Snapshot channeled imaging spectrometer using geometric phase holograms.

Yifan Wang,Michael W Kudenov,Michael J Escuti

doi:10.1364/oe.27.015444

Abstract

In this paper, we present the design and experimental demonstration of a snapshot imaging spectrometer based on channeled imaging spectrometry (CIS) and channeled imaging polarimetry (CIP). Using a geometric phase microlens array (GPMLA) with multiple focal lengths, the proposed spectrometer selects wavelength components within its designed operating waveband of 450-700 nm. Compared to other snapshot spectral imagers, its key components are especially suitable for roll-to-roll (R2R) rapid fabrication, which gives the spectrometer potential for low-cost mass production. The principles and proof-of-concept experimental system of the sensor are described in detail, followed by lab validation and outdoor measurement results which demonstrate the sensor's ability to resolve spectral and spatial contents under both experimental and natural illumination conditions.

Highlights

An imaging spectrometer samples the irradiance across a two-dimensional (2D) scene at multiple wavelengths
Some of the notable snapshot imaging spectrometers developed in the past 30 years include: the computed tomography imaging spectrometry (CTIS) technique first invented in 1991/1992, which simultaneously projects the image of the 2D scene onto a spatial plane with different directions and reconstruct the spectral information using computed tomography algorithms [11,12]
We report a snapshot imaging spectrometer design which simultaneously records both spatial and spectral information using a pair of polarization gratings (PG), a geometric phase microlens array (GPMLA) that has multiple focal lengths, and a common focal plane array (FPA) sensor

Summary

Introduction

An imaging spectrometer samples the irradiance across a two-dimensional (2D) scene at multiple wavelengths. Some of the notable snapshot imaging spectrometers developed in the past 30 years include: the computed tomography imaging spectrometry (CTIS) technique first invented in 1991/1992, which simultaneously projects the image of the 2D scene onto a spatial plane with different directions and reconstruct the spectral information using computed tomography algorithms [11,12]. We report a snapshot imaging spectrometer design which simultaneously records both spatial and spectral information using a pair of polarization gratings (PG), a geometric phase microlens array (GPMLA) that has multiple focal lengths, and a common focal plane array (FPA) sensor. Compared to the complicated and hard-to-fabricate components in other snapshot spectral imagers, the PGs and GPMLA in the proposed spectrometer have great potential to be rapidly fabricated with roll-to-roll (R2R) processing due to the recent improvement in geometric phase hologram (GPH) technique [18,19].

Principle of operation

Radiometric and spatial resolution tradespace

Experimental setup and lab validation

Outdoor imaging and measurement results

Conclusion