A compact and cost-effective fiber-fed Fourier transform spectrometer for astronomical and laboratory applications: balancing spectral resolution, sensitivity, and stability

We present a compact and cost-effective fiber-fed Fourier Transform Spectrometer (FTS) assembled using off-the-shelf optical components for high-precision spectral metrology. The system incorporates a frequency-stabilized 633.178 nm He-Ne laser for real-time correction of nonlinear scanning artifacts and operates across the near-infrared range of 9,090 to 16,667 cm^-1 (0.6-1.1 μm). The instrument performs reliably on high-flux targets such as the Sun, producing well-defined absorption features. However, traditional FTS methods suffer from poor signal-to-noise ratios (SNR) when observing faint planetary sources. To address this limitation, we integrate a lock-in amplifier with a 3 kHz optical chopper and operate at scan speeds below the Nyquist limit. We also characterize the effects of scan-induced jitter and introduce a post-processing correction method that significantly improves both spectral resolution and SNR. Our results demonstrate key trade-offs among resolution, sensitivity, and stability, offering a practical approach for high-dynamic-range spectroscopy in both laboratory and astronomical settings.