Study Of Crystal Nonlinear Refractive Index Measuring System

Mansoor Sheik Bahae introduced a high sensitive single-beam Z-scan technique in 1989.It requires relatively simple experimental apparatus and simple analysis. Z-scan technique has been widely employed since it is reported. Now, it has become an important method used in studing the nonlinear optical characteristics.We developed a computer-controlled laser-based Z-scan system, which is automated, convenient, fast and relatively high degree of precision and accuracy advantages on the basis of comprehensively introducing the basic principles of Z-scan technology.The system includes four modules: computer control operating platform, stepper motor controller, data acquisition cards, electrical platform.The computer control module is windows graphical controlling interface which users use to control Z-scan systems and do experimental operation with the help of Microsoft's Visual C + + 6.0 development tool .Programming is mainly based on the procedure MFC. The control software has two modes, namely manual mode and automatic mode.Corresponding user can control automatically and continuously the achievement of Z-scan experiment and complete Z-scan experiment steps by single-step operation manually.The software mainly completes stepper motor drivers, data acquisition cards, serial communication settings and does data coding for control ,data serial communication, data acquisition, data storage and graphics rendering. Stepper motor controller module integrated SCM AT89S52, max232, power supply voltage conversion circuit, stepper motor driven fans, serial communications, switching, power supply interface. Keil C51 programming software was used in the preparation of o the codding of the MCU Microcontroller end.Using Protel 99SE software, we designed a power supply voltage conversion circuit schematic and microcomputer system circuit schematics, and on this basis produced a single-chip microcomputer systems and the corresponding power supply voltage circuit board. We finally integrated all of the above components of a system assembly in a control box and thus constituted a stepper motor controller. For the data acquisition card module we employed the USB7333 . Afeter the correspondingly setting of parameters it can be using during acquisition and data transmission of light detector data.The electrical platform is a samples contained supporting majorly composed by a stepper motor. Finally, using the lens, laser light sources and light detectors as well as by boards and other peripherals and devices, we can assemble a entire experimental platform of Z-scan.Finally, we set up a Z-scan experimental platform. In the experimental platform, we tested the HNbO₃ niobate crystal samples .During the testing, we introduced how to use the software and hardware of the system .The test results indicated that the system basically meeted the needs of the experiment the requirements to achieve the desired functionality.