The Method For Non-parallel Light Beam Based On Image Processing

Beam parallelism is an important index to measure the light source of the instrument. It is very important to accurately measure the divergence angle of the light source and improve the quality of the instrument. In the instrument light source, the common light source are the laser light source and the LED light source. The laser light source generally has a good collimation effect, which has the characteristics of small divergence angle and good parallelism in long distance measurement. With the development of LED technology, LED has the characteristics of high luminous intensity, low energy consumption, easy drive, long service life and high reliability. LED is widely used in lighting, intelligent instrument display, instrument and meter, indicator light, billboard, visibility meter and so on. For the use of LED in the measuring instrument light source is more and more common, it is urgent to study a kind of measurement device which can quickly detect the divergence angle of LED light source. It has great value to improve the performance of the measuring instrument and reduce the cost.Aiming at the problem of beam detection and method design, this paper designs a LED light source divergence angle measurement system based on digital camera. Firstly, the LED light source is arranged in a parallel guide rail sliding module, light through the refraction beam splitter mirror can be paralleled with the camera lens on the screen; Secondly, digital camera can shoot the different position of spot images; Then the shooting spot pictures import digital image processing module, the gray conversion, filtering, object extraction, thinning, chain code fitting; The chain code set, maximum inscribed circle and minimum circumscribed circle will be handled. The round spot of minimum radius length, the maximum radius length and the geometric relation for divergence angle will be demanded. Finally, the feasibility of the design method is verified by comparing with the values measured at different locations.Based on the image processing technology of beam parallel detection method for measuring device includes fixed focus camera system and step into the motor of a straight line parallel to the rail system and the development of the graphic oriented GUI PC interface, which realize the function of the stepper motor control, camera and image processing light source through the beam divergence angle.The experimental results show that the calculated maximum inscribed circle and minimum circumscribed circle radius and obtained the average maximum divergence angle is 7.82 degree. The minimum divergence angle is 6.86 degree, errors are 0.056 and 0.052 degrees. In this paper, the design of the measurement device matches the experimental results and the calibration values are high, which can effectively measure the LED light source of the beam divergence angle.