Measuring the spot diameter of the pyrometer by a slit diaphragm method
摘要
The main optical characteristic of pyrometers is the dependence of their spot diameter on the distance between the pyrometer and the measured object. However, this dependence is currently not amenable to strict calculation and is measured experimentally, emphasizing the importance of selecting the adequate method for measuring the spot diameter. This parameter can be determined using either circular (iris) or slit diaphragm. The first method utilizes the results of measuring the diameter of a variable iris diaphragm installed near the emitter aperture. However, this method is suboptimal due to high cost of labor associated with the measurements. The second method is based on the results of measuring the width of a slit diaphragm, which is also placed near the emitter aperture and moved in a plane perpendicular to the optical axis of the pyrometer. The results obtained by these two methods are slightly different due to the difference in areas of the iris diaphragm and the surface cut by the slit diaphragm, with the width of the slit being equal to the diameter of the iris diaphragm. A relationship has been derived linking the results of measuring the spot diameter of the pyrometer by both circular and slit diaphragm methods. This relationship enables the accurate measurement of this parameter using the slit diaphragm, which is a faster and less labor-intensive method compared to the iris diaphragm. The obtained results are important for non-contact temperature measurements in both technological processes and R&D projects.