Xiaofang Cheng

The set-up of a vision pyrometer

The paper presents a new radiation pyrometer, a vision pyrometric device based on a commercial digital colour camera and SUNPRO software, which converts the calibrated commercial digital colour camera into a scientific instrument for temperature measurement. We introduce the calibration experiments and the principle of this vision pyrometer, and the application of the vision pyrometer is illustrated in the specific examples. The analysis shows that the vision pyrometer established in this paper is convenient and promising and will be able to realize real-time measurements of two-dimensional temperature fields.

Theoretical evaluation of measurement uncertainties of two-color pyrometry applied to optical diagnostics

We present a theoretical analysis of two-color pyrometry applied to optical diagnostics. A two-color pyrometer built with a single CCD is advantageous due to the simple system design. We evaluate the possibility and degree of ill-conditionness on the basis of measurement uncertainties for different measurement approaches of this two-color system. We classify measurement approaches. The corresponding ill-conditionness criterion is established. The greater the criterion value is, the worse the ill-conditioned degree of solution is. So, the optimum choice of measurement approach for the two-color system is achieved through intercomparison of the criterion values. Numerical examples are also given to illustrate this point. The theoretical analysis not only provides an effective way of evaluating different measurement approaches, but also may help us to better understand the influences that determine the choices between wavelength/waveband measurements and calibration/noncalibration modes for temperature and soot distribution.

The theoretical prediction analyses of the measurement range for multi-band pyrometry

In the applications of multi-band pyrometry, the coupled correlation of multi-channel measurement information is a distinct characteristic. Considering this point, in order to realize the non-distortion and effective measurement, the theoretical differentiation formula of the measurement range is put forward in this paper. It may estimate not only the temperature range, but also the emissivity parameter range for the specific measured surface. Then, the corresponding simulation results are given. For an exploited multi-band pyrometer, the theoretical estimations are verified through blackbody measurement experiments. Therefore, the analyses in the paper provide the necessary theoretical supports for the design and application of a multi-band pyrometer.

The measurement coordinates for multi-band pyrometry

The purpose of this paper is to investigate the distribution characteristics of temperature and emissivity in the applications of multi-band pyrometry. We establish the concept of the measurement coordinates, including the temperature coordinate axis and emissivity coordinate axis. Through numerical simulations, we present the corresponding results. The discussions not only provide a simplified and effective expression of the solutions of multi-band pyrometry, but are also helpful to design or optimize a multi-band radiation pyrometer by investigating beforehand the distribution rules of temperature and emissivity in the measurement coordinates.

Study of correlated colour temperature and thermodynamic temperature of a radiating source

Here, we analyse the chromaticity characteristics of the correlated colour temperature (CCT) and thermodynamic temperature of a radiating source. Our analysis correlates the colour coordinates of a radiating source to the CCT and gives the thermodynamic temperature and emissivity information related to the radiating source. The mathematical relationship between the CCT of the source and its thermodynamic temperature is presented. The simulation results indicate that there is a discrepancy between the CCT and its actual thermodynamic temperature, but the discrepancy may be estimated.

Error Transfer Analysis of Normalized Multichannel Measurement

In multichannel measurement, multiple signals affect the output result through the normalization process. It is difficult to analyze the error transfer, which represents the relation between the error of input and output, in this kind of measurement, especially in the normalization process. Thus, a new method of error transfer analysis is needed. Taking the primary spectrum pyrometry for example, this paper establishes a model for error transfer analysis in three-channel measurement by introducing the concept of solid angle. In the model, the error transfer is represented by the concept of error magnification, which is a dimensionless ratio of projection area of error sphere on the normalized plane to the cross section area of the error sphere. The error magnification can not be measured actually through experiment, but can be obtained from theoretical calculation. It is useful in the design of measurement system, especially the analysis of influence of different gain in different channel. The influence factors of the error magnification, including the absolute value and relation between them, are analyzed base on the model. The formula for analysis of two-channel and n-channel measurement is also derived from the three-channel model. Finally, some principles of operation and improvements in normalized multichannel measurement are proposed in order to reduce error.