Low Duty Cycle Pulsed UV Technique for Spectroscopy of Aluminum Monochloride

TL;DR

This paper introduces a low duty cycle pulsed UV technique using FPGA control to reduce optical damage in spectroscopy experiments, demonstrated on aluminum monochloride isotope measurements at 261.5 nm.

Contribution

A novel pulsed UV method with FPGA-based cavity control that minimizes optical damage and extends optics lifetime in spectroscopy.

Findings

Effective reduction of UV-induced damage in experiments.

Successful measurement of AlCl isotope shift at 261.5 nm.

Implementation of FPGA-based cavity ramping for precise control.

Abstract

We present a novel technique to minimize UV-induced damage in experiments that employ second-harmonic generation cavities. The principle of our approach is to reduce the duty cycle of the UV light as much as possible to prolong the lifetime of the used optics. The low duty cycle is achieved by ramping the cavity into resonance for a short time during the experimental cycle when the light is used and tuning it to an off-resonant state otherwise. The necessary fast ramp and length-stabilization control of the cavity is implemented with the FPGA-based STEMlab platform. We demonstrate the utility of this method by measuring the isotope shift of the electronic transition ($X^1\Sigma \leftarrow A^1\Pi$) in AlCl at 261.5 nm in a pulsed molecular beam experiment.