Construction of Nonlinear Symplectic Six-Dimensional Thin-Lens Maps by Exponentiation

The aim of this paper is to construct six-dimensional symplectic thin-lens transport maps for the tracking program SIXTRACK, continuing an earlier report by using another method which consistes in applying Lie series and exponentiation as described by W. Groebner and for canonical systems by A.J. Dragt. We firstly use an approximate Hamiltonian obtained by a series expansion of the square root. Furthermore, nonlinear crossing terms due to the curvature in bending magnets are neglected. An improved Hamiltonian, excluding solenoids, is introduced in Appendix A by using the unexpanded square root mentioned above, but neglecting again nonlinear crossing terms...Comment: 57 pages, late

6D Beam-Beam Kick including Coupled Motion

The 6D beam-beam interaction as developed in 1992 by Hirata, Moshammer and Ruggiero [1,2] has been extended to include linear coupled motion and an arbitrary crossing plane. The technique of sympletic mapping the six-dimensional phase space, called synchro-beam mapping (SBM), is applied to investigate the beam-beam kick within a solenoid. A linear beam-beam model including coupling is discussed in detail, also in the framework of a six-dimensional symplectic dispersion formalism

In-situ analysis of small microplastics in coastal surface water samples of the subtropical island of Okinawa, Japan

Marine plastic debris is widely recognized as a global environmental issue. Sun-micron plastic particles, with an upper size limit of 20 um, have been identified as having the highest potential for causing damage to marine ecosystems. Having accurate methods for quantifying the abundance of such particles in a natural environment is essential for defining the extent of the problem they pose. Using an optical micro-Raman tweezers setup, we have identified the composition of particles trapped in marine aggregates collected from the coastal surface waters around the subtropical island of Okinawa. Chemical composition analysis at the single-particle level indicates dominance by low-density polyethylene, which accounted for 75% of the total sub-micron plastics analyzed. Our results show the occurrence of plastics at all test sites, with the highest concentration in areas with high human activities. The average, smallest sub-micron plastics size is (2.53 +/- 0.85)um for polystyrene. We also observed additional Raman peaks on the plastics spectrum with decreasing debris size which could be related to structural modification due to weathering or embedding in organic matter. By single-particle level sub-micron plastics identification, we can begin to understand their dispersion in the ocean and define their toxicity and impacts on marine biodiversity and food chain.Comment: 9 page

Simulations of imperfect refractive index matching in scanning laser optical tomography and a method for correction

Since additive manufacturing has become increasingly popular in prototyping, printed optics are also beginning to enter the market. Novel characterization methods for printed optics are needed because traditional, destructive methods often do not work on these optics. The scope of investigation is also different for additively manufactured optics. Homogeneity of subtractive manufactured optics such as glass lenses is usually granted but for printed optics the interfaces in-between layers can cause absorption, scattering or refraction. Functionalized optics can also have characteristics such as fluorescence that cannot be tested with traditional methods. The presented work tries to fill the void for this particular challenge by studying two non-destructive methods for optical characterization of such components and expanding their use by clever combination. In Scanning Laser Optical Tomography (SLOT), a needle-like beam is formed and focused into the sample. The sample is scanned to form projection images and rotated to allow for reconstruction, which yields volumetric data about scattering, transmission and fluorescence of sample structures. Simulated SLOT measurements with imperfect Refractive Index (RI) matching of sample and medium are presented. A method to correct distorted measurements is presented and evaluated. The simulations imply that a measurement with a RI mismatch of up to 0.1 can still yield reasonable results. Copyright 2023 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited