JPH11151205A - Refractometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refractometer of high performance and a low cost capa ble of high-speed determination though small-sized. SOLUTION: This instrument is provided with a slit device 3 for slit-scanning the light of a light source 1 in a prescribed direction, a projection optical system 5 for projecting the light scanned by the slit device 3, a light receiving optical system 6 for receiving the light projected and reflected by an optical system E to be examined and a calculation means 7 for calculating refractive power based on the phase difference of signals between light receivers in the light receiving optical system 6. In this case, the light source 1 is formed from LEDs 11 and 12 and they are arranged separately at about 90 degrees to the rotation center of a chopper 31. Also, on the chopper 31, plural slits mutually turned to the almost same direction are formed and a synthetic optical system 4 for leading the light of the LEDs 11 and 12 scanned by the slit device 3 through the same route to the projection optical system 5 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refracting power measuring device for measuring a refracting power of a test optical system by projecting a scanning light onto the test optical system.

[0002]

2. Description of the Related Art Today, an optical system to be inspected (refers to all lenses, lens groups, or eyes to be reflected, specifically, spectacle lenses, contact lenses, interchangeable lenses of cameras, intraocular lenses, etc. The objective type refracting power measuring device which objectively measures the refractive power of the method (1) based on the principle of the radiographic method is widely used. Since this scanning method needs to project light scanned in two or more directions, the objective refractometer is provided with scanning means for scanning light from a light source in two or more directions.
Here, in recent years, miniaturization of the objective type refracting power measuring device has been promoted due to a demand for a handheld device, and a miniaturized scanning unit has been proposed.

As an example of an objective refractive power measuring apparatus in which such a scanning means is miniaturized, Japanese Patent Application Laid-Open No.
5147 and JP-A-6-165775. FIG. 5 is a configuration diagram of an optical system of the apparatus in Japanese Patent Laid-Open No. 62-5147,
FIG. 6 is a view taken along the line CC ′ of FIG. In FIG. 5, light from a light source 90 is scanned in a predetermined direction by passing through a chopper 92 of a chopper device 91, and is projected via a projection optical system 93 onto a fundus of an eye E to be inspected, which is an optical system to be inspected. Then, the projection light reflected by the fundus is received by the light receiving means 94, and the refractive power of the eye E is calculated. Reference numeral 95 denotes a fixation optical system.

[0004] As shown in FIG. 6, a slit 96a is formed above the drawing and a slit 96b is formed below the drawing centering on a reference line DD 'at the center of the chopper 92 in the radial direction. These slits 96a, 96
b is line-symmetric with respect to the reference line DD ′. One slit 96a scans the light of the light source in a predetermined direction, and the other slit 96b scans the light in a direction orthogonal to the predetermined direction. Therefore, the light of the light source is irradiated on a predetermined one portion of the intermediate portion of the chopper 92, and the light of the light source is scanned in two directions by rotating the chopper 92 once.

In Japanese Patent Application Laid-Open No. 6-165775, the basic configuration is substantially the same as that in Japanese Patent Application Laid-Open No. 62-5147, but the slit shape of the chopper is different. FIG. 7 shows a view of the chopper viewed from a direction corresponding to FIG. As shown in FIG. 7, the chopper 97 is formed with four slits 98a to 98d having the same shape and six slits 99a to 99f having the same shape. One of the slits 98a to 98d scans the light of the light source in a predetermined direction, and the other slits 99a to 99f scan the light in a direction orthogonal to the predetermined direction. Therefore, the light of the light source is irradiated to a predetermined one portion of the intermediate portion of the chopper 97, and the light of the light source is scanned in two directions by rotating the chopper 97. The number of the slits 98a to 98d and the number of the slits 99a to 99f are changed so that they can be distinguished from each other by frequency separation.

[0006]

However, in such a conventional refractive power measuring apparatus, although the device for reducing the size of the scanning means has been devised as described above, there have been the following problems. . For example, in a hand-held refractive power measuring device, the subject and the examiner often move, and it is desired that the measurement be performed in the shortest possible time.
With the device of 2-5147, it was difficult to shorten the measurement time. This is because in Japanese Patent Application Laid-Open No. Sho 62-5147, the scanning direction is changed every half rotation of the chopper, so that it is necessary to rotate the chopper once to perform scanning in two directions. This is because it takes time for the rotation. Further, at the position where the scanning direction of the chopper changes by 90 degrees, that is, at the position on the reference line DD ′ in FIG. 6, since the slit 96a in the predetermined direction and the slit 96b in the direction orthogonal to the predetermined direction are mixed, accurate measurement is performed. The inability to do so also contributed to the time-consuming refractive power measurement.

In the apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 6-165775,
Since scanning in two directions is performed almost simultaneously through the slits 98a to 98d and the slits 99a to 99f, it is necessary to separate received signals by frequency, and a frequency separation circuit having a filter having a high separation ability is required. There is a problem that the cost of the apparatus is increased, for example, it is necessary to provide the apparatus. Further, in the radiographic method, the scanning time varies depending on the width of the slit, and as a result, the measurement time, the measurement accuracy, or the measurement range varies. In other words, in order to perform measurement with a desired accuracy and range, the optimum width of the slit is determined to some extent. Here, when the number of slits 98a to 98d for scanning in a predetermined direction and the number of slits 99a to 99f for orthogonal scanning are changed as in JP-A-6-165775, the widths of these slits are different from each other. Even if the width of the slit is set to the optimum width, the other cannot be set to the optimum width, and there is a problem that the optimum measurement accuracy and the like cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the problems of such a conventional refractive power measuring apparatus, and is capable of high-speed measurement while being small in size, and of high performance and low cost. It is intended to provide a device.

[0009]

In order to achieve the above object, according to the present invention, there is provided a light source, scanning means for slit-scanning light from the light source in a predetermined direction via a chopper, A projection optical system for projecting the light scanned by the scanning means onto the test optical system, a light receiving optical system for receiving the light projected and reflected on the test optical system by the projection optical system, and A refractive power measuring device comprising: a calculating unit configured to calculate a refractive power of the test optical system based on a phase difference of a signal between optical receivers in the optical system, wherein the light source includes a first light source and a second light source. At the same time, the first light source and the second light source are arranged at substantially 90 degrees from each other with respect to the rotation center of the chopper of the scanning unit, and are arranged on the chopper of the scanning unit in substantially the same direction. Formed multiple slits, A combination for guiding the light of the first light source and the light of the second light source scanned by the scanning unit between the scanning unit and the projection optical system to the projection optical system via the same path. It is characterized by providing an optical system.

[0010] The present invention described in claim 2 provides the present invention in claim 1.
In the present invention described in the above, further comprising light source control means for alternately lighting the first light source and the second light source at a predetermined interval,
The calculation means is configured to identify the light of the first light source and the light of the second light source based on the predetermined interval.

The present invention described in claim 3 provides the present invention in claim 1.
In the present invention described in above, further comprising light source control means for lighting the first light source and the second light source at predetermined frequencies different from each other, the calculating means and the light of the first light source based on the predetermined frequency It is characterized in that it is distinguished from the light of the second light source.

The present invention described in claim 4 provides the present invention in claim 1.
In the present invention described in any one of (3) to (3), a parallel optical system that converts the light of the first light source and the light of the second light source into parallel light that is substantially parallel to each other is provided. It is characterized in that a chopper of the scanning means is disposed therebetween.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the refractive power measuring apparatus according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of an optical system of the present measurement apparatus, and FIG.
(A) is a view taken along the line AA ′ in FIG. 1, FIG. 2 (b) is a conceptual diagram showing the arrangement of the chopper and the LED in an arrangement corresponding to FIG. 2 (a), and FIG. 3 is a BB in FIG. FIG. 4 is a configuration diagram of the calculation circuit of FIG. In FIG. 1, the present measuring apparatus objectively measures the refractive power of an optical system E to be inspected (illustrated as an eye to be inspected), and includes a light source 1, a parallel optical system 2, a chopper device 3 as a scanning means, It comprises an optical system 4, a projection optical system 5, a light receiving optical system 6, a calculation circuit 7 as calculation means, and a light source control circuit 8 as light source control means. The basic measuring principle of this measuring apparatus is described in Japanese Patent Application Laid-Open No. 62-514.
7 and disclosed in Japanese Patent Application Laid-Open No. HEI 6-165775, in which the measurement is performed by projecting onto the test optical system E scanned in two directions. However, in this embodiment, the chopper is formed with only one slit in one direction, while two light sources are provided to achieve two-way scanning.

The light source 1 emits light for projecting onto the test optical system E. The light source 1 is a first light source LED 11 and a second light source which are arranged as described below and are turned on at a later-described timing. It has an LED 12.
The parallel optical system 2 converts light emitted from the LEDs 11 and 12 into parallel light substantially parallel to each other.
12 are provided with lenses 21 and 22 arranged on the respective optical axes. And two LEDs 11, 12
Is guided to a half mirror 42, which will be described later, in a state where the light is collimated by the lenses 21 and 22.
And the length of an optical path from the optical path to a half mirror 42 described later, and L
Since the length of the optical path from the ED 12 to the half mirror 42 is different, obstacles occurring in the light (such as blurring caused by a difference in the light width) are prevented.

The chopper device 3 serving as a scanning means includes an LED 1
The light emitted by the light sources 1 and 12 is scanned in two directions perpendicular to each other (in the present embodiment, the horizontal direction and the vertical direction). The thin circular chopper 31 and a rotation motor for rotating the chopper 31 are provided. 32. As in the prior art, this chopper 31
As shown in FIG. 2A, by providing a portion of the substrate having a lower transmittance than that of the substrate (a portion shown in black in FIG. 2A), the rotation speed of the chopper 31 is reduced at the outer peripheral edge. A pattern 33 for detection is formed, and a chopper 31 is similarly provided on the inner peripheral side of the pattern 33.
Six radial slits 34a to 34f are formed so as to spiral from the center of rotation. These slits 34
The light from the LEDs 11 and 12 is blocked by a to 34f to form a stripe, and the stripe is projected onto the optical system E to be measured. The transmittance of the substrate and the transmittance of the slits 34a to 34f are L
When the light from the EDs 11 and 12 passes through the chopper 31 and is received by a light receiving element described later, the substrate and the slit 34a
To 34f may be used as long as the difference is large enough to discriminate which one of the substrates has transmitted the light.
00%, and the transmittance of the slits 34a to 34f is 50%.

Each of the slits 34a to 34f is, as in the prior art, given by the following equation: r = EXP (tanΦ.theta. + K / n.pi.) R: distance from the center of chopper 31 .theta .: angular position on chopper 31
N: Number of slits (6 in this embodiment) Φ: Angle indicating the direction of slit scanning on the light receiving unit (based on the upper right 45 ° direction in FIG. 3) K: 0, 1, 2. . . Are formed in a curved shape generally represented by.

In particular, the six slits 34a in the present embodiment
As shown in FIG. 2 (a), .about.34f are formed in substantially the same shape and are arranged at equal intervals. Particularly, unlike the conventional art, they are arranged in substantially the same direction. Here, “toward the same direction” means the value Φ in the above equation.
Are equivalent. Thus, the slit 34
a to 34f, the chopper 3
The description will be made with reference to the arrangement relationship between 1 and the two LEDs 11 and 12.

FIG. 2 (b) shows the chopper 31 and the LED 11,
12 is a conceptual diagram for explaining the arrangement with reference numeral 12, and reference numeral 3
5, 36, 37 and 38 are the outer shapes of the chopper 31, respectively.
Center of rotation of chopper 31, center of optical axis of LED 11, LE
The center of the optical axis of D12 is shown. As shown in FIG.
D11 and D12 are arranged at a distance of about 90 degrees from the rotation center 36 of the chopper 31. That is, LED11
The angle α between the line segment connecting the optical axis center 37 of the chopper 31 and the line segment connecting the optical axis center 38 of the LED 11 and the rotation center 36 of the chopper 31 is approximately 90.
It is arranged so that it becomes a degree.

Therefore, in FIG. 2A, when the chopper 31 rotates in the direction of the arrow, for example, when the slit 34a of the chopper 31 starts to block light in the horizontal direction in the drawing with respect to the light of the LED 11, for example, The slit 34c terminates the light shielding in the vertical direction in the drawing. Thus L
The light of the ED 11 is constantly scanned in the horizontal direction by the chopper 31, while the light of the LED 12 is constantly scanned in the vertical direction by the chopper 31, that is, the light of the LED 11 and L
The light from the ED 12 is always scanned in directions orthogonal to each other,
Therefore, scanning light scanned in two directions can be obtained.

Here, the reason why the scanning direction is set to the horizontal direction and the vertical direction is to correspond to the arrangement direction of the light receiving elements described later, and in the case where the light receiving elements are arranged in another direction, the scanning direction is set in the arrangement direction. The scanning direction may be changed accordingly. Further, the directions need not be orthogonal to each other. Alternatively, it is not necessary to correspond to the arrangement direction of the light receiving element, and it is also possible to correspond by the arithmetic processing. For example, LED11 and LED1
2 can be rotated around the rotation center 36 of the chopper 31 while maintaining the relative relationship with each other, and can be arranged at a position different from that shown in FIG.

Next, the combining optical system 4 guides the light of the LED 11 scanned in the horizontal direction by the chopper device 3 and the light of the LED 12 scanned in the vertical direction to the projection optical system 5 through the same path. , Reflection mirror 41 and half mirror 42
Is configured. The half mirror 42 is arranged on the optical axis of the lens 21 with the device 3 interposed therebetween, and transmits the light emitted from the LED 11 and scanned by the chopper device 3 to guide it to the projection optical system 5. The reflection mirror 41 is disposed on the optical axis of the lens 22 with the chopper device 3 interposed therebetween, and the LED 12
The light emitted by the chopper device 3 and scanned by the chopper device 3 is guided to the half mirror 42. The light guided to the half mirror 42 via the reflection mirror 41 in this manner is
Is combined with the light from the LED 11 and guided to the projection optical system 5 by the half mirror 42. Therefore, light scanned in two directions is guided to the projection optical system 5 through the same path indicated by reference numeral 43 in FIG. 1 as in the prior art, so that light emitted from a single light source and scanned in two directions is used. Light of substantially the same quality can be obtained.

The projection optical system 5 projects the light scanned by the chopper device 3 onto the optical system E to be measured, and includes a lens 51 and a half mirror 52 as in the prior art. The lens 51 and the half mirror 52 are disposed on the transmission optical axis of the half mirror 42, and light from the half mirror 42 is transmitted through the lens 51 to the half mirror 52.
And reflected by the half mirror 52 toward the test optical system E.

The light receiving optical system 6 receives the light projected by the projection optical system 5 and reflected by the test optical system E. The light receiving optical system 6 includes a lens 61, a diaphragm 62 and a light receiver 63 as in the prior art. It is configured to have. The lens 61, the aperture 62, and the light receiver 63 are arranged on the optical axis of the half mirror 52, and are reflected by the optical system
The light transmitted through 2 is guided to a stop 62 through a lens 61 and is stopped down to a predetermined range by the stop 62.
The light is received at 3. The light receiver 63 outputs an output signal of a voltage corresponding to the amount of received light. This light receiver 63
Are four light receiving elements 63a to 63d as shown in FIG.
The four light receiving elements 63a
63d are arranged in a cross shape symmetrical about the point P in the vertical and horizontal directions.

The calculating circuit 7 serving as calculating means includes a light receiving optical system 6
The refractive power of the test optical system E is calculated based on the phase difference between the signals of the light receiving elements 63a to 63d. Since the calculation principle is similar to that of Japanese Patent Application Laid-Open No. 6-165775, only the outline will be described.
The time required for the fringes formed by blocking the light of No. 2 to pass between the light receiving elements (hereinafter, phase difference) is measured, and based on the measured phase difference, the test optical system E is measured. Can be calculated.

As shown in FIG. 4, the calculation circuit 7 specifically includes signal amplifiers 71a to 71d, a multiplexer 72,
A horizontal phase difference detector 73 that detects a phase difference during horizontal scanning, a vertical phase difference detector 74 that detects a phase difference during vertical scanning, an arithmetic unit 75, and a control unit 76 are configured. I have. Among them, the signal amplifiers 71a to 71a
1d amplifies the output signals of the light receiving elements 63a to 63d, and the multiplexer 72 includes signal amplifiers 71a to 71d.
The input destination of the signal amplified by 71d is selectively distributed. By synchronizing with the light source control circuit 8 described later, the output at the time of horizontal scanning is output to the horizontal phase difference detector 73.
, While the output during vertical scanning is input only to the vertical phase difference detector 74. The arithmetic unit 75 calculates the refractive power of the optical system E based on the phase difference detected by the horizontal phase difference detector 73 and the phase difference detected by the vertical phase difference detector 74. The control unit 76 controls the signal amplifiers 71a to 71d, the multiplexer 72, the horizontal phase difference detector 73, the vertical phase difference detector 74, and the arithmetic unit 75.

The light source control circuit 8 serving as light source control means
D11, 12 are electrically connected to these LEDs 11,
12 are turned on alternately at predetermined intervals. Here, the predetermined interval means that at least one stripe is completely formed during the lighting time of each of the LEDs 11 and 12, and scanning in two directions, horizontal and vertical, is possible without waiting for one rotation of the chopper 31. It is such an interval. In particular, when an LED is used as a light source as in the present embodiment, alternate high-speed lighting is possible.

The light source control circuit 8 is electrically connected to the multiplexer 72 of the calculation circuit 7, and the multiplexer 72 obtains the lighting timing of the LEDs 11 and 12 from the light source control circuit 8, and based on this timing, the signal of the LED 11 and 12 is obtained. Make a distribution. That is, when the LED 11 is turned on, it is during the horizontal scanning, so that the signal amplifier 7 is turned on.
The signals amplified by 1a to 71d are converted to horizontal phase difference detector 7
3, and when the LED 12 is lit, it is during vertical scanning, so that the signal amplified by the signal amplifiers 71 a to 71 d is output only to the vertical phase difference detector 74. In the present embodiment, as described above, the LEDs 11 and 12 are alternately lit, and the output in the horizontal direction and the output in the vertical direction are separated based on the lighting interval. Therefore, it is not necessary to use a frequency separation circuit as in the related art. The device can be configured at low cost.

It is needless to say that the time lag between the lighting of the LEDs 11 and 12 and the allocating operation by the multiplexer 72 is taken into account in the allocation of the multiplexer 72. The multiplexer 72 is connected to the light source control circuit 8.
It is not necessary to obtain the lighting timing of the LEDs 11 and 12 from the multiplexer 72 and the light source control circuit 8.
, A reference circuit for providing a reference signal may be provided, and the lighting timing may be obtained from the reference circuit.

Since the refractive power measuring device of the present embodiment is configured as described above, the light source control circuit 8 controls the LED 1
The light emitted from the LEDs 11 and 12 is turned on alternately, and the light emitted from the LEDs 11 and 12 is converted into parallel light by the parallel optical system 2, and then scanned by the chopper 31 of the chopper device 3.
Particularly, in this scanning, the LEDs 11 and 12
Because the slits 34a to 34f are formed only in the same direction in the chopper 31, the LEDs 11 and 12 are respectively scanned in directions different from each other by 90 degrees, so that two-directional scanning is achieved. can do. The light scanned in two directions is guided by the combining optical system 4 along the same path, and as a single light, the test optical system E
Projected to The light is received by the light receiving optical system 6, and the refractive power is calculated via the calculation circuit 7 based on the lighting interval of the light source control circuit 8.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea. Therefore, these different modes will be described below. First, all the optical elements shown in FIG.
All the electrical elements shown in FIG. 4 may be replaced or diverted by well-known and known means. Further, in the above embodiment, the parallel light is generated by the parallel optical system 2, thereby preventing the obstacle due to the length of the optical path. However, if the obstacle is negligible, the parallel optical system 2 may be omitted.
Alternatively, the obstacle may be prevented by adjusting the distance between the LED and the slit.

The horizontal direction and the vertical direction can be identified by alternately lighting the LEDs by the light source control circuit. However, it is also possible to identify by a different method. For example LE
By providing a light source control circuit for lighting D and the LED at predetermined different frequencies and providing a frequency separating circuit in place of the multiplexer in the calculating means, the horizontal direction and the vertical direction can be distinguished based on the frequency difference. Good. In this case, simultaneous scanning in two directions becomes possible,
Further, high-speed measurement becomes possible.

[0032]

As described above, according to the first aspect of the present invention, the light source is formed of the first light source and the second light source, and the first light source and the second light source are used as scanning means. The slits are arranged at substantially 90 degrees from each other with respect to the center of rotation of the chopper, and a plurality of slits are formed in the chopper of the scanning unit so as to be oriented substantially in the same direction. By providing a combining optical system that guides the light of the first light source and the light of the second light source scanned by the scanning means to the projection optical system via the same path, two directions without waiting for one rotation of the chopper. Since the scanning is completed and the slits are arranged in one direction, the slits in two directions do not intersect with each other, so that the measurement can be performed at an extremely high speed as compared with the related art. In addition, since light can be scanned in two directions by slits having the same width, measurement can be performed only with the slit having the most optimal width, and various performances of the measuring device such as measurement accuracy can be improved.

Further, according to the present invention, there is provided a light source control means for alternately turning on the first light source and the second light source at a predetermined interval, and the calculating means comprises a first light source based on the predetermined interval. By distinguishing the light of the second light source from the light of the second light source, the output can be separated in each direction based on the lighting interval of the light source, and a relatively expensive circuit such as a frequency separation circuit becomes unnecessary. Therefore, the refractive power measuring device can be configured at low cost.

Further, according to the present invention, there is provided a light source control means for turning on the first light source and the second light source at predetermined mutually different frequencies, and the calculating means based on the predetermined frequency. By distinguishing the light of the light source from the light of the second light source, simultaneous scanning in two directions becomes possible, so that a higher-speed refractive power measurement can be performed.

Further, according to the present invention, there is provided a parallel optical system for converting the light of the first light source and the light of the second light source into parallel light which is substantially parallel to each other. By arranging the chopper of the scanning means between the light source and the system, the light emitted at the two locations is scanned and synthesized after being brought into substantially the same state as each other, so that the difference in the optical path length from each light source to the synthesis point is reduced. The resulting failure can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an optical system of an apparatus according to an embodiment of the present invention.

FIG. 2A is a view taken along the line AA ′ of FIG. 1, FIG.
FIG. 2B is a conceptual diagram showing the arrangement of the chopper and the LEDs in an arrangement corresponding to FIG.

FIG. 3 is a view taken in the direction of arrows B-B 'in FIG.

FIG. 4 is a configuration diagram of a calculation circuit of FIG. 1;

FIG. 5 is a diagram showing a configuration diagram of an optical system of a conventional device.

6 is a view taken in the direction of arrows C-C 'in FIG.

FIG. 7 is a view of a chopper of another conventional apparatus viewed from a direction corresponding to FIG.

[Explanation of symbols]

 E Test optical system α angle 1 Light source 2 Parallel optical system 3 Chopper device 4 Synthetic optical system 5 Projection optical system 6 Light receiving optical system 7 Calculation circuit 8 Light source control circuit 11, 12 LED 21, 22, 51, 61 Lens 31 Chopper 32 Rotation motor 33 Pattern 34a-34f Slit 35 Chopper outer shape 36 Chopper rotation center 37,38 LED optical axis center 41 Reflection mirror 42,52 Half mirror 43 Path 61 Aperture 62 Light receiver 63a-63d Light receiver 71a-71d Signal amplifier 72 Multiplexer 73 Horizontal phase difference detector 74 Vertical phase difference detector 75 Operation unit 76 Control unit

Claims (4)

[Claims] A light source; scanning means for slit-scanning the light of the light source in a predetermined direction via a chopper; a projection optical system for projecting the light scanned by the scanning means onto an optical system to be measured; A light receiving optical system that receives the light projected and reflected on the test optical system by the projection optical system, and a refractive power of the test optical system based on a phase difference of a signal between light receivers in the light receiving optical system. A refractive power measuring device comprising: a calculating means for calculating; a light source formed from a first light source and a second light source; and the first light source and the second light source being rotated by a chopper of the scanning means. A plurality of slits are arranged at substantially 90 degrees from each other with respect to the center, and a plurality of slits are arranged in the chopper of the scanning unit in substantially the same direction, and between the scanning unit and the projection optical system, Before being scanned by the scanning means A refracting power measuring device, comprising: a combining optical system that guides the light of the first light source and the light of the second light source to the projection optical system via the same path. 2. A light source control unit for alternately lighting the first light source and the second light source at a predetermined interval, wherein the calculation unit determines the light of the first light source and the second light source based on the predetermined interval. The refractive power measuring device according to claim 1, wherein the light from the light source is identified. 3. A light source control means for lighting the first light source and the second light source at predetermined frequencies different from each other, wherein the calculation means determines the light of the first light source and the second light source based on the predetermined frequency. The refractive power measuring device according to claim 1, wherein the light from the light source is identified. 4. A parallel optical system for converting the light of the first light source and the light of the second light source into parallel light substantially parallel to each other, wherein the scanning is performed between the parallel optical system and the combining optical system. 4. A refracting power measuring device according to claim 1, wherein a chopper of means is arranged.