Abstract: An optical sensor includes: a metal base formed into a cylindrical shape; an optical fiber member inserted into the base; and a sensor head that is bonded to the base and is optically connected to the optical fiber member, the sensor head including a head portion formed from monocrystalline alumina, in which the base includes a fitting portion into which the sensor head is inserted, and the sensor head is bonded to the fitting portion via a bonding member.

Abstract: An optical sensor includes a tube-shaped base formed from a metal, an optical fiber member received inside the base, and a sensor head formed from monocrystalline alumina and bonded to the base to be optically connected with the optical fiber member. The sensor head is provided with a first cavity including a first reflection surface configured to reflect a part of light introduced through the optical fiber member and a second reflection surface provided facing the first reflection surface and configured to reflect a part of the light reflected by the first reflection surface. A first interference light produced by an interference between the light reflected by the first reflection surface and the light reflected by the second reflection surface is output from the first cavity.

Abstract: A pressure sensor module 2, wherein a holding space 34 is formed between a diaphragm 22 and a thin film layer 31, and a vent hole 321 communicating with the exterior of a first case is provided in the holding space 34. In the above pressure sensor module, even when a corrosive gas or chemical solution is used as a fluid to be measured and a corrosive gas component originated from the fluid to be measured permeates into the holding space 34, the permeated corrosive gas component can be discharged to the outside of the case through the vent hole 321. As a result, the corrosion of the diaphragm 22 by the fluid to be measured can be prevented, which results in the achievement of a prolonged service life of the pressure sensor module 2.

Abstract: A pressure sensor module 2, wherein a holding space 34 is formed between a diaphragm 22 and a thin film layer 31, and a vent hole 321 communicating with the exterior of a first case is provided in the holding space 34. In the above pressure sensor module, even when a corrosive gas or chemical solution is used as a fluid to be measured and a corrosive gas component originated from the fluid to be measured permeates into the holding space 34, the permeated corrosive gas component can be discharged to the outside of the case through the vent hole 321. As a result, the corrosion of the diaphragm 22 by the fluid to be measured can be prevented, which results in the achievement of a prolonged service life of the pressure sensor module 2.