Experiment with a diffractive lens with a fixed focus position at several given wavelengths

Abstract

The paper presents results of the experimental investigation of “spectral” diffractive lenses the same focus position for several given wavelengths. Two spectral diffractive lenses designed to focus radiation of three and five specified wavelengths in the visible spectrum were investigated. Using a method of direct laser writing in photoresist with iterative correction of writing parameters, we fabricated a diffractive microrelief of the spectral lenses with the height deviation from the designed relief of less than 30 nm. Using a pinhole located at the focus of the fabricated lenses, we estimated the operation wavelengths. The point spread functions of the spectral lenses at the designed wavelengths were measured with the use of a tunable laser. The imaging properties of the spectral lenses were illustrated by the images of a reference color table.

Impact of fabrication errors and refractive index on multilevel diffractive lens performance

“…Various research groups have designed achromatic MDLs via careful parametric optimization of the lens surface topography in the visible 3,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] , NIR 26 , SWIR 27 , LWIR 28 , THz 29,30 and microwave 31 bands. In fact, we have recently shown the design of a single achromatic MDL with a focal length of 18 mm and aperture of ~ 1 mm, operating across a continuous spectrum of wavelengths from 450 nm to 15 μm 32,33 .…”

“…Hence, employing metalenses to model scalar properties of light can be considered "an overkill", from all the perspective of theoretical modeling, fabrication as well as performance [3,11]. These advantages have already been exploited by research groups to design achromatic MDLs via careful parametric optimization of the lens surface topography in the visible [3,[11][12][13][14][15][16][17][18][19][20][21][22], NIR [23], SWIR, [24] LWIR [25], THz [26,27] and microwave [28] bands. In fact, we have recently shown the design of a single achromatic MDL with a focal length of 18mm and aperture of ~1mm, operating across a continuous spectrum of wavelengths from 450nm to 15μm [29,30].…”

Inverse designed achromatic flat lens operating in the ultraviolet

“…Design of achromatic multi-level diffractive lenses (MDLs) via computational optimization of the lens surface topography have now already been successfully demonstrated in the visible [13][14][15][16][17][18][19], near infrared [20], short-wave infrared, [21] long-wave infrared [22], THz [23,24], and microwave [25] bands. Recently, we also highlighted the design of a single achromatic MDL operating across a continuous spectrum of wavelengths from 450nm to 15μm [26,27] by utilizing the same "phase as a free parameter" concept as has been adopted in this paper.…”

Computer simulation of diffractive imaging lenses using hyperspectral images

“…При исследовании зависимости степени хроматических искажений от числа учитываемых дифракционных порядков для каждого значения длины волны  k формировались различные варианты наборов коэффициентов k m ( k ) для дифракционных порядков m, вычисленных в соответствии (8). Число этих коэффициентов определялось максимальным числом моделируемых порядков.…”