To realize high spatial resolution imaging ellipsometric measurement with large field of view, we developed a rotatable Offner system with unit magnification. When the conventional Offner imaging system is tilted relative to the sample plane for the ellipsometric measurement, only a small region of plane is in focus. The rotatable Offner system developed here renders the entire object in focus through all rotations. The performance of the prototype of the Offner system and imaging ellipsometer is tested by generating maps of the ellipsometric parameters Δ and Ψ for samples such as a silicon wafer and a resolution target made of chromium film evaporated on a glass substrate.

Ellipsometry is a standard metrology tool for measuring thin films and characterizing surfaces. As an extension of single-point ellipsometry, imaging ellipsometry is implemented by replacing a detector with an imaging system and a detection array. The compensator used in an ellipsometer is often nonideal. In single point ellipsometry, the beam is aligned in an effort to pass it through the center of the compensator, and the retardation error is considered to remain near-constant during compensator rotation. In imaging ellipsometry, however, the retardation of the imperfect compensator manifests inhomogeneity across the whole view field, and then, the rotation of the compensator changes the error distribution for the same view field. In this paper, we describe imaging ellipsometry with polarizer and imperfect compensator rotations and propose a method of calibrating the inhomogeneous retardation of the compensator. We simultaneously compensate the alignment errors of the compensator and polarizer. The method can extract calibration parameters directly from one measurement, without the need for a separate calibration step. The approach was tested practically using a homemade imaging ellipsometer by generating maps of the ellipsometric parameters Δ and ψ of Si and SiO2/Si wafers.

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With the increasing availability of the COVID-19 vaccines, vaccination has been rapidly promoted globally as a countermeasure against the spread of COVID-19. In Japan, vaccination was first introduced in February 2021. However, the amount of concern towards vaccination differs between individuals, and topics of concern include adverse reactions and side effects. This study investigated attitudes toward vaccines or vaccination during the COVID-19 pandemic across different Japanese prefectures, using Yahoo! JAPAN search queries. We first defined a vaccine concern index (VCI) by aggregating the search counts of vaccine-related queries from Yahoo! JAPAN users before examining VCI across all Japanese prefectures, accounting for gender and age. Our results demonstrated that VCI tended to be lower in more populated areas, and VCI was higher in their 20s to 40s than older people, especially in female users. Furthermore, there was a significant positive correlation (Spearman’s Rank correlation coefficient $$\rho$$ ρ = 0.60, $$p < 0.001$$ p < 0.001 ) between VCI and prefectural vaccination rate, suggesting that web searching of adverse vaccine reactions may precede actual vaccination. This could reflect the information-seeking behavior of individuals who are accepting of vaccinations.

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