JP2013141560A - Optical system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system allowing the simultaneous photography of a notice portion (a central part of a screen) and a portion distant from the notice portion, and allowing the enhancement of the magnification of the notice portion to perform the photography.SOLUTION: This optical system includes: a wide lens having a view angle of 120-200 degrees, and having a curvature becoming larger as coming apart from an optical axis; an imaging lens focusing light having passed the wide lens, on a prescribed plane; and a light receiving element converting the light focused by the imaging lens into an electric signal.

Description

  The present invention relates to an optical system.

  2. Description of the Related Art Conventionally, a vehicle periphery monitoring device using a fisheye lens is known as a device that monitors a situation around an area to be monitored at a wide angle (see, for example, Patent Document 1).

  In addition to visually recognizing the periphery of the vehicle, it is conceivable to use a fish-eye lens also in an endoscope, whereby the periphery of the distal end of the endoscope can be visually recognized in a wide range.

  In this case, a fisheye lens is provided as a photographing lens at the tip of an optical fiber group in which optical fibers are bundled, an element for converting light such as a light receiving element into an electric signal is provided at the opposite end of the optical fiber, and an electric signal output from the light receiving element Based on the above, a device for displaying on the display can be considered. Then, from the tip of the optical fiber group provided with the fisheye lens, for example, the stomach is inserted through the mouth and throat of the subject, the stomach wall image is displayed on the display, and the image is stored as a photograph.

  By doing this, it is possible to image the site of interest in the stomach wall, and since the angle of view of the fisheye lens is wide, it is possible to determine in which area the site of interest is located in the entire stomach. You can know just by looking at the display or photos.

JP 2007-000250 A

  By the way, in the example where the fisheye lens is provided at the distal end of the endoscope, the stomach wall can be photographed at a wide angle, so it is possible to know where the target region is located in the entire stomach by just looking at the photograph. However, there is a problem that the magnification of the part of interest (the central part of the screen) is low and it is not possible to respond to a request for a more enlarged display.

  This problem occurs not only when the stomach wall is imaged with an endoscope, but also when other gastrointestinal systems such as the throat and large intestine are imaged. This problem also occurs in other observation devices.

  The present invention is capable of simultaneously imaging a site of interest (the center of the screen) and a site away from the site of interest, and capable of imaging with a higher magnification of the site of interest. The purpose is to provide.

  The present invention is a wide lens having an angle of view of 120 degrees to 180 degrees, and has a wide lens whose curvature increases as it moves away from the optical axis, and an image that forms an image of light passing through the wide lens on a predetermined plane. An optical system comprising: a lens; and a light receiving element that converts light imaged by the imaging lens into an electrical signal.

  According to the present invention, it is possible to simultaneously image a region of interest (the center portion of the screen) and a region that is away from the region of interest, and it is possible to perform imaging while increasing the magnification of the region of interest. There is an effect.

It is a figure which shows the optical system 100 which is Example 1 of this invention. It is a figure which shows the to-be-photographed object 40 which the optical system 100 is going to image | photograph. It is a figure which shows the state in which the image 50 image | photographed with the optical system 100 is displayed on the display D1. It is a figure which shows the optical system 200 which is Example 2 of this invention. It is a figure which shows the state in which the image 50a image | photographed with the optical system 200 is displayed on the display D2.

  The modes for carrying out the invention are the following examples.

  FIG. 1 is a diagram showing an optical system 100 that is Embodiment 1 of the present invention.

  The optical system 100 includes a wide lens 10, a telecentric imaging lens 20, and a light receiving element 30.

  The wide lens 10 is a wide lens having an angle of view of 120 degrees to 200 degrees and a curvature that increases with distance from the optical axis. That is, the lens has a curvature near the optical axis that is a predetermined value, and the curvature away from the optical axis is larger than the predetermined value. In other words, the wide lens 10 is a lens that has a large magnification near the optical axis and a magnification at a portion away from the optical axis smaller than the magnification near the optical axis. Note that the curvature of the wide lens 10 continuously changes from the optical axis toward the periphery, and the curvature gradually increases.

  The angle of view may be any of 120 degrees, 130 degrees, 140 degrees, 150 degrees, 160 degrees, 170 degrees, 180 degrees, and 200 degrees, or may be an angle of view between them. If it is difficult to realize an angle of view of 180 to 200 degrees with only a lens, it is possible to realize an angle of view of 180 to 200 degrees by using a mirror or the like. Further, the angle of view is preferably 120 to 180 degrees, and more preferably 160 to 180 degrees.

  The telecentric imaging lens 20 is a lens that images light that has passed through the wide lens 10 on the light receiving surface 31 of the light receiving element 30. The telecentric imaging lens 20 is an imaging lens that images light that has passed through the wide lens 10 onto the light receiving surface 31 of the light receiving element 30 substantially perpendicularly.

  The light receiving element 30 has a light receiving surface 31 and converts light imaged on the light receiving surface 31 by the telecentric imaging lens 20 into an electric signal.

  Next, the operation of the optical system 100 will be described.

  FIG. 2 is a diagram illustrating a subject 40 to be photographed by the optical system 100.

  The subject 40 is an English letter F, and is composed of an upper horizontal line 41, a vertical line 42, and a central horizontal line 43. The horizontal line 41, the vertical line 42, and the horizontal line 42 have the same thickness.

  FIG. 3 is a diagram illustrating a state in which an image 50 captured by the optical system 100 is displayed on the display D1.

  As shown in FIG. 3, the image 50 of the subject 40, which is an English letter F, includes a horizontal line 51, a vertical line 52, and a horizontal line 53. The horizontal line 51, the vertical line 52, and the horizontal line 53 are respectively horizontal lines 41. , Corresponding to a vertical line 42 and a horizontal line 43. As shown in FIG. 3, the horizontal line 51 and the vertical line 52 are thin, and the horizontal line 53 is thick. That is, the horizontal line 53 is a part of an image located at the central part of the field of view, and this is enlarged by the central part of the wide lens 10, so the thickness of the horizontal line 53 increases. On the other hand, the horizontal line 51 and the vertical line 52 are images located at the edge of the field of view, and the light of this image passes through the peripheral part of the wide lens 10, and there is little enlargement of the image in the peripheral part of the wide lens 10, In addition, the horizontal line 51 and the vertical line 52 become thinner because they are located far from the center (position on the optical axis).

  According to Example 1, since the angle of view is wide, a part away from a target part (center part of the screen) (a characteristic part of the stomach wall such as cardia and pylorus when photographing the stomach with a stomach camera) Since the region of interest can be imaged at the same time, it can be inferred only by looking at the picture which part of the whole stomach is the region of interest. Moreover, since the curvature of the wide lens 10 in the vicinity of the optical axis is smaller than the curvature of the periphery of the wide lens 10, the magnification of the image of the attention region is high. It can be visually recognized.

  By the way, the fisheye lens is a lens whose angle of view is usually about 180 degrees and whose curvature is constant. When photographing using this fisheye lens, the periphery of the captured image is displayed in an arc shape, the periphery of the image is displayed relatively small, and the center of the image is displayed relatively large. In the conventional fisheye lens, the periphery of the image is displayed small, because the object displayed on the periphery is far away from the fisheye lens, the image is displayed small and the center of the image is displayed large. This is because the object existing in the center is present near the fisheye lens. In the image taken with the conventional fisheye lens, the center is displayed larger because the magnification of the object existing in the center of the image is increased.

  In the first embodiment, the curvature of the wide lens 10 continuously changes as the distance from the optical axis increases. However, instead of this, the lens may change in a stepwise manner. In this case, the image 50 displayed on the display D1 has no continuity, but the lens can be designed so that the image displayed on the center of the display D1 is not missing. Further, since an image of a part away from the point of interest (image displayed at the center of the display D1) is displayed on the edge of the display D1, attention is paid to which part of the entire subject (object). The operator can easily grasp whether the point is located.

  In addition, since the telecentric imaging lens 20 is used, the light that has passed through the wide lens 10 is imaged almost perpendicularly on the light receiving surface 31 of the light receiving element 30. Therefore, even if the distance between the light receiving surface 31 and the telecentric imaging lens 20 changes slightly, the magnification of the image on the light receiving surface 31 does not change. That is, even if the distance from the telecentric imaging lens 20 to the light receiving element 30 changes slightly in manufacturing, the focus changes, but the imaging magnification does not change, so that the positioning tolerance is high in manufacturing.

  In the first embodiment, a non-telecentric imaging lens may be used instead of the telecentric imaging lens 20. However, in this case, if the position of the light receiving surface 31 is shifted in the optical axis direction, the magnification of the image formed on the light receiving surface 31 changes.

  In Example 1, if a shutter is provided, a still camera is obtained. Further, the first embodiment may be an imaging apparatus that captures a moving image instead of an imaging apparatus that captures a still image.

  Furthermore, a film may be provided instead of the light receiving element 30.

  FIG. 4 is a diagram showing an optical system 200 that is Embodiment 2 of the present invention.

  In the optical system 200, the telecentric imaging lens 20 is composed of two lenses 21 and 22, and a relay lens L1 is provided between the wide lens 10 and the telecentric imaging lens 20.

  FIG. 5 is a diagram illustrating a state in which an image 50a captured by the optical system 200 is displayed on the display D2.

  As shown in FIG. 5, the image 50a of the subject 40, which is an English letter F, is composed of a horizontal line 51a, a vertical line 52a, and a horizontal line 53a, but the horizontal line 51a and the vertical line 52a are thin. The horizontal line 53a is thick. This is because the horizontal lines 51a and the vertical lines 52a are images corresponding to the edge portions of the field of view, so that their thicknesses are reduced. On the other hand, the horizontal line 53a is an image corresponding to the central portion of the field of view, and since the curvature near the optical axis of the wide lens 10 is relatively small, the image passing there is enlarged, and the horizontal line 53a is thick. Become.

  The telecentric imaging lens 20 may be composed of three or more lenses. That is, the telecentric imaging lens 20 is composed of at least one lens.

  In Embodiments 1 and 2, the wide lens 10 is composed of one lens. However, the wide lens 10 may be composed of two or more lenses, that is, the wide lens 10 is composed of at least one lens. ing.

  The third embodiment of the present invention is an embodiment in which the optical systems 100 and 200 are used in an endoscope (not shown).

  In the first and second embodiments, an optical fiber is provided between the image formation position of the telecentric imaging lens 20 and the light receiving surface 31 of the light receiving element 30, and this thickness is set to a thickness that passes through the throat. If set, it becomes an endoscope, and the digestive system such as the esophagus, stomach and large intestine can be visually recognized. In this case, since the magnification at the center of the image captured by the endoscope is high, the point of interest can be clearly seen, and at the same time, since the angle of view in Examples 1 and 2 is wide, the current point of interest is For example, it is possible to easily grasp which part of the stomach it is.

  The fourth embodiment of the present invention is an embodiment in which the optical systems 100 and 200 are used in a remote operation device (remote operation device) although not shown.

  Telesurgery is an operation performed in a state where the patient undergoing the operation and the doctor performing the operation are separated from each other. For example, when a doctor working in an urban hospital operates a patient admitted to a hospital on a remote island, a manipulator (magic hand) is provided around the patient, and this manipulator handles a medical instrument such as a scalpel. The local doctor operates the operation means while observing the patient's condition, and the operation content (command signal) by the operation means is transmitted as an electric signal to the manipulator by wire or wirelessly, and according to the electric signal The manipulator performs the movement and the operation is performed.

  In other words, the fourth embodiment is used for a remote operation device, and is used for observing a region centered on an affected part (surgical site) that is a surgical target of a patient when operating a surgical instrument by a remote command signal. It is used.

  In this case, in Example 4, not only the affected part (surgical site) that is the patient's surgical target but also the image around the affected part is transmitted to the display device on the doctor side, and the magnification of the image of the affected part that is the target site is Because it is higher than the image around the affected area, the doctor can clearly see the condition of the affected area and can also grasp the situation around the affected area, and therefore perform an appropriate operation. Can do.

  The fifth embodiment of the present invention is an embodiment in which the optical systems 100 and 200 are used in an observation robot (not shown).

  Among the observation robots, when the optical systems 100 and 200 are attached to a movable robot, the fifth embodiment has a wide angle of view, so that the foot of the observation robot can be reliably photographed. The observation robot is suitable for observing areas that are disturbed by humans (areas with a lot of dust, areas with high temperature and high humidity, areas with explosion potential, areas with strong radiation, etc.) In such a region, obstacles are often scattered around the observation robot such as the feet. In this case, when the observation robot moves, the operator present in the remote place can surely see the obstacle, so that the observation robot does not collide with or touch the obstacle. Oversight due to narrowing of the visual field is reduced, and thus observation can be performed efficiently and with little oversight.

100: optical system,
10 ... Wide lens,
20 ... Telecentric imaging lens,
30. Light receiving element,
40 ... Subject,
50 ... Image.

Claims (8)

A wide lens having an angle of view of 120 degrees to 200 degrees, the curvature of which increases with distance from the optical axis;
An imaging lens that forms an image of light passing through the wide lens on a predetermined plane;
A light receiving element that converts light imaged by the imaging lens into an electrical signal;
An optical system comprising: In claim 1,
The optical system, wherein the imaging lens is a telecentric imaging lens that forms an image of light that has passed through the wide lens substantially perpendicularly to the predetermined plane. In claim 1,
The wide lens is composed of at least one lens, and the imaging lens is composed of at least one lens. In claim 1,
The optical system according to claim 1, wherein the wide lens is a lens in which the curvature changes continuously or stepwise as the distance from the optical axis increases. In claim 1,
The optical system is used in an endoscope. In claim 1,
The optical system is used for a telesurgical apparatus, and is used for observing a region centered on a surgical site when operating a surgical instrument by a remote command signal. In claim 1,
An optical system, wherein the optical system is used for observing the periphery of an observation robot. In claim 1,
The angle of view is preferably 120 to 180 degrees, more preferably 160 to 180 degrees.

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