A high-flux and high-efficiency setup for magneto-infrared spectroscopy

We report the design and implementation of a high-flux, high-efficiency magneto-infrared spectroscopy system optimized for broadband measurements in high magnetic fields, which requires a high signal-to-noise ratio. The setup integrates a Fourier transform infrared spectrometer, a 12 T cryogen-free superconducting magnet, precision-polished and gold-plated light tubes, custom-designed reflective focusing modules for Faraday and Voigt geometries, and an external multi-detector chamber with motorized selection. Optical throughput is maximized by reducing light tube loss from 65.5% to 22.0% m⁻¹ via abrasive flow and mechanical polishing followed by gold electroplating and by adopting a single-on-axis parabolic-mirror Faraday module that increases the effective numerical aperture from 0.14 to 0.36, enhancing collection efficiency by nearly an order of magnitude. An eight-position motorized sample stage and fully automated control over magnetic field, temperature, optical path, and detector choice enable high-throughput measurements without repeated warm-ups. The optimized configuration achieves a root-mean-square noise level of 0.0061% in a 2-min integration for a 40% reflectivity sample, corresponding to a signal-to-noise ratio exceeding 1.6 × 10⁴. System capabilities are demonstrated by resolving weak replica bands in EuCd₂As₂ and high-index Landau level transitions in LaAlSi with amplitudes as low as 0.06%.