Internal reflection apparatus and method using holographic optical element for free space optical communication system

一种用于自由空间光通信系统的装置包括具有前表面和后表面的元件(16)。设置全息光学元件(24)以便接收来自自由空间光通信系统的光信号(18)并使具有某一波长的光信号倾斜地射向所述元件的表面之一、以便使光信号借助内反射在所述元件的前表面和后表面之间传播。所述内反射的光信号最终在光检测器电路处会聚并被接收。同时，具有其它波长的光、包括可见背景光都可通过所述全息光学元件，从而使所述装置看上去是透明而不引人注目的。 An apparatus for a free space optical communication system includes an element having a front surface and a back surface. A holographic optical element (HOE) is disposed to receive a light signal from the free space optical communication system, and to angularly direct the light signal, having a certain wavelength, towards one of the surfaces of the element to allow the light signal to propagate between the front and back surfaces of the element via total internal reflection. The internally reflected light signal eventually converges and is received at an optical detector circuit. At the same time, light having other wavelengths, including visible background light, passes through the HOE, thereby giving the apparatus an appearance of being transparent and unobtrusive.