Invention:
Researchers at the University of Arizona have designed an optical device comprising a multiple-order diffractive Fresnel lens (MOD-DFL) and an achromatizing compensation mechanism that reduces refractive dispersion created by the MOD-DFL, thereby reducing the focal range of the MOD-DFL. A method is also provided of using the optical device in an image processing system to obtain images of an object and processing the images to perform image enhancement.
Background:
A multiple-order diffractive Fresnel lens (MOD-DFL) operates over a set of higher diffracted orders where each order contains a wavelength of peak diffraction efficiency and each of these wavelengths come to a common focus. For a singlet design, refractive dispersion quickly becomes an undesirable characteristic of the MOD-DFL over large wavelength bandwidths, increasing the focal range across the bandwidth. In practice, this increase in focal range is detrimental to most imaging systems. It is caused by refractive dispersion from the MOD-DFL lens material. A need exists for a MOD-DFL having reduced refractive dispersion, and consequently, a reduced focal range.
Advantages:
- Reduces focal dispersion
- Allows for large aperture, light weight lenses
Applications:
- Ground-based telescopes
- Space-based telescopes
- Spectrometers
Status: issued U.S. patent #11,671,706
