Abstract: An optical sensor includes a first light-receiving element with one of a first polygonal ring shape and a first circular ring shape, a second light-receiving element with one of a second polygonal ring shape and a second circular ring shape, the second light-receiving element being provided separately from the first light-receiving element and concentrically with the first light-receiving element, and a subtraction device configured to conduct subtraction between an output from the first light-receiving element and an output from the second light-receiving element.

Abstract: A chain which does not generate hydrogen brittleness is formed with components having improved wear resistance. At least one part of the chain, for example a surface, is covered with a diamond-like amorphous carbon coating (DLC). Further, metallic particles are dispersed into the diamond-like amorphous carbon coating.

Abstract: A chain which does not generate hydrogen brittleness is formed with components having improved wear resistance. At least one part of the chain, for example a surface, is covered with a diamond-like amorphous carbon coating (DLC). Further, metallic particles are dispersed into the diamond-like amorphous carbon coating.

Abstract: A tensioner is formed with components having improved wear resistance. At least one component of the tensioner is covered with a diamond-like amorphous carbon coating (DLC). The coating is applied to the tensioner without causing hydrogen brittleness in metallic members. In addition, the coating may be formed on tensioner components formed with resin. In one embodiment of the invention, a metal element is dispersed into the diamond-like amorphous carbon coating.

Abstract: Cylindrical support 20 having dope prism 2 built therein is rotatably fitted in barrel 23 as a constituent of stomatocamera frame 11. The support 20 has pin 22 erected on its periphery, and the barrel 23 is furnished with guide channel 4 formed along its circumference. The pin 22 pierces the guide channel 4 and protrudes from the periphery of the barrel 23. Protrudent end of the pin 22 is locked to locking channel 6 of operating ring 5 fitted to the periphery of the barrel 23. The dope prism 2 built in the camera frame is rotated by revolving the operating ring 5. Thus, the image can be rotated without the need to revolve the CCD camera frame.

Abstract: A process for producing an ethenyl amide compound, which comprises reacting a Schiff base compound having a carbon atom adjacent to a carbon atom constituting an imino group and at least one hydrogen atom on the carbon atom with an acylhalide at a reduced pressure while removing by-produced hydrogen halide by distillation to produce an ethenyl amide compound having an amide bond in the molecule and a double bond between carbons at .alpha.-position and .beta.-position with respect to the nitrogen atom of the amide bond.