High-precision Temperature Control And Ptf Measurements

With the development of new technology, precision measurement technology also has evolved very much. At present the influence of environment and outside condition must to be considered which become more and more important in precision measurement. On one side, using optical methods for measuring the dimension of the object in the air, the air refractive index measurement need to be real-time. On the other side, measurement need a wonderful environment where have a stable temperature and suitability humidity.There are two kinds of methods to measure the air refractive index: direct method of measurement, indirect method of measurement. Each kind of method still has specialty and shortage. Some direct methods have complex structure in huge size, or need calibration to key component ,while indirect method are very simple relatively, so it is used more and more broad. To control temperature in different domain have different ways. In precision measurement there are three kinds of ways to control temperature: direct heat and direct refrigeration, direct heat and physical refrigeration, water heater and so on. Water heater was used more abroad.In this paper a measurement system of air refractive index and a temperature control system with high precision are presented. One the one hand, using the Edlen formula, air refractive index have been obtained from measuring atmospheric pressure, temperature, humidity, carbon dioxide concentrations of the environment. In the temperature measurement system, temperature of object is acquired by thermocouples referenced temperature of thermoelectric couple is measured by platinum-resistance thermometer. On the other hand, temperature control system is made up of Single Chip Micyoco, frequency transducer constant temperature water baths and instrument box. The influx of constant temperature water come form water baths into instrument box become heat exchanger to make temperature of instrument box constant.In the course of measure temperature, the ingredient of signals and noises of multiplexer and nanometer is analyzed based on stationary random process theory and modern digital signal processing methods. And the character and distribution of...