Undergraduate Research & Mentoring Program

Document Type


Publication Date

Spring 5-23-2018


Terahertz spectroscopy, Terahertz technology, Imaging systems -- Testing, Beam optics -- Testing


The goal of this project is to create a time and cost-effective solution for THz beam profiling.

The knife edge method of beam characterization is a technique to verify the intensity profile of a beam involving traveling a blade orthogonal to the beam path and measuring transmission in successive steps. We use a vector network analyzer (VNA) to measure S21 transmission from a THz source. Manual implementation of this method was time-consuming and inefficient.

Project hardware includes an Arduino, a motor shield, and a ball screw linear rail with stepper motor actuator. Software was created in LabView and data is analyzed with a script written in GNU Octave. Data resolution is improved by a factor of 10 and speed of data collection is improved by a factor of 20 compared to the manual method.

Initial data shows high noise indicating poor focus in the vertical axis. An uncollimated setup shows less, but still present noise. Next steps include installing a sharper blade which may reduce reflection noise. In addition, improving the user-friendliness of the LabView VI and Octave script will make this useful for characterizing the focusing properties of rapidly prototyped THz optics.

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Previous Versions

May 31 2018