The Measurement And Evaluation Of Speckle In Laser Projection Display Systems

Existing of speckle degrade the quality of image in laser projection display system seriously, and it becomes an obstacle for spreading laser display. We need standardized speckle measurement system to evaluate different laser projection systems and speckle suppression methods. Human as the final observer for laser projection display, and it is very important to set-up a speckle measurement system matched to human speckle perception. This thesis mainly studied for speckle measurement and evaluation methods in laser projection display system. The main research content is as follows:(1) We have analyzed speckle perceptual characteristics of the human eye in laser projection display systems, combined with statistical properties of speckle, and optical properties and visual characteristics of the human eye. As the measured speckle contrast strongly depends on the experimental setup, we investigate and discuss the influence of each of the measurement configuration parameters, such as the depth of field, clear aperture, F-number, integration time, distance from the screen and so on.(2) According to the analysis results, we summarized the whole idea and procedures of speckle measurement based on speckle contrast, and experimental study the influence of each of the measurement configuration parameters, such as the depth of field, clear aperture, F-number, integration time, distance from the screen and so on. Through analyze the experimental results, combined with the optical characteristics of the human eye, we built a set of the speckle measurement system match to the human eye.(3) Given the shortage of speckle contrast as the method to evaluate speckle, we proposed a comprehensive method based on the power spectral density function of speckle pattern, which allows the simultaneous measurement of three components of laser speckle:severity, anisotropy and granularity. We analyzed the principle of this method, and experimental verification of the feasibility of measuring speckle based on the power spectral density function. Then we compared the measurement method based on speckle contrast with that based on power spectral density function.The above study provides some reference value for parameter selection and speckle measurement system design. The work presented here will be useful in evaluating not only speckle in images, but current and future speckle reduction technologies as well.