Temperature control system supplied by pulse-drive current for laser range finder

The light emitting and light receiving devices in laser range finders are low-power components characterized by temperature sensitivity. When a Pt resistance is set in a circuit for temperature measurements,the self-heating effect of Pt resistance influences the resolution of the temperature control system.In order to decrease the error caused by the self-heating effect,a new set of circuit is proposed based on a pulse-current drive.The models of pulse-current drive circuit and the equivalent heat loop of self-heating effect are set up.Then,the relationship between pulse width and heat quantity accumulation is given and the measuring error from the self-heating effect is decreased sharply by controlling the pulse width properly.Finally,a high-order orthogonal polynomial method is used to compensate the Pt resistor nonlinearity and the high precision of compensation is proved by comparison tests of the temperature measuring module and the absolute standard Pt resistance thermometer.The experimental results show the absolute value of maximum error is less than 0.000 6 ℃ at different temperatures and the stability of temperatures in 0~15 ℃ is better than 0.005 ℃.These results meet the needs of high-accuracy laser range finders.