . . e ₁₇ .
Similarly, (C) shows the detection output waveform of the linear image patterns 20'a, 20'b...20'h by the linear sensor 16,
(D) is a straight line pattern 21' created by the linear sensor 15.
Detection output waveforms of a, 21'b...23'...21'i,
(E) is a straight line pattern 2 projected by the linear sensor 16
1'a, 21'b...23'...21'i are detected output waveforms. (F) ~ (I) are the detection output waveforms (B) ~
This is the rectangular wave output waveform obtained by shaping (E) into a rectangular wave using a Schmitt trigger circuit, and the output waveform (F) ~
(I) corresponds to output waveforms (B) to (E), respectively.
Next, the center position of each rectangular wave of the obtained rectangular wave output waveforms (F) to (I) is found, and this center position is positioned using the sensor element number of the linear sensor as a scale. That is, as shown in FIG. 10, E ₁ , E ₂ . . .
A rectangular wave output e _A is outputted by the sensor elements numbered Ep to E _p+o of the linear sensor LNS consisting of N sensor elements numbered E _N-1 and E _N , and the sensor _{element number} E
When a rectangular wave output e _B is output from the sensor elements numbered E _{l + n} , the width Δ _A of the rectangular wave output e _A is equal to the number of sensor elements n, and the width Δ _B of the rectangular wave output e _B is the sensor Since each corresponds to m elements, the center position O ₁ of the rectangular wave output e _A corresponds to the element E _{p + o} / 2 = E _{c 1} , which is n/2 elements from the E p element. I understand. Similarly, the center position of the square wave output e _B
O ₂ corresponds to E _1+n /2=E _c second element.
In addition, in order to further improve detection accuracy, interpolation between sensor element pitches is necessary, but this is done by accurately detecting the envelope of the rising and falling parts of the output signal, and then shaping the waveform at an appropriate slice level and linearizing it. This is accomplished by detecting the center position using clock pulses that have a sufficiently higher frequency than the pulse train that drives the sensor. In this way, the position of the projected linear pattern can be obtained by determining the center position of the rectangular wave output waveform of the linear sensor obtained from the detection point, and by positioning it by the element number of the linear sensor, that is, as a coordinate value with the linear sensor as the coordinate axis. FIGS. 9 J to M are diagrams showing each detection point as the coordinate value of the linear sensor using the above method, and the coordinate values e' ₁₁ , e' ₁₂ ... e' ₁₇ are the detection points e ₁₁ , e ₁₂ ,...e ₁₇ respectively. Further, the following coordinate values f' ₁₁ to f' ₁₉ correspond to detection points f ₁₁ to f ₁₉ , and coordinate values e' ₂₁ to e' ₂₀ correspond to detection points e ₂₁ to
At e ₂₀ , coordinate values f' ₂₁ to f' ₂₆ correspond to detection points f ₂₁ to f ₂₆ , respectively. Furthermore, as shown in FIG. 10, the number m of sensor elements that output the rectangular wave output e _B is different from the number n of sensor elements that output the other rectangular wave output e _A , and m>n
Therefore, it can be seen that this rectangular wave output e _B is the detection output of the projected straight line pattern based on the reference straight line pattern as shown in FIGS. 7a and 7b.
In this example, the detection points shown in FIGS. 18 and 19 are
e ₁₅ , f ₁₆ , e ₂₅ , and f ₂₃ are detection points at which the reference projected straight line patterns 22' and 23' are detected, respectively;
It can be seen that e′ ₁₅ , f′ ₁₆ , e′ ₂₅ , and f′ ₂₃ are the respective reference coordinate values. Then, the equation of the standard projected straight line pattern 22' can be determined from the standard coordinate values e' ₁₅ and f' ₁₆ , and the standard coordinate value
The equation of the reference projected straight line pattern 23' can be determined from e' ₂₅ and f' ₂₃ . Also, the reference coordinate values e′ ₁₅ , f′ ₁₆ , e′ ₂₅
，
Equations of other projected straight line patterns can be determined from each coordinate value ordered with f′ ₂₃ as a reference. For example, the next coordinate value e′ ₁₆ after the reference coordinate value e′ ₁₅ and the reference coordinate value
Projected straight line pattern 2 from the next coordinate value f′ ₁₇ of f′ ₁₆
The equation for 0'f can be determined. In this way, the equations of a large number of projected straight line patterns can be determined from each coordinate value, and since these projected straight line patterns do not lose their parallelism if they belong to the same parallel straight line group, these many straight line equations can be averaged. By doing so, more accurate and precise detection results can be obtained. Furthermore, it is possible to obtain a large number of values for the pitch P' of each of the large number of equations obtained, and by averaging these values, it is possible to obtain an accurate and precise pitch P'. This is a major feature of the present invention. Next, while referring to Figures 11 to 13,
A virtual straight line is generated from the equation of the projected straight line pattern detected by the linear sensor, and based on this straight line, four arbitrary points are determined on the same plane as the projected straight line pattern projection plane, and changes in these four points are used to determine the A method for measuring the curved surface characteristics of the cornea will be described. FIG. 11 shows the case where the linear patterns 20 and 21 are projected onto the linear sensors 15 and 16 when the reflecting mirror 90 is inserted into the measurement optical path without the cornea C to be examined being placed in the measurement optical path. At this time, the projected straight line pattern 20'' (in FIG. 11, the reference projected straight line pattern 2
2″, 23″ and projected straight line pattern 20″e, 2
Although only 0''f, 21''d, 21''e are selected and illustrated) and 21'', their straight line equations and pitch p are determined by the method described above. Then, for example, using the projected straight line pattern 20''e as a reference,
An imaginary straight line 30 with an inclination of fxm ₂ at a position exP apart
It is also possible to generate a virtual straight line 31 with an inclination fxm ₂ at a position separated by gxP on the reflection side. Using a similar method, for example, with the straight line pattern image 21''d as a reference, a straight line 32 with an inclination of fxm ₁ can be generated at a position separated by hxP, and a straight line 33 with an inclination of fxm ₁ can be generated at a position separated by ixP. Here, the coefficient e, f, g, h, and i are coefficients that can be selected arbitrarily, and usually generate a virtual straight line with the same slope as f=1, that is, the slopes m ₁ and m ₂ of the linear pattern image equation. , g, h, and i are selected so that the intersection points 36, 37, 38, and 39 of the generated virtual straight lines are symmetrical with respect to the center 24 of the mask. As already mentioned in the principle explanation, generating a virtual straight line in this way makes it easier to calculate the amount of alignment with the test cornea.Next, move the device and A method in which the mirror 90 is withdrawn, the cornea to be examined is placed in the measurement optical path, a line sensor is used to detect a projected straight line pattern by a light beam that is changed depending on the curved surface characteristics of the cornea to be examined, and a virtual straight line is determined from this straight line pattern. is shown in FIG.
In the following explanation, it is assumed that alignment adjustment between the cornea to be examined and the measurement optical axis has already been completed by the method described in the explanation of the principle above. First, due to the curved surface characteristics of the cornea to be examined, the pitch
As described above, the projected straight line patterns 20' and 21' whose slopes have been changed to P'P'' and slopes m ₁ ' and m ₂ ', respectively, are detected and their equations are calculated. The position of exP'' with the same amount of coefficient e as used to generate the virtual straight line 30 in FIG. A virtual straight line 30' is generated.The slope of this virtual straight line 30' is determined by setting the coefficient f of the slope fxm ₂ of the virtual straight line 30 to f= ₁ in FIG. Similarly, the coefficient f is f=1
It is said that In the same way, projected straight line pattern 2
Virtual straight line 31' at position gxP'' with 0'e as reference
, with the projected straight line pattern 21'd as a reference.
A virtual straight line 32' is generated at the position hxP', and a virtual straight line 33' is generated at the position ixP'. Intersection points 36', 37', 38' and 39' can be obtained from these virtual straight lines 30', 31', 32' and 33', and the center 34' can be obtained from these four intersection points. In this way, the four points sought were 36-39.
(FIG. 11), four points 36' to 39' are displaced on the detection surface D depending on the curved surface characteristics of the cornea to be examined. FIG. 13 shows this situation. Based on this amount of displacement, the curved surface characteristics of the lens to be tested can be calculated using the above-mentioned equations (3) to (5). As in this embodiment, when the plane reflector 90 is inserted without placing the cornea to be examined in the measurement optical path, the four intersections of virtual straight lines are used as reference points, and when the cornea to be examined is then inserted into the measurement optical path, If the above method of determining the displacement positions of the four intersection points is used, the third equation described above becomes completely unchanged with respect to the coordinate system created by the two linear sensors, so there is no need to manage the intersection angle and intersection position of the linear sensors at the time of assembly. The big advantage is that you don't have to do it. FIG. 14 is a simple block diagram showing an example of a processing circuit for performing the above-mentioned arithmetic processing. The linear sensors 15 and 16 driven by the linear sensor drivers 100 and 101 are the ninth
As shown in FIGS. B to C, first, the drive circuit 60
Detection output signals based on the linear aperture pattern projected image of the light flux limiting mask 13a are sent to the signal lines 102 and 103 by the light emission of the light source 70 driven by the light flux limiting mask 13a. 104 is an analog switch, which is controlled by a microprocessor 105. Microprocessor 105 is linear sensor 1
When the linear sensor scan start pulse 106 is interrupted by the driver 100 that drives the linear sensor 15, the analog switch is controlled so that the output of the linear sensor 15 is input to the A/D converter 107. The A/D converter 107 is the driver circuit 1
The output of each element of the linear sensor read by the linear sensor read pulse 108 as shown in FIG. 9A from 00 is converted from analog to digital, and the converted digital value is supplied to the microprocessor. Here, the A/D converter 107 is selected to have a resolution of about 8 bits (1/256) and a conversion time faster than the scanning frequency of the linear sensor. The microprocessor 105 is
The output of the linear sensor 15 converted into a digital value for each element is read and sequentially stored in a data memory 109 constituted by a RAM (random access memory) or the like. Therefore, the output from the first element of the linear sensor is sequentially stored as a digital value in the data memory 109 from a predetermined position (address). For example, a linear sensor
If it is a device with 1728 elements, when the data acquisition of 1728 pieces is completed, the microprocessor 105
It stops taking in any more data and waits for an interruption by the scan start pulse 110 that drives the linear sensor 16. When receiving an interrupt, the linear sensor 16 controls the analog switch 104 and reads out the linear sensor readout pulse 111.
The output is continuously stored in the data memory 109 as a digital value. Next, the microprocessor 105 controls the drive circuit 1 to turn off the light source 70 that has been emitting light and causes the light source 71 to emit light.
Then, the detection outputs shown in FIGS. 9D and 9E are stored in the data memory 109 as digital values by driving in the same manner as described above. All measurement data has now been stored in the data memory 109. Thereafter, the arithmetic circuit 112 in the microprocessor 105 performs the following processing based on the data written in the data memory 109. (1) Detecting which element of the linear sensor the center position of the linear sensor output waveform generated by the projected image of the linear aperture pattern of the light flux limiting mask is located. (2) In the coordinate system created by the two linear sensors,
Find the equation for each linear aperture pattern image. (3) 30' in Figure 12 by the method already described.
Generate the equation of a virtual straight line such as ~33',
As their intersection points, the four points 3 shown in Figure 12 are
The coordinate positions of 6' to 39' are determined, and then the center position 34' is determined. (4) When the reflecting mirror 90 is inserted into the measurement optical path in advance, the four reference positions 36 to 39 and the coordinate positions of the center 34 and each point 36' to 39' and 34 found in the previous section (3) From the coordinate position of ′, the above (3)
The radius of curvature R ₁ of the first principal meridian of the cornea to be examined, the radius of curvature R ₂ of the second principal meridian, calculated according to equation (5),
The first principal meridian angle θ and alignment amounts α and β are determined. Each value obtained through the above processing is output to the display 113 and printer device 114 shown in FIG. 14. It goes without saying that the second principal meridian angle is θ+90°. Furthermore, a well-known CRT display device is used as a display, and it is convenient for measurement to display the alignment amounts α and β graphically. Furthermore, automatic alignment is also possible by inputting the alignment amounts α and β as electrical signals to the device housing drive section 117 and driving the device electrically in accordance with the signals. All of the above processing is performed according to the program recorded in the program memory 115.
It is not unusual for a microprocessor to perform the above processing, and can be easily accomplished by those skilled in the relevant technical field. The present invention is not limited to the embodiments described above, but includes various modifications. A few examples will be disclosed below. FIG. 15 is a partial optical arrangement diagram showing a second embodiment of the present invention. Note that the illumination optical system and the fixation optical system are the same as those in the first embodiment described above, so illustration and description thereof will be omitted. Further, similar components are given the same reference numerals and explanations are omitted. In the measurement optical system 2, a second relay lens group 87 is arranged behind the relay lens 14, and the mask plate 9 shown in FIG. 16 is arranged between this relay lens group 87 and the relay lens 14. ing. The mask plate 9 has at least one thick straight opening 25a and thin straight openings 251, 252, . . .
A parallel straight line group 25 formed by arranging 259 in parallel,
A thick line straight opening 26a having a different arrangement direction from this,
A parallel straight line group 26 is formed by arranging thin straight line openings 261, 262, . . . 269 in parallel. Thick straight openings 25a, 26a in each parallel straight line group
was formed to serve as a reference when determining the equation of the projected straight line of other straight apertures. A conjugate image of this mask plate 9 is created at a position MA in the figure by a relay lens 14. Second relay lens 8
Behind the mirror 7 is a dichroic mirror 86, and the reflected and transmitted optical paths of this mirror 87 form a first optical path 120 and a second optical path 121, respectively.
An image rotator 125 is provided in the second optical path 121.
is arranged to rotate around the optical axis at a predetermined angle. Further, the first optical path 120 and the second optical path 121 are combined by a dichroic mirror 123, a third relay lens 124 is arranged behind this dichroic mirror 123, and a linear position sensor 15 is arranged behind it. has been done. The linear sensor 15 has a relay lens 1
4. A conjugate image thereof is created at position D in the figure by the second relay lens group 87 and the third relay lens 124. Since the image rotator 125 is disposed within the second optical path 121 as described above, the linear sensor 15 is equivalent to two linear sensors intersecting within this conjugate detection plane D. During measurement, when the light emitting source 70 (see FIG. 6) emits light, the reflected light from the cornea C is selectively transmitted by the group of parallel straight lines 25 and 26 of the light flux limiting mask 9, and passes through the first optical path 120 to the linear sensor. 15 as a projected parallel straight line pattern group 25', 26', and this projected pattern group is detected by the linear sensor 15 as detection points e ₁ , e ₂ . . . e ₆ as shown in FIG. Next, when switching to the light emitting source 71 (see FIG. 6), the light beam reflected by the cornea is similarly selected by the group of parallel straight lines 25 and 26 of the mask 9, and the selected light beam passes through the second optical path 121, Rotated by the image rotator, it becomes equivalent to placing the linear sensor 15 at the position 15' as shown in FIG. 17, and detects the projected parallel straight line pattern groups 25' and 26' of the parallel straight line groups 25 and 26. Points f ₁ , f ₂
...detected as f ₆ . Thereafter, a virtual parallelogram is found based on these detection points and the curved surface characteristics of the cornea to be examined are calculated. In the first embodiment described above (FIG. 6), measurement is possible even if the linear sensors 15 and 16 are arranged so that the conjugate plane D of the relay lens 14 is parallel to each other. In addition, as shown in FIG. 18, the relay lens group 8
After 7, a light beam shifting means 301 made of parallel plane glass is arranged, and this is rotated to four positions (A), (B), (C), and (D) with the axis perpendicular to the optical axis _O1 as the rotation axis. If the displacement occurs, the reflected light beam from the cornea C selected by the light beam limiting mask 9 in the above-mentioned second embodiment (FIG. 15) is shifted and the one linear sensor 15 is conjugated as shown in FIG. This is equivalent to 4 lines arranged in parallel on plane D, and from this, two points of each projected straight line pattern of each projected parallel straight line pattern group 25', 26' are detected, so the equation can be determined.
A virtual parallelogram is created from this, and the curved surface characteristics of the cornea C to be examined can be measured in the same manner as in the above embodiment. Furthermore, in place of the light flux shifting means 301 in FIG. 18, if the image rotator is rotated about the optical axis _O1 , each projected parallel line pattern group can be detected as shown in FIG. 17, as described in the second embodiment. It will be seen quite easily from the example. Also, instead of rotating the image rotator, a pulse motor drive circuit 303 is used as shown in FIG.
The projection pattern may be detected by rotating the linear sensor 15 with the optical axis _O1 as the rotation axis using a pulse motor 302 whose rotation is controlled by the pulse motor 302. Also, instead of a linear light emitting element array, a third
As shown in FIG. 0, one end of a large number of optical fibers 510 is arranged linearly, the other end is bundled into a cylindrical shape, and the other end of the cylindrical bundle of optical fibers is a rotating circle with a built-in laser light guide optical system 511. Board 5
The laser beam from the semiconductor laser 512 may be scanned while rotating the semiconductor laser 12 with the pulse motor 311. FIG. 21 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 are given the same reference numerals, and illustrations and explanations of the common components are omitted. When measuring the base curve of the contact lens CL, hold the cylindrical protrusion 6 of the contact lens holding means 600 with the convex surface of the contact lens facing down.
It is held at 10. A reflecting mirror 602 having a similar function to the reflecting mirror 90 shown in FIG. 6 is fitted into the bottom surface of this cylindrical projection. Contact lens CL holding means 60
The reference coordinate system can be set using this reflecting mirror 602 before holding it at 0. In this embodiment, the position sensor 1
5, 16 and masks 13a, 13b (see Figure 6)
The conjugate planes D and MA of the relay lens 14 are 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 is formed with 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. It goes without saying that the same effects as those of the present invention can be obtained. Furthermore, the circuit that scans and drives the light-receiving element and processes the detected data is not limited to the circuit described above, but may be any circuit as long as it can obtain the necessary data and process the arithmetic expressions described above. It will be apparent to those skilled in the art that a variety of circuits could be designed.

[Brief explanation of the drawing]

Figure 1 is a perspective view showing the measurement principle of the present invention, Figure 2 is a perspective view showing the measurement principle of the present invention;
The figure is a plan view of the above-mentioned figure 1, Figures 3a, b, and c are schematic diagrams showing the relationship between the projection of the mask pattern and the linear sensor, showing that curved surface characteristics can be measured by the present invention, and Figure 4 is an orthogonal diagram. FIG. 5 is a diagram showing the relationship between the coordinate system and the needle intersection coordinate system, FIG. 5 is a diagram showing the relationship between the mask pattern and the virtual parallelogram, FIG. 6 is an optical layout diagram showing the first embodiment of the present invention, and FIG. Figures a and b are diagrams showing an example of a mask pattern, Figure 8 is a schematic diagram showing the projection of a mask pattern onto a linear sensor and its detection state, and Figures 9A to M are detection outputs and coordinates by the linear sensor. 10 is an element arrangement diagram of the linear sensor showing the method of determining coordinate values from the detection output of the linear sensor. 11, 12, and 13 are measurements according to the first embodiment. Schematic diagram for explaining the 14th
15 is a partial optical layout diagram showing a second embodiment of the present invention; FIG. 16 is a diagram showing an example of the aperture pattern of the mask 9 of the second embodiment; FIG. FIG. 17 is a schematic diagram showing the projection of a mask pattern and its detection in the second embodiment, FIG. 18 is a partial optical layout diagram showing the third embodiment of the present invention, and FIG. 19 is a schematic diagram showing the mask pattern in the third embodiment. A schematic diagram showing pattern projection and its detection, FIG. 20 is a diagram showing a linear sensor drive section showing a fourth embodiment of the present invention, and FIG. 21 is an optical layout diagram showing a fifth embodiment of the present invention. , 9...Aperture plate, 10...Pinhole, 14...
Relay lens, 15, 16...Linear position sensor, 25, 26...Parallel linear aperture pattern, 25', 26'...Projected parallel linear pattern, 7
3... Collimator lens, 125... Image rotator, 301... Luminous flux shifting means.

Claims (1)

[Scope of Claims] 1. 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 straight line pattern forming at least two groups of parallel straight lines each having different arrangement directions in a substantial plane for selection; and a detection optical system having a detection means for detecting reflected light; calculating a radius of curvature of the curved surface to be inspected from changes in inclination and pitch of a projected linear pattern corresponding to the linear pattern of the reflected light detected by the detection means; 1. A curvature measuring device, characterized in that both the masking means and the detecting means are disposed on different planes that are optically non-conjugate with the light source. 2. The curvature measuring device according to claim 1, wherein the straight line pattern is formed by varying the thickness or number of the straight lines constituting the straight line pattern or the selectivity of the reflected light. 3. The mask means is composed of at least two mask means, and at least one set of the parallel straight line groups is formed in one of the mask means, and another set of the parallel straight line groups is formed in the other mask means. A curvature measuring device according to claim 1 or 2, characterized in that: 4. According to any one of claims 1 to 3, wherein the linear pattern is constituted by an opening formed in the mask means to selectively transmit the reflected light. Curvature measuring device as described. 5. Curvature measurement according to any one of claims 1, 2, and 4, characterized in that the straight line pattern is formed by forming all the straight lines on one mask means. Device. 6. The curvature measuring device according to any one of claims 1 to 5, wherein the illumination light beam is infrared light. 7. The curvature measuring device according to any one of claims 1 to 6, wherein the detection means is a planar position sensor. 8. Claim 1, wherein the detection means is at least two linear position sensors that substantially intersect within the non-conjugate plane.
The curvature measuring device according to any one of items 6 to 6. 9. The detection means according to any one of claims 1 to 6, wherein the detection means is at least two linear position sensors that are substantially parallel within the nonconjugate plane. Curvature measuring device. 10. The curvature measuring device according to any one of claims 1 to 6, wherein the detection means is at least one linear position sensor that rotates within the nonconjugate plane. . 11. 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 measuring device according to any one of claims 1 to 6. 12. The curvature measuring device according to any one of claims 1 to 6, wherein the detection means is at least one linear position sensor that moves in parallel within the nonconjugate plane. . 13. 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 6 to 6. 14. Claims 1 to 13, 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. 15. 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 curved surface to be inspected and the detection means. The curvature measuring device according to any one of Items 1 to 14. 16. The curvature measuring device according to claim 14 or 15, characterized in that the optical axis of the relay optical means and the illumination optical axis are at least partially common.