Dependency of speckle reduction by wavelength diversity on angular diversity in laser projection system

Abstract

AbstractSpeckle is one of the most serious problems in laser projection system. Most speckle reduction methods in a laser projector can be categorized into wavelength diversity, angular diversity, and polarization diversity. In order to reduce speckle to the acceptable level, the combination of some or all of these methods are used. When the speckle reduction by wavelength diversity and angular diversity are used at the same time, the total speckle reduction can be different from the product of each speckle reduction effect when each of them is used separately. Here, the theoretical model of speckle reduction by wavelength diversity and angular diversity when they are used at the same time is derived. The calculation results by the theoretical model are compared with the experimental results. It is shown that theoretical calculation agrees well with the experimental results.