Design Method of a Wide-Field, Dual-Slit, Low-Distortion, and High-Sensitivity Hyperspectral Imager.

Area of Science:

• Optical Engineering
• Spectroscopy
• Image Processing

Background:

• Hyperspectral imaging requires high signal-to-noise ratio (SNR) and accurate image registration.
• Existing imagers face challenges in target acquisition and spectral performance.
• Dual-slit designs offer potential for SNR enhancement but demand precise alignment.

Purpose of the Study:

• To develop a wide-field, dual-slit Offner hyperspectral imager with improved SNR and registration accuracy.
• To address spectral performance and dispersion nonlinearity for accurate dual-slit image fusion.
• To evaluate the imager's performance against modulation transfer function (MTF) and registration criteria.

Main Methods:

• Designed a wide-field, dual-slit Offner hyperspectral imager (0.4-0.9 μm wavelength, 0.15 NA).
• Employed dual slits with 2.4 mm spacing to avoid aliasing and enable SNR enhancement via fusion.
• Utilized a low-dispersion internal reflection curved prism and high-dispersion double-pass curved prisms for spectral correction.
• Implemented tilt eccentricity of the internal reflection curved prism as a compensator for spectral performance.

Main Results:

• Dual-slit image fusion increased the SNR by 1.4 times.
• The hyperspectral imager achieved registration accuracy for dual-slit images.
• Modulation Transfer Function (MTF) was used as the evaluation criterion, with results exceeding 0.4.
• Spectral smile and keystone distortions were controlled to <= 0.3 pixels.

Conclusions:

• The developed dual-slit Offner hyperspectral imager effectively enhances SNR and meets stringent registration accuracy requirements.
• The spectral correction techniques, including the prism compensator, are critical for achieving high-quality dual-slit hyperspectral data.
• The imager demonstrates suitability for applications demanding high target acquisition probability and precise spectral information.