@article{oai:nagoya.repo.nii.ac.jp:00031343, author = {Nakamura, Yusuke and Suzuki, Takumi and Kinefuchi, Kiyoshi and Sasoh, Akihiro}, issue = {1}, journal = {Experiments in Fluids}, month = {}, note = {An advanced background-oriented schlieren (BOS) method, named as the speckle beam-oriented schlieren technique, was newly developed to measure the distribution of refraction angles in transparent media. A speckle pattern is generated by passing a coherent laser beam through a holographic diffuser, a pinhole, and a lens, generating a collimated background image that is projected directly onto the image sensors. Since the intensity of the background image is maintained at a high level, this method is, in principle, useful for diagnosing fast and/or low signal-to-noise phenomena, such as high-temperature gasses with radiation emission. Moreover, by splitting the background beam into two imaging paths with different focal lengths, the refraction angles can be measured for a schlieren object with uncertain location, and the depth position of the refraction angles can be resolved. This technique was demonstrated by measuring the refraction angle and the depth position distribution in a sonic jet with different injected locations., Published: 08 January 2021 ファイル公開:2022/01/08}, title = {Speckle beam-oriented schlieren technique}, volume = {62}, year = {2021} }