Development of a temperature controller for the order-sorting interference filters

Abstract

A Fabry-Perot narrow band imager (NBI) is being built for solar studies at IIA [1]. The NBI has an order sorting pre- lter that selects an optical beam within desired wavelength band. A constant temperature is required to keep the transmission response of the interference lter stable during the observations. This technical report describes the design and construction of a digital temperature sensor and control system for the pre- lter assembly. Temperature measurement and thermostat operations are performed by DS1621 -a semiconductor IC from Maxim. An I2C serial interface (also called 2-wire interface) was developed using computer's parallel port. The design of the I2C interface circuitry and LabVIEW programmes to implement serial communication between the temperature sensor and the PC are described in details.The device operation is validated and results of laboratory test are presented.