JPH0330099B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus used for measuring optical properties of optical systems such as lenses. In particular, the present invention relates to an apparatus for automatically measuring optical properties of an optical system such as a spectacle lens, mainly spherical refractive power and its base direction, cylindrical refractive power and its axial angle, and prismatic refractive power.

Conventionally, a device disclosed in US Pat. No. 3,880,525 has been known as a device for measuring the spherical refractive power, cylindrical refractive power, etc. of a lens. This device makes parallel light rays incident on the test lens, projects the light rays refracted by the test lens onto a detection surface through a point aperture mask provided behind the test lens, and coordinates the aperture position of the point aperture mask. The refractive characteristics of the lens to be tested are calculated from the relationship between the coordinates of the detection point on the detection surface and the coordinates of the detection point on the detection surface. However, this conventional device requires two-dimensional scanning for detection, which not only takes a long time for scanning but also requires a large amount of unnecessary information, making the arithmetic processing mechanism complicated and expensive. Furthermore, since the mask aperture is a point aperture, it is necessary to detect a one-to-one correspondence between the aperture point of the mask and the image point on the detection surface, and the light ray from the aperture point to the image point must not intersect with other light rays. For this reason, the number of mask apertures and their positions are also limited, resulting in a small amount of required detection information, which poses a problem in terms of measurement accuracy.

Furthermore, since point image detection is used, if dust or the like adheres to the lens to be tested or the detection surface, the point image becomes undetectable and measurement becomes impossible.

The present invention was obtained with the aim of solving the above-mentioned drawbacks of the conventional optical characteristic measuring device.As in the conventional method, the present invention detects and measures the one-to-one correspondence between the mask point aperture and the image point on the detection surface. The present invention provides an optical property measuring device based on a new measurement principle that is completely different from conventional devices.

That is, the first feature of the configuration of the present invention is that: a collimator means for collimating light from a light source; a mask means for selecting a part of the light beam from the collimator means; holding means for holding the optical system to be tested between the mask means; a detection means for detecting the light beam selected by the mask means; and calculating optical characteristics of the optical system to be tested from the detection results of the detection means. In the optical characteristic measuring device for an optical system, the mask means has a mask pattern formed by arranging a plurality of groups of parallel straight lines, each of which is a set of a plurality of parallel straight lines, so as to virtually intersect with each other. the detection means has two linear sensors, the first linear sensor is located in a plane substantially perpendicular to the optical axis of the first measurement optical path, and the second linear sensor is disposed in a plane substantially perpendicular to the optical axis of the first measurement optical path; The first and second linear sensors are arranged on a plane substantially perpendicular to the optical axis of the second measurement optical path divided by the optical path splitting means arranged between the mask means and the first and second linear sensors optically intersect. and the first and second linear sensors cooperate to detect at least two projection straight lines on each of the projected parallel straight lines corresponding to the parallel straight lines selected by the mask pattern and projected onto themselves. Detecting a projection point of a point; the calculating means determines an equation of each of the projected straight lines from the detected projection point, determines changes in pitch and slope of the group of projected parallel straight lines based on the equation, and calculates changes in these. The present invention provides an optical characteristic measuring device for an optical system, which determines the optical characteristics of the optical system to be tested from the above.

A second feature of the configuration of the present invention is that the detection means is configured to measure optical characteristics of an optical system, wherein the detection means is composed of a plurality of mutually parallel linear sensors arranged in a plane substantially perpendicular to the optical axis of the measurement optical path. It's in the device.

A third feature of the configuration of the present invention is that the detection means includes one linear sensor arranged in a plane substantially perpendicular to the optical axis of the measurement optical path, and a light beam selected by the linear sensor and the mask means. An apparatus for measuring optical characteristics of an optical system has a moving means for relatively moving the optical system.

More specifically, in the present invention, the refractive properties of the lens to be tested are measured from changes in the pitch between straight lines in one group of parallel straight lines and changes in the intersection angle between two groups of parallel straight lines.

The principle of the present invention will be explained below.

When parallel light rays are incident on a spherical lens, a cylindrical lens, or an astigmatic lens, the light rays are refracted according to the refractive properties of the lens. Here, a spherical lens is a lens consisting of two spherical surfaces, a cylindrical lens is a lens in which at least one surface is a cylindrical surface, and an astigmatic lens is a lens in which at least one surface is a toroidal surface. This is well known. Now, a toroidal surface consists of a principal meridian with the largest radius of curvature and a principal meridian with the smallest radius of curvature, which are orthogonal to each other. A spherical surface is considered to be a toroidal surface where two orthogonal curved surfaces have the same radius of curvature, and a cylindrical surface is considered to be a case where one curved surface has an infinite radius of curvature. Therefore, spherical surfaces and cylindrical surfaces can be considered as special cases of toroidal surfaces. In the following explanation of the principle of the present invention, an astigmatic lens made of a toroidal surface will be taken as an example, and as a special case, a spherical lens,
We will be dealing with cylindrical lenses.

When parallel rays are incident on a test lens, which is an astigmatic lens, and the rays are considered after refraction, it is known that if the incident ray is a circular ray bundle, the exit ray will be an elliptical ray bundle, but the incident ray When is a straight ray bundle, the emergent ray bundle has the basic property that its linearity is preserved, but its slope differs according to the refractive characteristics of the lens to be tested. Here, the refractive characteristics are the refractive power of the two principal meridians with the maximum and minimum radii of curvature forming the toroidal surface of the test lens, and the inclination of these two principal meridians from a predetermined reference line. This is a prism amount representing the angle and the amount of deviation between the geometric center and the optical center of the lens to be tested or the amount of setting deviation of the lens to be tested.

However, when a mask is placed just in front of the lens to be tested and various restricted ray bundles are made incident, and the output ray bundle is observed, other refractive characteristics, that is, two shape factors in both refraction directions, are required. will be added.

The addition of this new refractive characteristic means that the relationship between the incident ray bundle and the exit ray bundle changes due to a difference in at least one of the radius of curvature of the first surface, center thickness, and refractive index of the lens to be tested. There is. This shape factor adds unnecessary uncertainty to the measurement of the refractive properties that the present invention attempts to measure. The addition of this shape factor can be avoided by limiting the refracted ray bundle after passing through the lens to be tested. That is, a general circular parallel beam is made incident on the test lens, and an elliptical beam that is refracted by the test lens according to its refraction characteristics is restricted by passing through a certain aperture pattern. By detecting this limited light beam, it is possible to know the refraction characteristics that are not affected by the shape factor. Thus, in the present invention, the mask means having the aperture pattern needs to be placed behind the lens to be tested.

Referring to FIG. 1, a light beam I emitted from a light source LS is made into a parallel light beam by a collimator lens CL. The lens T to be tested, which has a first principal meridian R ₁ having the minimum radius of curvature and a second principal meridian R ₂ having the maximum radius of curvature, has its optical axis O' from the measurement optical axis O perpendicular to the measurement optical axis. On the X-Y plane, Y within that plane
It is shifted by E _V in the axial direction and E _H in the X-axis direction, and the meridian R ₂ is arranged at an angle of θ with respect to the X-axis. Also,
A mask MA is placed a distance Δd behind the test lens T on the measurement optical axis O, with its center aligned with the optical axis O.

This mask MA contains at least 2 of Pitch P.
The opening is formed such that a group of parallel straight lines L consisting of book straight lines intersect with the x-axis at an inclination m.

The light flux that passes through the test lens T and is refracted by the refractive properties of the test lens is restricted by the mask M, and passes only through the aperture pattern to become a restricted light flux. It converges to the position of the focal line F ₁ of the first principal meridian R 1 of T and the position of the focal line F ₂ of the second principal meridian R ₂ of _T. Considering the detection plane x-y plane between the focal line F ₁ and the mask MA, on this detection plane, the group of parallel straight lines L, which is the aperture pattern of the mask MA, projects the group of parallel straight lines L' of the pitch P'. , and its slope from the x-axis changes to M. Here, the slope M is expressed by the following equation.

M=m{1-d(sin ² θ/Z ₁ +son ² θ/Z ₂
)}+d(1/Z ₂ −1/Z ₁ ) sinθcosθ/md(1/Z ₂ −
1/Z ₁ ) sinθcosθ−d(son ² θ/Z ₁ +son ² θ/Z ₂ )+
1...(1) Also, pitch P' is It is expressed as

Here, Z1 is the distance from the mask MA to the first focal line _F1 , and _Z2 is the distance to the second focal line _F2 .

From equations (1) and (2), if we trace the changes in the group of parallel straight lines by focusing only on their slope and pitch, we can see that what is related to these changes is the refractive power of the two meridians and their slope. It can be seen that the prism amount is not involved in the deviation amounts E _H and _EV at all. This shows that the calculation of the prism amount can be performed by a calculation means that is completely different from the refractive power of the lens to be tested, and means that the calculation process is simplified and the calculation time is shortened.

During actual measurement, in order to measure the refractive characteristics of the test lens T from changes in the slope and pitch of the group of parallel straight lines from equations (1) and (2), the unknowns in equations (1) and (2) must be F ₁ ,F ₂ ,
Since there are three θ, it can be seen that the solutions to equations (1) and (2) cannot be obtained by changing only one group of parallel straight lines. Therefore, in reality, it is necessary to know the changes in the slope and pitch of the two parallel straight line groups together with one other parallel straight line group. This configuration is shown in FIG. The mask MA in Fig. 2 has a slope m ₁ and a pitch P ₁ of 2
An aperture pattern is formed consisting of a book parallel straight line group L ₁ and two parallel straight line groups L ₂ with an inclination m ₂ and a pitch P ₂ . On D, two projected parallel straight lines L ₁ ' with slope m _{1 ' and pitch P 1 '} and two with slope m ₂ ' and pitch P ₂ '
The projection of the book forms a group of parallel straight lines L ₂ ′. Since two sets of (1) and (2) are obtained from these two sets of projected parallel line groups, totaling four equations, the unknowns θ, Z ₁ , Z 2 of equations (1) and ( ₂ )
can be found. If solving the quadratic equations (1) and (2) to obtain Z ₁ , Z ₂ , and θ is complicated in terms of arithmetic processing, increasing the cost of the processing mechanism and increasing the processing time, the following intermediate All you have to do is apply arithmetic processing.

FIG. 3a shows pattern openings L ₁ and L ₂ formed in the mask MA of FIG. 2. FIG. The slope of L ₁ is m ₁
The pitch is P ₁ , the slope of L ₂ is m ₂ , and the pitch is P ₂ as in Figure 2. Now, parallel straight line group
Distance from one of L ₁ L ₁₁ to pitch P ₁ times e
Consider a parallel line extending to eP ₁ and a parallel line with a distance fP ₁ .

Also, the distance from one line L ₂₁ of the group of parallel straight lines L ₂
Consider parallel lines of gP ₂ and parallel lines of distance hP ₂ . A virtual parallelogram UVWQ is formed from these parallel lines, , , and the virtual coordinates of the x-y coordinate system of these four vertices are defined as U( _p x ₁ , _p y ₁ ), V( _p
x ₂ , _p y ₂ ), W ( _p x ₃ , _p y ₃ ), and Q ( _p x ₄ , _p y ₄ ).

FIG. 3b shows a beam of light passing through the group of parallel straight lines L ₁ and L ₂ which is the aperture pattern of FIG. 3a. This is a diagram showing a group of projected parallel straight lines L ₁ ′ and L ₂ ′, where L ₁ ′ has a slope
Similar to FIG. 2, L 2 ' changes to m ₁ ' pitch P ₂ ', L ₂ ' changes to slope m ₂ ', and pitch P ₂ '. The origin of this group of projected parallel straight lines is translated from the origin O' of the x'-y' coordinate by ξ in the x'-axis direction and by η in the y'-axis direction.
Linear sensors intersecting at intersecting angle γ with O″
Assuming that S ₁ and S ₂ are used for detection, a linear sensor
S ₁ detects a group of projected parallel straight lines at detection points A, B, C, and D, and linear sensor S ₂ detects a group of projected parallel straight lines at detection points E, H, G, and C. And detection point ro,
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 G. 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 C 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 ′ is multiplied by the same magnification e as that in Fig. 3a, and the parallel point ″ of the pitch eP ₁ ′ can be considered, and similarly, the parallel line ′′ of the pitch fP ₁ ′ , parallel lines from L ₂₁ ′ to gP ₂ ′ pitch
V′W′ can be considered as hP ₂ ′ parallel lines′′, and these parallel lines′′,′′,′′,
The virtual parallelogram U′V′W′Q′ can be found from U′Q′. x- of the four vertices of this virtual parallelogram
Let the virtual coordinates in the y coordinate system be U′(x ₁ , y ₁ ),
If V' (x ₂ , y ₂ ), W' (x ₃ , y ₃ ), Q' (x ₄ , y ₄ ), then the virtual parallelogram UVWQ in Fig. 3a and 3b
The virtual parallelograms U′V′W′Q′ in the figure correspond,
This change is directly related to the refractive properties of the lens to be tested.

Now, the following coefficients and equations are defined for the four virtual points.

A _ij = ( _p x _i − x _i ) − ( _p x _j − x _i ) A _ik = ( _p x _i − x _i ) − ( _p x _k − x _k ) B _ij = ( _p y _i − y _i ) − ( _p y _j − y _i ) B _ik = ( _p y _i − y _i ) − ( _p y _k − y _k ) C _ij = _p x _i − _p x _j C _ik = _p x _i − _p x _k D _ij = _p y _i − _p y _j D _ik = _p y _i − _p y _k (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), Z ₁ and Z ₂ regarding the refractive powers of the two principal meridians can be expressed by the following quadratic equation.

(C _ik D _ij −C _ij D _ik ) (d/z) ² + (A _ij D _ik +B _ij C _ij
−A _ik D _ij −B _ij C _ik ) (d/z) + (A _ik B _ij −A _ij B _ik )=
0...Equation (3b) Here, the Katsuko equation of the above coefficient is defined as follows.

[p, q]≡p _ij q _ik −q _ij p _ik [p, q]=−[q, p] Here, if p and q are each A, B, C, or D, The formula (3b) is [C, D] (d/z) ² + {[B, C] - [A, D]
}(d/z)+[A,B]=0...It is expressed as equation (3c).

As shown in FIG. 1, d is the distance between the mask MA and the detection surface D, and z is the distance between the mask MA and its focal line.

Therefore, as shown in Figure 2, two sets of projected parallel straight lines
The pitches P ₁ ′, P _{2 ′} and the slopes m ₁ ′, m 2 ′ of L ₁ ′, L ₂ ′ are detected, a virtual projection quadrilateral is created as shown in Figure 3b, and the parallelogram is formed. From the vertex, the two roots z ₁ and z ₂ can be found by solving the quadratic equation of equation (3). From these two roots z ₁ , z ₂ , the refractive powers D 1 , D ₂ of the first principal meridian R ₁ and second principal meridian R ₂ of the tested lens T _are obtained.
can be determined as D ₁ =1/z ₁ /Δd/z ₁ −1 D ₂ =1/z ₂ /Δd/z ₂ −1 (4), respectively.

Also, the angle of the circumferential axis (first principal meridian R ₁ in Figure 1)
The angle θ that it makes with the X axis has a relationship of =θ+90°. ) is = 1/2 tan ^-1 {[B, D] - [A, C] / [A, D
]+[B,C]}+90°...(5)

In Figures 3a and 3b described above, pitches P ₁ , P ₂ , P ₁ ' and
P ₂ ′ is multiplied by arbitrary magnifications e, f, g, and h, respectively, but in reality, e=1 and g=1, and the virtual parallelograms U ₀ V ₀ W ₀ Q and U ₀ ′V ₀ ′W The process can be simplified by using _0′Q ′.

Also, the coordinates of each vertex of the virtual parallelogram are x ₀ −y ₀
The explanation was made using the orthogonal coordinate system and x-y orthogonal coordinate system, but if we consider the oblique coordinate system x'-y' coordinate system along with the arrangement of linear sensors S ₁ and S ₂ , As shown in Figure 4, the coordinate transformation between the and The origin O ₂ of the '-y' coordinate system is shifted by ξ in the x-axis direction and η in the y-axis direction from the origin O ₁ of the x-y coordinate system. At this time, the coordinate transformation from the x'-y' coordinate system to the x-y coordinate system is x = x'sinα + y'sinβ + ξ y = y'cosβ - x'cosα + η ... (6) From equation (3) above, A _ij = ( _p x _i −x _i )−( _p x _j −x _j ) Substituting equation (6) into this, A _ij = {( _p x′ _i sinα＋ _p y′ _i sinβ+ξ)−(x′ _i sinα
+y′sinβ+ξ)}−{( _p x″ _y sinα + _p y′ _j sinβ+ξ)−(x′ _j sinα−y′ _j sinβ+ξ)
}=sinα{( _p x′ _i −x′ _i )−( _p x′ _j −x′ _j )} ＋sinβ{ _p y′ _i −y′ _i )−( _p y′ _j −y′ _j )}= A′ij
sinα＋B′ijsinβ……(7a) Also, B _ij = ( _p y _i −y _i )−( _p y _j −y _j ), and using the same calculation as above, B _ij = cosβ {( _p y′ _i −y′ _i ) −( _p y′ _j −y′ _j )}−co
sα{( _p x′ _i −x′ _i )−( _p x′ _j −x′ _j )} =B′ijcosβ−A′ijcosα ……(7b) Similarly, C _ij =C′ijsinα＋D′ijsinβ …… (7c) D _ij = D′ijcosβ−C′ijcosα ……(7d)

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′ijsinα+D′ijsin
β) (D′ikcosβ−C′ikcosα)−(D′ijcosβ−C′ijcosα)(C′iksinα+D′iksinβ)=(sin
αsinβ+cosαsinβ) [C, D′] Similarly, [B, C] = (sinαsinβ+sinβcosα) [A′, B′] [A, D] = sinαcosβ[A, D]−sinαcosα[A′
,C′]+sinβcosβ[B′,D′]−sinβcosα[B′,
C′] [A, B] = (sinαcosβ+cosαsinβ) [A′, B
′] Also, [B, C] - [A, D] = (sinαcosβ+co
sαsinβ) {(B′, C′] − [A′, D′]}) Therefore, equation (3c) is sin (α + β) × {[C′, D′] (d/z) ²
+ ([B′, C′] − [A′, D′]) (d/z) + [A′
, B′]}=0...(8), and the inside of { } is a quadratic equation with the same form as equation (3c). From this, the quadratic equation of equation (3c) is dependent on the way the coordinate system is taken. It can be seen that these are unrelated invariant equations. This shows that the degree of freedom in the arrangement of the two linear sensors as detectors is very large. In other words, it is not necessary to place two linear sensors on the x-y coordinate system and orthogonal coordinate axes as in the past, but it is also possible to place the two linear sensors on the x'-y' coordinate system, which improves the orthogonal accuracy of the linear sensor. And optical axis alignment can be made irrelevant to measurement accuracy without much thought.
During measurement, a linear sensor S is used in which the parallel straight line group patterns L ₁ and L ₂ are arranged on the x' and y' axes of the oblique coordinate system ₁ , _S2 , and the virtual parallelograms U, V, W, and Q created from this detection are used as reference virtual parallelograms. Next, insert the test lens to be measured into the measurement optical system, and In this method, projected virtual parallelograms U', V', W', and Q' are created, and the refractive characteristics of the test lens are determined from the reference virtual parallelogram and the projected virtual parallelogram. In this case, the biparallelogram is in an oblique coordinate system x′−, which can be arbitrarily selected.
The coordinate system is considered only for the y′ coordinate system, and the selection of this oblique coordinate system According to the present invention, linear sensors S ₁ ,
This has the very advantageous effect of not requiring any assembly or maintenance adjustments to the _S2 arrangement.

The cylindrical axis direction of the lens to be tested is given by equation (5). Equation (5) is an equation for the orthogonal coordinate system, but if the sensor is located in the oblique coordinate system It can be calculated as a cylindrical axis when used.

θ=1/2 tan ^-1 × {cos2β[B′, D′]−cos(α−β
)・([A′, D′]+[B′,C′]+cos2α[A′,C′
]/sin2α[B′, D′]+sin(α−β)([A′, D′
]+[B′, C′])−sin2α[A′,C′]}……(9) The cylinder axis can be determined as =θ+90° from θ in (12) above.

Next, the principle of measuring prism refractive power will be explained based on FIG. 5.

x _p - y _p , the calculation of the prism value using the x- _y orthogonal coordinate system is based on the group of parallel straight lines L ₁ of pitch P ₁ and the parallel straight lines of pitch P ₂ , which are arranged symmetrically at the same angle γ with respect to the y p axis. One straight line each of group L ₂ L ₁₁ , L ₂₁
Similarly, draw the straight line at e′P ₁ from f′P ₁ , g′P ₂ , _{h′P 2} , and the four vertices of the virtual parallelogram are Take it to match _{the p-} axis. That is, if a virtual parallelogram is made symmetrically with respect to the measurement optical axis O, the center of this virtual parallelogram will coincide with the measurement optical axis O. Next, the lens to be tested is measured to detect a group of parallel projection straight lines L′ ₁ and L′ ₂ , and from the parallel projection straight line L′ ₁₁ to e′P′ ₁
Draw straight lines ′, ′ at f′P′ ₁ .
Subtract ′′ from W′′, δ′P′ ₂ and ′′h′P′ ₂ to create a virtual parallelogram ′′′′. The four vertices of this virtual parallelogram are ′(x ₁ , y ₁ ) in the x-y coordinate system,
V′ (x ₂ , y ₂ ), ′ (x ₃ , y ₃ ), ′ (x ₄ , y ₄ ), and from the coordinates of these four vertices, the horizontal prism amount P _H ,
and the vertical prism amount P _V is expressed by the following equation.

Here, d is the distance between the mask surface and the detection surface.

When measuring in the oblique coordinate system x′−y′, the initial virtual point is defined as ( _p x ₁ , _p y ₁ )( _p x ₂ , _p y ₂ ) ( _p x ₃ , _p y ₃ ), ( _p x ₄ , _p
y4 )
Set the virtual point so that _p x ₁ + _p x ₂ + _p x ₃ + _p x ₄ = 0 _p y ₁ + _p y ₂ + _p y ₃ + _p y ₄ = 0 ... (12) Bye. And horizontal prism P _H , vertical prism P _V
are given by equation (10), respectively, so equation (12) can be transformed into (6)
If you convert it using the formula So, if we convert equation (10) using equation (6) in the same way, we get becomes. Coordinates ( _p x′ _i , _p y′ _i ) of the initial virtual point ( _p x _i , _p y _i ) in the oblique coordinate system when the test lens is not inserted and when the test lens is inserted into the measurement system Since this is the difference between the measured coordinates of and the coordinates (x′ _i , y′ _i ) in the oblique coordinate system, the following equation can be obtained from equations (13) and (14).

This formula represents the prism value.

As described above, in the present invention, the refractive power of the tested lens can be calculated using an invariant equation that is independent of the coordinate system, but oblique-orthogonal coordinate transformation is required for the cylinder axis and prism value. Equation (12),
It is necessary to transform equation (15), but if the calculation mechanism is complicated, perform orthogonal coordinate transformation from the measurement coordinates (x′, y′) in the oblique coordinate system using equation (6), and then The astigmatism axis and prism value may be calculated using the system-based calculation formulas (5) and (10).

In this way, in the present invention, the group of parallel straight lines on the mask is measured without inserting the test lens into the measurement optical system.
If a symmetrical virtual parallelogram is created from L ₁ and L ₂ with respect to the optical axis O, then the lens to be tested is inserted into the measurement optical system, and a similar projected virtual parallelogram is created from the projected parallel straight line image. By creating this, the amount of prism can be calculated, and this means that the amount of prism can be measured independently without knowing anything about the refractive power of the first and second principal meridians of the lens to be tested or its inclination angle. This is very advantageous considering that with conventional lensmeters, the prism value could only be calculated by knowing the refractive characteristics of the lens to be measured. Since the step of calculating the refractive characteristic of the detection lens and the step of calculating the prism value can be performed independently and in parallel, the calculation time can be significantly reduced.

Further, the present invention is not limited to so-called lensmeters for measuring eyeglass lenses, but can be applied to a wide range of devices for measuring optical characteristics of optical systems.

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 Fig. 3c, a virtual straight line _l11 having an angle β with respect to the straight line _L11 is created, and a straight line _L21
Create a virtual straight line l ₂₁ with an angle α to
It goes without saying that the virtual parallelogram uvwq may be created based on the created virtual straight lines l ₁₁ and l ₂₁ , but this does not change the measurement principle of the present application.

Below, a specific example of a refractive characteristic measuring device for an optical lens based on the above-mentioned measurement principle will be described in detail with reference to the drawings. FIG. 6 is a diagram showing the optical system arrangement of the device according to the invention. In the figure, 2 is a light source driven by the drive circuit 1, for example an LED.
The light beam emitted from the light source is focused on the pinhole 4 by the relay lens 3. The pinhole 4 is used to set the apparent size of the light source to an appropriate size in consideration of the amount of light during measurement and the diffraction phenomenon, and has a diameter of about 0.1 to 0.3 mm. The light flux exiting the pinhole 4 is made into a parallel light flux by the collimator lens 5, reflected by the mirror 6, and incident on the light flux limiting mask 8 perpendicularly. As described above, the light flux limiting mask 8 has two sets of slit groups each consisting of at least two parallel linear apertures, and has a pattern in which the two sets of slit groups have different inclinations. An example of such a pattern is shown in FIG. In FIG. 6, 7 is a lens to be tested, which is fixed by a lens holder (not shown) or the like. The parallel light beam emitted from the collimator lens 5 is refracted according to the optical characteristics of the lens to be tested, and then the amount of information necessary to detect the optical characteristics of the lens to be tested is selected by the light beam restriction mask 8. It reaches the detection surface S after being detected. Although the detection surface S needs to be shorter than the strongest positive power of the lens to be tested, it may be physically impossible to arrange an actual detection element or the like on the detection surface S. Therefore, in the figure, the relay lens 10 and the half mirror 11 are configured so that a surface conjugate to the detection surface S is formed on the line sensors 12 and 13. As the line sensors 12 and 13, linear CCD solid-state imaging devices or the like are used.

FIG. 7 is a diagram showing the pattern of the light flux limiting mask 8 and its relative positional relationship with the line sensors 12 and 13 on the detection surface S. The light flux limiting mask 8 has a slit group 14 consisting of parallel linear apertures 141 and 142, and a slit group 15 consisting of parallel linear apertures 151 and 152. In FIG. 6, the parallel light incident on the test lens 7 is
The straight apertures 141, 142, 151, 152 of the rear luminous flux limiting mask 8 are refracted according to the optical properties of
Only the luminous flux selected by reaches the detection surface S. There are equivalently two line sensors 1 on the detection surface.
2 and 13 are arranged as shown in FIG.
Similarly, for the straight aperture 142, points c and d are detected. If the two points of the straight aperture are detected as positions on the line sensor in this way, the equation of the straight line is determined, and the two straight apertures 141,
Pitches between 142 and 142 can also be detected by performing arithmetic processing. Therefore, it is possible to generate an arbitrary straight line at an arbitrary position on the light flux detection surface S by calculating the equation of the straight line between the two linear apertures. This also applies to the slit group 15. In FIG. 8, the outputs of the line sensors 12 and 13 are shown as a and b, respectively. For example, by detecting which element on the line sensor the peak position of the line sensor output waveform due to the linear aperture corresponds to, points a to d in FIG. ′～
It can be recognized as d′. Then, the equation of the straight line 141 can be found using a' and b', and the equation of the straight line 142 can be found using c' and d'.

The line sensors may be arranged so that they are not parallel to the straight aperture, and the angle at which the two sensors intersect can be selected arbitrarily. or,
The line sensors do not intersect and may be arranged in parallel as shown in FIG. At this time, four line sensors 12, 12', 13, and 13' are required. That is, since a straight line is determined as long as two points can be detected, the line sensor may be arranged so as to intersect at least two points of the light beam limited by the linear aperture on the detection surface S in FIG.

Next, while referring to Fig. 10, a virtual straight line is generated from the equation of the straight line of the straight aperture detected by the line sensor, and any four points on the same plane as the straight aperture are set as the intersection points of the straight line. We will explain how to decide. In FIG. 6, if the inclination M ₁ and pitch P ₁ of the linear openings 141 and 142 of the slit group 14 are determined by the line sensors 12 and 13,
As a result, for example, a straight line 16 with an inclination of f×M 1 can be generated at a position e×P ₁ away from the straight aperture 141 as a reference, and a straight line ₁₆ with an inclination of f×M ₁ can be generated on the opposite side.
A straight line 17 with an inclination of f×M ₁ can be generated at a position separated by . By a similar method, virtual straight lines 18 and 19 can be generated arithmetically from the straight line apertures of the slit group 15. Here e,
Although f and g are arbitrary coefficients, usually f=1, that is, a straight line with the same slope as the straight aperture, is selected, and for e and g, the straight line 1 generated on the mask 8 is selected.
6 to 19 are selected so as to be symmetrical with respect to the instrument axis, that is, the center 24 of the light flux limiting mask 8 when no test lens is arranged. As already mentioned, this makes it easier to calculate the prism refractive power of the lens to be tested. Therefore, it is possible to obtain the coordinates of the four points 20 to 23 as the intersection points of each of the virtual straight lines 16 to 19 generated by the above method. These four points 20 to 23 have coordinate positions calculated from the four linear apertures of the light flux limiting mask 8 detected on the detection surface S in FIG. When the light beam reaching the detection surface S through the restriction mask 8 is refracted, the coordinate positions of the four points 20 to 23 shown in FIG. 10 also change accordingly. This is shown in FIG. When the four reference positions (0 positions) calculated on the light flux limiting mask 8 are set to 20 to 23, detection is made on the detection surface S by a light beam refracted by the optical characteristics of the test lens 7.・The calculated 4 points are 20′
~23'. Therefore, from this change in coordinate position, the spherical refractive power, cylindrical refractive power, and cylindrical axis direction of the test lens can be determined by solving the above equations (3), (4), and (5). Further, the amount of change from 24 to 24' in FIG. 11, which represents the prism refractive power, can be determined from the above equation. In Fig. 11, the four reference positions (0 position) 20 to 23 are not calculated from the pattern format of the light flux limiting mask 8, but are detected on the detection surface with the test lens removed from the optical path. , memorize the coordinates of the four calculated points,
If the optical characteristics of the lens to be tested are measured from then on using these four reference positions, the above formula (3) can be obtained.
Since it is completely unchanged with respect to the coordinate system created by the two line sensors, there is a great advantage that there is no need to manage the intersecting angle and intersecting position of the line sensors at the time of assembly.

FIG. 12 briefly shows a block diagram of a processing circuit for performing the above-described arithmetic processing.

Line sensors 12 and 13 driven by line sensor drivers 25 and 26 send signals to signal lines 120 and 130 based on the linear apertures of the light flux limiting masks, as shown in FIG. 2
7 is an analog switch, which is controlled by the microprocessor 29. When the microprocessor 29 receives an interrupt from the line sensor scan start pulse 121 from the driver 25 that drives the line sensor 12, it controls the analog switch so that the output of the line sensor 12 is sent to the A/D converter 28. Make it so that it is input.
The A/D converter 28 converts the output of each element of the line sensor from analog to digital, and supplies the converted digital value to the microprocessor.
Here, the A/D converter 28 is 8 bits (1/256)
A sensor is selected that has a certain level of resolution and a conversion time faster than the scanning speed of the line sensor.
The microprocessor 29 reads the output of the line sensor 12, which is converted into a digital value for each element, and sequentially stores it in a data memory 30 composed of a RAM (random access memory) or the like. Therefore, the data memory 30 stores the output from the first element of the line sensor as a digital value from a predetermined position (address). For example, line sensor is 1728
If it is from an element, once the 1728 data have been captured, the microprocessor 29
is a scan start pulse 131 that stops further data acquisition and drives the line sensor 13.
wait for the interrupt to be driven by When an interrupt is received, the analog switch 27 is controlled and the output of the line sensor 13 is stored in the data memory 30 as a digital value. Through the above operations, all outputs of each element of the line sensors 12 and 13 are stored in the data memory 30. Thereafter, the arithmetic circuit performs the following processing based on the data written to the data memory.

(1) Detect which element of the line sensor the center position of the line sensor output waveform as shown in FIG. 8, which is generated by the linear aperture of the light flux limiting mask, is located.

(2) In the coordinate system created by the two line sensors,
Find the equation of the straight line for each straight aperture.

(3) By the method already described, 16 to 16 in Figure 10
19 is generated, and the four points 20' to 2 shown in FIG.
The coordinate position of 3' is determined, and from there, the center position 24' is determined.

(4) Based on the coordinate positions of the four reference positions 20 to 23 and 24 calculated and stored in advance and the coordinate positions of 20' to 23' and 24' obtained in the previous section (3), the above formula is used. Then, calculate the spherical power S, cylindrical power C, astigmatic axis direction A, and prism refractive powers Px and Py of the lens to be tested.

Each value obtained through the above processing is output to the display 32 and printing device 33 shown in FIG. All of the above processing is performed by the program memory 31.
It is carried out according to the program recorded in . It is not unusual for a microprocessor to perform the above processing, and can be easily accomplished by those involved in related work.

FIG. 13 shows an example of another luminous flux limiting slit used in the present invention. In this example, the slit groups 14 and 15 each include a large number of straight apertures and one straight aperture 34 and 35 that can be distinguished from other straight apertures that provide reference positions for the linear aperture array.
It consists of

The light flux limiting mask shown in FIG. 7 has little redundancy for the minimum amount of information required, for example,
In FIG. 7, there is a strong possibility that it will be impossible to measure the optical characteristics of the lens to be tested due to insufficient information such as dust adhering to the detection points a to d. In addition, in an optical characteristic measuring device configured as shown in Fig. 6, if high accuracy is desired, it is necessary to detect changes in the luminous flux due to the lens to be tested on the detection surface S with an accuracy of several microns or less on the line sensor. . Therefore, as shown in Figure 10, measurements can be made by providing a large number of straight apertures, removing singular points due to adhesion of dust, etc., and performing statistical processing from the large number of detection points detected on the line sensor. It is possible to improve the accuracy and reliability of
For example, if the inclinations and pitches of the straight apertures that make up the slit groups 14 and 15 are made equal, the pitches of the straight apertures that make up the two slit groups will all be the same on the line sensor unless there is a detection error. should be detected. However, the detected pitch contains errors due to dust adhering to the light flux limiting mask, unevenness in the illumination light illuminating the mask, uneven sensitivity between each element of the line sensor, and the like. Therefore, if the pitch is significantly different from the others, it is removed as a singular point, and after applying processing such as arithmetic mean or least squares method to the other points, the reference straight apertures 34 and 35 are used as the reference point. The accuracy and reliability can be improved by generating the imaginary straight line already described as .

FIG. 14 shows another embodiment of the present invention, in which the configuration of the detection means after the mirror 9 in FIG. 6 is changed. In this embodiment, instead of using two linear sensors as in the above-mentioned embodiment, only one linear sensor 12 is used, and a parallel plane glass 200 is arranged in front of the sensor 12. By rotating this parallel plane glass 200, the light flux is translated in parallel on the sensor 12. This is equivalent to substantially moving the linear sensor 12 in parallel as shown in FIG. 15, and thereby, for each projected parallel straight line image, two points can be detected and a straight line can be determined. Also, instead of using parallel plane glass, the sensor itself may be moved within the plane.

As described above, according to the method for measuring optical properties and the apparatus therefor of the present invention, the arrangement of the two linear sensors for detecting the projected image is not subject to any restrictions regarding the measurement of the optical properties of the lens to be tested. No adjustment is required, and the linear sensor detects a straight pattern, so the amount of detected information is large and it is resistant to noise. Further, changes in pitch and inclination of both the plurality of parallel straight lines and the projected parallel straight lines are caused only by the refractive power of the lens to be tested, and are not affected by the amount of prism of the lens to be tested. Conversely, the group of parallel straight lines and the group of projected straight lines only move in parallel depending on the amount of prism of the lens to be tested, but the pitch and inclination do not change at all. Therefore, the refractive power of the test lens can be calculated by measuring the change in pitch and inclination between the parallel straight lines and the projected parallel straight lines, and By measuring the amount of parallel movement, the amount of prism of the tested lens can be calculated.
These can be performed separately and independently of each other. In other words, since prism value calculation and refractive power calculation can be performed simultaneously and in parallel, there is an excellent effect that calculation time can be shortened.

[Brief explanation of drawings]

Figures 1 and 2 are perspective views of a projection system showing the principle of the present invention, and Figures 3 a, b, and c show the relationship between the projection of a mask pattern and the linear sensor, showing that optical characteristics can be measured by the present invention. FIG. 4 is a diagram showing the relationship between an orthogonal coordinate system and an oblique coordinate system, FIG. 5 is a diagram showing the relationship between a mask pattern and a virtual parallelogram, and FIG. 6 is a diagram showing an embodiment of the present invention. FIG. 7 is a front view showing an example of a mask pattern, FIG. 8 is a diagram showing pulses detected by the sensor, FIG. 9 is a diagram showing another arrangement example of the line sensor, and FIG. 10 is a schematic diagram of the optical system shown in FIG. 11 is a schematic diagram for explaining measurement according to the principle of the present invention, FIG. 12 is a block diagram showing an example of an arithmetic circuit, FIG. 13 is a front view showing another example of a mask pattern, and FIG. 14 1 is a schematic diagram of a part of an optical system showing another embodiment of the present invention;
FIG. 5 is a diagram showing an example of parallel movement of a linear sensor. 2...Light source, 5...Collimator lens, 7...
Test lens, 8...Light flux limiting mask, S...Detection surface, 12, 13...Linear sensor.

Claims (1)

[Claims] 1. Collimator means for collimating light from a light source; Mask means for selecting a part of the light beam from the collimator means; Collimator means and mask means; holding means for holding the optical system to be tested between; detection means for detecting the light beam selected by the masking means; and calculation means for calculating optical characteristics of the optical system to be tested from the detection results of the detection means. In the optical characteristic measuring device for an optical system, the mask means has a mask pattern formed by arranging a plurality of groups of parallel straight lines, each of which includes a plurality of parallel straight lines, so as to virtually intersect; the detection means; has two linear sensors, the first linear sensor is located in a plane substantially perpendicular to the optical axis of the first measurement optical path, and the second linear sensor is located between the first linear sensor and the mask means. The first and second linear sensors are arranged on a plane substantially perpendicular to the optical axis of the second measurement optical path divided by the optical path dividing means arranged between them, and the first and second linear sensors optically intersect, The first and second linear sensors cooperate to detect at least two projected points on each projected line of a group of projected parallel straight lines corresponding to the group of parallel straight lines selected by the mask pattern and projected onto themselves. detecting; the calculation means: determines an equation of each of the projection straight lines from the detected projection point; determines changes in the pitch and slope of the group of projected parallel straight lines based on the equation; An optical property measuring device for an optical system, characterized by determining the optical properties of the system. 2. Collimator means for collimating light from the light source; Mask means for selecting part of the light beam from the collimator means; Optical system to be tested between the collimator means and the mask means. an optical characteristic of an optical system comprising: a holding means for holding; a detecting means for detecting the light beam selected by the masking means; and an arithmetic means for calculating the optical characteristic of the optical system to be tested from the detection result of the detecting means. In the measuring device: The masking means has a mask pattern formed by arranging a plurality of groups of parallel straight lines so as to virtually intersect each other; The detecting means includes: It is composed of a plurality of mutually parallel linear sensors arranged in a plane substantially perpendicular to the axis, and the linear sensors cooperate to correspond to the group of parallel straight lines selected by the mask pattern and projected onto themselves. detect at least two projection points on each projected straight line of a group of projected parallel straight lines; the calculation means: determines an equation of each of the projected straight lines from the detected projection points, and calculates the projected parallel line based on the equation; What is claimed is: 1. An optical characteristic measuring device for an optical system, comprising: determining changes in pitch and slope of a group of straight lines, and determining optical characteristics of the optical system under test from these changes. 3. Collimator means for collimating light from the light source; Mask means for selecting part of the light beam from the collimator means; Optical system to be tested between the collimator means and the mask means. an optical characteristic of an optical system comprising: a holding means for holding; a detecting means for detecting the light beam selected by the masking means; and an arithmetic means for calculating the optical characteristic of the optical system to be tested from the detection result of the detecting means. In the measuring device: The masking means has a mask pattern formed by arranging a plurality of groups of parallel straight lines so as to virtually intersect each other; The detecting means includes: one linear sensor arranged in a plane substantially perpendicular to the axis; and a moving means for relatively moving the linear sensor and the light beam selected by the masking means, the linear sensor having at least two At least two projection straight lines on each of a group of projected parallel straight lines corresponding to the group of parallel straight lines selected in the mask pattern and projected onto themselves at a relatively moved position of the spot.
detecting a projection point of a point; the calculating means: determining an equation of each of the projected straight lines from the detected projection point; determining changes in the pitch and slope of the group of projected parallel straight lines based on the equation; and calculating these changes. An optical characteristic measuring device for an optical system, characterized in that the optical characteristic of the optical system to be tested is determined from the following. 4. The optical characteristic measuring device for an optical system according to claim 3, wherein the moving means is a light flux shifting means arranged between the linear sensor and the mask means. 5. The optical system according to any one of claims 1 to 4, wherein the calculation means calculates the refractive characteristics of the optical system to be tested from changes in pitch and inclination of the group of projected parallel straight lines. System optical property measuring device. 6. The calculation means creates a virtual parallelogram from the equation of the projection straight line and the pitch and inclination of the group of projected parallel straight lines, and determines that the optical system under test of the virtual parallelogram does not exist in the measurement optical path. 6. The apparatus for measuring optical characteristics of an optical system according to claim 5, wherein the refractive characteristics of the optical system to be tested are determined from changes in shape between cases. 7. The calculation means creates a virtual parallelogram based on the pitch and inclination of the projection straight line, and calculates the difference between the virtual parallelogram when the optical system to be measured is not present in the measurement optical path and when it is present. 5. An optical characteristic measuring device for an optical system according to claim 1, wherein the prism characteristic of the optical system to be tested is determined from a change in position. 8. Optical characteristics of the optical system according to any one of claims 1 to 7, characterized in that the intersection angle of the group of parallel straight lines is divided into two equal angles by a plane including the measurement optical axis. measuring device. 9. The optical system according to any one of claims 1 to 8, wherein each group of the parallel straight lines has at least one straight line that can be distinguished from other straight lines. Characteristic measuring device.