Broadly
tunable mid-infrared (IR) lasers, including quantum
cascade
lasers (QCL), are an asset for vibrational spectroscopy wherein high-intensity,
coherent illumination can target specific spectral bands for rapid,
direct chemical detection with microscopic localization. These emerging
spectrometers are capable of high measurement throughputs with large
detector signals from the high-intensity lasers and fast detection
speeds as short as a single laser pulse, challenging the decades old
benchmarks of Fourier transform infrared spectroscopy. However, noise
in QCL emissions limits the feasible acquisition time for high signal-to-noise
ratio (SNR) data. Here, we present an implementation that is broadly
compatible with many laser-based spectrometer and microscope designs
to address these limitations by leveraging high-speed digitizers and
dual detectors to digitally reference each pulse individually. Digitally
referenced detection (DRD) is shown to improve measurement sensitivity,
with broad spectral indifference, regardless of imbalance due to dissimilarities
among system designs or component manufacturers. We incorporated DRD
into existing instruments and demonstrated its generalizability: a
spectrometer with a 10-fold reduction in spectral noise, a microscope
with reduced pixel dwell times to as low as 1 pulse while maintaining
SNR normally achieved when operating 8-fold slower, and finally, a
spectrometer to measure vibrational circular dichroism (VCD) with
a ∼ 4-fold reduction in scan times. The approach not only proves
versatile and effective but can also be tailored for specific applications
with minimal hardware changes, positioning it as a simple and promising
module for spectrometer designs using lasers.