The “third wave" of PSP/TSP development has arisen and Japan plays a central role in R&D of this technology. Current activities are focused on two aspects; the application to industries and the expansion of application fields. Industrial applications of the techniques have been pursued particularly in the fields of transportation and energy. The performance and measurement accuracy of PSP/TSP keep improving progressively. The current targets of PSP are to measure small pressure fluctuation which acts as the source of aerodynamic noise, pressure fluctuation on a blade with high-speed rotation, and so on. For TSP, measurement of temperature fluctuation due to combustion in the high-temperature region exceeding 1000 degrees in Celsius is feasible. Since PSP/TSP is a system measurement technique, integration of PSP/TSP with MEMS and IoT (Internet of Things) is expected. In the near future, PSP/TSP will advance not only as flow visualization techniques but also flow control technology with various types of actuators.

Fundamental elements for the unsteady PSP/TSP measurement, which were measurement hardware, paint, and data reduction method, were introduced in this paper. Especially, difference from the conventional PSP/TSP measurement in papers in the special issues were described in detail. Important researches for the unsteady PSP/TSP measurement progress were picked up to understand key points of the technologies. Recent progresses in PSP/TSP paint developments and data reduction methods were also introduced.

Pressure- and temperature-sensitive paints provide visualizing technique based on photochemical process of sensing materials. Spatial and temporal resolutions, selectivity and applicable range crucially depend on the materials. In this article, we review recent development of advanced materials such as functional polymers, nanomaterials and luminescent rare-earth complexes, for PSP/TSP application.

Measurement technique using Pressure-Sensitive Paint (PSP) has already been utilized in practical wind tunnel tests in aircraft development because of a large amount of information in pressure distribution measurement. Temperature-Sensitive Paint (TSP) has also been developed in the aerospace field to correct the temperature of the PSP. This technique is also applied to the measurement of the aerodynamic heating rate generated at hypersonic speed, and it is expected to be applied to databases that contribute to the design of spacecraft.

  In this paper, we introduce the state-of-the-art practical applications of these PSP/TSP measurement technique. It also touches development trends in the aerospace field of PSP/TSP in Europe.

This review summaries the application of phosphorescence measurement for the various fields except for aerospace field. Especially we focused on the application to fuel cell, turbomachinery , biogeochemical processes in aquatic environments, medical field, and single cell analysis.