A Spectral Encoding Simulator for Broadband Active Illumination and Reconstruction-Based Spectral Measurement

Area of Science:

• Optics and Photonics
• Spectroscopy
• Computational Imaging

Background:

• Spectral measurements are crucial for material identification across various fields.
• Existing methods using narrow-band light sources lack spectral resolution and accuracy.
• Limitations stem from the low adjustability of traditional spectral encoding light sources.

Purpose of the Study:

• To develop an advanced spectral encoding simulator for active illumination.
• To overcome the limitations of current spectral measurement techniques.
• To enhance the accuracy and resolution of spectral reflectance and transmittance measurements.

Main Methods:

• Designed a spectral encoding simulator integrating a prismatic spectral imaging system and a digital micromirror device (DMD).
• Adjusted spectral wavelengths and intensity by dynamically switching DMD micromirrors.
• Employed convex optimization to solve for DMD patterns corresponding to desired spectral encodings.
• Simulated spectral encodings and performed numerical reconstruction of spectral reflectance and transmittance.

Main Results:

• Successfully simulated existing spectral encodings and a high-resolution Gaussian random encoding for compressed sensing.
• Achieved accurate numerical reconstruction of spectral reflectance for vegetation and minerals.
• Experimentally reconstructed the spectral transmittance of a calibrated filter with high accuracy.
• Demonstrated the simulator's capability for high-resolution and accurate spectral measurements.

Conclusions:

• The developed spectral encoding simulator effectively addresses the accuracy and resolution limitations of traditional methods.
• The system enables precise spectral reflectance and transmittance measurements through active illumination.
• This technology holds significant potential for applications requiring detailed material spectral analysis.