Laser Self-mixing Interference Micro-displacement Measurement System Drive And Control Circuit Design And Realization

When a portion of light emitted from a laser source is reflected or scattered back into the laser cavity by an external target, the reflected light will mix with the light inside the cavity, causing a modulation of the laser output power. This phenomenon is called as self-mixing effect, in which the reflected light carries some information of the external target. The self-mixing effect comes from the optical feedback effect. People always tried to eliminate the optical feedback effect previously. Gradually people began to make use of it actively to measure some physical quantities, thus self-mixing interference technology was brought forth.Semiconductor laser generator is a kind of device which has high power density and very high quanta efficiency. Its endurance ability to electronic impaction is so bad that a weak currency can induce great changes in light power outputs and parameters (for example: laser radio wave length, noise performance, mode flop ) of device . And these changes directly endanger the safety in using device, so we have high request to the performance of semiconductor driver and safety protection in application . In addition, this thesis researches and analyzes the hardware circuit design which has relation to the last level and protective circuit of semiconductor laser driver.In this thesis, combining the measurement system of micro displacement, we introduce optical characteristics and electro-optical properties of the EOC, and the electro-optic effect of the crystal. From the principles of self-mixing interferometry and phase modulation using electro-optic crystals, the article put an electro-optic modulator in the external cavity and analyzes sinusoidal phase modulation using electro-optic crystal in self-mixing interference. According as the capacitive of electro-optic crystal, the driver circuit of electro-optic crystal is designed and analyzed . The driver circuit of electro-optic crystal runs in dissimilar frequency rage and high voltage.The temperature of laser-diode is connected with the type of laser-diode . If requests the laser diode to have the high stability, then need to use to make use of the TEC as the performance piece of temperature control system . Currently, many laser temperatures control systems take he TEC as the performance piece . When the direct current passes the TEC, driving the direction of the electric current of TEC from the change to carry out to make cold or heat . The nicety regulate with the current or the voltage sizes of the TEC, can carry out precise temperatures control, this is the papers core part—the intelligence temperature control part.The temperature-controlling and driving laser circuits are studied, the theories of its unit circuits are discussed, and the data of the key material is introduced. The controlling and driving system are realized by a series of process, and its three-dimensional effect photos are shown in the thesis . Some problems in the experiment system and its improvement approach are discussed in the end.