Personal electronic devices such as cell phones and tablets continue to decrease in size while the number of features and add-ons keep increasing. One particular feature of great interest is an integrated projector system. Laser pico-projectors have been considered, but the technology has not been developed enough to warrant integration. With new advancements in diode technology and MEMS devices, laser-based projection is currently being advanced for pico-projectors. A primary problem encountered when using a pico-projector is coherent interference known as speckle. Laser speckle can lead to eye irritation and headaches after prolonged viewing. Diffractive optical elements known as diffusers have been examined as a means to lower speckle contrast. This paper presents a binary diffuser known as a Hadamard matrix diffuser. Using two static in-line Hadamard diffusers eliminates the need for rotation or vibration of the diffuser for temporal averaging. Two Hadamard diffusers were fabricated and contrast values measured showing good agreement with theory and simulated values.

中文翻译：

---

用于减少激光微型投影仪中散斑的非移动 Hadamard 矩阵漫射器

手机和平板电脑等个人电子设备的尺寸不断减小，而功能和附加组件的数量不断增加。一个非常有趣的特殊功能是集成的投影仪系统。已经考虑过激光微型投影仪，但该技术还没有发展到足以保证集成的程度。随着二极管技术和 MEMS 设备的新进步，目前正在为微型投影仪推进基于激光的投影。使用微型投影仪时遇到的主要问题是称为散斑的相干干扰。长时间观看后，激光散斑会导致眼睛刺激和头痛。被称为漫射器的衍射光学元件已被研究作为降低散斑对比度的一种手段。本文介绍了一种称为 Hadamard 矩阵漫射器的二元漫射器。使用两个静态内嵌 Hadamard 扩散器消除了对扩散器进行旋转或振动以进行时间平均的需要。制造了两个 Hadamard 漫射器，测量的对比度值显示出与理论值和模拟值的良好一致性。