Abstract: A slit for selectively allowing the transmission of emitted light from a light-emitting portion that has been diffracted through passing through a pipe wherein there is no fluid is provided on the slit side of the pipe, between a slit of the light-emitting portion and a slit of a detecting portion. The emitted light from the light-emitting portion, which is diffracted by passing through the pipe wherein there is a fluid, is blocked by the plate member wherein the slit is formed, so as to not arrive at the detecting portion.

Abstract: In a thermoelectric device, a thermoelectric element has one surface on a low temperature side and the other surface on a high temperature side. A member is attached to at least one of the low- and high-temperature-side surfaces of the thermoelectric element. A temperature detection element is provided between the member and the surface of the thermoelectric element to which the member is attached. A mirror surface state detection device is also disclosed.

Abstract: The long-side surface of a triangular prism is a detection surface. The distal end portions of coaxial light-emitting/light-receiving optical fiber cables are joined to one short-side surface of the prism. A thermoelectric cooling element is mounted on the other short-side surface of the prism. A mirror is provided between the cooling surface of the thermoelectric cooling element and the short-side surface. When dew condensation occurs on the detection surface, part of light applied from an optical fiber on the light-emitting side onto the lower surface of the detection surface exits from the prism through the condensed dew. The specular reflection returns to the lower detection surface by a mirror surface and is specularly reflected again. The specular reflection then enters an optical fiber on the light-emitting side. Dew condensation on the detection surface is detected by a change in the intensity of light received through the optical fiber.

Abstract: The long-side surface of a triangular prism is a detection surface. The distal end portions of coaxial light-emitting/light-receiving optical fiber cables are joined to one short-side surface of the prism. A thermoelectric cooling element is mounted on the other short-side surface of the prism. A mirror is provided between the cooling surface of the thermoelectric cooling element and the short-side surface. When dew condensation occurs on the detection surface, part of light applied from an optical fiber on the light-emitting side onto the lower surface of the detection surface exits from the prism through the condensed dew. The specular reflection returns to the lower detection surface by a mirror surface and is specularly reflected again. The specular reflection then enters an optical fiber on the light-emitting side. Dew condensation on the detection surface is detected by a change in the intensity of light received through the optical fiber.

Abstract: In a thermoelectric device, a thermoelectric element has one surface on a low temperature side and the other surface on a high temperature side. A member is attached to at least one of the low- and high-temperature-side surfaces of the thermoelectric element. A temperature detection element is provided between the member and the surface of the thermoelectric element to which the member is attached. A mirror surface state detection device is also disclosed.