Zeroth-order phase-contrast technique

Abstract

What we believe to be a new phase-contrast technique is proposed to recover intensity distributions from phase distributions modulated by spatial light modulators (SLMs) and binary diffractive optical elements (DOEs). The phase distribution is directly transformed into intensity distributions using a 4f optical correlator and an iris centered in the frequency plane as a spatial filter. No phase-changing plates or phase dielectric dots are used as a filter. This method allows the use of twisted nematic liquid-crystal televisions (LCTVs) operating in the real-time phase-mostly regime mode between 0 and p to generate high-intensity multiple beams for optical trap applications. It is also possible to use these LCTVs as input SLMs for optical correlators to obtain high-intensity Fourier transform distributions of input amplitude objects.

Aplicação da técnica de contraste de fase da ordem zero na geração de pinças ópticas multi-feixe

“…As an alternative to HOTs, this technique has found its way into the implementation of static and dynamic multi-beam traps by way of the generalized phase contrast (GPC) method (Eriksen et al, 2002a;Eriksen et al, 2002b) and by hybrid holographic phase contrast techniques such as that proposed by Woerdemann (2012). In this master's project, we propose a new method, which consists of the integration of the zeroorder phase contrast technique (Pizolato et al, 2007) in a microscopy system for generation of static multi-beam optical traps. This technique makes use of existing concepts of Zernike phase contrast and two-pixel encoding techniques to generate intensity patterns in the image plane that are directly related to phase distributions in the input plane, which is comprised by a spatial light modulator (SLM).…”

“… Chapter 3 -Theoretical treatment of the zero order phase contrast technique. Using Fourier optics and the theory proposed by Pizolato et al (2007), we discuss the mathematical and optical details of this technique. Also, since an LCTV operating in the phase-mostly regime is used as the input DOE, we treat the main parameters of operation of this device.…”

“…The zero order phase contrast technique uses these same principles and modern methods to produce intensity distributions from phase distributions projected onto an LCTV operated in the phase modulation regime. whose phase shift is assumed to be less than one radian and is normalized in order to assure the linearity condition (0 ≤ a(x,y ) ≤ 1) (Neto, 1998;Goodman, 2004;Pizolato et al 2007).…”

“…Each macropixel in the diffractive element is divided into two phase regions, one that is Considering that the system is illuminated by a uniform, coherent wave of amplitude equal to unity, and applying the Taylor series approximation used in Equation 3.2 to the exp [ja(x,y)] term, the transmittance of t(x,y) can be expressed as follows (Banyal;Prasad, 2005;Pizolato et al 2007):…”

Uma nova abordagem da técnica de contraste de fase de ordem zero: geração e mapeamento direto de potenciais ópticos arbitrários

“…Nesse trabalho descrevemos o que acreditamos ser uma nova abordagem da Técnica de Contraste de Fase de Ordem Zero descrita por Pizolato 25…”