Analysis method of the Offner hyperspectral imaging spectrometer based on vector aberration theory

Area of Science:

• Optical Engineering
• Spectroscopy
• Freeform Optics Design

Background:

• Compact hyperspectral imaging spectrometers with wide fields of view (FoV) are valuable but face challenges with wavelength-dependent aberration fields.
• Traditional aberration theories struggle to explain aberration variations in miniaturized spectrometers.

Purpose of the Study:

• To extend Vector Aberration Theory (VAT) for analyzing Offner imaging spectrometers.
• To provide a novel analytical framework for designing compact, wide FoV Offner imaging spectrometers.

Main Methods:

• Deduction of the aberration field decenter vector expression for Offner spectrometers using real ray-tracing.
• Derivation of the third-order vector aberration expression for the system.
• Application of the developed method to design a spectrometer with a freeform tertiary mirror.

Main Results:

• The new analysis method successfully explains common phenomena in Offner imaging spectrometers.
• A compact, wide FoV Offner imaging spectrometer was designed, achieving a 37% reduction in length and 75% in volume.
• Tolerance analysis confirmed the feasibility of the freeform optics with existing machining technology.

Conclusions:

• The extended VAT provides crucial insights into aberration fields in Offner imaging spectrometers.
• This analytical approach is significant for advancing the design of compact, wide FoV Offner imaging spectrometers, particularly those incorporating freeform optics.