JPH11102001A - Range gate camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a range gate camera being resistant to vibration and dust and compact, at a low cost. SOLUTION: As to a range gate camera provided with an irradiating device 7 for irradiating an object with light having a suitable wavelength, in a pulse- liek state and an image pickup device 8 for opening a shutter (image intensifier 25) in an instant when the pulse-like light is reflected/returned on/to the object, to pick up an image, a light source for the irradiating device 7 is constituted of a flash lamp 16 for flashing by the application of a voltage to a sealing gas consisting essentially of a rare gas and a concave mirror 17 which is arranged so as to surround the flash lamp 16 and reflects the flash as parallel light luminous flux facing in the fixed irradiation direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a range gate camera for imaging an object through turbid water or light scatterers such as fog and smoke.

[0002]

2. Description of the Related Art When conducting marine surveys or marine construction, it is necessary to visually check the state of the sea floor and the structure of structures installed on the sea floor. Even if the illumination light is turned on, the light is scattered, and it is not possible to visually recognize the state in front or the subject.

For this reason, in recent years, light having a wavelength having the highest transparency is radiated toward a subject in a pulse shape in accordance with the turbidity of suspended water and the diameter of suspended particles, and this pulse light is reflected back to the subject. A range gate camera that opens the shutter at the moment of shooting and captures an image has been developed and used. According to such a range gate camera, the influence of the backscattered light of the light toward the subject is reduced. Since only the light that has been reflected back to the subject and returned can be picked up and imaged, the image can be captured well even in turbid water with extremely low transparency, even in distant subjects.

FIG. 5 shows a schematic configuration of a range gate camera. In the figure, reference numeral 1 denotes a support boat waiting on the sea, 2 denotes an unmanned submersible which is remotely operated by the support boat and travels by itself in muddy waters. The ship 1 and the unmanned submersible vehicle 2 are connected via an optical fiber cable F and a connection cable C.

A control device 3 includes a microprocessor and various peripheral devices, and performs remote control processing and image processing of the unmanned underwater vehicle 2 under the operation of predetermined software. In the image processing by the control device 3, when an image signal (described later) supplied from the unmanned submersible vehicle 2 via the connection cable C is displayed as an image, noise removal, contrast enhancement, and the like are performed. Image can be displayed.

Reference numeral 4 denotes a laser oscillator which is a light source for imaging, and a pulsed laser beam output from the laser oscillator 4 via a wavelength conversion mechanism 6 is optically transmitted through an optical fiber cable F and is used for unmanned diving. The laser beam is supplied to an irradiating device 7 mounted on the boat 2, and the irradiating device 7 irradiates the laser light into muddy water through a collimating lens or the like.

[0007] The unmanned submersible vehicle 2 is also equipped with an imaging device 8 composed of a high-sensitivity camera having an image intensifier or the like as a shutter, and captures reflected light from a subject existing in muddy water. An image pickup signal is output, and the image pickup signal is supplied to the control device 3 via a connection cable C to perform image processing.

As shown in FIG. 6, in a wavelength conversion mechanism 6 for converting the wavelength of the laser light from the laser oscillator 4, the laser light (YAG laser fundamental wave) having a wavelength of 1064 nm oscillated from the laser oscillator 4 Second harmonic generator 9
Is converted into a laser beam (second harmonic) having a wavelength of 532 nm by passing through the optical crystal of No. 3, and further transmitted through the optical crystal of the third harmonic generator 10 to obtain a wavelength of 355 nm.
Laser light (third harmonic), and the second harmonic generator 9 and the third harmonic generator 10
The laser beam having a wavelength of 1064 nm (YAG laser fundamental wave) and the laser beam having a wavelength of 532 nm (second harmonic) which have not been converted by the laser beam pass through the dichroic mirror 11 and are absorbed by the beam damper 14, and the laser beam having a wavelength of 355 nm (Third harmonic) only the dichroic mirror 11
Is reflected to the optical parametric oscillator 13 via the total reflection mirror 12, and the laser light (third harmonic) having a wavelength of 355 nm guided to the optical parametric oscillator 13
The light is converted into an appropriate wavelength in the visible region of 80 to 660 nm and guided to the optical fiber cable F via the condenser lens 15.

[0009]

However, since the conventional range gate camera uses the laser oscillator 4 as a light source, the wavelength of the laser beam (YAG laser fundamental wave) from the laser oscillator 4 is converted. The dichroic mirror 1 as a component of the wavelength conversion mechanism 6
1. It is necessary to equip a common base plate, such as a total reflection mirror 12, a condenser lens 15, and a filter (not shown), with optical systems that are difficult to firmly fix, and these optical systems are susceptible to vibration. Also, the second harmonic generator 9 and the third harmonic generator 1 which are components of the wavelength conversion mechanism 6
If dust adheres to the optical crystal such as the optical parametric oscillator 13 and the optical parametric oscillator 13, there is a problem that the dust is burned by a laser beam to deteriorate the transmittance.

Further, the wavelength conversion mechanism 6 having many components as described above is required together with the laser oscillator 4, and the conversion by the second harmonic generator 9, the third harmonic generator 10, and the optical parametric oscillator 13 is performed. Since a large power supply is required to obtain a light beam of a predetermined intensity due to poor efficiency, a compact device configuration cannot be realized, and the manufacturing cost is high.

The present invention has been made in view of the above circumstances, and has as its object to realize a compact range gate camera resistant to vibration and dust at low cost.

[0012]

According to the present invention, there is provided an irradiation apparatus for irradiating light of an appropriate wavelength to an object in a pulsed manner, and a shutter is opened at the moment the pulsed light is reflected on the object and returned. A range gate camera comprising: a flash lamp that emits a flash when a voltage is applied to a sealed gas containing a rare gas as a main component; and a flash lamp that surrounds the flash lamp. And a concave mirror arranged to reflect flash light as a parallel light flux directed in a predetermined irradiation direction.

When a flash is generated by applying a voltage to the gas filled in the flash lamp, the flash is reflected by the concave mirror as a parallel light beam directed in a predetermined irradiation direction and illuminates the subject. If the image is taken by the image pickup device at the moment when the light returns to the subject, as in the case of the conventional range gate camera, the influence of the backscattered light toward the subject is shielded by the shutter and removed, and the subject is removed. It becomes possible to receive and image only the light that has been reflected back, and it is possible to satisfactorily image a distant subject through turbid water or a scatterer of light such as fog or smoke.

In addition, a simple light source consisting of a flash lamp and a concave mirror is used in place of a laser oscillator conventionally used as a light source, and the light of the flash lamp is directly irradiated without performing wavelength conversion on the way. This eliminates the need for a wavelength conversion mechanism attached to the laser oscillator, thereby eliminating the need for an optical system that is sensitive to vibration and an optical crystal that is not sensitive to dust. Can be reduced.

In the present invention, the irradiation device and the imaging device can be integrally formed by a common housing, or the irradiation device and the imaging device can be separately formed by separate housings. is there.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an embodiment of the present invention, in which the same reference numerals as in FIG. 5 denote the same parts.

The range gate camera of this embodiment has the same basic principle as that of the conventional example described above, but irradiates with a flash lamp 16 and a concave mirror 17 which will be described later, instead of a conventional laser oscillator. The difference is that the light source of the device 7 is configured. In particular, in the example shown in the drawing, the irradiation device 7 that irradiates light of an appropriate wavelength toward the subject in a pulse shape.
And an imaging device 8 that opens a shutter and captures an image at the moment when the pulsed light is reflected back to the subject, and is integrated with a common housing 19 as an example.

More specifically, the inside of the housing 19 is divided into an upper space 21 and a lower space 22 by a partition plate 20 (the space may be divided into right and left). The illumination device 7 is constituted by the flash lamp 16, the concave mirror 17, and the power supply 23 for the light source, and the high sensitivity camera 24, the image intensifier 25 disposed in the lower space 22, and the shutter disposed in the upper space 21. The imaging device 8 is configured by the power supply 26 for use.

The flash lamp 16 emits flash light when a voltage is applied from a light source power supply 23 to a sealed gas containing a rare gas such as xenon as a main component. The light source window 27 is disposed so as to face the light source window 27 provided on the end face).
Numeral 7 reflects the flash light of the flash lamp 16 toward the light source window 27 as a parallel light beam, and is arranged so as to surround the flash lamp 16.

Further, the high-sensitivity camera 24 is provided on a front end face (right end face in the drawing) of the housing 19 via an image intensifier 25 functioning as an electronic shutter by power supply from a shutter power supply 26. Imaging window 28
It is arranged to face.

The image intensifier 25 is
The reflected light from the subject incident through the imaging window 28 is formed on the front image receiving surface 30 via the objective lens 29, and the image is converted into an electric signal and amplified, and then the rear fluorescent plate 31 is formed.
And an image thereof is formed on the imaging surface of the high-sensitivity camera 24 via the relay lens 32, and can be electrically switched between a closed state and an open state. 3 ns, which is impossible with any shutter
It is possible to realize a shutter speed as high as ec.

When a voltage is applied to the gas filled in the flash lamp 16 from the light source power supply 23 to generate flash light, the flash light is reflected by the concave mirror 17 toward the light source window 27 as a parallel light flux, and A subject in the muddy water is radiated through the window 27, and when the image is reflected by the subject and returned, the image intensifier 25 is opened and an image is taken by the high-sensitivity camera 24. In the same manner as in the case (1), the effect of the backscattered light of
It is possible to receive and image only the light that has been reflected back to the subject and shielded by the closed state of 5 in the closed state of 5, so that a distant subject can be well imaged even in muddy water with extremely low transparency. Become.

In addition, a simple light source comprising a flash lamp 16 and a concave mirror 17 is used instead of the laser oscillator conventionally used as a light source, and the light of the flash lamp 16 is used as it is without performing wavelength conversion on the way. Irradiation eliminates the need for a wavelength conversion mechanism attached to the laser oscillator, which eliminates optical systems that are sensitive to vibration and optical crystals that are not sensitive to dust. It is also possible to reduce the power required to obtain a high intensity light beam.

For controlling the shutter of the image intensifier 25, a method similar to that of the conventional range gate camera may be used. For example, the flash is emitted from the irradiation device 7 and the light is received from the imaging device 8 Detecting the time delay until the shutter distance is calculated and calculating the separation distance to the subject, or calculating the separation distance to the subject by another distance measuring means using ultrasonic waves or the like to appropriately set the shutter timing. Just set it.

In addition, since the calculation of the separation distance to the subject is necessary for performing the automatic focus control at the time of imaging by the high-sensitivity camera 24, the signal used for the automatic focus control is diverted. Thus, the shutter control of the image intensifier 25 can be easily performed.

Further, as for the wavelength of the pulsed light from the flash lamp 16, it is necessary to select the wavelength having the highest transmittance according to the turbidity of the turbid water and the diameter of the suspended particles. Since the wavelength (spectral characteristic) of light can be changed by changing the composition of the sealing gas, several types of flash lamps 16 corresponding to a plurality of wavelengths in the visible region are prepared in advance, and an image pickup site is obtained. A flash lamp 16 that emits light of an appropriate wavelength may be selected from the preliminary survey of the water area and provided to the irradiation device 7.

Therefore, according to the above-described embodiment, the laser oscillator conventionally used as the light source and the wavelength conversion mechanism installed in association with the laser oscillator can be dispensed with, and the optical system which is weak against vibration can be provided. This eliminates the need for a sturdy structure and prevents performance degradation due to dust.

Further, the light source can be constituted by a small number of components including the inexpensive flash lamp 16 and the concave mirror 17, and the power required for obtaining a light beam having the same intensity as that of the conventional laser beam can be reduced. As a result, the power source can be reduced in size, so that a compact device configuration can be realized, and the manufacturing cost can be greatly reduced.

FIG. 4 shows another embodiment of the present invention.
An example in which the irradiation device 7 and the imaging device 8 are separated from each other by a separate housing is shown. More specifically, a flash lamp 16 is provided in one housing 19A provided with a light source window 27 on the front end face. And the concave mirror 17 and the light source power supply 23 are arranged to constitute the irradiation device 7, and the image intensifier 25 is provided in the other housing 19 </ b> B provided with the imaging window 28 on the front end face.
The imaging device 8 is configured by arranging a high-sensitivity camera 24 having a camera and a power supply 26 for a shutter. However, even with such a configuration, it is possible to achieve the same operation and effects as those of the above embodiment. is there.

Incidentally, the range gate camera of the present invention is not limited to the above-described embodiment, but shows an example in which the irradiation device and the image pickup device are mounted on an unmanned submersible. Etc., or it can be used by having a diver have it,
It can be used not only in water but also on land such as imaging an object through scatterers such as fog and smoke.In addition, various changes can be made without departing from the gist of the present invention. Of course.

[0032]

According to the range gate camera of the present invention described above, the following various excellent effects can be obtained.

(I) A laser oscillator conventionally used as a light source and a wavelength conversion mechanism attached to the laser oscillator can be dispensed with, and a robust structure is eliminated without an optical system that is vulnerable to vibration. And performance degradation due to dust can be prevented.

(II) The light source can be constituted by a small number of components including an inexpensive flash lamp and a concave mirror,
In addition, since the power required to obtain a light beam having the same intensity as that of a conventional laser beam can be reduced, the power supply can be reduced in size, so that a compact device configuration can be realized and the manufacturing cost can be greatly reduced. be able to.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an embodiment of the present invention.

FIG. 2 is a view in the direction of arrows II-II in FIG.

FIG. 3 is a schematic diagram showing the overall configuration of the embodiment.

FIG. 4 is a sectional view showing another embodiment of the present invention.

FIG. 5 is a configuration diagram showing a conventional example.

FIG. 6 is a block diagram showing details of a wavelength conversion mechanism in FIG. 5;

[Explanation of symbols]

Reference Signs List 7 Irradiation device 8 Imaging device 16 Flash lamp 17 Concave mirror 19 Case 19A Case 19B Case 25 Image intensifier (shutter)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Satoshi Ueda 2-1-1 Toyosu, Koto-ku, Tokyo Ishikawajima-Harima Heavy Industries Co., Ltd. Tokyo 1st Plant (72) Inventor Ken Kobayashi 3-1-1 Toyosu, Koto-ku, Tokyo No. 15 Ishikawajima Harima Heavy Industries Co., Ltd.

Claims (3)

[Claims] 1. An irradiation device for irradiating a subject with light of an appropriate wavelength in a pulsed manner, and an imaging device for opening a shutter and capturing an image at a moment when the pulsed light is reflected back to the subject. A range gate camera, wherein a light source of the irradiating device includes a flash lamp that emits a flash when a voltage is applied to a sealed gas containing a rare gas as a main component, and a flash light that is arranged to surround the flash lamp and emits a predetermined amount of flash light. A range gate camera, comprising: a concave mirror that reflects a parallel light beam directed in a direction. 2. The range gate camera according to claim 1, wherein the irradiation device and the imaging device are integrally formed by a common housing. 3. The range gate camera according to claim 1, wherein the irradiation device and the imaging device are separated from each other by a separate housing.