Abstract: A vortex chamber includes an outer circumference wall, a container, an annular shoal portion provided between the container and the outer circumference wall so as to encircle the outer circumference of the container, and a dam portion protruding upward from the upper surface of the outer circumference of the container so as to partition the container from the shoal portion. An undried nonferrous metal block is fed into the shoal portion, the block having such a size that is not completely submerged into the molten metal in the shoal portion. The fed nonferrous metal block is gradually melted to have a reduced volume of small pieces and particles of nonferrous metal, which are re-circulated in the shoal portion, flown over the dam portion, and dropped into the container, thereby forming a vortex in the container in which remaining small pieces and particles submerged into the molten metal are melted.

Abstract: A vortex chamber includes an outer circumference wall, a container, an annular shoal portion provided between the container and the outer circumference wall so as to encircle the outer circumference of the container, and a dam portion protruding upward from the upper surface of the outer circumference of the container so as to partition the container from the shoal portion. An undried nonferrous metal block is fed into the shoal portion, the block having such a size that is not completely submerged into the molten metal in the shoal portion. The fed nonferrous metal block is gradually melted to have a reduced volume of small pieces and particles of nonferrous metal, which are re-circulated in the shoal portion, flown over the dam portion, and dropped into the container, thereby forming a vortex in the container in which remaining small pieces and particles submerged into the molten metal are melted.

Abstract: The present invention relates to a low pass filter including a wave plate capable of modulating incident light serving as image information such that A-polarized light and B-polarized light orthogonal to the A-polarized light are at an equivalent light quantity level over a visible light region, i.e., a transmittance takes a value close to 50%. According to the low pass filter of the present invention, it is possible to appropriately reduce a moiré phenomenon generated by an image sensor constituting the optical low pass filter including the above-described wave plate, and suppress degradation of an image quality caused by light quantity deflection of a separated light beam, and the low pass filter of the present invention is therefore useful.

Abstract: The present invention relates to a low pass filter including a wave plate capable of modulating incident light serving as image information such that A-polarized light and B-polarized light orthogonal to the A-polarized light are at an equivalent light quantity level over a visible light region, i.e., a transmittance takes a value close to 50%. According to the low pass filter of the present invention, it is possible to appropriately reduce a moiré phenomenon generated by an image sensor constituting the optical low pass filter including the above-described wave plate, and suppress degradation of an image quality caused by light quantity deflection of a separated light beam, and the low pass filter of the present invention is therefore useful.