THE DESIGN OF A SIGNAL CONDITIONING & ACQUISITION ELEMENTS OF A CHOPPED BROADBAND RADIATION PYROMETER

Abstract

This paper presents the design of signal conditioning and acquisition elements of a chopped broadband radiation pyrometer. This instrument is capable of measuring temperature between 900oC and 1200oC. This work aims at solving the problem of measuring hot objects with a thermometer. The radiation pyrometer is a non-contact temperature sensor that infers the temperature of an object by detecting its naturally emitted thermal radiation. It collects the visible and infrared energy and focuses it on a detector. The detector used in this device is a thermal sensor. It receives heat energy reflected from a mirror inclined at 45o to the incident signal from the hot object. The design achieved the following: temperature range measured, from 900℃ to 1200℃; the calibrated instrument is fairly linear with a tolerable non-linearity of 3.6%, with the sensitivity of 0.014𝑉℃−1 ; the resolution was quite very small as such it can easily detect the slightest change at its input; the rotating shutter was configured to supply the chopped signal; it operates at a frequency of 50Hz that is lower than the system frequency of 200Hz; the data acquisition system was able to capture data at a periodic time of 0.02 second and below, the system operates within the specified sampling range thus, satisfying Nyquist criteria. The signal so received by the detector is translated to a human readable form and sent to a display.