Making compact and innovative dual-band thermal imagers using hybrid optical elements

Infrared (IR) remote sensing offers a huge range of applications, mostly addressing make-or-break issues of our century (crops water content monitoring, forest fires and volcanic eruption detection and imaging, etc.). These applications fall under different spectral bands, known as mid and long-wave infrared, which are very hard to combine in a single compact instrument. In this article we propose to explore the infrared (IR) behaviour of a dual-band diffractive component: the multilayer diffractive optical element (MLDOE). We use and discuss the thin element approximation as a valid phase model. Using Fourier optics, we are able to simulate the resulting image of the MLDOE. Thereby, ray-tracing software are not accurate to model a complex diffractive component. The Strehl ratio is used to determine the focalization efficiency for the working order, which is above 95% in the mid and long-wave infrared bands. This result, along with the very low energy content of the other orders, proves the strong imaging potential of MLDOEs for dual-band applications. It is also demonstrated that the MLDOE has the same chromatic behaviour as standard DOEs, making it a very useful component for infrared achromatization.

[1]  Changxi Xue,et al.  Optimal design of a multilayer diffractive optical element for dual wavebands. , 2010, Optics letters.

[2]  Saleh Taghvaeian,et al.  Remote sensing for evaluating crop water stress at field scale using infra-red thermography : potential and limitations , 2013 .

[3]  J. Rogers,et al.  Optical performance of holographic kinoforms. , 1989, Applied optics.

[4]  Digvir S. Jayas,et al.  Applications of Thermal Imaging in Agriculture - A Review , 2005 .

[5]  Vicente Moreno,et al.  High efficiency diffractive lenses: Deduction of kinoform profile , 1997 .

[6]  Clive Oppenheimer,et al.  Volcano surveillance using infrared cameras , 2011 .

[7]  G. M. Morris,et al.  Spectral properties of multiorder diffractive lenses. , 1995, Applied optics.

[8]  Fabio Del Frate,et al.  Review of Thermal Infrared Applications and Requirements for Future High-Resolution Sensors , 2016, IEEE Transactions on Geoscience and Remote Sensing.

[9]  V. A. Danilov,et al.  Comparison of electromagnetic and scalar methods for evaluation of efficiency of diffractive lenses for wide spectral bandwidth , 2015 .

[10]  Xiaojian Xu,et al.  Optimal Band Selection of Multispectral Sensors for Wildfire Detection , 2017, 2017 Sensor Signal Processing for Defence Conference (SSPD).

[11]  Lidong Zhao,et al.  High diffraction efficiency of three-layer diffractive optics designed for wide temperature range and large incident angle. , 2016, Applied optics.

[12]  Hideki Ogawa,et al.  Research on multi-layer diffractive optical elements and their application to camera lenses , 2002 .

[13]  S. Habraken,et al.  Modeling infrared behavior of multilayer diffractive optical elements using Fourier optics. , 2021, Applied optics.

[14]  T. Nakajima,et al.  Optimization of the Advanced Earth Observing Satellite II Global Imager channels by use of radiative transfer calculations. , 1998, Applied optics.

[15]  G E Sommargren,et al.  Harmonic diffractive lenses. , 1995, Applied optics.

[16]  Gary J. Swanson,et al.  Binary Optics Technology: Theoretical Limits on the Diffraction Efficiency of Multilevel Diffractive Optical Elements , 1991 .

[17]  M. Moharam,et al.  Limits of scalar diffraction theory for diffractive phase elements , 1994 .

[18]  Mark Peter Rast,et al.  The optical imaging instruments and their applications: AATSR and MERIS , 2001 .

[19]  Tomoyoshi Shimobaba,et al.  Band-limited angular spectrum method for numerical simulation of free-space propagation in far and near fields. , 2009, Optics express.

[20]  Changxi Xue,et al.  Optimal design of multilayer diffractive optical elements with effective area method. , 2016, Applied optics.

[21]  Site Zhang,et al.  Parabasal thin element approximation for the analysis of the diffractive optical elements , 2014, Photonics West - Micro and Nano Fabricated Electromechanical and Optical Components.

[22]  Bo Zhang,et al.  Effect of substrate material selection on polychromatic integral diffraction efficiency for multilayer diffractive optics in oblique incident situation , 2018 .

[23]  Thomas S. Pagano,et al.  Moderate Resolution Imaging Spectroradiometer (MODIS) , 1993, Defense, Security, and Sensing.

[24]  Daniel G. Smith.  Angular Spectrum of Plane Waves , 2013 .