| Optical phased array is a novel kind of optical beam scanning technology. Compared to other traditional rotating mirror scanning system and acoustic-optical scanning system, its scanning speed is faster and it can also offer higher resolution. In the same time, it offers precise stabilization and random-access optical beam scanning. It can satisfy the need of high-speed scanning systems, for example, high-resolution laser TV, high-speed printer and laser radar, and so on.In this paper, On the basis of analyzing of the property of traditional scanning systems, we draw in a new kind of scanning technology-optical phased array. Firstly, we discussed the background of its developing, then we discussed the concept of optical phased array. Some electro-optical crystals can result in birefringency when they are pressed by electric field, By controlling the intensity of the electric field, we can change the phase of the output optical beam, so the desired scanning direction can be got. Optical phased array can be divided into regular optical phased array and irregular optical phased array depending on the size of modulation units. Continuous angle scanning can be got by using regular optical phased array, but the scanning angle is very small, Because there will generate ajoint beams when the scanning angle is very large, which can affect the quality of scanning, in this paper the reason is discussed in detail. For the reason above, regular optical phased array is used only when the size of the modulation unit is smaller than half of the size of the working wavelength. In order to overcome the strict of the modulation unit' size, we draw in the irregular optical phased array theory and the equal irregular optical phased array theory. These two theories and their modulars are discussed. In the irregular phased array theory the modulation units' size is not stricted any more, it can be enlarged to ten of the size of modulation units of regular optical phased array, or more. The equal irregular optical phased array theory is got from the irregular optical phased array directly. So they all can overcome the problem of the fabrication of modulation unit. These two theories will accelerate the practice of optical phased array theory.On the basis of the discussion of the optical phased array theory, the design of the equal irregular optical phased array system for experiment is presented. The material ofthe modulation units is liquid crystal. The response time of liquid is very long, but the drive voltage is very slow, the fabrication of modulation units are easy, the technology is mature and the price of fabrication is very low, so liquid crystal is used intensively. After the discussion of the electro-optical property of liquid crystal, several methods of accelerating the responding time are presented. Using these methods the respond time can be accelerated effectively. The whole system is consisted of laser, auxiliary optical system, controlling system, lens array, optical phased array and software. Controlling system is composed of drive circuit, locking memory, shift register. Temperature compensating circuit and drive power circuit are also needed. So in this paper the controlling system is discussed in detail. Software is an important part of the equal irregular optical phased array system, the method of database programming is given, and the controlling flow path is presented. At last, the future of the optical phased array is discussed. |
PDF Full Text Request