JP2009128846A - Compound optical system and optical device having the compound optical system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound optical system in which an imaging optical system and an information acquiring optical system are integrated, and also to provide an optical device having the compound optical system. <P>SOLUTION: The compound optical system 1 arranged in one space RI of spaces divided by a window W composed of an optical member through which light is transmitted, and photographing the other space RO through the window W and mounted on a photographing system 10, is constituted of: the imaging optical system 2 for photographing the other space RO; and the information acquiring optical system 3 having a function for picking up an image of a surface (observation surface Wa) in contact with the other space RO or the vicinity of the surface by the imaging optical system 2, or observing the image of the surface or an object in the vicinity of the surface. The information acquiring optical system 3 is constituted of at least one optical member (for example, a concave mirror 31) having positive refractive power, and is arranged so that its rear side focus and the position of an entrance pupil of the imaging optical system 2 are nearly aligned, and that a nearly object side is telecentric optical system when the position of the entrance pupil of the imaging optical system 2 is set as a pupil. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a composite optical system and an optical apparatus having the composite optical system.

There are various types of cameras using an electronic image sensor that is also used outdoors for surveillance purposes and in-vehicle use. In these optical systems, it is well known that measures for maintaining good image quality of the camera, for example, auto gain, auto focus, color balance correction, and the like are applied. What is extremely important in the environmental conditions that contribute to the image quality is the influence of surface refraction abnormalities caused by dirt and clouding on the surface of the window glass and rain when monitoring far away through the window glass. If it is possible to detect surface dirt or cloudiness adhering to the window glass and an abnormal refraction of the surface due to rain, it is possible to issue a warning as to whether to wash or blow away according to the degree of raindrop adhesion. Even in surveillance applications, it is possible to detect raindrops and dust on the surface of the environmental protection glass in real time and drive the wiper to clear the surface and maintain image quality. . Even in crime prevention devices that monitor the entrance from the inside, it is possible to take measures such as washing or blowing away when raindrops or dust on the surface of the window glass is detected. An imaging optical system that always looks at different fields of view near the window or outside the window, such as the key opening and closing status, and monitoring the status in real time. It is desired to continue imaging with the direction of a necessary part having an abnormality. In addition, a wide angle lens etc. are used for the optical system used for such a monitoring purpose (for example, refer patent document 1).
Japanese Patent Publication No. 51-14017

  However, these detection devices (sensors) and cameras have been conventionally configured as separate devices, and it has been necessary to individually install them in the vicinity of the windows and further adjust them individually. That is, there is a problem that the installation location is restricted, each adjustment takes time, and each device is expensive because there is an extra member such as a light receiving portion in each sensor.

  The present invention has been made in view of such problems, integrates an imaging optical system and an information acquisition optical system, improves the degree of freedom of installation location by a rational optical arrangement, facilitates adjustment, It is an object of the present invention to provide a composite optical system in which a part of the members is shared and made inexpensive, and to provide an optical device having the composite optical system.

  In order to solve the above problems, the composite optical system according to the present invention is disposed in one of the spaces divided by the window made of an optical member that transmits light, and the other space through the window or through the window. An imaging optical system for photographing and a function of capturing an image of a surface in contact with the other space of the window or an image in the vicinity of the surface, or observing an image of the object in the vicinity of the surface or the surface by the imaging optical system The information acquisition optical system includes at least one optical member having a positive refractive power, and the rear focal point of the information acquisition optical system and the imaging When the position of the entrance pupil of the optical system is substantially coincident and the entrance pupil position of the imaging optical system is the pupil, the object is arranged so that the approximate object side is a telecentric optical system.

  In such a composite optical system according to the present invention, the information acquisition optical system is disposed such that the front focal point of the information acquisition optical system is located on or near the surface in contact with the other space of the window. It is preferred that

  Further, in such a composite optical system according to the present invention, the information acquisition optical system is preferably configured by a reflection system or a catadioptric system.

  In this case, the information acquisition optical system is preferably configured to have at least one concave reflecting surface.

  Alternatively, the information acquisition optical system is configured to have at least one each of a concave reflecting surface (for example, the concave mirror 31 in the embodiment) and a convex reflecting surface (for example, the convex mirror 32 in the embodiment). It is preferable.

  Further, in such a composite optical system according to the present invention, the information acquisition optical system is a light beam that transmits at least a light beam having a predetermined wavelength through the reflective member constituting the reflective system or the catadioptric member constituting the catadioptric system. It is preferable to configure the transmission member integrally.

  In this case, in the information acquisition optical system, it is preferable that the light transmitting member has a member that limits the amount of light other than the predetermined wavelength.

  Further, in such a composite optical system according to the present invention, the information acquisition optical system has at least one concave reflecting surface and a convex reflecting surface, and the concave reflecting surface is a substantially off-axis paraboloid. It is preferable that the convex reflecting surface is formed by a substantially hyperboloid having a position on the optical axis of the entrance pupil and the center of the concave surface as a focal point.

  Furthermore, in such a composite optical system according to the present invention, the optical axis of the imaging optical system and the optical axis of the information acquisition optical system intersect at the position of the entrance pupil of the imaging optical system or in the vicinity of the entrance pupil. It is preferable that the angle formed by the optical axis of the imaging optical system and the optical axis of the information acquisition optical system is configured to be changeable about the point where the optical axes intersect.

  In addition, the optical device according to the present invention (for example, the imaging system 10 in the embodiment) includes an illumination optical system that irradiates the vicinity of the object plane of the information acquisition optical system and any one of the above-described composite optical systems.

  Alternatively, the optical device according to the present invention includes an illumination optical system that illuminates a subject of the imaging optical system and any one of the above-described composite optical systems.

  When the composite optical system and the optical apparatus having the composite optical system according to the present invention are configured as described above, the imaging optical system and the information acquisition optical system can be integrated, and are extremely compact and easy to adjust. And an inexpensive optical system can be achieved, information on the surface state of the window can be acquired, and the information can be fed back to the peripheral device or the imaging optical system as necessary.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an imaging optical device arranged in one space RI (for example, in the case of a surveillance camera, inside a housing) among the spaces RI and RO divided by the protection window W for the surveillance camera. A composite optical system 1 including a system 2 and an information acquisition optical system 3 is shown.

  The imaging optical system 2 is divided by a window W, and through the window W from the space RI in which the imaging optical system 2 is disposed, the other space RO (for example, in the case of a surveillance camera, the front of the outside of the housing). It is configured to image (observe) the space (RO). As such an imaging optical system 2, a wide-angle lens is preferably used. In this embodiment, the embodiment shown in Japanese Patent Publication No. 51-14017 is used while being proportionally shortened to a predetermined focal length, but any lens may be applied.

  The information acquisition optical system 3 includes, in order from the window W side, an optical member 31 having a positive refractive power and an optical member 32 having a negative refractive power. In the embodiment shown in FIG. 1, the optical member 31 having a positive refractive power is constituted by a concave mirror 31 having a concave surface 31a facing the window W side, and the optical member 32 having a negative refractive power is used as an imaging optical. The case where it comprises with the convex mirror 32 which orient | assigned the convex surface 32a to the system 2 side is shown. In this information acquisition optical system 3, the rear focal point (the focal point on which the light beam incident on the information acquisition optical system 3 from the window W side is focused) is roughly the position of the entrance pupil of the imaging optical system 2. They are arranged to match. That is, the rear focal point of the information acquisition optical system 3 is arranged so as to coincide with or be positioned near the point where the entrance pupil plane of the imaging optical system 2 and the optical axis intersect. Further, when the entrance pupil position of the imaging optical system 2 is the pupil of the information acquisition optical system 3, the information acquisition optical system 3 is configured so that the approximate object side is a telecentric optical system. By disposing the information acquisition optical system 3 in this way, all of the light rays incident on the information acquisition optical system 3 can be captured by the imaging optical system 2.

  The illumination optical system 4 can be appropriately arranged inside or outside the window W, but is not shown in FIG. In the case of FIG. When the illumination optical system 4 is not used, the background scattered light is incident, so the background image and the image of the surface of the window W are superimposed, but the front focus of the information acquisition optical system 3 is superimposed on the surface Wa of the window W. Therefore, the image of the window surface Wa is more clearly observed. Here, for example, if raindrops adhere to the outer surface of the window W (the surface on the space RO side) due to rain, for example, a refraction abnormality of the light beam occurs in the portion where the raindrops are attached on the observation surface Wa, and the image of the observation surface Wa is displayed. Is collected by the imaging optical system 2 to form an image, and the image sensor can detect the state of raindrops by enhancing image distortion and contrast of light and dark.

  In FIG. 1 described above, the case where the information acquisition optical system 3 is configured by a reflection system composed of the concave surface (reflection surface) 31a of the concave mirror 31 and the convex surface (reflection surface) 32a of the convex mirror 32 has been described. As shown in FIG. 2, it is also possible to form a positive cemented lens 35 in which a biconvex lens 33 and a negative meniscus lens 34 with a concave surface facing the window W are bonded together in order from the window W (here, FIG. In FIG. 2, the illumination optical system 4 is omitted). That is, the information acquisition optical system 3 can be composed of at least one optical member having a positive refractive power (for example, the above-described positive cemented lens 35). In addition to FIGS. 1 and 2, the information acquisition optical system 3 may be a catadioptric system in which a refractive system such as a lens is added to the reflecting system.

  When the information acquisition optical system 3 is configured by a reflection system or a catadioptric system, in order to collect the illumination light reflected by the observation surface Wa of the window W, the information acquisition optical system 3 has a concave surface. It is necessary to provide at least one reflecting surface (in the case of FIG. 1, the concave surface 31a of the concave mirror 31 is provided), and furthermore, by providing at least one concave reflecting surface and at least one convex reflecting surface (FIG. 1). In this case, the concave surface 31a of the concave mirror 31 and the convex surface 32a of the convex mirror 32 are provided), and the Petzval sum can be reduced to reduce the curvature of field. Furthermore, in order to correct various aberrations such as coma and obtain a good image on the observation surface Wa, the concave surface (reflective surface) 31a of the concave mirror 31 is formed of an off-axis paraboloid, and the convex surface of the convex mirror 32 ( It is desirable that the (reflecting surface) 32a is constituted by a substantially hyperboloid having the focal point at the position on the optical axis of the entrance pupil of the imaging optical system 2 and the center of the concave surface (reflecting surface) 31a of the concave mirror 31.

  More specifically, the optical member 31 having a positive refractive power is a concave rotating paraboloid that passes through the focal point of the paraboloid and has an optical axis parallel to the incident light as a rotation axis, and has a negative refractive power. The optical member 32 has a convex rotationally symmetric dual axis with the focal point of the optical member 31 as the first focal point, the position of the incident axis of the imaging optical system 2 as the second focal point, and a straight line connecting the two focal points as the rotational axis. In the case of a curved surface, the light beam can be ideally concentrated on the entrance pupil of the imaging optical system 2 with no aberration, and as a result, the light beam having no loss of light amount and various aberrations corrected is guided to the imaging optical system 2. It is possible to put. Further, the optical member 31 and the optical member 32 are sufficiently good even if they are rotating bodies having approximate spherical surfaces each having the above-mentioned axis as a rotation axis, and an optical system that is easy to process and relatively inexpensive can be obtained. Is possible. Each reflecting surface may be a spherical surface or an aspherical surface having another aspherical shape.

  By the way, it is difficult to dispose each of the concave mirror 31 and the convex mirror 32 as described above alone in the space RI with high accuracy. Therefore, a curved surface corresponding to the reflecting surfaces 31 a and 32 a of the concave mirror 31 and the convex mirror 32 is used as a light transmitting member that transmits at least a light beam having a predetermined wavelength, that is, illumination light (for example, infrared light) irradiated by the illumination optical system 4. It is desirable that the reflective system or the catadioptric system of the information acquisition optical system 3 is integrally formed by forming a reflective layer thereon. Thereby, the arrangement of the information acquisition optical system 3 is facilitated, and the entire composite optical system 1 can be easily adjusted. At this time, although the above-mentioned illumination light is transmitted as the light transmitting member, light other than the illumination light (for example, RI in the housing) is used by using an optical material that restricts the amount of light of other wavelengths. Light and natural light that passes through the window W from the external space RO and enters the information acquisition optical system 3) can be removed, so that an image of the observation surface Wa can be acquired with high accuracy. .

  Further, when such a composite optical system 1 is installed on the space RI side, there is a case where it is desired to point the imaging optical system 2 in a free direction with respect to the window W. As described above, the back focal point of the information acquisition optical system 3 is that the entrance pupil plane of the imaging optical system 2 and the optical axis intersect, in other words, the information acquisition optical system 3 and the imaging optical system 2. It is arranged so as to be located at or near the point where the optical axes intersect. For this reason, the imaging optical system 2 constituting the composite optical system 1 is configured to be rotatable about the position of the entrance pupil (position where the entrance pupil plane and the optical axis intersect) or the vicinity thereof, thereby obtaining the information acquisition optical system. It is possible to correspond to the difference in the angle of the system 3 with respect to the window W. FIG. 3 shows a case where the imaging optical system 2 is rotated around the position of the entrance pupil by 25 degrees compared to FIG.

  FIG. 4 shows an embodiment in which the composite optical system 1 is installed indoors and applied to a security camera device or the like for monitoring or photographing the outdoors through a window W arranged so as to extend substantially vertically. In the present embodiment, the illumination optical system 4 is used as a bright field light source. The illumination optical system 4 of the present embodiment includes a light source 41 that emits illumination light (for example, infrared light) having a predetermined wavelength, and a condenser lens that collects the illumination light emitted from the light source 41 and converts it into a parallel light beam. 42. The illumination optical system 4 is configured to irradiate illumination light that has become a parallel light flux with respect to the window W from the external space RO. This illumination light is incident on the window W, but passes through a boundary surface between the window W and the space RO (in the following description, the boundary surface irradiated with the illumination light is referred to as “observation surface Wa”). The image pickup device is incident on the information acquisition optical system 3, reflected by the concave mirror 31, and further incident on the image pickup optical system 2, condensed by the image pickup optical system 2, and disposed on the image plane I. (Not shown in FIG. 1) is detected as an image of the window W (a boundary surface between the window W and the space RO, that is, an image of the observation surface Wa).

  Here, for example, when raindrops adhere to the outer surface of the window W (surface on the space RO side) due to rain, the difference between the refractive index of the window W and the refractive index of the raindrops (water) is small. In the adhering part, it is not optically flat, part of the parallel light is transmitted in a disordered manner rather than parallel, and part of the light beam is out of the optical path. Therefore, when the composite optical system 1 is arranged so that the observation surface Wa is positioned in the vicinity of the front focal point of the information acquisition optical system 3, an image of the observation surface Wa is condensed by the imaging optical system 2 to form an image. As a result, an image in which lightness and darkness is emphasized as compared with a normal image can be detected by the image sensor. At this time, when the image is displayed brighter as the intensity of the image of the observation surface Wa detected by the image sensor is higher, only the portion to which raindrops are attached becomes a black image. It is possible to detect the state of the boundary surface with the outer space RO in the window W, that is, whether or not raindrops or the like are attached to the observation surface Wa (the configuration of the imaging device for detecting the state of the window W) Will be described later).

  Even when, for example, mud or leaves other than raindrops adhere to the observation surface Wa, the image is identified as a black image. When the imaging area RO is bright, it may be difficult to distinguish it by superimposing it on the image of the information acquisition optical system 3, but means for separating information on the observation surface Wa by causing a light emitting diode (LED) to emit light and applying modulation. Is effective. By using the wavelength selective optical material described above for the information acquisition optical system 3, light other than illumination light (for example, light generated from the indoor RI or the window W from the external space RO is used for information acquisition) It is also effective to remove natural light incident on the optical system 3.

  FIG. 5 shows the configuration of an imaging system 10 that has the above-described composite optical system 1 and that captures the situation in front through the window W of the housing of the monitoring camera, for example. The imaging system 10 includes an image recording device 8 disposed in the housing divided by the window W as described above, an irradiation optical system 4 that irradiates illumination light to the observation surface of the window W, and the image recording device 8. It is comprised from the control part 9 which detects the state of the observation surface of the window W from the produced | generated image. Here, the image recording device 8 detects the image formed by the imaging optical system 2 that is disposed on the imaging surface of the imaging optical system 2 that constitutes the above-described complex optical system 1 and the imaging optical system 2. The image sensor 5 includes an image processing unit 6 that generates an image of a subject from an electrical signal output from the image sensor 5, and an image storage unit 7 that stores an image generated by the image processing unit 6. The image generated by the processing unit 6 is configured to be output also to the control unit 9.

  FIG. 6 shows a signal imaged by the image pickup optical system 2 and detected by the image pickup device 5 as an image 50 by the image processing unit 6. An information acquisition optical system is included in a part of the image 50. 3 includes an image 51 of the observation surface that is condensed at 3 and imaged by the imaging optical system 2. Therefore, the state of the observation surface of the window W (the state of the boundary surface with the outside) can be detected by analyzing the observation surface image 51 by the control unit 9 using the method described above. For example, if the image 51 of the observation surface includes a raindrop image 52 and it is determined that raindrops are attached to the observation surface, the control system 9 controls the drive system (wind, hot air, wiper, etc.). Thus, raindrops can be removed, whereby the image quality of the image recorded by the image recording device 8 can be maintained.

It is explanatory drawing for demonstrating the structure of the compound optical system which concerns on this invention. It is explanatory drawing which shows the case where the said composite optical system is comprised with a refractive system. It is explanatory drawing which shows the case where the imaging optical system which comprises a composite optical system is rotated. It is explanatory drawing for demonstrating arrangement | positioning of a composite optical system in case the window is arrange | positioned so that it may extend in a substantially perpendicular direction like a house. It is a block diagram which shows the structure of an imaging | photography system. It is explanatory drawing which shows the image image | photographed with the said imaging | photography system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compound optical system 2 Imaging optical system 3 Information acquisition optical system 4 Illumination optical system 10 Imaging system (optical apparatus) 31 Concave mirror 32 Convex mirror 41 Light source 42 Condenser lens W Window Wa Observation surface

Claims (11)

An imaging optical system that is arranged in one of the spaces divided by a window made of an optical member that transmits light, and shoots the other space through the window or the window,
Information acquisition optics having a function of capturing an image of a surface in contact with the other space of the window or an image in the vicinity of the surface or observing an image of an object in the vicinity of the surface or the surface by the imaging optical system Consisting of a system,
The information acquisition optical system includes at least one optical member having a positive refractive power, and the rear focal point of the information acquisition optical system and the position of the entrance pupil of the imaging optical system are approximately A composite optical system that is matched and arranged so that the object side is a telecentric optical system when the entrance pupil position of the imaging optical system is a pupil.   The said information acquisition optical system is arrange | positioned so that the front side focus of the said information acquisition optical system may be located on the said surface which contact | connects the said other space of the said window, or the vicinity of the said surface. Compound optical system.   The composite optical system according to claim 1, wherein the information acquisition optical system is configured by a reflection system or a catadioptric system.   The composite optical system according to claim 3, wherein the information acquisition optical system has at least one concave reflecting surface.   The composite optical system according to claim 3, wherein the information acquisition optical system is configured to have at least one concave reflecting surface and a convex reflecting surface.   The information acquisition optical system comprises a reflecting member constituting the reflecting system or a catadioptric member constituting the catadioptric system integrated with a light transmitting member that transmits at least a light beam having a predetermined wavelength. The composite optical system according to any one of 5.   The composite optical system according to claim 6, wherein the light acquisition member includes a member that restricts the amount of light other than the predetermined wavelength. The information acquisition optical system has at least one concave reflecting surface and at least one convex reflecting surface,
The concave reflecting surface is composed of a substantially off-axis paraboloid,
The compound optical system according to any one of claims 3 to 7, wherein the convex reflecting surface is configured by a substantially hyperboloid having a focal point at a position on an optical axis of the entrance pupil and a center of the concave surface. The optical axis of the imaging optical system and the optical axis of the information acquisition optical system intersect at the position of the entrance pupil of the imaging optical system or in the vicinity of the entrance pupil,
The angle formed by the optical axis of the imaging optical system and the optical axis of the information acquisition optical system is configured to be changeable about a point where the optical axes intersect with each other. The composite optical system described in 1. An illumination optical system that illuminates the vicinity of the object plane of the information acquisition optical system;
The optical apparatus comprised from the compound optical system as described in any one of Claims 1-9. An illumination optical system for illuminating a subject of the imaging optical system;
The optical apparatus comprised from the compound optical system as described in any one of Claims 1-9.

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