JPH0566962B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to an optical image interval measuring device for determining the interval between a plurality of optical images in a predetermined direction.

(Background of the invention) As a conventional device of this type, for example,
There is an automatic measuring device for the radius of curvature as shown in Japanese Patent No. 197405. This device uses a beam splitter to split the light beam into two in order to find the interval between the four light images in a predetermined direction (two orthogonal directions), and rotates one split light beam by 90 degrees. Thereafter, each beam of light was passed through a drum-shaped chopper, and signals from light receivers arranged in correspondence with each divided beam of light were input to an arithmetic unit.

However, this method not only requires a beam splitter or other light beam member and a rotating member at the speed of light, but also requires the provision of a receiver corresponding to each split beam, resulting in an expensive and complex structure. was.

(Object of the Invention) An object of the present invention is to obtain an optical image interval measuring device that is inexpensive and has a simple structure.

(Summary of the Invention) The present invention provides an optical image interval in which an interval in the X direction and a Y direction between at least two optical images generated on the light receiving surface of a light receiver is determined by a photoelectric conversion signal output from the light receiver. In the measuring device, the slits are formed by dividing a first slit group that scans the light receiving surface in the X direction and a second slit group that scans the light receiving surface in the Y direction; A tipper member disposed adjacent to each other, a rotational drive device for rotating the tipper member at a constant speed, and an identification signal indicating in which direction, the X direction or the Y direction, the tipper member is scanning on the light receiving surface. an identification signal output device that outputs the identification signal and a photoelectric conversion signal from the light receiver; and an arithmetic device for calculating the distance in the Y direction of the optical image from the photoelectric conversion signal when the light receiving surface is scanned in the Y direction. This is a device for measuring the distance between optical images.

(Example) The present invention will be described below based on the example shown in the drawings.

FIG. 1 is a diagram showing an optical system in which a first embodiment of the present invention is applied to an automatic radius of curvature measuring device.

In FIG. 1, in order to project a pair of light spots onto the eye E ₁ from a direction symmetrical to the optical axis O of the objective lens 4 of the measurement optical system, a plane including the optical axis O of the objective lens ( Inside) is the optical axis of a pair of projection optical systems.
O ₁ and O ₂ are formed. Optical axis of objective lens O
On the other hand, the angles formed by the projection optical axes O ₁ and O ₂ are both θ. The light beams emitted from the illumination light sources 1a and _1b on the optical axes O ₁ and O 2 pass through pinhole plates 2a and 2b, and then are converted into parallel light beams by collimator lenses 3a and 3b with focal planes on the pinhole plates 2a and 2b. After that, it is projected onto the eye _E1 .

On the other hand, as can be seen from FIG. 2, which shows the optical system in FIG. ₁ viewed from the direction of the subject's eye E1, the objective lens is A pair of optical axes O ₃ and O ₄ of a pair of projection optical systems are formed to project a pair of light spots onto the eye E ₁ from a direction symmetrical to the optical axis O. The angles that the projection optical axes O ₃ and O ₄ make with the optical axis O of the objective lens are both θ.
The projection optical axes O ₁ , O ₂ , O ₃ , and O ₄ are arranged so as to intersect at one point of the optical axis O of the objective lens. This projection optical system, which is located in a plane perpendicular to the plane of the paper in Figure 1, also has its own optical axis, similar to the projection optical system shown in Figure 1.
On O ₃ and O ₄ are provided illumination light sources 1c and 1d, pinhole plates 2c and 2d, and collimating lenses 3c and 3d, respectively.

The measurement optical system is separated into an automatic measurement optical path and an observation optical path for the examiner by a beam splitter (not shown) placed behind the objective lens 4, but for the sake of simplicity, FIG. Here, the observation optical path is omitted.

A rear objective lens 6 that forms a telecentric system together with the objective lens 4 is provided in the automatic measurement optical path. Aperture 5
is provided. The optical path of the objective lenses 4, 6 passes through a chopper disk 7 connected to a motor 10 and reaches a four-part receiver 8 placed adjacently behind it. As shown in FIG. 3, which is a view taken along arrow A-A' in FIG.
8d, the photoelectric conversion element 8a receives a light spot (pinhole image) from the light source 1a, and the photoelectric conversion element 8a receives a light spot (pinhole image) from the light source 1a.
b is arranged to receive a light spot from the light source 1b, a photoelectric conversion element 8c receives a light spot from the light source 1c, and a photoelectric conversion element 8d is arranged to receive a light spot from the light source 1d.

The chopper disk 7 has a planar shape as shown in FIG. That is, the chopper disk 7 has a triple structure in the radial direction, and marks are formed on the outer side to separate the first region and the second region in the circumferential direction. That is, half the circumference is formed by the light shielding part (first region) 40, and the remaining half circumference is formed by the light transmitting part (second region) 41. middle part 4
2, light shielding portions and light transmitting portions are formed by vapor deposition or the like at equal angular intervals in the circumferential direction. And the inner part 43
In the first region of Chiyotsupa disk 7, γ=
A chopper slit defined by a function curve expressed as ae ⁽ 〓 ⁺ 〓 ^/n) is formed by vapor deposition, etc.
Further, in the second region, a chopper slit defined by a function curve represented by γ=ae ^-( 〓 ⁺ 〓 ^/n) is formed by vapor deposition or the like. The details of this chopper slit are as follows.

An optical system that automatically forms a measuring optical path on the light receiving surface of the light receiver 8 so that a plane including a normal l having an angle of 45 degrees with a reference direction (for example, the horizontal direction) among the normals of the chip disk 7 passes through it. When placed perpendicular to the optical axis of
Letting the angle at which the function curve that determines the slit for the chopper intersects the above normal line be, each function curve divides the semicircle into n equal parts, tan {(90−)・(θ+K/nπ)} γ= Expressed as a ₁ e. However, γ is the radius in polar coordinates, θ is the angle in polar coordinates, k is an integer 0,
1, 2, . . . , and a corresponds to the inner diameter of the inner peripheral portion.

Here, if the angles are 45 degrees and 135 degrees, γ ₁ =a ₁ e ⁽ 〓 ^+K/n 〓 ⁾ ...Equation (1) γ ₂ =a ₁ e ^-( 〓 ^+K/n 〓 ⁾ ... ...Equation (2) is obtained. Equation (1) is used to form the slits in the first region, and equation (2) is used to form the slits in the second region. That is, the bright and dark boundaries of each region are defined by the above equations (1) and (2), and slits are formed on the transparent glass plate by vapor deposition or the like. However, a ₁ <γ ₁ <a ₂ , a ₁ <γ ₂ <a ₂
(a ₂ corresponds to the outer diameter of the inner circumference), and
Each curve of the slit is defined using the boundary between the first region and the second region as a reference for the angular position in polar coordinates.

Then, as shown in FIGS. 5a and 5b when viewed from the front direction (opposite direction from FIG. 3) of the chipotspa disk 7, the first region becomes the light receiver due to clockwise rotation of the chipotspa disk 7. When the second area crosses over the light receiver 8, the light receiving surface is scanned from bottom to top, that is, in the Y direction (Fig. 5a), and when the second area crosses over the light receiver 8, the light receiving surface is scanned from left to right, that is, in the Y direction. It will be scanned in the X direction perpendicular to the Y direction (FIG. 5b).

The outer part of the tipper disk 7 is sandwiched between a light source and a photoelectric conversion element to constitute an area identification device, and therefore, the first area and the second area are identified from the photoelectric conversion signal of the photoelectric conversion element. Further, the intermediate portion 42 is sandwiched between another dedicated light source and a dedicated photoelectric conversion element to form a so-called rotary encoder, and frequency information of the chopper disk 7 is obtained from the photoelectric conversion signal of this dedicated photoelectric conversion element. These light sources and photoelectric conversion elements are collectively shown as a photointerrupter device 9 in FIGS. 1 and 2 on the same normal line l as the light receiver 8.

The light receiver 8 includes four independent photoelectric conversion elements 8a,
8b, 8c, and 8d, and each photoelectric conversion element 8a to 8d corresponds to a pinhole plate 2a to 2d. In this embodiment, the second region of the tipper disc 7 is located on the light-receiving surface of the light receiver ₈ in a direction perpendicular to the paper surface of FIG. The slit is scanned in the direction connecting 2c' and 2d' (X direction). Eye to be examined
When E ₁ is a toric surface, the images 2a' to 2d' of the pinhole plate are affected by twisting by the eye E ₁ , and for example, the directions of the images 2a' and 2d' are the same as the scanning direction of the slit (arrow x). will be shifted by an angle α corresponding to the twist (see Figure 6). Photoelectric conversion element 8
d outputs a high-level signal only when the slit of the chopper disk 7 is exactly on the image 2d' of the pinhole plate 2d, so the output signal of the photoelectric conversion element 8d is The pulse signal is generated at regular intervals (determined by the pitch of the slit and the rotational speed of the chopper) as shown in FIG. 7a. Similarly, the output signal of the photoelectric conversion element 8c becomes a signal as shown in FIG. 7b. Even if the directions of the images 2c' and 2d' of the pinhole plate shift by a predetermined angle due to twisting, the scanning direction of the slit does not change, so the photoelectric conversion element 8
Time from generation of pulse c (Figure 7a) until generation of pulse of photoelectric conversion element 8d (Figure 7b)
t ₁ (see Figure 7) is the image 2c', 2 of the pinhole plate.
The distance h ₁ (see FIG. 6) is obtained by projecting the distance d' in the scanning direction X of the slit on the light receiving surface of the light receiver 8. Furthermore, the time from the generation of a pulse of the photoelectric conversion element 8b until the generation of a pulse of the photoelectric conversion element 8a is such that the interval between images 2a' and 2b' of the pinhole plates 2a and 2b is Corresponds to the interval △ ₁ projected onto . Similarly, when scanning the light-receiving surface of the light receiver 8 in the first region of the chopper disk 7, the time from the generation of a pulse of the photoelectric conversion element 8d until the generation of a pulse of the photoelectric conversion element 8c (not shown) ) corresponds to the distance _h2 obtained by projecting the distance between the images 2c' and 2d' of the pinhole plates 2c and 2d onto the light receiving surface of the light receiver 8 in the scanning direction Y of the slit. Similarly, photoelectric conversion elements 8c, 8
From d, the time corresponding to the interval Δ ₂ (not shown) obtained by projecting the image interval between the pinhole plates 2c and 2d onto the light receiving surface of the light receiver 8 in the scanning direction Y of the slit can be determined.

As shown in FIG. 8, the output signals of the photoelectric conversion elements 8a to 8d are amplified by the corresponding amplifier circuits 71 to 74, respectively. The output signals of the amplifier circuits 71, 71 are sent to the first time difference measuring circuit 75,
The output signals No. 3 and 74 are input to the second time difference measuring circuit 76, respectively. The time difference measurement circuits 75 and 76 are 2
Outputs a signal according to the time difference between two input signals (pulses).

The output signals of the time difference measuring circuits 75 and 76 are input to a computer 77. The computer 77 is
The identification signal from the area identification device 78 and the frequency signal from the rotary encoder 79 are also input, and calculations are performed between them and the output signals of the time difference setting circuits 75 and 76 to determine the curvature in the direction of one main meridian. The radius γ ₁ , the radius of curvature γ ₂ in the direction of the other main radius, and the angle α of the thread (this is the angle that determines the direction of the main radius) are determined and displayed on the display device 80 .

That is, as shown in the flowchart of FIG. 9, the computer 77 first inputs a signal corresponding to the rotational frequency of the chopper disk 7 from the rotary encoder 79 (step 81), and then inputs a signal corresponding to the rotational frequency of the chopper disk 7 (step 81). A correction value is determined and input to the time difference measuring circuits 75 and 76 (step 82). If the time difference measuring circuits 75, 76 are configured to count the pulse interval by the number of clock pulses, for example, the above-mentioned correction value can be calculated using a variable frequency clock pulse generator (which the time difference measuring circuits 75, 76 have built-in). ), regardless of the rotational frequency.
The frequency of the clock pulse is varied so that a number of clock pulses corresponding one-to-one to the interval between pinhole images are always counted. Next, computer 77
is the identification signal from the area identification device 78 (for example, in the first area, the photoelectric conversion element is shielded from light by the light-shielding part, resulting in a low-level signal; in the second area, the light-shielding is released by the light-transmitting part 41, so the signal is high-level). If it is in the second region (step 84), then in step 85, the interval _h2 is calculated from the output signal of the first time difference measuring circuit 75.
The interval △ ₁ is calculated from the output signal of the time difference measuring circuit 76, and if it is determined in step 84 that it is the first region, the interval Δ1 is determined from the output signal of the first time difference measuring circuit 75.
Find h ₂ (step 86). And step 85,
From the intervals h ₁ , h ₂ , and △ obtained in step 86, calculate the radius of curvature γ ₁ in the direction of one main meridian, the radius of curvature γ ₂ in the direction of the other main meridian, and the angle of twist α (step 87),
The information is displayed on the display device 80 (step 88).

In this way, in the above embodiment, scanning in two orthogonal directions can be performed by continuous rotation of the flat chipper disk, so that a chipper disk with a simple configuration and high precision can be manufactured at a low cost. I can do it. Furthermore, on the normal line of a predetermined direction, the slit always scans alternatively in two perpendicular directions (according to equations (1) and (2)...of course, it is 45 degrees).
Since the slit was formed at an angle of 135 degrees,
This has the advantage of providing flexibility in the arrangement of the light receivers.

By the way, if we ignore the need to have flexibility in the placement of the photoreceiver, as shown in Figure 10, the slits can be selected in two directions perpendicular to each other on the normal line of a predetermined direction and on a predetermined radius. A straight slit can be formed in one scan. This device has the same effect as the Chotsupa disk shown in FIG. 4, although there is a restriction that the receiver must be placed on the normal line in a predetermined direction and on a predetermined radius _R1 .

Furthermore, a drum-shaped chopper can be used instead of the flat chopper shown in FIGS. 4 and 10 above. In that case, the center of rotation of the drum should be made parallel to the optical axis of the objective lens 6, and
The optical axis of the objective lens 6 may be bent with a right angle prism or the like so that it passes from the inner peripheral surface to the outer surface of the drum, and a slit that scans orthogonally in two predetermined directions may be formed on the side surface of the drum.

(Effects of the Invention) As described above, according to the present invention, a prism or the like for changing the optical path is not required, and by using a chopper member that scans in the orthogonal X and Y directions, the invention is inexpensive and has a simple structure. A device for measuring the distance between optical images can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an optical system in which the first embodiment of the present invention is applied to an automatic radius of curvature measurement device, FIG. ₂ is a diagram of the optical system in FIG. Figure 3 is a view taken along the line A-A' in Figure 1, Figure 4 is a plan view of the Chiotsupa disc of the first embodiment, and Figures 5a and b illustrate how the optical receiver is scanned by the Chiotspa disc. Figure 6 shows the photoreceiver and the projection interval of the pinhole image on the photoreceiver in the scanning direction, and Figures 7a and b show the state of the signal obtained from the photoelectric conversion element forming the photoreceiver. 8 is an electrical block diagram for determining the radius of curvature, FIG. 9 is a flowchart of the computer shown in FIG. 8, and FIG. 10 is a plan view showing another embodiment of the chopper disk. (Explanation of symbols of main parts), 7... Chotsupa disk, 8... Light receiver, 9... Photo interrupter device, 10... Motor, 75... First time difference measurement circuit, 76... Second time difference measurement Circuit, 77...computer, 78...area identification device.

Claims (1)

[Scope of Claims] 1. An optical image interval in which the interval in a first direction and a second direction between at least two optical images generated on a light receiving surface of a light receiver is determined by a photoelectric conversion signal output from the light receiver. In the measuring device, a first slit scans the light-receiving surface in a first direction, and a second slit scans the light-receiving surface in a second direction.
a chopper member formed by dividing a slit into faces and disposed adjacent to the light-receiving surface; a rotational drive device for rotating the chopper member; an identification signal output device that outputs an identification signal indicating which direction of the scanning direction and the second direction; and an identification signal output device that inputs the identification signal and a photoelectric conversion signal from the light receiver, The distance between the optical images in the first direction is determined from the photoelectric conversion signal when the light receiving surface is scanned in the second direction, and An apparatus for measuring an interval between optical images, comprising: an arithmetic device for determining an interval between the optical images in the second direction.