Single pixel sensing for THz laser beam profiler based on Hadamard Transform

• A single pixel camera for THz domain with mechanical encoding mask is proposed.
• 2.5 THz methanol laser beam was analyzed for three different profile patterns.
• Information about beam power, waist dimensions and beam shape was revealed.

We present our experimental set-up and results for a THz beam profiling system based on a mechanical spatial light modulator (SLM) for one pixel sensing. By placing a synthetic aperture into the path of a propagating THz beam we achieved the optical ON/OFF keying of its various intensity components. Further, by successively expose a series of predesigned binary masks we manage to encode within their features the beam spatial distribution. The masks used are of a predefined size and can be designed for different resolutions. Our approach eliminates the need of using an array of pixels for detection while still maintaining the high sensitivity and dynamic range of one detector.