A system for determining the profile of a laser beam includes a detector having a thermochromic liquid crystal film (TLCF) in thermal communication with a heat spreader and a thermoelectric cooler. The liquid crystal film has a thermochromic response such that heating of the film by a received laser beam creates a detectable color response at the film. The system also includes an image sensor and a controller configured to output an operating current for the TEC and receive images from the sensor. The system can selectively vary the temperature set point of the TEC to change the steady state temperature of the TLCF to examine the full intensity profile of the received beam even when the temperature response bandwidth of the TLCF is too narrow to display the full beam profile in a single color spot.