CN1153559A - Method of observing objects under low levels of illumination and device for carrying out said method - Google Patents

Abstract

The invention provides a method of observing objects under low levels of illumination and device for carrying out said method. The device includes a pulse light source 1 having transparent lens 2, a synchronization unit 3, a control unit 4, an optical image receiver 5 has receiving object lens 6, an object lens control unit 7. The device employs natural illumination in observing field as well as auxiliary illumination to provide uniform luminance image of the objects at different distance and to separate objects in the observing field.

Description

In equipment that weakens object image-forming under the illumination condition and method

The present invention relates to a kind of optical instrument engineering, particularly optical radar equipment.

Known a kind of be disclosed among the EP.No.03263735 low light according to the time with the method for object image-forming, according to this method, by a light-pulse generator irradiation object of observation.Receive by an optical imagery receiver from the light of object reflected back.The action of the control shutter of picture receiver and light pulse emission are synchronously.The device of realizing this method comprises a light-pulse generator with transmission lens, the optical imagery receiver with control shutter.Delay between adjustment light pulse x time and shutter are opened constantly can obtain to be in most interested regional subject image.

A shortcoming of known method and device is, uses a light source and camera only can obtain to be in the subject image of narrow visibility region.A kind of approach that enlarges visibility region is, increase many light sources of working simultaneously (pulse) or camera (each light source or camera are worked in its scope) and and then the overlay video signal, but such device energy foot (seeing EP NO0468175) of heaviness or light source too.In addition, such device does not utilize the physical environment illumination of the side information that can obtain object.

Be the methods and apparatus disclosed in BrP NO.2212689 near this method and device.According to this method, an object (a plurality of object) is by a light-pulse generator and an auxiliary constant illumination source lighting.The light that reflects from object receives with an optical imagery detecting device, and the work of its controllable gate and the emission of light pulse are synchronous.Be used for comprising a light-pulse generator and an auxiliary constant light source weakening the device of illumination with combined lens with object image-forming, optical imagery detecting device with adjustable gain, a device that is used for regulating automatically the average image brightness, and a control module that output terminal links to each other of its input end and lock unit, another output terminal of lock unit links to each other with the input end of light-pulse generator.

This invention has partly overcome above-mentioned shortcoming.By utilizing the floor light of the scenery that physical environment illumination maybe will observe, can obtain side information about target.Do like this, from the device different distance and by the brightness meeting difference of the target of constant light source irradiation, and have at the display foreground place under the situation of many objects, the image of background object will be covered.If work in the media (mist, snowfall, cigarette or the like) of poor visibility will produce same effect.

The present invention has overcome the above-mentioned shortcoming of immediate analog machine, and provide the uniform luminance image that is in the different distance object in the device visual field, by not only utilizing physical environment illumination but also utilize a secondary light source, provide possibility according to object in their the most interested zone of brightness difference.

Because in the equal fact of the brightness of image that reduces the object that is in different distance under the level of illumination condition, the present invention is suitable for being used on such motor vehicle, promptly need to obtain simultaneously the image of vehicle front all objects, and be not only the image that is positioned at the object of a certain distance.This makes can control current situation constantly, and situation is become can predict, keep distinguishing a certain possibility apart from object of the panoramic picture that is received.

Above-mentioned purpose of the present invention realizes by an embodiment, promptly after each light pulse emission, the gain of optical imagery receiver constantly increases, light up to the reflection of object farthest in a selection zone of observing promptly keeps the image of the iso brightness of irradiated selected observation object to turn back to the moment of receiver by this way, in order to be received in the image of object in the supplementary illumination, gain is set to a fixing horizontal, and is maintained at this level and launches up to next light pulse.In addition, in order to separate the concrete object in the observed irradiation area, the instantaneous increase that when arriving receiver, gains by the light of these object original reflection, gain constant increases then, and instantaneous minimizing gains when by the light arrival receiver of the last reflection of these objects after again.Physical environment illumination can be used as secondary light source.

In order to reach above-mentioned purpose of the present invention, lock unit and control module are made like this, be used to provide such possibility, even each light pulse is synchronous, and the gain that increases the optical imagery receiver in by viewing area farthest the light of object reflection return the moment of receiver, and make gain remain on the moment of a constant value until next light pulse emission.The optical imagery receiver can comprise an image intensifier, and its gain is Be Controlled by the control voltage on the change microchannel plate.Lock unit and control module can be used to provide instantaneous increase image intensifier gain further to increase and the possibility of instantaneous minimizing, to separate some the concrete object in the observed zone.

Above-mentioned and further feature of the present invention and advantage will be subjected to correctly estimating and understanding from following detailed description and accompanying drawing.

Referring now to accompanying drawing, wherein the same parts label is identical in following accompanying drawing:

Fig. 1 is a block scheme, shows according to device of the present invention;

Fig. 2 is the lock unit of optical imagery receiver and the block scheme of control module;

Fig. 3 is the block scheme of optical imagery receiver and object lens control module;

Fig. 4 is the time layout of device work when being used under weakening illumination object image-forming.

At first with reference to Fig. 1, the device of object image-forming comprises a light-pulse generator 1 in weakening illumination.Light is transmitted to object observing by printing opacity (gathering) eyeglass 2.The input end of light source links to each other with first output terminal of lock unit 3.Second output terminal of lock unit 3 links to each other with the control module 4 of optical imagery receiver.The output terminal of the control module of optical imagery receiver links to each other with optical imagery receiver 5.Picture receiver comprises that receives an eyeglass (object lens) 6.The control module of object lens is coupled to picture receiver and lock unit.

Lock unit 3 trigger pulse light sources 1, this light source is used to provide the pulsed light of target (not shown in figure 1) to shine with focusing lens.When light source 1 triggers, lock unit 3 trigger control unit 4, this control module increases continuously the gain of receiver 5 by this way, and the image that promptly shines target is an iso brightness.In addition, lock unit 3 produces a signal, and this signal attempts to be chosen in the target that is positioned at specific range within a certain depth of field zone.The described depth of field and distance are by the external signal setting.Above-mentioned selection signal imposes on control module 4, and the gain of these control module 4 instantaneous increase picture receivers 5 when the light that reflects at last when the target from a specific range arrives receiver then, keeps its instantaneous increase and reduces gain.When the signal of lock unit 3 output terminals failed, control module 4 was changed to a constant level with the gain of receiver.This makes it possible to the image of receiving target under the physical environment illumination condition.The target image brightness of numerical value decision under physical environment light of constant-gain level.When then determining to use additional optical to shine, the numerical value that instantaneous gain increases/subtracts selects the brightness of image of objectives.These brightness number can be by the external signal setting.The image of that the picture receiver 5 with a receiving objective is used for forming is observed (optics or TV) object.The gain of receiver is adjusted by control module 4.The average level of the gain of picture receiver 5 is determined the mean flow rate of the image that receives, and can be by the external signal setting.Object lens control module 7 is adjusted aperture and focal length automatically according to the respective distance of concrete selected target and the brightness of image that is received.

Referring now to Fig. 2, lock unit comprises a master oscillator 8, and it produces the pulse that triggers light source.Light pulse by light emitted passes to object observing.Light is by object reflection and return to receiver then.When light source triggered, master oscillator 8 triggered an one shot multivibrator 9, forms a pulse, and this duration of pulse equals light and arrives the required time of ultimate range object that is in.This ultimate range is the reflection ray detected distance of usable image receiver still of object observing.Import a sawtooth-voltage generator 10 from the pulse of one shot multivibrator 9, form a triangular pulse, see Fig. 4.Triangular pulse is imported a totalizer 11 then.This pulse is used for equilibrium and is in the brightness of image of different distance by the object of light illumination.Or rather, this pulse is used for equilibrium and is in the object brightness of visual field different distance under light-pulse generator irradiation.

Master oscillator 8 also triggers an one shot multivibrator 12, and the generation cycle is by the pulse of operator's manual adjustment, and the recurrence interval equal light from light source to nearest edge, the irradiated area at some objectives places and return the required time of receiver.One shot multivibrator 12 triggers an one shot multivibrator 13 again, produces its cycle by manual setting and equal light nearest edge is transmitted to distal-most edge and is back to the pulse of required time of nearest edge from the irradiated area.The pulse that is produced by one shot multivibrator is by utilizing amplifier 14 artificiallies and adjust amplitude and being added on the totalizer 11.The pulse decision of amplifier 14 outputs this means that to wanting the distance at nearest edge, irradiated area, the depth of field and brightness far away it is used for separating some objectives according to the brightness that object is in the most interested zone.Signal from totalizer is applied in to switch 15, and when the pulse of one shot multivibrator 9 output terminals was worked, switch 15 was sent to output terminal with signal from totalizer 11, and this is equivalent to receive the image that mainly obtains under the light of light-pulse generator.After the pulse of one shot multivibrator 9 output terminals failed, the signal of the constant level of manual presetting was added to the output terminal of switch 15.This signal is used to be adjusted at the brightness of formed image under other (comprising nature) light source, thereby, solved a difficult problem that under physical environment illumination, forms subject image.The result, formed the signal of the shape with three special parts at the output terminal of switch 15: 29 parts are used to form the image that the iso brightness of supplementary illumination is provided by light-pulse generator, 27 parts are used to shine most interested target, and 28 parts are used to form the image in physical environment illumination.

The gain control signal of Xing Chenging is applied in to picture receiver 5 in such a manner.Picture receiver can be made on the basis of the image intensifier with microchannel plate (MCP).Above-mentioned as shown in Figure 3 signal amplifies the after-applied microchannel plate 25 of giving image intensifier 17 at amplifier 16, forms one by utilize the enhancing image of the image that receiving objective 6 receives on photocathode 26 on image intensifier 17 screens 24.Since the gain of MCP be proportional to voltage square, so the linear gain-controlled voltage that changes pulsed light according under the image reception period, the anti-quadratic relationship that the illumination of the observed object of compensation is adjusted the distance, thus image will be to wait brightness.

TV camera 22 can be used to the image transformation on the screen of image intensifier 17 is become TV signal.For further processing, be applied in to video monitor 23 or other television equipment from the vision signal of TV camera.

For control the average image brightness automatically, the signal that is directly proportional with electric current on the image intensifier screen is applied in to threshold amplifier 18, and its work threshold value is manually adjustable, is used for being provided with the average image brightness.The average gain of the signal controlling amplifier 16 of amplifier 18 outputs, and be used to control the aperture that is contained in the receiver object lens.

For automatic object lens focusing to the irradiated area, control to the distance in this zone and be used for the voltage of one shot multivibrator 12, be applied in the amplifier 20 that has the nonlinear amplitude characteristic to.And further impose on one control object lens focusing servo-driver 21.The selected optimum focusing that any distance is all provided receiving objective of the shape of amplifier amplitude characteristic.

Weakening the current technical standard realization that allows this method of object image-forming and device utilize this industrial circle under the illumination.The utilization of device has proved its high-level efficiency, because except all advantages of existing similar device, it for example can help that the driver works under situations such as snowfall, snowstorm, reduce because the harmful effect of the light scattering that the particle of mist, snow causes, and alleviate near and surmount the dizzy of front lamp of vehicle.

Claims (6)

1. one kind is used in the method that weakens under the illumination condition object image-forming, shone by a light-pulse generator and an additional constant light source according to this method object (many objects), received by an optical imagery receiver from the light of object reflected back, the work of this optical imagery receiver and the emission of light pulse are synchronous, it is characterized by, during each light pulse emission, the gain of optical imagery receiver continuously changes, until moment of returning in a kind of mode that keeps irradiated selected observation object to equate brightness of image of the light of object reflection farthest from selected viewing area, and the numerical value of gain is maintained at constant level, till next light pulse emission.

2. method according to claim 1, it is characterized in that in order to separate some concrete object in viewing area, receiving after the light of these object reflected backs, gain increases then immediately and continuously increases, and reduces immediately behind the last light that receives by concrete object reflection.

3. the method according to claim 1 and 2 is characterized in that, physical environment illumination is used as auxiliary constant light source.

4. one kind is used at the equipment that weakens under the illumination condition object image-forming, comprise a light-pulse generator with transmission lens and an auxiliary constant light source, optical imagery receiver with adjustable gain, a device that is used for the control of automatic average brightness of image, and control module, the input end of control module is coupled to an output terminal of lock unit, another output terminal of lock unit is coupled to the input end of light-pulse generator, it is characterized in that, lock unit and control module be designated to be used to provide such possibility, even each light pulse is synchronous, increase the gain of optical imagery receiver, until light moment of returning of object reflection farthest from selected viewing area; And before next pulse emission, keep gain in a constant level.

5. according to the equipment of claim 4, it is characterized in that the optical imagery receiver comprises one by changing on its microchannel plate the image intensifier II that control voltage has controllable gain.

6. according to the equipment of claim 5, it is characterized in that lock unit and control module be designated to be used for instantaneous increase figure image intensifying gain, the instantaneous minimizing of gain further constant increase and gain is so that some concrete object in the ken separately.