JPH11271602A - Focus detection device and optical apparatus using the same - Google Patents

Abstract

(57) [Problem] To obtain a focus detection device capable of detecting a focus over a wide range on a photographing screen or an observation surface, and an optical apparatus using the same. SOLUTION: An aperture having a pair of apertures on the image plane side of the objective lens and optical means having a pair of secondary imaging systems corresponding to the aperture are provided, and the pupils of the objective lens differ depending on the optical means. A plurality of light amount distributions for the subject image are formed using the light flux passing through the region, and a relative positional relationship between the plurality of light amount distributions is obtained by a photoelectric conversion element including a plurality of elements, and a signal from the photoelectric conversion element is obtained. In the focus detection device for detecting the in-focus state of the objective lens by using, the configuration of the pair of openings and the lens surfaces of the pair of secondary imaging systems are appropriately set.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detection device suitable for a photographic camera, a video camera, an observation device, and the like, and an optical apparatus using the same. And forming a light amount distribution for a plurality of subject images (object images) using the light flux passing through each area, and obtaining a relative positional relationship between the plurality of light amount distributions, thereby obtaining a focusing state of the objective lens. Is suitable for detecting over a wide area in the photographing range.

[0002]

2. Description of the Related Art Conventionally, there has been a so-called image shift method (position difference detection method) in a light receiving type focus detection apparatus utilizing a light beam passing through an objective lens.

[0003] This image shift type focus detection device is characterized in that the amount of defocus that can be detected is large and that the focus state can be detected satisfactorily regardless of the subject distance.

In an image shift type focus detection apparatus, an aperture having a pair of apertures on the image plane side of an objective lens and optical means having a pair of secondary imaging systems (re-imaging lenses) corresponding thereto are provided. A photoelectric conversion element comprising a plurality of light quantity distributions relating to a subject image formed by using the light beams having passed through different regions of the pupil of the objective lens by the optical means, and a relative positional relationship between the plurality of light quantity distributions comprising a plurality of elements. And the in-focus state of the objective lens is detected using the signal from the photoelectric conversion element.

In an image shift type focus detection device, the opening shapes of a pair of openings greatly affect the focus detection accuracy.

The stop in the focus detecting device disclosed in Japanese Patent Application Laid-Open No. 56-130725 has two oval-shaped openings, each of which is narrow in the direction in which the re-imaging lens is arranged, and is orthogonal to it. The opening is long in the direction.

A stop in a focus detecting device proposed in Japanese Patent Application Laid-Open No. Sho 62-95511 has two apertures made of two circular arcs arranged side by side, and a square opening obliquely inclined at about 45 degrees. It has become. The apertures of the apertures having these shapes can be superposed on the other by moving one of them in parallel.
As described in Japanese Patent Application Publication No. 1-210, even when the objective lens is out of focus, two blurred images on a sensor that convert an optical image into an electric signal are combined with extremely high accuracy. Therefore, by setting the aperture opening in such a shape, it is possible to detect the defocus amount with high accuracy.

[0008] By the way, as the functions of single-lens reflex cameras become more sophisticated, the focus detection devices used change from those that detect the focus only at the center of the imaging surface to those that have a plurality of focus points in the imaging surface. . For this reason, the aperture stop having the shape according to the above-mentioned known technique is not always optimal.

The aperture of the focus detection device is a very important factor in determining the operation limit subject brightness of the focus detection device. That is, in order for the output of the focus detection device to maintain the desired detection accuracy, it is premised that the luminous flux to be taken into the re-imaging lens reaches the sensor without being shaken by the objective lens. In order to normally operate a dark subject, it is desirable to capture a light beam as thick as possible within a range that is not blurred by the objective lens.

[0010]

A photographic lens (objective lens) has a reduction in photographic light flux on a peripheral image plane, which is generally called vignetting. In the above focus detection device, the entire focus detection area is configured to be re-imaged on the area sensor with only a pair of re-imaging lenses, and thus the focus detection area on the focus detection area farthest from the optical axis of the imaging lens is configured. There is a need to determine the aperture aperture based on points.

In such a setting of the aperture opening, there is a remarkable tendency that the amount of light captured by the focus detection device is reduced. In order to maintain the performance of the operation limit subject luminance, it is necessary to capture a beam as thick as possible before. It is even more important.

Accordingly, the above-mentioned Japanese Patent Application Laid-Open No. Sho 56-130725 has been disclosed.
In some cases, the shape of the aperture opening disclosed in Japanese Unexamined Patent Application, First Publication No. Sho.

The present invention has a sufficient operation limit subject luminance characteristic by appropriately setting each element of an optical means for focus detection provided on an image plane side of an objective lens (photographing lens), and has a luminance characteristic within a photographing range. It is an object of the present invention to provide a focus detection device capable of performing focus detection at an arbitrary point with high accuracy and an optical apparatus using the same.

[0014]

According to the present invention, there is provided a focus detection apparatus comprising: (1-1) a diaphragm having a pair of apertures on an image plane side of an objective lens, and a pair of secondary imaging systems corresponding thereto. Optical means having a plurality of light amount distributions for a subject image using light beams having passed through different regions of the pupil of the objective lens by the optical means, and a relative positional relationship between the plurality of light amount distributions is formed. A focus detection device that determines the in-focus state of the objective lens by using a signal from the photoelectric conversion element and detects the in-focus state of the objective lens using an optical path near the optical axis of the objective lens. And the pair of 2
The center is located on both the first plane including the center of curvature of the lens surface of the next imaging system and the second plane parallel to the optical path near the optical axis of the objective lens and orthogonal to the first plane. It is characterized by having a shape including four arcs that do not have, and being plane symmetric with respect to the first plane.

In particular, (1-1-1) the in-focus state of the objective lens is detected in a plurality of regions in the field of view.

(1-1-2) The optical means has a light-collecting reflecting mirror for reflecting a light beam from the objective lens to form a subject image on a predetermined surface. The subject image formed on the predetermined surface is re-imaged on the photoelectric conversion element surface. And so on.

The optical apparatus according to the present invention comprises: (2-1) driving a focusing lens constituting an objective lens by using a signal from the focus detection device according to any one of the constitutions (1-1). It is characterized in that focusing is performed and a subject image is formed on the imaging means surface.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 are schematic views of a main part of a first embodiment when a focus detection device according to the present invention is applied to an optical apparatus such as a camera. FIG. 1 shows a first detection system for separating a pupil of an objective lens (photographing lens) in a vertical direction in a focus detection device, and FIG. 2 shows a second detection system for separating a pupil of an objective lens in a horizontal direction. I have.

In the figure, reference numeral 101 denotes an objective lens, 1 denotes an optical axis of the objective lens 101, 2 denotes a film (imaging surface), 3 denotes a semi-transparent main mirror arranged on the optical axis 1 of the objective lens 101,
Reference numeral 103 denotes a reticle, on which a subject image formed by the objective lens 101 is formed via the main mirror 3.

Reference numeral 4 denotes a first reflecting mirror which is arranged obliquely on the image plane side of the objective lens 101 with respect to the optical axis 1, and comprises a condensing concave mirror, an elliptical mirror and the like. Reference numeral 5 denotes a paraxial image plane conjugate to the film 2 formed by the first reflecting mirror 4, on which a subject image is formed. Reference numeral 6 denotes a second reflecting mirror, 7 denotes an infrared cut filter, 8 denotes a stop having four openings 8e, 8f, 8g, 8h, and 9 denotes four lenses 9e arranged corresponding to the four openings of the stop 8. , 9f, 9g, 9h, a secondary imaging system (re-imaging lens block), 10 is a third reflecting mirror,
Reference numeral 11 denotes an area sensor, which indicates a photoelectric conversion element (light receiving unit) having two pairs of two-dimensional light receiving area sensors 11e, 11f, 11g, and 11h. First reflecting mirror 4, second reflecting mirror 6, stop 8, and secondary imaging system 9
Etc. constitute one element of the optical means.

Each of the light receiving area sensors 11e to 11f is composed of a plurality of sensor rows, and the sensor rows also form a pair.

Here, the first reflecting mirror 4 is an elliptical mirror, and the two focal points defining the ellipse reverse the optical path after the light beam on the optical axis 1 of the objective lens 101 is refracted by the main mirror 3. First, on the line extended to the objective lens 101 side and the ray
Are positioned on lines extending the optical path after being reflected by the reflecting mirror 4. The first reflecting mirror 4 also functions as a field mask that limits the focus detection area, so that only the necessary area reflects light. The second reflecting mirror 6 and the third reflecting mirror 10 are plane mirrors. The optically functioning portions of these components are all symmetrical with respect to the paper.

FIG. 3 is a plan view of the stop 8. In FIG. 3, the stop 8 is a stop made of a light-shielding thin plate made of metal or resin, 8e to 8f are stop openings (openings), 8i and 8j.
Is a positioning hole. The stop 8 is fixed to the re-imaging lens block 9 via the positioning holes 8i and 8j.

The light incident side of the re-imaging lens block 9 is the first
A single concave spherical surface centered on the optical axis of the objective lens 101 deflected by the reflecting mirror 4, and the exit side is a pair of convex lens surfaces 9e to 9h eccentric in opposite directions.
Further, the center of the concave spherical surface is located on the paraxial imaging plane 5 of the objective lens 101 formed by the first reflecting mirror 4, and the center of the two pairs of lens portions 9e to 9h is located at the stop aperture 8e.
Approximately equal to around 8h. By arranging the power of the lens in this manner, it is possible to perform highly accurate focus detection over a wide wavelength range and in a plurality of regions of the photographing range.

The positional relationship between the stop 8 and the re-imaging lens block 9 is such that two pairs of lenses 9e to 9h are located behind the stop 8 as shown by broken lines in FIG. The aperture centroids of the aperture openings 8e and 8g are parallel to the optical path near the optical axis of the objective lens 101 and are on a first plane (paper surface in FIG. 1) PL1 including the centers of curvature P6 and P7 of the lens portions 9e and 9g. The center of curvature of the apertures 8f and 8h and the center of curvature of the lens sections 9f and 9h include a second plane (including the optical path near the optical axis of the objective lens 101) and orthogonal to the first plane PL1 (the plane of FIG. 2). ) On PL2.

As the optical path of the focus detection light beam, the aperture openings 8e to 8h and the lens portions 9e to 9h correspond to each other with the same suffix, and the light beam passing through each opening is a third reflecting mirror. A secondary object image is formed on the area sensor 11 via the reference numeral 10. It should be noted that the luminous flux passing through the elements with different subscripts does not reach a predetermined position on the area sensor and does not contribute to focus detection.

The detection system using the light beam passing through the elements indicated by the subscripts e and g separates the exit pupil of the objective lens in the vertical direction, while detecting the light beam using the light beam passing through the elements indicated by the subscripts f and h. The system laterally separates the exit pupil of the objective lens. Hereinafter, a detection system for separating the pupil in the vertical direction is referred to as a first focus detection system (first detection system), and a detection system for separating the pupil in the horizontal direction is referred to as a second focus detection system (second detection system). I will call it.

Next, the optical function of the above configuration will be described. 12e, 12g, 12f, shown in FIG. 1 and FIG.
Reference numeral 12h denotes a light beam passing through the aperture 8 and used for focus detection at the center of the screen. To add a description in the order in which these rays travel, first, the light beam from the objective lens 101 is transmitted through the main mirror 3 and then reflected by the first reflecting mirror 4 in a direction substantially along the inclination of the main mirror 3. As described above, the first reflecting mirror 4 is an elliptical mirror, and the vicinity of the two focal points can be substantially in a projection relationship.

Here, one focal point is set to the optical equivalent point of the representative exit pupil position 101a of the objective lens 101, and the other focal point is set to the optical equivalent point of the stop 8, so as to have a function as a field lens. ing. The representative exit pupil position 101a of the objective lens 101 is a hypothetical pupil position unique to the focus detection system which is comprehensively determined in consideration of the conditions of the exit windows of various projection lenses mounted on the camera.

The light beam reflected by the first reflecting mirror 4 is reflected again by the second reflecting mirror 6 and enters the infrared cut filter 7. Here, infrared rays which cause a reduction in the accuracy of focus detection are removed, and only the light in the wavelength range in which the aberration of the objective lens is sufficiently corrected is placed up to the aperture 8 and the re-imaging lens block 9 placed behind. To reach. The luminous flux converged by the action of the re-imaging lens block 9 passes through the third reflecting mirror 10
A next object image is formed on the area sensor 11.

FIG. 4 is a diagram showing the state of the secondary object images 22e to 22h on the area sensor 11, and is an example of a grid-like object. Four secondary object images are formed by the four lenses of the re-imaging lens block 9, and 22
g, 22e and 22f, 22h are pairs of images (secondary object images) for which relative positional relationships are to be detected.

Here, the distance between the openings 8e and 8g of the stop 8 and the distance between the openings 8f and 8h are different from each other, and the second focus detection system having a wider distance is more sensitive to the movement of the secondary object image. Therefore, highly accurate focus detection is possible.

The range in which the object is projected is the secondary object image 22
g, 22e are different from the secondary object images 22f, 22h,
In the secondary object images 22g and 22e, the main mirror and the second reflection mirror are located in a region determined by the size of the first reflecting mirror 4 in the secondary object images 22f and 22h due to the difference in the distance between the aperture openings 8f and 8h. It is an area through which light rays can pass on the mirror, and is smaller than the secondary object images 22g and 22e. Further, due to the oblique arrangement of the first reflecting mirror 4, each image has a considerably large distortion without axial symmetry.

However, even if such a distortion is present, there is no problem as a focus detection device for a camera that requires particularly quick focusing if the following two conditions are satisfied.

The conditions are as follows in order to obtain an accurate focus determination. At least when the objective lens is in focus, a secondary object image corresponding to the same position on the object is projected on a pair of sensor rows to be detected, that is, in a direction orthogonal to the sensor rows. , The difference in magnification between the two images is small.

In order to obtain accurate defocus detection, When a defocus of the objective lens occurs, a secondary object image corresponding to the same position on the object is projected with a positional phase difference on a pair of sensor rows to be detected. It is.

Now, the focus detection system will be described from such a viewpoint. First, regarding the first focus detection system that separates the pupil in the vertical direction, since the inclination of the first reflecting mirror 4 is in the plane of FIG. Regarding any of 22e, the distortion has a fan shape symmetric to the plane of the drawing, and the amount of the distortion itself is considerably large. However, if attention is paid to the difference in distortion between the two images, the difference is small. In particular, the image magnification difference between the secondary object images 22g and 22e in the horizontal direction in the figure corresponding to the direction orthogonal to the pupil separation is almost zero. There is no.

Therefore, if the sensor rows 11e and 11g in the light receiving area are arranged as shown in FIG. 6, the object image 22 projected on an arbitrary sensor row on one light receiving area 11e can be obtained.
The object image 22g paired with e is projected onto the corresponding sensor array on the other light receiving area 11g. That is, the above condition is satisfied.

The factor of the distortion of the secondary object image lies in the first reflecting mirror 4, that is, the pupil projection optical system, and the distortion generated on the paraxial imaging plane 5 of the first reflecting mirror 4 is re-imaged. Lens block 9
Can be said to be projected on the area sensor 11 as it is. Therefore, the moving direction of the secondary object images 22e and 22g is the direction in which the aperture openings 8e and 8f are arranged.
On the area sensor, it is the direction of the arrow shown in FIG.

Accordingly, by setting the sensor rows as shown in FIG. 6 as described above, the same condition is satisfied, and the relative positional relationship between the secondary object images 22e and 22g is compared based on this, and the defocus amount of the objective lens is determined. Is possible.

FIG. 8 shows a focus detection area on the imaging surface by the light receiving areas arranged as described above. Light receiving areas 11g and 11e in which a distorted secondary object image 22g is arranged in a rectangle.
The focus detection area 31 for photoelectric conversion by the
The shape becomes distorted as shown in the figure.

Next, a second focus detection system for separating the pupil in the horizontal direction will be described. The difference in image magnification difference between the two images in the direction orthogonal to the pupil separation is reduced only in the region near the center of the imaging surface. Therefore, if the light receiving area is limited to only this part, the object image that is paired with the object image projected on an arbitrary sensor row on one light receiving area is projected on the corresponding sensor row on the other light receiving area. Thus, the above condition is satisfied.

FIG. 7 is a plan view of the area sensor 11 showing the light receiving areas 11f and 11h for the second focus detection system in addition to the light receiving areas 11g and 11e of the first focus detection system shown in FIG. is there. Secondary object images 22f and 22 that form a pair
The moving direction of h is the direction in which the aperture openings 8f and 8h are arranged for the same reason as in the first focus detection system, and the above conditions can be satisfied by setting the sensor rows as shown in the figure. . The focus detection area on the imaging surface by such a light receiving area is as shown in FIG. 9, and the focus detection area 34 is a central portion in the imaging surface 30.

The light amount distribution is output as an electric signal by using such an area sensor 11, and the relative positional relationship between the images (secondary object images) on a pair of sensor rows to be detected is detected. It is possible to detect the focal position of the lens. At this time, if the sensor row pair to be detected is appropriately selected, a two-dimensional imaging state can be detected on the imaging surface.

Further, as shown as an area 32 or an area 33 in FIG. 8, for example, a defocus map on the image pickup surface is obtained from the focus information of the more subdivided focus points obtained by dividing the sensor array into a plurality of areas. It is also possible to automatically control the focus of the objective lens at an arbitrary position most appropriate among the main subjects. As a result, focus detection is performed in a plurality of regions in the subject.

Next, the shapes of the openings 8e to 8h of the stop 8 will be described with reference to FIGS. Here, a first focus detection system having a wide focus detection area will be described. First, FIG. 11 is an explanatory diagram of the exit window of the objective lens, which is restricted when determining the light flux of the first focus detection system.
Here, when the exit windows of various objective lenses are obtained for the point P1 on the focus detection area furthest from the optical axis 1 of the objective lens shown in FIG. 48 is shown.

Generally, the exit window is substantially circular when viewed from the optical axis direction, and is represented as a line in FIG. In order to guarantee the focus detection accuracy at the point P1 on the focus detection area, it is necessary that the focus detection light beam be taken into the focus detection system without being shaken by any objective lens, but this is hatched. This means that the focus detection light beam must be included inside the region 49.

In order to know this state in detail, it is sufficient to define a surface on the optical axis of the objective lens, project an exit window on this surface, and examine the relationship with the focus detection light beam. Here, the representative exit pupil position of the objective lens is selected as the projection plane. With such a setting, the positional relationship of the focus detection light beam with respect to the optical axis 1 on the projection plane can be replaced with the positional relationship of the stop aperture with respect to the optical axis on the stop 8, which is convenient.

In FIG. 11, reference numeral 46 denotes a representative exit pupil position serving as a projection plane, and a position where the cross section of the region 49 spreads substantially uniformly around the optical axis 1.

FIG. 13 shows the projected images 40,
FIG. 9 is a diagram showing a relationship between 41 and a focus detection light beam, showing a state in which a light beam of a first focus detection system incident on a center point of the imaging surface shown in FIG. 8 is cut on an exit pupil of an objective lens. Things. In the figure, reference numerals 42e and 42g denote passing ranges at a representative exit pupil position of a light beam which is incident on the center point of the imaging surface and passes through the openings 8e and 8g of the stop 8.

The center line L3 is an intersection line between the paper surface of FIGS. 1 and 2 and the projection surface 46. The center line L4 is the objective lens 1
It is a straight line passing through the optical axis 1 of No. 01 and orthogonal to the center line L3. The passing ranges 42e and 42g are located along the center line L3, while the projected images 40 and 41 of the exit window are two circular images centered on the optical axis 1 of the objective lens. Thus, the passing ranges 42e and 42g enter the hatched area 50 with a margin, and the light flux is not blocked.

As described above, at the point close to the optical axis of the objective lens, the passing ranges 42e and 42 of the focus detection light beam are generally used.
The projected image of the exit window with respect to g becomes large and the focus detection light beam is not shaken. That is, the optical axis 1 of the objective lens
The shape of the aperture of the stop 8 is determined at a point on the focus detection area far from the aperture.

FIG. 12 is a diagram showing the relationship between the projected images 43 and 44 of the exit windows 47 and 48 at peripheral points on the focus detection area and the focus detection light flux. In the figure, reference numerals 45e and 45g denote passing ranges at a representative exit pupil position of a light beam incident on the point P1 on the focus detection area and passing through the openings 8e and 8g of the stop 8. Since the first focus detection system separates the pupil in the vertical direction, the passing ranges 45e and 45g are located along the center line L3, and the projected images 43 and 44 are located at the point P1 on the focus detection area.
Is a point at the corner of the imaging surface, so that two circular images are obliquely shifted.

The projection plane 4 of the hatched area 49 in FIG.
The range on 6 is the area 50 where the projected images 43 and 44 intersect.
Is equivalent to

In order to ensure that the focus detection light beam is not eclipsed by any objective lens, at least the passing ranges 45e and 45g of the focus detection light beam must be in the region 5.
0 must be included. On this,
In order to realize a focus detection device having sufficient operation limit subject luminance characteristics, the areas of the passing ranges 45e and 45g must be as large as possible.

However, in this case, as a restriction,
As described in JP-A-95511, it is impossible to detect the defocus amount with high accuracy unless the shape of the aperture opening is changed in parallel to one side and changed to the other.

The maximum area satisfying the above conditions can be obtained by forming the passing ranges 45e and 45g as follows. First, since the focus detection system has symmetry, a line symmetric shape with respect to the center line L3 is premised to maximize the area of the passing ranges 45e and 45g.

Next, it is necessary to define arcs along the projected images 43 and 44. However, the passing ranges 45e, 45
In order for g to overlap each other by the translation, the arc 45
e-1 and 45g-1, 45e-2 and 45g-2, 45e
-3 and 45g-3 and 45e-4 and 45g-4 need to have the same radius.

When combined with the above symmetry condition, the arc 45e-
The set of 1,45g-1, 45e-2, 45g-2 and the set of 45e-3, 45g-3, 45e-4, 45g-4 have the same radius.

As described above, the stop 8 and the representative exit pupil position of the objective lens are in a projection relationship due to the action of the first reflecting mirror 4 as a field lens, and the above-described passing range 45 is set.
The shape of e, 45 g may be replaced with the aperture 8.

FIG. 10 is an explanatory diagram for defining the shape of the stop 8. Since the pair of openings 8e and 8g of the diaphragm have the same shape, the opening 8g will be described here. The opening 8g is composed of four arcs like the passage range 45g, and their centers are located at P2, P3, P4, and P5. Further, from the correspondence with the passing range of 45 g, the circular arcs 8g-1,8
g-2, and then 8g-3 and 8g-4 have the same radius.

The center of these arcs is parallel to the optical path near the optical axis of the objective lens, and PL1 on the first plane including the centers of curvature P6 and P7 of the lens portions 9e and 9g and the optical axis near the optical axis of the objective lens. It is not located anywhere on the second plane PL2 that includes the optical path and is orthogonal to the first plane PL1.

In this embodiment, the openings 8e and 8g of the stop 8
Are set as described above to improve the operation limit subject brightness.

FIG. 14 is an explanatory view of the aperture of the stop 8 according to another embodiment of the present invention. The aperture opening of the focus detection device shown in FIGS. 1 and 2 is not limited to a shape whose entire circumference is surrounded by an arc, and may have a shape as shown in FIG. 14, for example.

In the figure, the opening 60g similarly includes four arcs, the centers of which are points P10, P11, P1
2, P13. Furthermore, arcs 60g-1, 60g-
2, 60g-3 and 60g-4 have the same radius. The center of these arcs is parallel to the optical path near the optical axis of the objective lens, and the center of curvature P of the lens portions 9e and 9g
6, including PL1 on the first plane including P7 and the optical path near the optical axis of the objective lens, and is not located on any of the second plane PL2 orthogonal to the first plane PL1.

This portion has the same configuration as that of the first embodiment for the purpose of increasing the area of the aperture. The difference from the first embodiment is the shape of the position where the arcs intersect at an acute angle. The position where the arcs 60g-1 and 60g-4 intersect is connected by a line 60g-5, and the position where the arcs 60g-2 and 60g-3 intersect is connected by a line 60g-6.

By doing so, the lens portions 9e, 9
It is possible to cut the light beam incident on the position farthest from the centers of curvature P6 and P7 of g, and to improve the unity of the point images on the light receiving area to improve the focus detection accuracy.

[0068]

As described above, according to the present invention, by appropriately setting each element of the focus detecting optical means provided on the image plane side of the objective lens (photographing lens), a sufficient operation limit subject luminance characteristic can be obtained. And a focus detection device capable of performing focus detection with high accuracy at an arbitrary point in the imaging range, and an optical apparatus using the same.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an optical path of a first focus detection system according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an optical path of a second focus detection system according to the first embodiment of the present invention.

FIG. 3 is a plan view of the diaphragm according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a state of a secondary object image on the area sensor according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating a moving direction of a secondary object image according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an arrangement direction of a sensor row according to the first embodiment of the present invention.

FIG. 7 is a plan view of the area sensor according to the first embodiment of the present invention.

FIG. 8 is a plan view of the area sensor according to the first embodiment of the present invention.

FIG. 9 is a plan view of the area sensor according to the first embodiment of the present invention.

FIG. 10 is an explanatory diagram of a shape definition of a diaphragm according to the first embodiment of the present invention.

FIG. 11 is a diagram illustrating an exit window of the objective lens according to the first embodiment of the present invention.

FIG. 12 is an explanatory diagram illustrating a relationship between a projection image of an objective window and a focus detection light beam according to the first embodiment of the present invention.

FIG. 13 is an explanatory diagram illustrating a relationship between a projection image of an objective window and a focus detection light beam according to the first embodiment of the present invention.

FIG. 14 is an explanatory diagram of another aperture shape definition according to the first embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 101 Objective lens 1 Optical axis 2 Imaging means 3 Main mirror 4 First reflecting mirror 5 Image plane 6 Second reflecting mirror 7 Infrared cut filter 8 Aperture 9 Secondary imaging lens 10 Third reflecting mirror 11 Area sensor 8e-8h Aperture opening 9e-9h Lens P6, P7 Center of curvature PL1 First plane PL2 Second plane

Claims (4)

[Claims] 1. An optical system comprising: a stop having a pair of apertures on an image plane side of an objective lens; and a pair of secondary imaging systems corresponding to the stop. A plurality of light amount distributions of the subject image are formed by using light beams that have passed through different regions, and a relative positional relationship between the plurality of light amount distributions is obtained by a plurality of photoelectric conversion elements, and a signal from the photoelectric conversion element is obtained. In a focus detection device that detects the in-focus state of the objective lens using a, the pair of openings is parallel to an optical path near the optical axis of the objective lens,
Any one of a second plane parallel to the optical path near the optical axis of the objective lens on the first plane including the center of curvature of the lens surfaces of the pair of secondary imaging systems and orthogonal to the first plane. And the first shape is a shape including four arcs having no center.
A focus detection device characterized in that it is plane-symmetric with respect to a plane. 2. The focus detecting device according to claim 1, wherein the in-focus state of the objective lens is detected in a plurality of regions in a field of view. 3. The optical means has a converging reflector for reflecting a light beam from the objective lens to form a subject image on a predetermined surface, and the secondary imaging system is provided on the predetermined surface. 2. The focus detection device according to claim 1, wherein the formed subject image is re-imaged on the photoelectric conversion element surface. 4. A focusing lens is formed by driving a focusing lens constituting an objective lens by using a signal from the focus detection device according to claim 1. An optical device characterized by forming: