High-flux, high-resolution compact Offner imaging spectrometer for hyperspectral applications

Area of Science:

• Optical Engineering
• Spectroscopy
• Imaging Technology

Background:

• Traditional Offner spectrometers face limitations in optical throughput and system volume.
• Achieving high resolution and aberration correction in compact designs is challenging.

Purpose of the Study:

• To propose and demonstrate a high-flux, high-resolution Offner imaging spectrometer with a compact configuration.
• To fundamentally alleviate astigmatism and enable a larger numerical aperture while preserving aberration-free benefits.

Main Methods:

• Introduced a custom-designed lens group to optically transform the entrance slit into a virtual slit with extended divergence.
• Conducted theoretical modeling and optical analysis to derive aplanatic conditions and optimize focal power.
• Employed a three-lens assembly, including a toroidal surface, for aberration correction.

Main Results:

• Achieved a larger numerical aperture (NA=0.3) while maintaining aberration-free performance.
• Measured spectral resolution of 1.35 nm over the 400-1000 nm range.
• Improved optical throughput by 2.25x and reduced system volume by 14.5% compared to conventional designs.

Conclusions:

• The improved Offner spectrometer offers a compact, aberration-free, and high-resolution solution.
• Demonstrated excellent spectral and spatial imaging performance through laboratory calibration and field experiments.
• Suitable for applications demanding high-precision spectral imaging.