The second chapter introduces the theory of single-frequency laser, and it is the theoretical basis of this paper.

The camera works by illuminating objects with a laser that emits a different infrared frequency for every single pixel, allowing them to custom-amplify a signal that would otherwise be too dim to see.

A method using the frequency divtion multiplexing technique of the laser speckle's spatial frequency to record multiple displacement information on a single specklegram is presented.