Background technology
Along with the progress of society, people are through with already and begin work at sunrise, sunset and the life, the production model that cease, and the activity at night increases greatly.But because human eye can only be distinguished object under the enough strong condition of visible light, the spectrum human eye that exceeds visible-range is invisible.Therefore, do not have at night under the situation of sufficient light, people need add light source in addition throws light on, such as the car light of the street lamp on the road, automobile, the searchlight of frontier station etc.
Progress along with science and technology, people can utilize the spectrum that exceeds visible-range that peripheral scenery is observed and monitored, as utilize the infrared night vision instrument, to Scenery Imaging, change the optical signal of imaging into the signal of telecommunication, again the signal of telecommunication is amplified and change into the visible optical signal of human eye.Generally speaking, make the situation of using up during according to imaging, night vision instrument can be divided into two big classes, one class needs night vision instrument that lighting source is provided, by the light of initiatively outside certain wavelength of emission of night vision instrument,, utilize these photoimagings of object reflection again as visible light, infrared light, ultraviolet light etc.The another kind of night vision instrument that do not need provides lighting source, main by low-light (since nature have some than sunshine faint the light of Duoing, as starlight, moonlight, airglow etc., because human eye retina's speed is not high, so normally imaging under the less situation of this luminous intensity) or object self come imaging (being also referred to as thermal imaging) to extraradial infrared ray.In addition, because the development of laser technology also is applied in laser in the illumination of night vision system.
But in the present active night vision system, the illumination of night vision system exists some problems, for example, light angle generally all is changeless, even reserved certain adjusting angle when design, but adjustable range is generally all less, and be manual, in case just immobilized after installing.Perhaps, even can regulate in use after installing, but the angle of regulating is very little, and is general all in the scope in several years.
Immobilize or change less situation for above-mentioned light angle, make the field of illumination constant, or change very for a short time, usually have the infull phenomenon of illumination and take place, can only shine part, therefore, imaging is incomplete.
Under the distant application scenario of distance, fixing light angle is just improper, for example, for one from closely to the night vision illumination scope more than 1000 meters, proper light angle scope should be generally between 0.5 ° to 20 °, corresponding to pick-up lens, in order to satisfy the imaging requirements to far and near distance, the most basic requirement is exactly can zoom, during to remote Scenery Imaging, remote scenery to be amplified, the focal length of pick-up lens is elongated, and the visual field diminishes, and therefore requires light angle also less, just enough brightness of illuminations can be arranged, in the time of closely, the focal length of pick-up lens shortens, and it is big that the visual field becomes, require light angle also bigger, just can be full of whole visual field.
In order to address this problem, people have also taked some measures, but all exist certain disadvantage, scan (as 99104568.6) as driving luminaire by mechanical device, at this moment, the problem that has sweep speed to bring, slow as speed, there is the shadow region, and problem such as mechanical device instability; If adopt some special optical element (as 200310118153.8), certainly will increase cost; If increase the intensity of light source, if laser lighting, then increase the power of laser, also can cause a series of problem, as heat dissipation problem, the installation question that volume, weight are brought uses cost problem that expensive optical element brings or the like.
In addition, the change scope illumination that the variation of the angle of divergence was carried out when also useful single lens or simple lens group utilized light source between lens and its focus, its field of illumination is generally border circular areas by the characteristics of luminescence decision of light source.Because light source is between lens and its focus, the light distribution of field of illumination is bright and the edge is very dark in the middle of being, as shown in Figure 2, the final formation of the light beam of illuminator outgoing be a circular illumination 109.At least there are two problems, the one, light distribution is inhomogeneous, the centre is too bright and periphery is too dim, uneven illumination is even, the curve of light distribution 110 as shown in Figure 2, this situation causes the imaging picture unclear, have again to be exactly, because the photo-sensitive cell 112 (as CCD) of imaging lens is generally rectangle, as shown in Figure 3, but because field of illumination 111 is circular, so even make full use of the field of illumination, efficient also only has 61% (area in the area of CCD/illumination circle zone), therefore, light energy losses is serious.
The utility model content
At the deficiencies in the prior art, the technical problems to be solved in the utility model is, a kind of illuminator that is applied in the night vision system is provided, and is used to realize the night illumination of long-distance large-range.
For solving the problems of the technologies described above, the utility model provides the illuminator that is applied in the night vision system, comprise: light source, variable focus lens package and zoom drive device, described zoom drive device is connected with described variable focus lens package and/or described light source, be used for making the lens of described variable focus lens package and described light source to produce relative displacement, changing the focal length of described variable focus lens package, and the light-emitting face of described light source is positioned at outside the focus or focus of described variable focus lens package.
Further, the described variable focus lens package in the above-mentioned illuminator that is applied in the night vision system comprises two or more simple lenses or set of lenses at least, and wherein a simple lens is convex lens, or wherein a set of lenses is the set of lenses with positive focal length.
Describedly be used for making the driving signal of the lens of described variable focus lens package and the described zoom drive device that described light source produces relative displacement from night vision system, so that the size of the illumination hot spot that described illuminator is sent is consistent with investigative range.
Further, the described illuminator that is applied in the night vision system comprises that also a light that is used for that described light source is sent carries out the dodging device of homogenising, described dodging device is between described light source and described variable focus lens package, and the light-emitting face of described dodging device is positioned at outside the focus or focus of described variable focus lens package.
Particularly, described dodging device comprises a light-emitting window, described light-emitting window be shaped as a geometry, and corresponding with the shape of detector in the described night vision system.Wherein, described geometry can be circle, square or rectangle.
In addition, described dodging device is a clear glass rod, or is made up of hollow polygonal mirror, or is made of two groups of microlens arrays, or is made up of diffraction element.
Described zoom drive device in the above-mentioned illuminator that is applied in the night vision system comprises actuating unit and transmission mechanism, described transmission mechanism is connected with described variable focus lens package and/or described light source, drive described variable focus lens package by transmission mechanism and/or described light source moves by described actuating unit, make lens and described light source in the described variable focus lens package produce relative displacement.If comprise dodging device in the system, described transmission mechanism is connected with dodging device with described variable focus lens package, change be lens in the variable focus lens package and the relative displacement between the dodging device.
Above-mentioned actuating unit comprises various motor-driven mechanism, or Piezoelectric Ceramic mechanism, or pneumatic mechanism, or sound-driving mechanism.Above-mentioned transmission mechanism comprises lead-screw drive mechanism, gear/rack gear, cam drive or belt gear.
Described light source in the illuminator that is applied in the night vision system described in the utility model is high-brightness LED, visible light source, laser instrument or ultraviolet light/infrared light light source.From another point of view, described light source is light-pulse generator or continuous illuminating source.Described light-pulse generator can be synchronous with described night vision system.
In addition, between described light source and the dodging device directly lotus root close or with optical fiber or Lens coupling.Lens in the described variable focus lens package or set of lenses can be diffraction lens or be made up of Fresnel Lenses.
The utility model is by changing the focal length of variable focus lens package, the light angle that makes system described in the utility model is along with the variation of variable focus lens package focal length can be carried out regulating on a large scale, and, the utility model illumination evenly, this will make that imaging is clear, there is not blackening, and can effectively improves the utilization rate of light, reduce optical energy loss.
Below in conjunction with the drawings and specific embodiments the technical solution of the utility model is done explanation in further detail.
The specific embodiment
Referring to Fig. 1, be the involved a kind of night vision system of the utility model and the theory diagram of illuminator, described night vision system 100 comprises detection system 108, system controller 107 and illuminator described in the utility model 106, wherein, illuminator 106 comprises: light source 101, Optical homogenizer 102 (embodiment of dodging device), variable focus lens package 103 and zoom drive device 105, described zoom drive device 105 is connected with described variable focus lens package 103, can certainly be connected with described Optical homogenizer 102, be used for making the lens of described variable focus lens package 103 and described Optical homogenizer 102 to produce relative displacement, to change the focal length of described variable focus lens package, and the exiting surface of described Optical homogenizer 102 is positioned at outside the focus or focus of described variable focus lens package.
Described illuminator 106 is controlled by system controller 107, particularly, zoom drive device 105 is accepted the driving signal that system controller 107 sends, drive the position that signal changes the lens in the variable focus lens package 103 according to this, change the focal length of focus lens group 103 with this, the feasible light that sends from light source is through the uniform treatment of Optical homogenizer 102, be imaged onto the target area by variable focus lens package 103, detection system 108 is the light of the acceptance target area reflection of having thrown light on then.
Referring to Fig. 4, be the theory structure schematic diagram of illuminator 106 described in the utility model among Fig. 1.Described illuminator comprises a light source 113, dodging device 114, variable focus lens package 200 and zoom drive device 105, wherein, described zoom drive device 105 is connected with described variable focus lens package 200, can certainly be connected with dodging device 114, its role is to make in the described variable focus lens package 200 lens 201 or 202 and described dodging device 114 produce relative displacements, to change the focal length of described variable focus lens package 200, and the light-emitting face of described dodging device 114 is positioned at outside the focus or focus of described variable focus lens package 200.
In the utility model, described variable focus lens package 200 is a compound lens, and it comprises two or more lens or set of lenses at least.Comprising that two lens are example, the principle of compound lens is described as follows:
If the focal length of first lens is f1, the focal length of second lens is f2, and the distance between the lens is d, then is called back focal length (BFL) from second lens to the distance this compound lens focus, as shown in Figure 5.So
The expression formula of the focal distance f of this compound lens is:
From following formula as seen, the focal distance f of the compound lens formed of two lens is only relevant with the focal length of the wherein distance between two lens and each lens element.
If lens are regarded as thin lens, and abut against a time-out d=0, the expression formula of the focal distance f of this compound lens is:
Variable focus lens package described in the utility model is used above-mentioned compound lens, as shown in Figure 4, form by two lens 201,202, with described dodging device 114 nearer be concavees lens 201, another is convex lens 202, dodging device 114 is the back focal length of this variable focus lens package 200 to the distance 116 of concavees lens 201, and distance 118 is the focal length of this variable focus lens package 200, and the distance 117 between concavees lens 201 and the convex lens 202 is d.Certainly, the variable focus lens package 200 in the utility model also can or all be made up of set of lenses lens and set of lenses, but combination in any case, it is that positive focal length is just passable that lens or set of lenses must be arranged.
Because light-emitting face of the present utility model is positioned at outside the focus or focus of described variable focus lens package 200, the dispersion angle of outgoing beam adopts following formula to calculate:
θ=2arctg(D/(2f)) (4)
Wherein, θ is the angle of divergence of outgoing beam, and D is the maximum gauge of dodging device 114 light-emitting windows; F is the focal length of variable focus lens package.
Can draw according to above formula, when D is a preset parameter, the size of θ changes along with the variation of f, and when f becomes big, then θ diminishes, otherwise when f diminishes, then θ becomes big.The size of focal distance f that therefore, can be by changing variable focus lens package changes the size of angle of divergence θ of the outgoing beam of illuminator.For example, work as D=4mm, during f=460-12mm, θ=0.5-20 degree can satisfy the night vision illumination for distance more than 1000 meters this moment fully.
In actual applications, the angle of divergence of illuminator is consistent with detection system, and for example the photosurface of CCD is that its diagonal of rectangle is maximum gauge L, if the focal length of CCD camera lens is fc at this moment, the angle of visual field of CCD camera system is exactly so:
α=2arctg(L/(2fc)) (5)
θ ≈ α in the ordinary course of things, so
f=fc?D/L (6)
Can obtain the focal range of illuminator zoom lens thus according to the zooming range of CCD camera system.
About the zoom process of variable focus lens package 200, as shown in Figure 5.Two coaxial lens 201 and 202 are respectively concavees lens and convex lens, and when changing apart from d between them, variation has also taken place the focal length of the compound lens of being made up of these two lens.Wherein, focus is called back focal length to the distance 204 of nearest lens 201.In the combination of negative lens and positive lens, therefore its interarea can effectively reduce the length of set of lenses outside positive lens.Distance 203 be the focal length of compound lens, as shown in Figure 5, when lens 201 along curve 208 move and lens 202 when curve 207 moves, lenticular spacing d increases, focal length diminishes, and back focal length also to shorten be apart from 204 '.
Said system is carried out optics emulation, and the result as shown in Figure 8.When the focal distance f 2=12mm of the focal distance f 1=-5mm of concavees lens 201, convex lens 202, along with the variation apart from d between convex lens 202 and the concavees lens 201, the focal distance f of its compound lens and back focal length BFL also change thereupon, and its change curve as shown in Figure 8.Wherein, transverse axis is the lenticular spacing value, and solid line is the change curve of focal distance f, and dotted line is the change curve of back focal length BFL.As seen from the figure when lenticular spacing d when 7mm increases to 12mm, focal distance f 430mm thus narrows down to 10mm.
Not only can form for variable focus lens package 200, also can form by two above set of lenses by two lens.And each set of lenses can be the combination of simple lens or a plurality of lens elements, and when the distance between the set of lenses changed, the focal length of variable focus lens package 200 also changed thereupon.In variable focus lens package 200, also can use diffraction lens or Fresnel Lenses.
In one embodiment, in this system, increase by a dodging device 114, as an Optical homogenizer, by increasing Optical homogenizer, illumination light in order to the described light source 113 of equilibrium sends makes the light that incides zoom lens 200 more even, so that the light beam illumination of final outgoing is even.
Certainly, if the light that sends from light source 113 is enough good, also can not having dodging device 114, at this moment, is that the light-emitting face of described light source is positioned at outside the focus or focus of described variable focus lens package 200.
Wherein, Fig. 6 a and Fig. 6 b are respectively a kind of principle assumption diagrams of simple and practical Optical homogenizer, its light exit is generally a geometry, concrete what shape that adopts, the shape of the photo-sensitive cell in the detection system (as shooting/photographic system) that can match with illuminator described in the utility model is complementary, for example, present photo-sensitive cell is CCD, the shape of CCD is generally rectangle, so the light exit of Optical homogenizer also can be rectangle.By coupling like this, can make the field of illumination fall into the photosurface of CCD fully, thereby improve the utilization rate of light greatly, reduce light loss.
Fig. 6 a and 6b are waveguide shape, and the rectangular bar shown in Fig. 6 a can certainly be the wedge type rod, and its material generally has the very optical material of high permeability, and at both ends of the surface 301 plating anti-reflection films, other four sides, 302 plating reflectance coatings.When the end input light time, light can only be propagated in rod and repeatedly be reflected, and as optical fiber, is uniform thereby make the light distribution of light its end face when other end outgoing.Uniformity of light is directly proportional with the length of rod and the space-bandwidth product of input light, is inversely proportional to the sectional area of rod and the refractive index of rod, and the optical index that therefore reduces material can increase optical uniformity.
Shown in Fig. 6 b, be a hollow waveguide of forming by speculum 303,303 ', hollow inner surface polishing is the plating reflectorized material also.When the end input light time, light is repeatedly reflected and from other end outgoing, it is uniform that the light of its outgoing end face distributes.
Fig. 7 is the another kind of Optical homogenizer of being made up of two microlens arrays 304,305.Its principle is, each lenslet unit of first lens arra 304 is imaged on light source on second lens arra 305, and the lenslet unit of two lens arras is one to one, each lenslet unit of second lens arra 305 with each lenslet cell imaging of first lens arra 304 at infinity.Just first lens arra 304 is positioned at the focal plane of second lens arra 305, so to be each lenslet cell configuration with first lens arra 304 identical and illumination is even for the far field pattern of emergent light.When throwing light on, the needs limited distance can add a fourier transform lens 306 again thereafter, then its far field pattern just is formed on its focal plane 307, sends on the focal plane 307 that converges in fourier transform lens 306 then from first lens arra 304 as light 308,309.In the utility model, light-emitting window can be located on the focal plane 307.Fourier transform lens 306 can certainly be put in the variable focus lens package 200, make its part that becomes variable focus lens package 200, its light-emitting window is at unlimited distance at this moment, and using the advantage of the Optical homogenizer of lens arra is that light is even, absorbs few.
In addition, Optical homogenizer also can be made up of diffraction element, designs because diffraction element is a characteristic at light source, and particularly LASER Light Source, and technological means is more, so do not repeat them here.
In the utility model, in general, light source 113 and dodging device 114 link together, as shown in Figure 4, and also can be with optical fiber or Lens Coupling.In order to realize changing the focal length of variable focus lens package 200, and use a zoom drive device 105 to be connected with lens in the variable focus lens package 200, or be connected with light source 113 and dodging device 114, with change the distance between the lens in this variable focus lens package 200 and with the distance of dodging device 114, make the light-emitting window of dodging device 114 be imaged onto the target area.
Described zoom drive device 105 comprises actuating unit 119 and transmission mechanism 120 at least, described transmission mechanism 120 and described variable focus lens package 200 and/or described light source 113 and dodging device 114 are connected, drive described variable focus lens package 200 and/or described light source 113 and dodging device 114 by described actuating unit 119 by transmission mechanism 120 and move, make described variable focus lens package 200 or described light source 113 and dodging device 114 produce relative displacement.
Wherein, as a simple implementation, actuating unit 119 can comprise a motor, and described transmission mechanism 120 can comprise lead-screw drive mechanism, gear/tooth bar transmission, cam drive or belt transmission or the like.
In addition,, independent control system be can adopt, the shooting or the systems such as photograph, monitoring that match and use with illuminator described in the utility model also can be integrated with the control of above-mentioned zoom drive device 105.105 work of control zoom drive device needn't be given unnecessary details at this for common automatic control.
In the utility model, described light source 113 can be high-brightness LED, also can be visible light source, also can be LASER Light Source or ultraviolet/infrared light supply, and by optical fiber or Lens Coupling in dodging device, can select according to different applications and place.
In the utility model, because light-emitting face is positioned at outside the focus or focus of variable focus lens package, so, variable focus lens package is imaged on light-emitting face on the target of being thrown light on, and, by described zoom drive device, light-emitting face is imaged on the target of being thrown light on focal length and the maintenance that changes described variable focus lens package.According to formula (4), by regulating the focal length of variable focus lens package 200, the angle of divergence that can regulate light source, and, because the focal length of variable focus lens package can be adjusted in the bigger even scope at hundreds of to tens millimeter, so, make the adjusting range of the angle of divergence of light source improve greatly.
Owing to behind light source, increased dodging device, make light be evenly distributed at light-emitting face, shape by the control light-emitting window, can be so that the shape of light-emitting face be identical with detector shape, so illumination is evenly, the imaging on illumination target is clear, there is not the dark space, and can utilize luminous energy efficiently, improve the utilization rate of light, reduce optical energy loss.
It should be noted last that: above embodiment is only unrestricted in order to explanation the utility model, although the utility model is had been described in detail with reference to preferred embodiment, those of ordinary skill in the art is to be understood that, the modification of under the prerequisite that does not break away from spirit and scope of the present utility model the utility model being carried out or be equal to replacement all should be encompassed in the middle of the claim scope of the present utility model.