No-scanning 3D measurement method using ultrafast dimensional conversion with a chirped optical frequency comb

A simultaneously high-precision, wide-range, and ultrafast time-resolution one-shot 3D shape measurement method is presented. Simultaneous times of flight from multiple positions to a target encoded in a chirped optical frequency comb can be obtained from spectral interferometry. We experimentally demonstrate a one-shot imaging profile measurement of a known step height of 480 µm with µm-level accuracy. We further demonstrate the extension of the dynamic range by measuring in one shot a large step height of 3 m while maintaining high accuracy using the accurate pulse-to-pulse separation of the optical frequency comb. The proposed method with its large dynamic range and measurement versatility can be applied to a broad range of applications, including microscopic structures, objects with large size or aspect ratio, and ultrafast time-resolved imaging. This study provides a powerful and versatile tool for 3D measurement, where various ranges of measurement performances can be tailored to demand

Synthesis of Poly(ethylene-block-vinylalcohol)for Use as Amphiphilic Film Surface at High Temperature

Poly (ethylene-block-vinyl alcohol), which consisted of both hydrophobic and hydrophilic blocks, was prepared by using polyethylene single crystals as starting material. Polyethylene single crystals reacted with fuming nitric acid resulting in long methylene chains with functional groups such as COOH and NO(2) at the ends (the chain length were almost same as the lamellar thickness of polyethylene single crystal). The functionalized methylene chains were allowed to react with 4-aminostyrene to give corresponding amides, i.e., methylene chains with vinyl groups at the ends (macromer). The macromers were extended by block-copolymerization with vinyl acetate, then saponified resulting in PE/PVA block co-polymer. The block copolymer was molded into sheets which were subsequently heat-treated in contact with hydrophilic or hydrophobic media. Depending on the media, the sheet surface changed at high temperature reversibly from hydrophilic to hydrophobic and vice versa. The surface property was fixed by quenching because both blocks were able to crystallize. Thus the surface of this material can be tailored for various purposes at high temperature, and then used in stable at room temperature

Scanning Probe Microscopy of Poly(p-phenylene benzobisthiazole) Lamellar Crystal

Rigid polymer, poly(p-phenylene benzobisthiazole), formed lamellar crystals where the molecular chains were oriented perpendicular to the lamellae. It was supposed that, because of wide distribution in the chain length, the lamellar surface bristled with the chain cilia among which many voids were included. Crystallographically, this region afforded us a transitional structure from full to deficient packings of chains. The structure was analyzed using the scanning probe microscope. In the course the method for imaging one molecular chain end was developed. From the images it was concluded that an isolated long cilius did not move so violently at room temperature

Ultraviolet emission from porous silicon photosynthesized in aqueous alkali fluoride solutions

Stable ultraviolet (UV) photoluminescence (PL) has been observed at room temperature in porous silicon (PSi) fabricated by photoetching in aqueous alkali fluoride solutions. The aqueous solutions used are 1 M NaF and 1 M KF.They give an alkaline reaction caused by partial hydrolysis. The PL peaks at ～3.3 eV have a full width at half maximum of ～0.1 eV, which is much smaller than those reported previously (?0.5 eV). Spectral analyses suggest that both quantum confinement and surface passivation effects enable the observation of UV emission in NaF- and KF-prepared PSi samples

High-resolution 3D imaging method using chirped optical frequency combs based on convolution analysis of the spectral interference fringe

We applied an imaging optical system and convolution analysis to a one-shot 3D imaging method with a chirped optical frequency comb to greatly improve the transverse spatial resolution and depth accuracy. We obtained the high contrast spectral interference of a diffusive surface using the designed lens system and developed a simple and robust analysis technique using convolution of an obtained the interference fringe. The developed method was demonstrated to realize submicron-level uncertainty for the depth measurement. When applied to the surface structure of a coin, it demonstrated a transverse spatial resolution of 8.98 lp/mm and depth resolution of 0.35 µm

Synthesis and Characterization of Poly[(benzo[1,2-d:5,4-d']bisthiazole-2,6-diyl)-1,4-phenylene]

Poly[(benzo[1,2-d:5,4-d']bissthiazole-2,6-diyl)-1,4-phenylene](cis-PBZT)with a relatively high molecular weight was prepared by a new synthesis route. Properties of the synthesized polymer, such as thermostability, liquid crystallinity etc. were investigated and compared with those of trans-PBZT. cis-PBZT was crystallized from dilute solution and the electron microscopy showed that the precipitate was a rod-like crystal similar to that of trans form. In spite of rigid nature of the back bone, cis-PBZT showed poor crystallinity

Solving multi-armed bandit problems using a chaotic microresonator comb

The Multi-Armed Bandit (MAB) problem, foundational to reinforcement learning-based decision-making, addresses the challenge of maximizing rewards amidst multiple uncertain choices. While algorithmic solutions are effective, their computational efficiency diminishes with increasing problem complexity. Photonic accelerators, leveraging temporal and spatial-temporal chaos, have emerged as promising alternatives. However, despite these advancements, current approaches either compromise computation speed or amplify system complexity. In this paper, we introduce a chaotic microresonator frequency comb (chaos comb) to tackle the MAB problem, where each comb mode is assigned to a slot machine. Through a proof-of-concept experiment, we employ 44 comb modes to address an MAB with 44 slot machines, demonstrating performance competitive with both conventional software algorithms and other photonic methods. Further, the scalability of decision making is explored with up to 512 slot machines using experimentally obtained temporal chaos in different time slots. Power-law scalability is achieved with an exponent of 0.96, outperforming conventional software-based algorithms. Moreover, we find that a numerically calculated chaos comb accurately reproduces experimental results, paving the way for discussions on strategies to increase the number of slot machines

Solution-Grown Crystals of Poly(p-phenylene benzobisthiazole)

Rigid polymer poly(p-phenylene benzobisthiazole) was crystallized from dilute solution. Electron microscopy showed that upon quenching, flat fibrils with several nm thick were produced. Subsequent heat treatment in solvent changed the fibril into "shish-kebab". On the other hand, by isothermal crystallization, an aggregate of parallel rod-like crystals was obtained. The molecular chains were accommodated normal to the rod. Based on the observation of crystal morphology, the isothermal crystallization mechanism was proposed. Because of regidity of polymer chains and wide distribution of the molecular length, the chain ends were inevitably included within the crystals resulting in crystal defects such as axial shift, lattice curvature and edge dislocation which were directly observed by lattice imaging