A Miniature Spot Position Detector Based on a Resonant Calorimeter for the Micro-Sized Spot

In this study, we introduce an innovative method for continuously tracking the positions of small laser spots using a resonant calorimeter. The detectable heat generated by the laser spot varies with its distribution on the proposed device. We first analyze the device’s sensitivity with varying structural parameters using finite element analysis (FEA) and subsequently fabricate and measure the optimized design. Our findings indicate that the resonant frequency of the calorimeter exhibits a linear relationship with the 2 μm-sized laser spot position along with the resonator beam, covering a range from 0 to 100 μm. Remarkably, we achieve an impressive spot position noise floor as low as 2 ${\text{nm}}/\sqrt {{\text{Hz}}}$, within a 95 dB dynamic range.