Super-Achromatic Quarter-Wave Phase Retarder for Visible, Near Infrared, and Short Wave Infrared Region Applications
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PTICAL MATERIALS
Super-Achromatic Quarter-Wave Phase Retarder for Visible, Near Infrared, and Short Wave Infrared Region Applications N. Mukhopadhyaya,*, A. Sahab, and K. Bhattacharyac a
Department of Electronics and Communication Engineering, Global Institute of Management and Technology, Krishnagar, Nadia, 741102 India b Department of Electronics and Communication Engineering, B.P. Poddar Institute of Management and Technology, Kolkata, 700 052 India c Department of Applied Optics and Photonics, University of Calcutta, Kolkata, 700098 India * e-mail: [email protected] Received December 8, 2018; revised May 7, 2020; accepted May 7, 2020
Abstract—Phase retarders are essential components in optical system design as they can control the phase shifts associated with the vector components of incoming light waves and hence, decide the state of polarization. Different optical systems are designed to work at different wavelength spectrums. Most of these developments focus on the different wavelength regions between visible to infrared, of which the near infrared and short-wave infrared ranges are popular domains for defense and remote sensing applications. In this present communication, a super achromatic quarter-wave phase retarder consisting of four birefringent plates of different materials, i.e., KDP, crystalline quartz, ADP and ZnS has been proposed, to cover the visible, near infrared and short wave infrared regions from 400–2100 nm. As circularly polarized light is less affected by atmospheric conditions the use of an achromatic broadband quarter-wave phase retarder as proposed is quite useful. The proposed system shows acceptable performance over the intended range of wavelengths. Keywords: wave plates, super achromatic, retarder, SWIR DOI: 10.1134/S0030400X20080251
1. INTRODUCTION Since a single quarter-wave plate is highly wavelength dependent, quarter-wave plates showing achromatic nature is in high demand. Earlier, different achromatic combinations were proposed which composed of two or more than two birefringent plates of different or same materials for particular wavelength regions. These systems were designed keeping particular applications in mind. A combination of three plates of same material, proposed by Pancharatnam, shows good a chromatism over the visible wavelength region [1]. Hariharan, Nicolas Passily and many others have proposed different systems for different spectrum regions [2, 3]. Achromatic systems designed with liquid crystals have also been proposed although they have limited temporal stability [4]. Recent developments suggest that SWIR region is very useful for defense applications such as high resolution infrared imaging [5, 6]. Phase retarder plays an important role as it can control the phase shifts and polarization states such as the use of broadband achromatic quarter-wave phase retarder in the astronomical polarimetry [7]. The use of UAV/drone for remote sensing applications demands designing of highly efficient optical system, and it uses the visible to infrared region of the w
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