JPS6341017B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for automatically measuring various characteristics of an optical system, such as spherical refractive power, cylindrical refractive power, and its axial direction, prismatic refractive power, and its base direction. The principles and embodiments of the present invention described below mainly relate to a method and apparatus for measuring the above-mentioned characteristics of eyeglass lenses. This does not mean that it is applied only to the above, but it can also be used to measure the above-mentioned characteristics of lens optical systems widely used in optical instruments.

In recent years, various measurement principles and devices have been proposed for so-called automatic lens meters that automatically measure various optical properties of eyeglass lenses, such as their spherical refractive power, cylindrical refractive power, and their axial directions. . One of them is US Pat. No. 3,880,525. This device based on the U.S. patent makes parallel light incident on the lens to be tested parallel to its optical axis, and attempts to determine the optical characteristics of the lens to be tested from the polarization of the emitted light. , a mask having a point aperture is arranged so that the point aperture is located off the optical axis of the lens to be tested, a detection surface is provided a predetermined distance away from the mask in the optical axis direction, and the detection surface passes through the aperture of the mask. The coordinates of the point where the light flux reaches the detection surface are detected, and the direction and amount of deflection of the light emitted from the test lens are calculated by comparing the detected coordinates with the coordinates of the aperture on the mask. It is configured to know the optical characteristics of the detection lens. In this case, at least three openings in the mask are required to obtain the necessary information.

In the device according to this US patent, it is necessary to accurately detect the point-to-point correspondence between the apertures on the mask and the arrival points on the detection surface, and each aperture must be arranged in a planar manner so that the emitted light beam must be made to be a non-coplanar luminous flux. For this purpose, a two-dimensional plane must be scanned, and the apparatus as a whole inevitably becomes expensive. Furthermore, it is necessary to solve a five-dimensional simultaneous equation using coordinate information of at least three points, and the calculation mechanism becomes complicated and expensive.

There is an apparatus described in US Pat. No. 4,180,325 that can solve the enormous information processing problem associated with such two-dimensional plane detection. This device intermittently blocks multiple light beams that have passed through the mask aperture using a rotating disk with a special pattern consisting of transparent and opaque areas, and allows each light beam to arrive at the detector at different times. , is configured to eliminate the need to determine the correspondence between the aperture on the mask and the light beam on the detection surface. However, in this device, the pattern on the rotating disk is very complex, and detection of its rotational position is very important. There are major problems in terms of construction and production.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical property measuring device that solves the above-mentioned problems in conventional devices and allows detection and subsequent calculations to be performed relatively easily.

That is, in the optical characteristic measuring device according to the present invention, the mask placed behind the test lens has a pattern consisting of at least three straight lines intersecting at least three points, and the detection section has two straight lines orthogonal to each other. The present invention is characterized in that a linear sensor is provided to detect the linear pattern at a position corresponding to the axis. Although two linear sensors may be disposed orthogonally in the detection section, in a preferred embodiment, the light flux passing through the mask is divided into two separate optical paths and guided to the detection section, and one optical path is guided to the detection section. By providing means for rotating the light flux passing through it by 90 degrees around the optical axis, one linear sensor can perform detection on two orthogonal axes. In this case, two light emitting diodes with different emission wavelengths are used as light sources, and the light of one wavelength is passed through one optical path, and the light of the other wavelength is passed through the other optical path,
Information from the two optical paths can be easily identified by providing a means such as a chopper that causes the light passing through both optical paths to enter the sensor alternately.

When the light that has passed through the lens to be tested is passed through a mask having a pattern of at least three straight lines that intersect with each other, this straight line pattern will be biased depending on the refractive characteristics of the lens to be tested. That is, when the lens to be tested has spherical refractive power, the intersecting angle of these straight line patterns does not change, but the length between the intersecting points changes according to the magnitude of the refractive power. Further, if the lens to be tested has a cylindrical refractive power, not only the length between the intersection points but also the intersection angle of the straight line pattern changes. When this projection pattern hits the linear sensor of the detection section, a change in the projection pattern due to the optical characteristics of the lens to be tested appears as a change in the position of the intersection between the projection of each straight line and the linear sensor. Therefore, by detecting the intersection position along two orthogonal axes using a linear sensor and performing necessary calculations, the optical characteristics of the lens to be tested can be determined.

According to the present invention, it is not necessary to detect a coordinate point on a plane, and therefore a scanning means on a plane is not required, and detection can be performed only by a linear sensor. It is much simpler than the conventional method, and the device can be constructed at a low cost.
Furthermore, since there is no need to move the rotation pattern or the sensor, the device can be simplified and error factors can be reduced. Furthermore, according to the principles of the present invention, equations for calculation are simple, and the calculation section can also be simplified.

Below, the principle and embodiments of the present invention will be explained with reference to the drawings. First, in Fig. 1, the test lens L _S
is located in a plane with Cartesian coordinates X ₀ − _{Y 0} ,
It has a first cylindrical axis r ₁ and a second cylindrical axis r ₂ , its optical center O ₀ is on the coordinate origin, and the first cylindrical axis r ₁ is X ₀
Assume that it is inclined by θ _r1 with respect to the axis. X ₀ −
x with orthogonal coordinates X-Y with the origin placed on the optical axis and △d away from the Y ₀ plane in the optical axis direction of the lens L _S
There is a −Y plane, and the mask M is placed on this XY plane. A pattern consisting of three straight lines A, B, and C that intersect each other is formed on the mask M, and the intersection of straight lines A and B is i, the intersection of straight lines A and C is j, and the intersection of straight lines B and C is Let be k. The angle between straight line A and the X-axis is θ ₁ , the angle between straight line B and the X-axis is θ ₂ , and the line segment
Let the length of ij be lA, and the length of line segment ik be lB.

Assuming a detection plane X'-Y' having orthogonal coordinates X'-Y' with the origin placed on the optical axis and a distance d away from the X-Y plane in the optical axis direction, the straight line A on the mask M,
B, C are projection straight lines A',
B' and C', and let the intersections corresponding to the intersections i, j, and k on the mask M be i', j', and k', respectively. Also,
The angles that straight lines A′ and B′ make with the X′ axis are θ ₁ ′ and θ ₂ ′, respectively.
Let the length of line segment i′−j′ be lA′, and the length of line segment i′−k′ be
Let it be l′B. Here, tanθ ₁ = m _A , tanθ ₂ = m _B ,
Letting tanθ ₁ ′=m _A ′ and tanθ ₂ ′=m _B ′, the imaging point or focal line of straight lines A and B by this test lens L _S , that is, the angle θ between straight lines A and B is θ. =
If the distance from the mask M to the point where θ = 180° is Z ₁ and Z ₂ respectively, then the lens to be tested
The refractive power of L _S is obtained as the following quadratic equation. _A・_B (m _A −m _B ) (d/Z+1) ² − [ _A (m _A −m _B ′)+ _B (m _A ′−m _B )] (d/Z+1)+(m _A ′−m _B ′)=0……(1) However, Therefore, if the two roots of equation (1) are respectively 1/Z ₁ and 1/Z ₂ , then Z ₁ and Z ₂ are the distance between the first focal line and second focal line of the test lens L _S and the mask surface. represents the distance in the optical axis direction between In this case, the vertex refractive powers 1/fr ₁ and 1/fr ₂ of the lens L _S to be tested are expressed by the following equations from the distance Δd between the lens L _S to be tested and the mask M.

1/fr ₁ = 1/Z ₁ /△d/Z ₁ -1 ...(2) 1/fr ₂ = 1/Z ₂ /△d/Z ₂ -1 ...(3) Also, the angle of the cylinder axis θ _r1 and θ _r2 are expressed by the following equations.

θ _r2 = θ _r1 +90° ...(4) θ _r1 = tan ^-1 [m _A・_A・(1+d/Z ₁ )−m _A ′/ _A (
1+d/Z ₁ )-1]...(5) θ _r1 = θ _r2 +90°...(6) θ _r2 = tan ^-1 [m _A・_A (1+d/Z ₂ )-m _A ′/ _A (1
+d/Z ₂ )-1]...(7) In the present invention, the projected images A', B', and C' of these straight lines A, B, and C on the X'-Y' plane are By detecting the position where it intersects with the axis, each straight line
The position on the X'-Y' plane is known, and the refractive power of the lens to be tested L _S is calculated based on the above equation. That is, as shown in Figure 2, the projection straight line intersects the X' axis at x ₁ , x ₂ , x ₃ and y ₁ ,
Intersects the Y′ axis at y ₂ and y ₃ . Therefore x ₁ and
From y ₂ we get the equation of the line A′, and from x ₃ and y ₁ we get the equation of the line A′.
The equation of B' and the equation of line C' are obtained from x ₂ and y ₃ , respectively. Based on the equations of these straight lines, the lengths lA' and lB' and the slopes m _A ' and m B' of straight lines A' and _B ' can be determined, and the intersection points i' and j' of the straight lines can be determined. , k′ can be found.
In this case, in order to determine which straight line projection image the points x ₁ , x ₂ , x ₃ , y ₁ , y ₂ , y ₃ correspond to,
The width of the straight lines in the mask pattern may be different, or a group of two or three straight lines may be used instead of one straight line. As the straight line pattern on the mask, it is desirable to use an arrangement in which two sets of parallel straight lines are orthogonal to each other. If the projection of the intersection of straight lines is located on the coordinate axis, the center position of the straight line will be It may be difficult to calculate this, but this problem can be solved by cutting one straight line at the intersection of the straight lines in the pattern on the mask and providing an appropriate gap.

In order to calculate the prism refractive power, in a mask pattern consisting of three straight lines, place the intersection of one of the straight lines at the origin of the coordinates on the mask surface, that is, on the optical axis, and calculate the coordinates of the corresponding point on the detection surface. All you have to do is ask. If the mask pattern is made up of two sets of parallel straight lines that are orthogonal to each other, the intersections of the diagonals of the rectangles formed by the intersections of the straight lines may be found, and the amount of deviation of the intersections may be calculated.

In the principle explanation explained above, at least three straight lines of the mask pattern have at least three intersection points as a pattern shape, but in the present invention, the intersection point images i', j', k' of the mask projection image Since it is not necessary to directly detect the mask pattern with a linear sensor, it is obvious that the mask pattern does not actually need to have intersections i′, j′, and k′, but only needs to have virtual intersections. be.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 3 is a schematic diagram showing the optical system of a lens meter employing the principle of the present invention. Two light emitting diodes 1 and 2 with different emission wavelengths are provided, and the light from these light emitting diodes 1 and 2 is , are directed to the optical path splitter 5 through collimator lenses 3 and 4, respectively. The optical path splitter 5 has wavelength selectivity and reflects the light of a specific wavelength out of the light from the light emitting diode 1 towards the mirror 6, and reflects the light of a specific wavelength out of the light from the light emitting diode 2. is transmitted toward mirror 6. A test lens 7 is placed on the reflected optical path of the mirror 6, and a mask plate 8 is placed behind it.

A relay optical system 10 is provided to enable detection at a detection surface 9 located a predetermined distance away from the mask plate 8 in the optical axis direction. The relay optical system 10 includes an optical path splitter 11 having wavelength selectivity similar to that of the optical path splitter 5.
reflects the light beam emitted from the light emitting diode 1 in the direction of the optical path 12, and transmits the light beam emitted from the light emitting diode 2 in the direction of the optical path 13. Optical path 12
A relay lens 14, a mirror 15, and a relay lens 16 are arranged, and the light beam transmitted through the relay lens 16 reaches an optical path splitter 17 having wavelength selection characteristics similar to those of the optical path splitter 11. Similarly, a relay lens 18 , a mirror 19 , and a relay lens 20 are arranged in the optical path 13 , and the light beam exiting the relay lens 20 is incident on the optical path splitter 17 . Further, an image rotator 21 is provided between the relay lens 18 and the mirror 19 to rotate the image by 90 degrees. The light beam incident on the optical path splitter 17 is directed toward the optical path 22 by the action of the optical path splitter 17.
A concave lens 23 and a linear sensor 24 are arranged on the optical path 22. This concave lens 23 is
This is to prevent the mask image projected onto the sensor 24 from becoming too small when the lens 7 to be tested is a strong plus lens. The linear sensor 24 is placed at a position conjugate to the detection surface 9.

On the mask 8, as shown in FIG.
A set of parallel straight lines 25 and 26 and a second line perpendicular to these
A straight line pattern consisting of a pair of parallel straight line groups 27 and 28 is formed. Each of the straight line groups 27 and 28 consists of three relatively thin straight lines, and each of the straight lines 25 and 26 is a relatively thick straight line. In addition, as shown in Figure 4b, the intersection of each straight line is such that the straight line group 27 or 28 made of thin lines is cut at the intersection, and does not overlap directly with the straight line 25 or 26 made of thick lines. There is. The pattern on the mask 8 may be such that the linear portion is transparent and the remaining portion is opaque, or the linear portion is opaque and the remaining portion is transparent.

The light that enters the test lens 7 as parallel light and passes through the test lens 7 passes through the transparent portion of the mask plate 8 and advances to the relay optical system 10 . Relay optical system 10
The light that has reached the linear sensor 24 through the
It will look like the figure. Here, the intersection points of each straight line or group of straight lines with the coordinate axes x, y are x ₁ , x ₂ , x ₃ , x ₄ , y ₁ , y ₂ ,
By determining y ₃ and y ₄ and performing necessary calculations, the refractive power of the lens 7 to be tested can be obtained. In the illustrated embodiment, two light emitting diodes 1 and 2 having different emission wavelengths are alternately blinked, and the light from one light emitting diode 1 is transmitted from an optical path 12 to an optical path 2.
The light from the other light emitting diode 2 reaches the linear sensor 24 via the optical path 22 from the optical path 18 having the image rotator 21, and performs detection on the x-axis, for example. Perform detection on the y-axis.

Next, referring to FIG. 6, a flip-flop 33 is connected to the light emitting diodes 1 and 2 for driving them.
is activated by a scan start pulse from the drive circuit 35. As the linear sensor 24, for example, a CCD consisting of 1728 elements is used, and its output is amplified by an amplifier 36 and given to a sample and hold circuit 37. Sample hold circuit 3
The output of 7 is given to a comparator 38, which comparator 38
It is compared with a reference value from the reference setter 39 and binarized to produce an output 701. Drive circuit 3
5 generates a scan start pulse 702 and a clock pulse 703, and these pulses are applied to the sensor 2.
given to 4. FIG. 7 shows various pulses, in which a shows the scan start pulse, b shows the clock pulse, c shows the output pulse of the sample and hold circuit 37, and d shows the output of the comparator 38.

In such an arrangement, when scanning is performed by the sensor 24, it is necessary to detect which position on the sensor 24 the projection of each straight line of the mask pattern has reached. To do this, the center of the output pulse corresponding to the width of the pattern straight line must be at the sensor 24.
It is only necessary to detect which sensing element is on which of the output pulses. For example, the purpose can be achieved by counting up to the midpoint between the rise and fall of each output pulse using a clock pulse. The circuit for this is shown in the 8th section.
As shown in the figure. In FIG. 8, output 701 from comparator 38 is applied to rise detector 40a and fall detector 40b, and scan start pulse 702 and clock pulse 703 are applied to counter 41.
Counter 41 is first cleared by scan start pulse 702 and then counts clock pulses 703. The output of the counter 41 is supplied to a latch circuit 44 which latches the output of the counter 41 at the rising edge detector output 101. The output of the latch circuit 44 at this time represents the position on the sensor 24 of the front end of the pulse _L1 in FIG. 7, for example. The gate circuit 42 outputs an output pulse 70
1 is "1", a clock pulse is supplied to the counter 43, which has been cleared in advance by the scan start pulse 702. The output of the gate circuit 42 is indicated by g in FIG. Therefore, the output of the counter 43 shows a value equal to the slit width projected onto the sensor 24. If the counter 43 is a binary counter, the adder 47 adds the value obtained by discarding the least significant bit of the output of the gate circuit 42 and shifting it by one bit toward the lower bit, and the output of the latch circuit 44. , the position of the center of the slit projected onto the sensor 24 is determined. A delay circuit 46 delays the output 102 of the falling edge detector 40 by Δt. This state is shown as f in FIG. 9. The output of delay circuit 46 is given to counter decoder 48. 48 sequentially latches the output of the adder 47 191, 192...
This is to latch up to 198. Note that the output of the delay circuit 46 is also used to reset the counter 43.

With the above circuit, when one scan of the sensor 24 is completed, the latch 191 stores the center position of the pattern straight line that appears first on the sensor, and the latch 192 stores the center position of the second slit. Ru. For example, when sensor 24 scans along the Y axis in FIG.
, signals corresponding to eight slits appear as shown in FIG. 7c. Therefore, the latch circuit has 1
Eight circuits from 91 to 198 are required.

In FIG. 8, 45 is a digital comparator which compares the output of the reference value generator 50 and the output of the counter 43 and supplies a comparison output to the latches 191-198. This is to determine whether the data represents the position of the landing point on the sensor by a thick straight line in the mask pattern or by a thin straight line. Therefore, the output of each latch is sent to the determination circuit 51 together with information on the position of the center of the slit and information on the size of the slit width. As mentioned above, the reason why the mask pattern is composed of one thick straight line and three thin lines is because of the sensor 2.
This is to facilitate the discrimination of straight lines projected onto 4. This will be explained in detail using FIG. 11. FIG. 11 is an enlarged view of the intersection of the straight lines.
25 is a thick straight line, and 27 is three straight lines 27- that are thin enough to be easily distinguished from 25.
This is a straight line group consisting of 1, 27-2, 27-3.

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

(1) Always make the center position of the sensor output by a thick straight line the position of the straight line 25 detected on the sensor.

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

(3) When only two thin straight lines are output, (a) If the order is thick, thin, thin, then the center of the first thin line, (b) If the order is thin, thick, thin. For example, the center position between two thin straight lines is: (c) If the order is thin, thin, and thick, then the center of the second thin line is the position of the straight line group 27 detected on the sensor.

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

Although the above explanation concerns the intersection of the straight line 25 and the group of straight lines 27, it goes without saying that other intersections can also be determined using the same method. Note that as sensor output, the output corresponding to the two intersections is output in one scan.
Divide into two sections at the center of the sensor,
By making the above determination for each division, the positions of y ₁ , y ₂ , y ₃ , and y ₄ shown in FIG. 10 on the sensor can be detected.

FIG. 12 shows an example of the overall configuration of a lens meter based on the measurement principle described above. In FIG. 12, 700 is constituted by the circuit shown in FIG. 6 and the optical system shown in FIG. Reference numeral 1000 consists of the circuit shown in FIG. 8, and inputs the position of each straight line of the mask pattern on the sensor to the microprocessor 52. microprocessor 52
These include a data memory section 53, a program memory section 54, a display interface section 55, a printer interface section 57, and an output register group 2 for outputting the results of calculations by the microprocessor.
91 to 295, but it is also easy to achieve such a configuration in the field of microprocessors.

One scan of the first sensor yields y ₁ , y ₂ , y ₃ , y ₄
Once the position of is obtained, the light emitting diode illuminating the mask is switched in the next scan. When the light emitting diodes are switched, the emission wavelength is different, so the optical path by the optical system is switched, equivalently causing the sensor to scan along the X axis in FIG. 10.
Therefore, the positions of x ₁ , x ₂ , x ₃ , and x ₄ on the sensor are determined.

Once the position of the straight line pattern on the sensor 24 is determined in this manner, the optical characteristics of the lens to be tested are calculated by the following calculation process.

(i) Find the equations of the straight lines 25, 26 and the group of straight lines 27, 28, and let the slope of the group of straight lines 27 be m' _A and the slope of the straight line 26 be m' _B.

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

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

(iv) Calculation of prism refractive power is as shown in Figure 10 i, j,
The coordinates of k and l are (x _i , y _i ), (x _j ,
y _j ), (x _k , y _k ), (x _l , y _l ), horizontal prism refractive power P _H (X-axis direction) and vertical prism refractive power P _V (Y-axis direction) are calculated as P _H =x _i +x _l /d×100 (8) P _V =y _j +y _k /d×100 (9), respectively. Here, d is the distance between the mask M and the detection surface.

(v) A microprocessor performs arithmetic processing based on the equations described above to obtain the required optical characteristics.

The results obtained in this way are output as cylindrical power, spherical power, astigmatic axis angle, and prism refractive power to the display 56, printer 58, and output registers 291 to 295 shown in FIG. 12. still,
The display 56 is equipped with a device capable of two-dimensional display (for example,
By using a CRT (display device, etc.),
The prism refractive power and astigmatic axis angle can be displayed as a two-dimensional pattern. By doing this, there is an advantage that alignment between the lens to be examined and the lens meter can be easily and quickly performed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an optical system showing the principle of the present invention;
FIG. 2 is a diagram showing an example of a projection pattern on a detection surface, FIG. 3 is a schematic diagram of an optical system of a lens meter showing an embodiment of the present invention, and FIG. 4 is a diagram showing an example of a mask pattern. 5 shows an example of the projection pattern on the detection surface, and FIG. 6 shows the detection part of a lens meter as an embodiment of the present invention. FIG. 7 is a block diagram showing pulses for detection, FIG. 8 is a block diagram showing the signal processing section, FIG. 9 is a diagram showing various signal pulses, and FIG. 10 explains scanning by the sensor. FIG. 11 is a diagram illustrating a method of detection at pattern straight line intersections, and FIG. 12 is a block diagram showing the entire electrical system. 1, 2... Light emitting diode, 3, 4... Collimator lens, 5, 11, 17... Optical path splitter,
7...Test lens, 8...Mask plate, 9...Detection surface, 14, 16, 18, 20...Relay lens,
21...image rotator, 24...linear sensor.

Claims (1)

[Claims] 1. A light source that projects a luminous flux onto a test optical system;
a device that is provided between the light source and the optical system to be tested, and converts the light beam from the light source into a parallel light beam; and a device that is provided behind the optical system to be tested, and selectively transmits the light beam that has passed through the optical system. a detection device disposed a predetermined distance from the mask in the optical axis direction, and a calculation device that calculates the optical characteristics of the optical system to be tested by calculating information obtained by the detection device. , the mask has a pattern of at least three straight lines intersecting at least three points, and the detection device has two straight lines passing through the optical axis and arranged perpendicular to the optical axis and intersecting each other. An optical characteristic measuring device for an optical system, characterized by comprising a linear sensor. 2 a light source that projects a luminous flux onto the optical system to be tested;
a device that is provided between the light source and the optical system to be tested, and converts the light beam from the light source into a parallel light beam; and a device that is provided behind the optical system to be tested, and selectively transmits the light beam that has passed through the optical system. a detection device disposed a predetermined distance from the mask in the optical axis direction, and a calculation device that calculates the optical characteristics of the optical system to be tested by calculating information obtained by the detection device. , the mask has a pattern of at least three straight lines intersecting at least three points, and the detection device includes a linear sensor passing through the optical axis and disposed perpendicular to the optical axis; An optical path splitter that splits the light beam transmitted through the mask into two optical paths and a means for guiding the light beams of these split optical paths to the linear sensor are provided between the mask and the detection device, and the light beam split by the optical path splitter is One of the optical paths is provided with a device that rotates the projected image, and a single linear sensor is used to detect the intersecting two-axis directions. 3 In the above item 2, the light source is composed of two light emitting elements having different emission wavelengths, and the optical path splitter has a wavelength selection characteristic, and the light beam from one light emitting element is directed to one split optical path, and the light beam from the other light emitting element is divided into two divided optical paths. A device configured to pass a light beam from one light emitting element to the other divided optical path, and provided with means for switching the light emitting element every scan of the linear sensor. 4. In any of the above items 2 to 3, the pattern of the mask includes two groups of parallel lines each consisting of a plurality of parallel lines, and two parallel lines perpendicular to these groups of parallel lines. A device consisting of. 5. The device according to item 4 above, in which straight lines of the group of parallel lines are cut at intersections of the mask patterns so that they do not directly overlap with other straight lines. 6 In any one of the second to fifth terms, the arithmetic device includes a first calculation unit that calculates an equation of a straight line of a straight line group pattern projected image from information detected by the detection device; A second calculation unit that calculates the intersection coordinates of the straight line image from the equation of the straight line. 7 In the above item 6, the calculation device includes a first calculation unit that calculates the length of the straight line from the calculation result of the second calculation unit, and a calculation unit that calculates the length of the straight line from the equation of the straight line obtained by the first calculation unit. It has a second calculation unit that calculates the tilt angle, and a third calculation unit that calculates the refractive characteristics of the test lens from the calculation results from the first calculation unit and the calculation results from the second calculation unit. Device.