JP5079546B2 - Target presentation device - Google Patents

Description

  The present invention relates to a space-saving target presentation device that includes a concave mirror in a predetermined housing and presents a test target to an eye to be examined.

A target plate having a visual acuity test target, a concave mirror, and a beam splitter (half mirror) are arranged in the housing, and the target luminous flux that has passed through the beam splitter is reflected by the concave mirror and directed again to the beam splitter. The target luminous flux reflected by the light is emitted from the presentation window and directed to the eye to be examined, and the space-saving target that optically secures a predetermined examination distance using the reflection of the concave mirror and beam splitter. A presentation device is known (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 7-236612

  However, in this type of conventional apparatus, the normal direction of the beam splitter is arranged at 45 degrees with respect to the horizontal axis of the apparatus, and the concave mirror is located above (or below) the beam splitter, The optical axis was arranged in the vertical direction. The installation distance of the device casing is 1.1 m from the eye to be inspected, and a concave mirror that optically secures an inspection distance of 5 m is used, and there is some variation in eye height (± 80 mm with respect to the center). However, in order to prevent the target luminous flux from being displaced, the concave mirror needs to have a width of about 200 mm in the front-rear direction. With such a concave mirror arrangement, the thickness of the housing cannot be made thinner than the size of the concave mirror, and the width of the main body housing exceeds 300 mm when the rotating mechanism of the beam splitter and the concave mirror holding structure are included. In this case, although the installation distance to the device casing could be shortened, the thickness of the device casing itself was not reduced.

  In view of the above-described problems of the prior art, it is an object of the present invention to provide a space-saving target presentation device that can reduce the thickness of a device housing that includes a concave mirror.

  In order to solve the above problems, the present invention is characterized by having the following configuration.

(1) Space saving in which the target luminous flux from the target plate is reflected by a concave mirror and guided from the display window of the housing to the eye to be inspected, and optically presents the test target at a predetermined distance test distance. In the type of target presentation device,
A beam splitter that reflects the target beam from the target plate toward the concave mirror and transmits the target beam reflected by the concave mirror; A light guide optical system that emits light and guides it to the eye to be examined is provided.
The concave mirror is disposed behind the beam splitter and the optical axis of the concave mirror is disposed substantially horizontally,
The beam splitter is placed upright so that the angle θ formed by the optical axis of the concave mirror and the normal direction of the reflection surface of the beam splitter is less than 45 degrees,
Placing the target plate below or on the concave mirror;
The vertical dimension Y of the concave mirror is set so as to present the target to the subject's eye without being displaced by the target luminous flux even when the subject's eye fluctuates in the vertical direction within a predetermined allowable range. Extending the size of the concave mirror to the opposite side of the plate placement position, forming the concave mirror in an eccentric shape in which the center of the outer diameter in the vertical direction of the concave mirror is offset from the optical axis of the concave mirror,
Further, the angle θ is set such that the total dimension W of the dimension W1 in the front-rear direction of the beam splitter and the dimension W2 in the front-rear direction of the concave mirror is smaller than the dimension Y.
(2) In the optotype presenting apparatus according to (1), even when the eye to be examined fluctuates in a vertical direction within a predetermined allowable range, astigmatism generated according to the deviation from the optical axis of the concave mirror is the largest The angle θ is set so that a small visual acuity test target is visible.
(3) In the optotype presenting apparatus according to (2), the concave mirror is an elliptic concave mirror with reduced astigmatism generated in accordance with a deviation from the optical axis.
(4) In the target presentation device of (3), the light guide optical system including the target plate, the beam splitter, and the concave mirror is rotated around a rotation center positioned on the optical axis of the concave mirror. A mechanism is provided.

  According to the present invention, it is possible to reduce the thickness of a device housing incorporating a concave mirror.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of an optotype presenting apparatus according to the present invention. 2 is a schematic configuration diagram when viewed from the right side of the apparatus main body 1, and FIG. 3 is a schematic configuration diagram when the apparatus main body is viewed from above.

  A presentation window 2 made of an acrylic plate provided with an antireflection film is arranged on the front surface of the casing 1a of the apparatus main body 1, and the subject can see the target in the casing through the presentation window 2. The interior of the housing 1a is painted black, making the internal structure difficult to see. A transmission / reception unit 4 for transmitting / receiving optical signals to / from a wireless remote controller 40 to be described later is arranged on the front surface of the housing 1a. A light guide optical system 20 is incorporated in the housing 1a.

  The light guide optical system 20 includes a target plate 22 composed of a transmissive liquid crystal panel that displays a visual test table, an illumination light source 21 that illuminates the target plate 22 from the back, a beam splitter 23, and the eye side to be examined. And a concave mirror 24 arranged in the vertical direction behind the beam splitter 23 as viewed from the front. The display of the optotype plate 22 is controlled by a display control unit (not shown), and a visual acuity test table such as a Landolt optotype and characters is displayed. Note that the target plate 22 has a high number of pixels (for example, the number of effective pixels is 1404) so that the smallest visual acuity test target (for example, a visual target having a visual acuity value of 2.0) can be presented. × 1054) is preferably used. As the target plate, as described in JP-A-7-236612, etc., a large number of test targets are formed on the concentric circumference of the disk plate, and these are selectively arranged in the illumination optical path. It may be a configuration.

  The target luminous flux illuminated by the illumination light source 21 and emitted from the target plate 22 is reflected by the beam splitter 23 and travels toward the concave mirror 24. When the distance between the eye E to be examined and the presentation window 2 of the housing 20 is 1.1 m, the concave mirror 24 is configured so that the inspection distance between the visual target and the eye E is optically 5 m. The focal length is designed. The target luminous flux reflected by the concave mirror 24 passes through the beam splitter 23 and then exits the presentation window 2 toward the eye to be examined.

  Here, the optical axis LO of the concave mirror 24 is set substantially parallel to the horizontal direction. On the other hand, the beam splitter 23 is not 45 degrees with respect to the angle θ that the normal direction of the mirror surface makes with the horizontal direction of the apparatus (the optical axis LO of the concave mirror 24), but is smaller than 45 degrees (however, the angle θ is It is arranged obliquely so that it is larger than 0 degree. By arranging the mirror surface of the beam splitter 23 upright as much as possible, the mirror surface of the beam splitter 23 is arranged at 45 degrees with respect to the horizontal direction in the front-rear direction of the housing 1a. Can be made thinner. The setting of the angle θ for reducing the thickness in the front-rear direction of the housing 1a as compared with the conventional case will be described later. In the present embodiment, the angle θ is 25 degrees. When the angle θ is 25 degrees, the arrangement space of the beam splitter 23 can be reduced by about 53% compared to the conventional case where the angle θ is 45 degrees. Further, the concave mirror 24 is disposed in the vicinity of the beam splitter 23.

  Here, in order to reduce the thickness of the apparatus body 1, it is preferable to reduce the angle θ so that the beam splitter 23 is set up in the vertical direction as much as possible. The target plate 22 interferes or the target plate 22 enters the optical path. In order to avoid this, it is necessary to limit the size (vertical size) Y of the concave mirror 24 in the direction in which the target plate 22 is located. However, if the vertical size Y of the concave mirror 24 is reduced, the problem of vignetting of the target will occur even if the eye E moves slightly in the vertical direction.

  Therefore, this problem is addressed by extending the size of the concave mirror 24 in the direction opposite to the arrangement of the target plate 22 without changing the vertical size Y of the concave mirror 24. In the configuration example of FIG. 2, since the target plate 22 is disposed below the concave mirror 24, the size of the concave mirror 24 is extended upward. When the size of the concave mirror 24 is extended upward, the outer diameter center M in the vertical direction of the concave mirror 24 is shifted from the position of the optical axis LO, and the concave mirror 24 becomes an eccentric shape. In addition, the allowable range ± Δd of the vertical movement of the eye E is, for example, ± 80 mm (this is a practically set value).

  FIG. 4 is a diagram showing an optical path diagram of the target presentation when the eye E moves up and down within an allowable range ± Δd (± 80 mm). 4A is an optical path diagram when the eye E is positioned at a height H0 on the horizontal axis of the outer diameter center M of the concave mirror 24. FIG. The height H0 is defined as the reference height of the eye E. In this optical path diagram, the virtual image of the target screen of the target plate 22 is formed in a size of 30 cm square at a distance of 5 m from the eye E to be examined. In this case, the eye E is positioned above the height of the optical axis LO of the concave mirror 24. FIG. 4B is an optical path diagram when the eye E is positioned at a height H1 that is lower than the reference height H0 by Δd (80 mm). FIG. 4C is an optical path diagram when the eye E is positioned at a height H2 that is raised by Δd (80 mm) from the reference height H0.

  In this way, the vertical size Y of the concave mirror 24 is determined in consideration of the case where the eye E moves in the vertical direction within the allowable range ± Δd from the reference height H0. In the above example, the size Y in the height direction of the concave mirror 24 is about 200 mm. The distance from the optical axis LO of the concave mirror 24 to the outer diameter center M of the concave mirror 24 is 30 mm. Note that the size of the concave mirror 24 in the left-right direction is also set so as to be able to cope with a case where the subject eye E fluctuates within an allowable range ± Δd from the left-right center position.

  By the way, the outer diameter center M in the vertical direction of the concave mirror 24 has an eccentric shape shifted from the optical axis LO, so that the mirror at a position away from the optical axis LO compared to the axially symmetric mirror centered on the optical axis LO. Will use the surface. Depending on the magnification of the light guide optical system, the astigmatism generated in accordance with the shift of the optical axis LO becomes large in the spherical mirror. In presenting the smallest visual acuity target (for example, a visual target having a visual acuity value of 2.0), the visual acuity target viewed from the eye E may not be optically decomposed due to an increase in astigmatism. Occur. In this case, by forming the concave mirror 24 as an elliptical concave mirror, astigmatism can be reduced and a practical level of optical performance can be obtained.

  Next, the casing 1a can be made thinner than the conventional case where the size Y of the concave mirror 24 determined in consideration of the allowable range ± Δd of the height variation of the eye E as described above is used. The setting of the angle θ of the beam splitter 23 (the angle θ formed between the normal direction of the mirror surface of the beam splitter 23 and the optical axis LO of the concave mirror 24) will be described.

  FIG. 5A is a view of the light guide optical system 20 as viewed from the side, and the vicinity of the optical axis LO of the concave mirror 24 is a cross-sectional view along the optical axis LO. 5B is a view of the concave mirror 24 viewed from the front direction (from the optical axis LO direction. N is a normal direction of the mirror surface of the beam splitter 23. In FIG. 5A, the beam splitter 23 is shown. , And the vertical size of the beam splitter 23 at the angle θ is substantially the same as the vertical size Y of the concave mirror 24 (the vertical size of the beam splitter 23 is secured at least equal to or larger than the vertical size Y of the concave mirror 24). The dimension W1 in the front-rear direction of the beam splitter 23 at the angle θ is obtained as follows.

次に、凹面ミラー２４の前後方向の寸法Ｗ２を考える。凹面ミラー２４を正面から見た形状は、上下方向及び横方向が共にサイズＹの正方形状である。このとき、凹面ミラー２４の光軸ＬＯ上の後端２４Ｂから最も前側の位置は、図５（ｂ）に示すように、上側のコーナＣ１となる。図５（ａ）において、ｔ１は凹面ミラー２４の光軸ＬＯ上の厚み、Ｚは凹面ミラー２４の光軸ＬＯ上の前端２４ＡからコーナＣ１までの光軸ＬＯ方向の寸法、ｙ１は光軸ＬＯから凹面ミラー２４の上側端までの寸法、ｙ２は光軸ＬＯから凹面ミラー２４の下側端までの寸法である。図５（ｂ）において、ｙｃは光軸ＬＯからコーナＣ１までの平面上の距離である。

Next, consider the dimension W2 of the concave mirror 24 in the front-rear direction. The shape of the concave mirror 24 viewed from the front is a square shape whose size is Y in both the vertical direction and the horizontal direction. At this time, the frontmost position from the rear end 24B on the optical axis LO of the concave mirror 24 is the upper corner C1 as shown in FIG. 5A, t1 is the thickness of the concave mirror 24 on the optical axis LO, Z is the dimension in the optical axis LO direction from the front end 24A on the optical axis LO of the concave mirror 24 to the corner C1, and y1 is the optical axis LO. , Y2 is a dimension from the optical axis LO to the lower end of the concave mirror 24. In FIG. 5B, yc is the distance on the plane from the optical axis LO to the corner C1.

  The center of the target plate 22 is located in the direction in which the optical axis LO of the concave mirror 24 is reflected by the beam splitter 23. At this time, the distance from the front side 24A on the optical axis LO of the concave mirror 24 to the reflection position 23B of the beam splitter 23 is a, and the distance from the position 23B to the center of the target plate 22 is b. At this time, a + b and the radius of curvature R of the concave mirror 24 (assuming that the concave mirror is designed as a spherical surface) are determined in design by the inspection distance and the projection magnification with respect to the size of the target plate 22. c is a distance from the lower end of the concave mirror 24 to the central optical axis of the target plate 22, and this distance c is a value determined by design so that the target luminous flux is not displaced. From FIGS. 5A and 5B, W2, Z, y1, y2, and yc are respectively expressed as follows.

上記の式より、Ｗ２は以下となる

From the above equation, W2 is

ここで、ビームスプリッタ２３の上端と凹面ミラー２４のコーナＣ１を近接して配置すれば、ビームスプリッタ２３の最前端から凹面ミラー２４の最後端までの寸法Ｗは、ビームスプリッタ２３の前後方向の寸法Ｗ１と凹面ミラー２４の前後方向の寸法Ｗ２との合計となる。すなわち、Ｗ＝Ｗ１＋Ｗ２である。

Here, if the upper end of the beam splitter 23 and the corner C1 of the concave mirror 24 are arranged close to each other, the dimension W from the foremost end of the beam splitter 23 to the rearmost end of the concave mirror 24 is the dimension in the front-rear direction of the beam splitter 23. This is the sum of W1 and the dimension W2 of the concave mirror 24 in the front-rear direction. That is, W = W1 + W2.

  In the conventional configuration in which the normal direction of the beam splitter 23 is set to 45 degrees with respect to the horizontal direction of the apparatus and the concave mirror 24 is disposed above the beam splitter 23, the dimension Y of the concave mirror 24 (200 mm). ) Is the width in the front-rear direction. If the angle θ of the beam splitter 23 is set so that the dimension W is smaller than the dimension Y, the casing 1a can be thinned.

  For example, if the size of the target plate 22 is 20 mm × 15 mm, and the projection magnification at an inspection distance of 5 m is about 19 times, it is designed as a = 95 mm, b = 110 mm, c = 10 mm, and R = 459 mm. Further, t1 = 5 mm, t2 = 20 mm, and Y = 200 mm. FIG. 6 shows the result of calculating the dimension W when the angle θ is changed under this condition. From FIG. 6, it can be seen that in order to make the dimension (main body thickness) W smaller than Y = 200 mm, the angle θ should be set smaller than 35 degrees.

  Further, if the concave mirror 24 is an elliptic concave mirror, the radius R becomes looser as the distance from the optical axis LO increases, so the dimension W can be further reduced. When the concave mirror 24 is an elliptical concave mirror, the dimension Z in FIG. 5A is expressed by the following equation. R is a radius near the optical axis LO, and k is a conic coefficient.

なお、計算上は、図６のように角度θをできるだけ小さくすれば寸法Ｗも小さくできる。しかし、角度θをあまり小さくし過ぎると、凹面ミラー２４を楕円凹面ミラーに形成したとしても、上記のように被検眼Ｅの高さ変動の許容範囲±Δｄを考慮すると、さらに光軸ＬＯから離れた位置でのミラー面を使用することになる。この場合、非点収差がさらに増大する。このため、実用的には、被検眼Ｅの高さが許容範囲±Δｄで上下方向に変動したときも、凹面ミラー２４の光軸からのずれに応じて生じる非点収差について、最もサイズの小さな視力検査視標が分解して見えるように角度θを設定する。これを考慮して、本実施例においては角度θが２５度に設定されている。

In calculation, if the angle θ is made as small as possible as shown in FIG. 6, the dimension W can be reduced. However, if the angle θ is made too small, even if the concave mirror 24 is formed as an elliptical concave mirror, it is further away from the optical axis LO in consideration of the allowable range ± Δd of the height variation of the eye E as described above. The mirror surface at the selected position will be used. In this case, astigmatism further increases. Therefore, practically, even when the height of the eye E varies in the vertical direction within the allowable range ± Δd, astigmatism that occurs according to the deviation of the concave mirror 24 from the optical axis is the smallest in size. The angle θ is set so that the visual acuity test target is disassembled. Considering this, the angle θ is set to 25 degrees in this embodiment.

  Next, a response when the height of the eye E changes greatly will be described. When the apparatus main body 1 is fixedly arranged at a certain height, if the height of the subject or the sitting height is different, the allowable range ± Δd of the height of the eye E may be exceeded. In this case, the rotation mechanism 30 for changing the direction of the target luminous flux emitted from the apparatus main body 1 is used.

  The configuration of the rotation mechanism 30 will be described. 2 and 3, the light guide optical system 20 including the illumination light source 21, the target plate 22, the beam splitter 23, and the concave mirror 24 is held by a holding member 31 inside the housing 1a. The holding member 31 is held so as to be rotatable in the vertical direction with the position S on the optical axis of the concave mirror 24 as the rotation center. Thereby, even if the direction of the target luminous flux is changed in the vertical direction, a constant inspection distance can be secured. The position of the rotation center S in the front-rear direction (thickness direction) is preferably approximately the center in the front-rear direction of the holding member 31. This makes it possible to reduce the touch width in the front-rear direction when the holding member 31 is rotated, which is advantageous when reducing the thickness of the apparatus body 1 in the front-rear direction.

  As shown in FIG. 3, on the left side and the right side of the holding member 31, rotation shafts 32 a and 32 b centering on the axis of the rotation center S are attached. The rotation shaft of the motor 33 is connected to the rotation shaft 32b. By rotating the motor 33, the entire light guide optical system 20 held by the holding member 31 is rotated in the vertical direction around the rotation center S, and the direction of the optical axis LO is changed in the vertical direction. That is, the target luminous flux exiting the presentation window 2 of the apparatus main body 1 is changed in the vertical direction. As a result, even when the height of the eye E to be examined differs greatly from the horizontal height of the outer diameter center M of the concave mirror 24, the whole of the light guide optical system 20 is rotated in the vertical direction, so that the target is presented. The target luminous flux on the screen can be directed to the eye E to be examined.

  The apparatus main body 1 is provided with a detection optical system 35 for detecting the height of the eye E to be examined. The detection optical system 35 includes a condenser lens 36 and a two-dimensional position detection element 37. Here, two detection optical systems 37 are arranged on both the left and right sides of the holding member 31. In addition, a light source such as an LED that emits infrared light to be detected by the detection optical system 35 is disposed in the communication window 40 a of the remote controller 40. When the remote controller 40 is positioned at the height of the eye E and the light source emits light, the light is received by the position detection element 37 of the detection optical system 35, and the height position of the remote control 40 is output by the output signal of the position detection element 37. That is, the height position of the eye E is detected.

  FIG. 7 shows a configuration of the remote controller 40 and a control block diagram of the whole optotype presenting apparatus. The remote controller 40 moves up and down the target display screen for viewing through the display window 2 by rotating the light guide optical system 20 up and down with the switch 42 for selecting the target to be displayed on the liquid crystal panel of the target plate 22. And a switch 45 used for automatically setting the target presentation position. In addition, the remote controller 40 includes a liquid crystal display 46 that displays a presentation target, operation information, and the like on the surface. A communication window 40 a for transmitting a signal for controlling the apparatus main body 1 and receiving a signal from the apparatus main body 1 is provided at the front side of the remote controller 40.

  A target selection signal from the remote controller 40 is transmitted from the communication window 40 a to the apparatus main body 1, and a signal received by the transmission / reception unit 4 is transmitted to the control unit 10. The control unit 10 controls the display of the visual target to be displayed on the visual target plate 22 based on the input signal from the transmission / reception unit 4. When the examiner sets the remote controller 40 to a height position near the eye E and presses the switch 45, infrared light having a predetermined wavelength for adjusting the target height is emitted from the communication window 40a. It is detected by the position detection element 37 of the detection optical system 35. The control unit 10 rotates the motor 33 based on the output from the position detection element 37 and rotates the light guide optical system 20 in the vertical direction (vertical direction) so that the target luminous flux is directed to the eye height position where the remote controller 40 is positioned. (Tilt) is controlled.

  The light guide optical system 20 can also be rotated by the manual switch 44. The manual switch 44 includes an up button 44a for moving the visual target confirmed from the presentation window 2 upward, and a down button 44b for moving downward. When the up button 44a is pressed, the control unit 10 controls the drive of the motor 33 so that the target luminous flux is directed upward, and when the down button 44b is pressed, the control unit 10 causes the target luminous flux to be directed downward. The drive of the motor 33 is controlled.

  Next, an inspection operation using the apparatus having the above configuration will be described. The apparatus main body 1 is driven by pushing a power switch (not shown). When the subject is positioned at a predetermined position of 1.1 m from the presentation window 2 of the main body 1, the inspection distance is set to a predetermined distance (5 m). Next, in order to input the height position of the eye E, the remote controller 40 is positioned near the eye of the eye E, and the switch 45 is pressed. The position signal transmitted from the communication window 40a by this operation is received by the position detection element 27 of the detection optical system 35, and the height position of the eye E is detected (the optical path of the target light passes through the height of the eye to be examined). For details on the method of adjusting to the above, refer to JP-A-7-236612. Based on this position data, the control unit 10 rotates the motor 33 by a corresponding amount. The holding member 30 that holds the light guide optical system 20 is rotated by the rotation of the motor 33, and the target luminous flux that passes through the outer diameter center M of the concave mirror 24 is substantially directed in the height direction of the eye E to be examined. At this time, even when the height of the eye E to be examined fluctuates within the allowable range ± Δd, the center of the outer diameter M in the vertical direction of the concave mirror 24 is decentered from the optical axis LO. Thus, the eye E can see the visual target screen.

  FIG. 8A shows a case where the eye E is located above the horizontal height MO of the outer diameter center M of the concave mirror 24 and exceeds the allowable range Δd. In this case, when the inspection target is viewed without rotating the light guide optical system 20, the upper part of the target C appears to be missing as shown in FIG. This is because vignetting of the visual target occurs at the upper end of the concave mirror 24. In this case, the entire light guide optical system 20 may be rotated in the direction of arrow A so that the target luminous flux reflected at the outer diameter center M of the concave mirror 24 is directed toward the eye E.

  FIG. 9A shows a case where the eye E is positioned below the allowable range Δd with respect to the horizontal height MO of the outer diameter center M of the concave mirror 24. In this case, when the inspection target is viewed without rotating the light guide optical system 20, the lower part of the target C appears to be missing as shown in FIG. 9B. Therefore, contrary to the case of FIG. 8, the entire light guide optical system 20 is rotated in the direction of arrow B so that the target luminous flux reflected at the outer diameter center M of the concave mirror 24 is directed toward the eye E. You can do it.

  In this way, by rotating the light guide optical system 20 in the vertical direction around the rotation center S, the vignetting of the target luminous flux is eliminated, and the test target is set in an appropriate state according to the height of the eye E to be examined. Can be presented.

It is a general-view schematic diagram of an optotype presenting apparatus. It is a schematic block diagram when an apparatus main body is seen from the right side. It is a schematic block diagram when an apparatus main body is seen from the top. It is an optical path diagram of the target presentation when the eye to be examined moves up and down. It is explanatory drawing about the angle setting of a beam splitter. It is a calculation result of the case width when the angle of the beam splitter is changed. It is a control block diagram of a remote control structure and the whole optotype presenting apparatus. The case where the eye to be examined is located above the horizontal range at the center of the outer diameter of the concave mirror and exceeding the allowable range will be described. A case where the eye to be examined is located below the horizontal height at the center of the outer diameter of the concave mirror and beyond the allowable range will be described.

Explanation of symbols

2 Presentation window 10 Control unit 20 Light guide optical system 21 Light source 22 Target plate 23 Beam splitter 24 Concave mirror 30 Rotating mechanism 32a Rotating shaft 32b Rotating shaft 33 Motor 35 Detection optical system 40 Remote control

Claims (4)

A space-saving vision system in which the target luminous flux from the target plate is reflected by a concave mirror and guided from the display window of the housing to the eye to be inspected, and the test target is optically presented at a predetermined distance test distance. In the sign presentation device,
A beam splitter that reflects the target beam from the target plate toward the concave mirror and transmits the target beam reflected by the concave mirror; A light guide optical system that emits light and guides it to the eye to be examined is provided.
The concave mirror is disposed behind the beam splitter and the optical axis of the concave mirror is disposed substantially horizontally,
The beam splitter is placed upright so that the angle θ formed by the optical axis of the concave mirror and the normal direction of the reflection surface of the beam splitter is less than 45 degrees,
Placing the target plate below or on the concave mirror;
The vertical dimension Y of the concave mirror is set so as to present the target to the subject's eye without being displaced by the target luminous flux even when the subject's eye fluctuates in the vertical direction within a predetermined allowable range. Extending the size of the concave mirror to the opposite side of the plate placement position, forming the concave mirror in an eccentric shape in which the center of the outer diameter in the vertical direction of the concave mirror is offset from the optical axis of the concave mirror,
Furthermore, the angle θ is set such that the total dimension W of the longitudinal dimension W1 of the beam splitter and the longitudinal dimension W2 of the concave mirror is smaller than the dimension Y. . The visual acuity presenting apparatus according to claim 1, wherein the visual acuity having the smallest size can be obtained with respect to astigmatism generated in accordance with a deviation from the optical axis of the concave mirror even when the subject's eye fluctuates in a vertical direction within a predetermined allowable range. The optotype presenting apparatus characterized in that the angle θ is set so that the inspection optotype is disassembled. 3. The optotype presenting apparatus according to claim 2, wherein the concave mirror is an elliptical concave mirror that reduces astigmatism generated in accordance with a deviation from the optical axis. 4. The optotype presenting apparatus according to claim 3, further comprising: a rotation mechanism that rotates the light guide optical system including the target plate, the beam splitter, and the concave mirror about a rotation center located on the optical axis of the concave mirror. An optotype presenting apparatus characterized by that.

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