Spectral Diffractive Lenses for Measuring a Modified Red Edge Simple Ratio Index and a Water Band Index.

Area of Science:

• Optics
• Remote Sensing
• Materials Science

Background:

• Hyperspectral imaging provides detailed spectral information but is complex and costly.
• Remote sensing of vegetation indices typically requires sophisticated sensor systems.
• Spectral diffractive lenses offer a potential solution for simplified spectral imaging.

Purpose of the Study:

• To design and fabricate novel spectral diffractive lenses for vegetation index measurements.
• To evaluate the performance of these lenses in a prototype imaging sensor.
• To demonstrate the utility of spectral lenses for generating vegetation index images.

Main Methods:

• Design and fabrication of spectral diffractive lenses using direct laser writing in photoresist.
• Microrelief fabrication with a thickness of 4 µm.
• Integration of fabricated lenses into a prototype imaging sensor.
• Linear scanning of vegetation specimens for index measurement.

Main Results:

• Successful synthesis of spectral diffractive lenses operating in the ±1 diffraction orders.
• Demonstration of sharp image generation for specific wavelengths of interest.
• Experimental measurement of vegetation index distributions (Modified Red Edge Simple Ratio Index, Water Band Index) using linear scanning.
• Validation of spectral lenses for obtaining remotely sensed vegetation index images.

Conclusions:

• Spectral diffractive lenses are a viable technology for simplified vegetation index imaging.
• These lenses provide a practical alternative to full hyperspectral imaging for specific remote sensing tasks.
• The fabricated lenses show promise for developing compact and cost-effective imaging sensors.