Measuring the refractive index of scintillation crystal with a Mach-Zehnder interferometer

Abstract

The refractive index of the scintillation crystal is a key parameter in the design of Positron Emission Tomography (PET) devices. However, existing methods to measure the refractive index always suffer from problems such as the complexity of optical path adjustment, long time cost, or high equipment consumption. To overcome these problems, we propose a method that can obtain the refractive index of the scintillation crystal with high accuracy in real time. In this method, we employ the Mach-Zehnder interferometer to generate the interference pattern when one beam of light passes through the scintillation crystal, which encodes the value of refractive index into the width of pattern. To obtain the width of interference pattern, we calculate the width pixels of dark/bright stripes in pattern with threshold, respectively, and finally get the average number of pixels of the pattern; this strategy can eliminate the coherent interference signal and random noise effectively. The optical path need not adjust during the whole measurement. Thus, the refractive index of scintillation crystals can be measured with reliability and efficiency. To validate the effectiveness of the proposed method, we measure different batches of BGO crystal and Ce:LYSO crystal samples. The results show that the proposed method can measure refractive indices with high accuracy and high efficiency, providing a reliable crystal refractive index measurement procedure for the PET detector module design. The proposed method is also suitable for refractive index measurements of transparent materials in visible light bands.

Simulation study of compressed ultrafast 3D imaging based on interferometry

“…The interferometer can realize equal thickness interference and equal tilt interference. According to the characteristics of the interference fringes, various physical properties, such as the refractive index of the liquid and the air velocity, are measured [20,21]. The compressed ultrafast 3D imaging system proposed in this paper is a 3D imaging system based on a Mach-Zehnder interferometer and streak camera.…”

Bio-inspired photonic and plasmonic systems for gas sensing: applications, fabrication, and analytical methods

“…93 Interferometric techniques such as Mach-Zehnder-type interferometers can be used to detect an analyte at low concentration from its slight change in the medium's refractive index, which produces detectable shifts in the interference fringes. 94,95 The optical response also depends on whether a medium is dielectric or metallic. In dielectric media, light interacts with a material by polarizing locally bound valence electrons.…”

“…One such technique is to measure the angle of refraction when light is incident on a region containing an analyte, enabling the determination of a refractive index using Snell’s law 93 . Interferometric techniques such as Mach–Zehnder-type interferometers can be used to detect an analyte at low concentration from its slight change in the medium’s refractive index, which produces detectable shifts in the interference fringes 94 , 95 …”

Suppressing the Zero-Frequency Components in Single Quantitative Phase Imaging by Filtering the Low-Frequency Intrinsic Mode Function Components

“…Quantitative phase imaging (QPI) [1][2][3][4], which is developed based on the principle of light interference and diffraction to reproduce the three-dimensional information of transparent or translucent measured objects [5], has been widely used in industrial micro-machining measurement [6], microscopic measurement [7] and environmental inspection [8]. It can be combined with compressed sensing [9][10][11], deep learning [12][13][14], autofocus [15][16][17], topological modulation [18][19][20] or compensation technology [21][22][23] to achieve higher precision measurement results for various applications.…”