A kind of High Precision Automatic adjustment image planes device
Technical field
The utility model relates to a kind of High Precision Automatic adjustment image planes device, is particularly useful for the image planes adjustment of space flight, aviation field optical lens.
Background technology
Optical lens is divided into tight shot and zoom lens, and tight shot has that volume is little, lightweight, reliability high, is widely used in the fields such as Aeronautics and Astronautics.Focus optical system for one, focal distance f ', object distance L, image distance L ' meet formula:
As shown in Figure 1, in general, a kind of object distance L of tight shot, focal distance f ' known, therefore its image distance L ' is also known, and in other words, the image planes position of this tight shot is definite value.In the time that camera lens image planes position is definite value, can think that the distance between lens flange and CCD image device is definite value.Under normal circumstances, CCD image device and optical lens are installed on the substrate left and right sides simultaneously, by adjusting the thickness of cutting pad of repairing between the flange of optical lens and substrate, thereby reach the object of adjusting image planes position.Therefore, the process of image planes adjustment is exactly to adjust the process of cutting spacer thickness of repairing.
Although it is simple to operation that this tradition is adjusted the method for image planes, because needs are constantly repaiied the position of cutting the thickness of adjusting pad and adjust image planes, not only under work efficiency, and image planes position judges by operating personnel, and its precision is difficult to ensure.Especially in the time that optical lens quantity is more, this kind of method is more inadvisable.
Utility model content
The utility model provides a kind of High Precision Automatic adjustment image planes device, to solve the technical matterss such as prior art operating efficiency is low, precision is low.
For realizing above object, the utility model provides following basic technical scheme:
A kind of High Precision Automatic adjustment image planes device, comprises for the lens bracket of fixed optics camera lens, for the substrate of fixation of C CD image device, makes motion platform and the feedback control system of axial direct displacement of the lines for dragging lens bracket with respect to substrate; Described motion platform comprises pedestal, linear electric motors, guide rail and is installed on the slide block on guide rail, and described guide rail is fixed on pedestal, and lens bracket is fixedly connected with slide block, and substrate is relative with pedestal fixing; The fixed part of linear electric motors is fixedly installed on pedestal, and the movable part of linear electric motors is fixedly connected with slide block along guide rail direction.
Based on above-mentioned basic technical scheme, the utility model has also further been done following optimization and has been limited and improve:
Be provided with the limited block corresponding with described slide position in the guide rail one end away from substrate, as mechanical position limitation; Front end at limited block is provided with hall device, spacing as electricity.
Aforesaid substrate is fixedly connected with pedestal by substrate holder.
Above-mentioned feedback control system adopts optical grating ruler measurement displacement information to feed back to computing machine and forms the FEEDBACK CONTROL to linear electric motors.
Above-mentioned grating scale is installed on pedestal one side near substrate.
Resolution chart comprises the some groups of chequered with black and white stripeds that differ in size, and when camera lens is during to resolution chart imaging, discernmible width of fringe is less, and now camera lens becomes image definition evaluation value higher, illustrates that the image quality of camera lens is better.
Apply a method of operating for above-mentioned High Precision Automatic adjustment image planes device, specifically carry out according to step:
Optical lens is installed on lens bracket, CCD image device and substrate are installed on substrate holder as a black box; Moving slider, moves to optical lens flange face concordant with substrate, is " 0 " by this set positions; Before optical lens, resolution chart is placed at object distance place, drive optical lens to move by linear electric motors, the image collecting is input to computing machine simultaneously, by Computer nomogram image sharpness evaluation of estimate, when present image sharpness evaluation of estimate does not meet the demands, linear electric motors drive optical lens to next image space, until the image definition evaluation value gathering meets the demands; Now, reading by grating scale distance that optical lens moves is and between optical lens and substrate, repaiies the one-tenth-value thickness 1/10 of cutting pad.
The utlity model has following advantage:
1, this apparatus structure is simple and clear, easy to operate, and control is simple, positioning precision is high, can be widely used in the engineering practice that optical lens image planes are adjusted.
2, adapt to widely, stability is relatively good.Any imaging system all can adopt this automatic focusing mode.In addition, the input of the method is the image that imaging system generates, and does not rely on other factors, and therefore disturbing factor is relatively few, and stability is better.
3, intellectuality.In the process of adjustment image planes, focusing can adopt resolution chart, also can adopt image local in resolution chart, the basis by this local contrast as focusing.
Brief description of the drawings
Fig. 1 is the utility model CCD image device and optical lens scheme of installation.
Fig. 2 is that the utility model is adjusted image planes device schematic diagram automatically.
Fig. 3 is that the utility model is adjusted image planes systematic schematic diagram automatically.
Fig. 4 is that the utility model is adjusted image planes process flow diagram automatically.
Drawing reference numeral explanation:
1-optical lens; 2-CCD image device; 3-lens flange; 4-substrate; 5-repaiies and cuts pad; 6-base; 7-slide block; 8-guide rail; 9-limited block; 10-linear electric motors; 11-Hall switch; 12-grating scale; 13-optical lens fixed support; 14-substrate fixed support.
Embodiment
The principle that optical lens of the present utility model is adjusted image planes is automatically the automatic focusing principle based on image processing, adopts focusing depth method.It is a kind of focusing mode being based upon in search process.It is evaluated the sharpness of different focus position imaging by an evaluation function, utilize maximum this feature of correct focusing position definition values to find correct focusing position, the method is searched for 10-12 width image in focus process can accurately find image planes position.The method takes full advantage of High-Speed Hardware and the software flexibility of computing machine processing digital signal.
As shown in Figure 2, this device mainly comprises pedestal, guide rail, slide block, linear electric motors and driver, optical lens fixed support, substrate fixed support, hall device, limited block, grating scale and computing machine to automatic adjustment image planes device of the present utility model.Wherein, motion platform is mainly made up of pedestal, slide block, linear electric motors, guide rail, limited block, hall device etc.The image planes adjustment that motion platform is mainly optical lens provides support and position control.Slide block is fixed on pedestal by two guide rails, and optical lens fixed support is installed on slide block, and substrate fixed support is installed on pedestal, and substrate is installed on substrate fixed support.The relative pedestal of CCD image device and substrate keeps static, and optical lens and lens bracket are by its relative CCD image device moving linearly of linear electric motors control.The positional information of optical lens is measured by grating scale, and measured value feeds back to computing machine as feedback signal, thereby forms closed-loop control.The adjustable range of this device can reach 100mm, and the image planes that can meet most of type optical camera lens are adjusted demand.In addition, according to actual needs, in the scope that the range of movement of motion platform can allow in precision, appropriately adjust, according to existing experimental data, maximum can expand to 300mm.
Mounting means: pedestal is installed on stable platform by 4 × M5 socket head cap screw; Two guide rails are installed on pedestal by 6 × M4 sunk screw, ensure that the depth of parallelism between guide rail is better than 0.02mm when installation; The fixed part of linear electric motors (magnet) is installed on pedestal; Slide block is placed on guide rail, adjusts the upper-lower position of linear electric motors motion parts (coil) simultaneously, while slips in slide block front and back, coil can be in free movement in the middle of magnet; Optical lens fixed support and substrate fixed support are installed on respectively on slide block and pedestal, when installation, ensure that the right alignment of optical lens fixed support and substrate fixed support top circular hole is better than 0.02mm; Grating scale is installed on to pedestal one side, adjusts the distance between grating scale position read module and grating scale simultaneously, grating scale can normally be worked.
This High Precision Automatic adjustment image planes device adopts linear electric motors to drive, and linear electric motors have controls simple, positioning precision high, has increased in addition electric spacing and mechanical stop limiter in this device, has guaranteed the reliability of working platform.In addition, the range of movement by optical grating ruler measurement platform, as the feedback signal of linear electric motors, has formed closed-loop control.For the location determination of optical lens image image planes, be automatically to judge by algorithm, it judges that precision improves a lot compared with operating personnel's judgement precision.
Image planes method of adjustment based on this device: optical lens is installed on camera lens fixed support, CCD image device and substrate are installed on substrate fixed support as a black box; Moving slider, moves to optical lens flange face concordant with substrate, is " 0 " by this set positions; Place resolution chart in the front a distance of optical lens, drive optical lens to move by linear electric motors, the image collecting is input to computing machine simultaneously, by Computer nomogram image sharpness evaluation of estimate, when present image sharpness evaluation of estimate does not meet the demands, linear electric motors drive optical lens to next image space, until the image definition evaluation value gathering meets the demands; Now, reading by grating scale distance d that optical lens moves is and between optical lens and substrate, repaiies the one-tenth-value thickness 1/10 of cutting pad.
Verification experimental verification: respond well in the process of the optical lens adjustment image planes that this device is F4.23mm at focal length.Image planes are adjusted precision in 5 μ m, have improved 2 times compared with classic method; Average each camera lens image planes adjustment time is 2min, has improved 5 times compared with classic method efficiency.
The just explanation of the preferred embodiment based on the utility model basic technical scheme of above-mentioned instantiation, and be further optimized, this instantiation should not be considered as the restriction of the protection domain that the utility model basic technical scheme is established.