Measurement of electromagnetic radiation force using a capacitance bridge interferometer
Abstract
We present a mechanical cantilever-based tabletop interferometer to measure the radiation force exerted by light. Using a high-power (∼1 W) pulsed laser beam, we excite mechanical oscillations in a thin metallic cantilever. The cantilever forms a parallel-plate capacitor with a printed circuit board trace. Using a capacitance bridge geometry, we measure small capacitance changes of the order of femto-farads, induced by the radiation forces of a few nano-newtons. This experiment uses equipment commonly found in an undergraduate teaching laboratory for physics and electronics while providing insight into electromagnetic wave theory, circuit design for low-noise measurements, and Fourier analysis.
Fields of Study & Subjects
Experimental and Theoretical Physics Studies
Mechanical and Optical Resonators
Quantum and Classical Electrodynamics
Publication details
- Journal / source
- American Journal of Physics
- Volume
- 94
- Issue
- 5
- Pages
- 397–404
- Publication date
- 22 April 2026
- Language
- EN