Target Characteristics Calibration Based On Capability Test For Photoelectric Measuring Equipment

Target capture capability is an important general performance indicator for photoelectric measuring equipment. Adjustable contrast target source device can provide an optical target for theodolite to capture, and is a critical indoor test equipment for detecting target capture capability of photoelectric theodolite.Currently, the work based on target characteristic calibration for the target source device to detect capture capability of theodolite has not been effectively developed.That mainly embody the following three aspects : 1) Target characteristic parameters calibration reference has not be established; 2) Relevant factors of influencing target characteristics parameters calibration has not be systematically analyzed, meanwhile the relevant analysis based on statistics has not be fully evaluated; 3) Intrinsic relationship between the parameters and equipment capture capability has not be established too.In the field of national defense, calibration analysis of photoelectric measuring equipment is an extremely important technical foundation and guarantee. Therefore,the work of exploring and researching target characteristics calibration based on adjustable contrast target source device is meaningful, which also do have certain value for guiding target characteristics calibration of similar photoelectric measuring equipment.This paper proposes the research thinking based on target characteristics calibration method of target source device. First, experimental environment of target characteristics calibration is assembled on the basis of adjustable contrast target source device. Considering dynamic multi-parameter target characteristics on optical target source, discusses the establishment condition of calibration reference, the related challenge and the methods for statistics analysis of data processing, in particular the application of descriptive statistics. By analyzing the relevant properties of target source, puts forward concrete implementation methods for establishing calibration reference. Correspondingly, sets up length calibration reference, optical contrast reference and angular velocity calibration reference about target source device, and the related uncertainty and traceability diagram are given.By means of mathematical statistics, the problem of time-drift on optical contrast is correct, the uniformity and stability of images are analyzed. Then, the static and dynamic contrast is calibrated through the functional relationship between optical contrast and image gray contrast. Finally, mathematical model between target characteristics parameters and gray contrast is deduced, and is further verified by experiment.In the process of establishing calibration reference, situation of radiance calibration reference is as follows: calibrate radiance meter PR735 by means of standard lamp and diffuse white board, and accuracy of PR735 is better than 1%;situation of angular velocity calibration is as follows: through photoelectric angle encoder and time calibration in Internet, uses the method of timing angle measurement, and angular velocity accuracy is better than 0.1°/s; situation of the length calibration reference is as follows: accuracy of universal tool microscope calibrated by a standard glass-line scale is better than 1μm.In the process of evaluating the influence of related factors for calibration target characteristics, analyzes the causes of time-drift problem on target optical contrast and corrects that by the curve fitting method, evaluates this method by residual plot,fitting accuracy is better than 0.15%. Under the combined conditions of three kindsof radiance and focal length, uniformity and stability of images on detection equipment are analyzed. By the means of DOE(design of experiment) and factorial analysis methods, analyzes the influence of radiance and focal length for image uniformity, and judges from using two-point correction method to correct image non-uniformity which is available or not, it’s clear that target source radiance range approximately from 33Wm-2str-1to 3.3 Wm-2str-1is reasonable. By using I-MR chart,the stability of image sequence based on time is evaluated, and stability is better than99.8%.In the process of contrast calibration, considering related characteristics of dynamic target, presents a dynamic optical target contrast calibration method by the means of using discriminant analysis, residual analysis, scatterplots and some diagrams based on statistics. By using the least squares method, obtains dynamic contrast calibration curves under different rates, and fitting accuracy of calibration curves is better than 99%.Finally, by the means of using DOE, factorial analysis, residual analysis and some statistics analysis, establishes the functional relationship model between the three calibrated target source parameters and image gray contrast of theodolite. It’s reasonable to set target characteristics parameters for detecting capture capabilities of theodolite through the model, and confirms the applicability of the model by the means of experiment. Experimental results show that test equipment can well capture the target at the threshold condition of image gray contrast which is greater than 0.03.