Development Of LD Driver With Function Of Avoiding Wrong Judgment For Over-current

III With the rapid development of photoelectron technology, the semiconductor laser (LD) has been used widely in the fields of communication, military affairs, national defense, scientific research, medical treatment and so on. It is very important to ensure that the LD could work safely and continuously. The function of over-current protection for traditional LD driver is simple. Because of imperfect over-current protection, it happens to wrong judgment for over-current or damage to LD when LD is used, what is more, which can bring on delay of work and unwanted economic loss.A LD driver with the function of avoiding wrong judgment for over-current is introduced in this paper, which can come true in two ways:one way is achieved by microprocessor and Field Programmable Gate Array(FPGA), and it mainly includes analogical and digitalcircuits. Analogical circuits consist of driving LD in variably, sampling parameters of LD, keyboard input and end-of-life alarm. Digital circuits consist of configuration FPGA by microprocessor, receiving data from FPGA and operating or dealing with data, driving outer circuits by microprocessor, controlling D/A and A/D converters by FPGA. Instead of partial hardware functions by software, in this way, it not only saves hardware expense, but also stabilizes the whole circuit, and avoids parameters variation of hardware circuits because of environment effect, meanwhile, improves the intelligence and controllability taking advantage of flexibility and amendment of the software. The other way is achieved by all the hardware circuits.All the function modules, such as collecting work parameters of LD, operating and comparing data, controlling LD, come true by hardware. In this way, the scheme which not only can drive LD under the way of invariable power, but also detect longevity of LD and protect it, meets design aims.The main contents of the thesis are as follows:(1)The operation principle, strcture and output characteristics of LD are introduced, and the driving source requirement of LD is discussed, and the driving technology and driving realization of LD are noted simply.(2)The overall structure of the circuit of the design is set up, and the operation principle of the design is elaborated according to the driving requirement of LD in continuous way, together with design ideas of the system.(3)Intelligent controllers used such as microprocessor, FPGA are introduced, and their operation principles are analyzed, and their roles in circuits are analyzed and discussed in details. What is more, the connection between with the intelligent controllers and extemal circuits is introduced.(4)Circuit principles of various functional modules in hardware are introduced,analyzed, and corresponding theoretical derivations are shown. The circuits about current driving of LD and collecting parameters of LD are analyzed emphatically, and the device of temperature control of LD is introduced.(5)The experiment data from tests is analyzed, and related conclusions are drawn.(6) Realization way of full hardware circuits is put up, the scheme is analyzed and noted in details according to corresponding principle diagrams.