Abstract: A method of reducing noise from a high-speed, including supersonic, jet, the method includes providing the high-speed or supersonic jet in a longitudinal flow direction; and inducing a rotation of a swirl layer of the high-speed or supersonic jet around a longitudinal direction of the jet and on the jet boundary so as to promote mixing of the high-speed or supersonic jet with surrounding air.

Abstract: Each of monodisperse spherical microcapsules for seeding a transparent fluid to track movements of the fluid both in translational and rotational directions comprises a core; a shell; and 1 to 5 light reflecting solid integral particles. Each of the particles reflects incoming light in a defined direction; and each of the particles is embedded in the core and fixed in its orientation with regard to the shell. The shell and the core are transparent for the incoming light to be reflected by the particles entering and exiting the microcapsule. The shell has a thickness of not more than ?, ? being a wavelength of the incoming light, so that the shell does essentially not deflect the incoming light entering and exiting the microcapsule. The core includes a main component of the fluid such that a refraction index of the core essentially matches a refraction index of the fluid.

Abstract: Each of monodisperse spherical microcapsules for seeding a transparent fluid to track movements of the fluid both in translational and rotational directions comprises a core; a shell; and 1 to 5 light reflecting solid integral particles. Each of the particles reflects incoming light in a defined direction; and each of the particles is embedded in the core and fixed in its orientation with regard to the shell. The shell and the core are transparent for the incoming light to be reflected by the particles entering and exiting the microcapsule. The shell has a thickness of not more than ?, ? being a wavelength of the incoming light, so that the shell does essentially not deflect the incoming light entering and exiting the microcapsule. The core includes a main component of the fluid such that a refraction index of the core essentially matches a refraction index of the fluid.

Abstract: Spherical microcapsules including light reflecting solid integral particles reflecting incoming light in a defined direction for determining the position and orientation of the microcapsule are produced by preparing a first liquid phase containing a first polymerization partner; preparing a second liquid phase containing a second polymerization partner, the first liquid phase not being soluble in the second liquid phase, and the second polymerization partner being configured to polymerize with the first polymerization partner under polymerization conditions; dispersing the solid particles in the first liquid phase; forming droplets of the first liquid phase including at least one solid particle; and immersing the droplets in the second liquid phase under the polymerization conditions.

Abstract: For determining positions and orientations of mirrors, the mirrors are illuminated with parallel light rays. A first camera is arranged in an image plane onto which an objective images the mirrors. A second camera is arranged in a focal plane of the objective, and a third camera is arranged in an intermediate plane located at distances to both the image and the focal plane. At a same point in time, a first, a second and a third picture are taken with the first, the second and the third camera, respectively. The positions and the orientations of the mirrors are determined from light spots in the first and the second picture, respectively; and which of the orientations belongs to which of the positions is determined by correlating light spots in the third picture with both the light spots in the first and in the second picture.

Abstract: Spherical microcapsules including light reflecting solid integral particles reflecting incoming light in a defined direction for determining the position and orientation of the microcapsule are produced by preparing a first liquid phase containing a first polymerization partner; preparing a second liquid phase containing a second polymerization partner, the first liquid phase not being soluble in the second liquid phase, and the second polymerization partner being configured to polymerize with the first polymerization partner under polymerization conditions; dispersing the solid particles in the first liquid phase; forming droplets of the first liquid phase including at least one solid particle; and immersing the droplets in the second liquid phase under the polymerization conditions.

Abstract: For determining positions and orientations of mirrors, the mirrors are illuminated with parallel light rays. A first camera is arranged in an image plane onto which an objective images the mirrors. A second camera is arranged in a focal plane of the objective, and a third camera is arranged in an intermediate plane located at distances to both the image and the focal plane. At a same point in time, a first, a second and a third picture are taken with the first, the second and the third camera, respectively. The positions and the orientations of the mirrors are determined from light spots in the first and the second picture, respectively; and which of the orientations belongs to which of the positions is determined by correlating light spots in the third picture with both the light spots in the first and in the second picture.