Hemispherical concentrators and spectral filters for planar sensors in diffuse radiation fields

Area of Science:

• Optics and Photonics
• Materials Science

Background:

• Dielectric hemispheres can concentrate isotropic diffuse radiation.
• Understanding concentrator gain is crucial for optical system design.

Purpose of the Study:

• To develop an analytic and numerical method for calculating the gain of dielectric hemispherical concentrators.
• To design and evaluate multilayer spectral filters for enhanced hemispherical concentrator performance.

Main Methods:

• Analytic expression for concentrator gain (neglecting reflections).
• Numerical methods for gain calculation with angle-dependent transmissivity.
• Design of 11-layer coupled-cavity spectral filters.

Main Results:

• Achieved 97% of ideal N(2) response at 950 nm.
• Demonstrated excellent bandpass performance with a Full Width at Half Maximum (FWHM) of 55 nm.
• Effective performance with concentrator radius as small as 3 times the sensor radius.

Conclusions:

• A dielectric hemisphere with a specifically designed spectral filter can achieve high concentration efficiency.
• The developed theory and filter design are effective for hemispherical concentrators.
• This combination offers a promising solution for efficient diffuse radiation concentration.