In the measurement of iron and steel processes, the measurement of temperature concentration distribution is very important for the analysis and control of in-furnace phenomena in order to obtain in-furnace information. However, thermocouples and gas sampling methods are used, but since they are contact and point measurements, they disturb the measurement field, require modification of equipment and piping, have low time response (10 Hz), and are affected in accuracy (20% or more) by environmental fluctuations. This report describes the development of a technology for simultaneous measurement of multiple components such as O₂, CO, and CO₂ concentrations in a furnace, acquisition of a spectral database necessary for measurement using various calibrators, adjustment of the optical axis when installing a sensor with a large laser beam path length (several tens of meters), and development of a technology for adjusting the optical axis by feeding back the laser beam position in real time to prevent optical axis fluctuations during equipment operation. We have developed a technology to adjust the optical axis by feeding back the position of the laser beam in real time when the optical axis fluctuates during the operation of the equipment.