Analysis of the modern technologies of speckle reduction in portable laser projectors

• Дата: 2018
• Автор: Kliuieva, T. Yu.
• Формат: Стаття
• Мова: Ukrainian
• Опубліковано: Інститут проблем реєстрації інформації НАН України 2018
• Теми: laser projector; DMD; GLV; MEMS; speckle; noise; speckle suppression; diffractive optical element; лазерный проектор; спекл; шум; спекл-подавление; дифракционный оптический элемент; лазерний проектор; сканування; спекли; дифракційні елементи
• Онлайн доступ: http://drsp.ipri.kiev.ua/article/view/142909
• Назва журналу: Data Recording, Storage & Processing

High-brightness miniature light emissive devices as well as projection technology increasingly used in mobile devices call for new solutions in creating projectors. Recent advances in diode technology and MEMS scanning devices promote the development of laser-based projection systems. Laser projectors have perfect light efficiency, high brightness, color gamut and contrast. Speckle, however, significantly impairs the resulting image quality and resolution because speckle is one of the factors preventing lasers from being widely used in projection systems. Consequently, it is obvious that in order to generate a high-quality image in laser projectors, it is necessary to suppress speckle. This paper primarily focuses on analyzing the various methods for speckle reduction. Inasmuch as the efficiency and practicability of various methods might be dependent on the projection system architecture, the paper highlights the main image projection techniques. The techniques are classified based on the approach applied to generate projected images. Strengths and weaknesses of various types of optical modulators (LCD, DMD, GLV) and MEMS-based scanning mirrors that are currently used in portable devices are analyzed. The current state of speckle reduction in laser projectors has been studied. It is suggested that active and passive methods for coherent noise reduction be distinguished based on the laser beam decorrelation method analysis. Active methods of laser beam decorrelation require mechanical movement whereas passive methods do not. Speckle reduction methods using moving stochastic diffuser, moving DOE, deformable mirror, and rota-ting light pipe, as well as multimode optical fiber are examined. Speckle reduction methods using mechanical motion are demonstrated to be most efficient.