MOISTURE SENSOR BY OPTICAL THIN FILM FILTER FROM GLANCING ANGLE DEPOSITION

摘要

The present invention uses an optical fiber and optical collimator slope deposition (glancing angle deposition) thin film optical fiber link relates to a humidity sensor, including how to interpret the structure and efficiently detect signals such that the packaging. Slope and the optical thin film is deposited fine porous structure, where the moisture penetration, and when the repeated escape have a correlation to the effective refractive index of the film by the moisture and humidity, so to know the humidity change by detecting the transmitted or reflected light to the incident light would that be. Slope deposition applied to the present invention is a thin film optical humidity sensor making miniaturized because it is possible to manufacture a packaging size of a few millimeters. Humidity sensor packaging according to the present invention is made parallel light via the optical fiber induced by the optical collimator, the optical thin film deposition inclined surface are separated by a transmission or reflection light from an optical characteristic change due to the moisture because it is incident to the optical fiber structure can be detected precisely. In addition, it selected a packaging structure using an epoxy or soldering property is excellent in environmental sensor is obtained in order to maintain the alignment structure. Placing the optical thin film deposited on a slope between the light collimator may cause noise to the etalon for the optical signal, in the present invention, the optical thin film deposition device for tilting the tilt direction perpendicular to the light proceeding to remove the noise in these etalon (tilted) or the optical film is arranged to apply a non-reflective thin film coating on the substrate back surface does not position the structure is selected to remove noise. Since the optical thin film is oblique evaporation sensitive to humidity change, but also respond to temperature changes, to separate the temperature change or humidity signal in the present invention in order to detect changes with temperature change at the same time when one optical thin film is deposited to package the moisture gradient is easy to open and out of the structure, and the other is made of a closed structure can not be detected separately from the humidity out of the influence of the temperature in parallel arranged in the same place. In the present invention, can detect the direction of the optical power changes due to changes in humidity over the two detection wavelength changed by oblique incident from the optical thin film deposited on the structure for detecting the transmitted light and the reflected light at the same time in each of the four transmitting and semi-independent detection wavelength from each other there. Humidity sensor according to the present invention is a structure which, because it is possible to use an optical fiber sensing the humidity changes from a distance without a separate power supply. In particular, the spectral characteristics of the optical thin film deposition inclined band is transmitted in accordance with the present invention cross-matching Fabry-Perot filter, etc. When designed to form an optical fiber from the same optical fiber line connected to the humidity sensor according to the present invention in series also many places at the same time may sense a change in humidity at the same time. In this case, read out on a specific location that the humidity change factor can use the measurement equipment such as OTDR. ; Thus, according to the optical thin film deposition slope humidity sensor according to the present invention, the humidity sensing distance is possible without an external power supply by using the optical fiber. This can be applied in real time or the like for the humidity-sensing module and a system exposed to the external environment.