The optical fiber sensing method of the present invention includes steps of: joining heat shrinkable tubes to two ends of a sensing segment of an optical fiber; coupling a fixing element on the heat shrinkable tube below the sensing segment; detachably connecting at least one floating element to the fixing element; placing the floating element into a fluid; and providing an input signal to the sensing segment and generating an output signal after the input signal is processed by the sensing segment, wherein the tensile force applied to the sensing segment would change with variation of the buoyant force upon the floating element, resulting in change of the output signal. Accordingly, the optical fiber sensing method has numerous advantages, including rapid on-site construction, recyclability of components and changeability of design parameters.

A tiltmeter to measure a variation in inclination of a structure from a given starting position. The tiltmeter has two pots, each pot contains an identical volume and identical height of an identical liquid. A communication device connects the two pots and allows the liquid to flow between the two pots by the principle of communicating vessels. Two optical measuring devices are provided, one optical measuring device per pot. Each optical measuring device measures a variation in height of the level of liquid in the associated pot. The optical measuring devices are fiber optic devices coupled to a common light source.

A tiltmeter to measure a variation in inclination of a structure from a given starting position. The tiltmeter has two pots, each pot contains an identical volume and identical height of an identical liquid. A communication device connects the two pots and allows the liquid to flow between the two pots by the principle of communicating vessels. Two optical measuring devices are provided, one optical measuring device per pot. Each optical measuring device measures a variation in height of the level of liquid in the associated pot. The optical measuring devices are fiber optic devices coupled to a common light source.

A micrometer system and water holding cup and related for use in connection with a hydrostatic level-measuring system for measuring with precision, a level normal to gravitation of physical surfaces, the micrometer system comprising: a micrometer; an elongated micrometer probe tip at a lower extremity of the micrometer; a micrometer dial for extending and retracting the probe tip in response to a dialing thereof; a micrometer alignment section fixed to the micrometer, and a substantially rigid support structure for supporting the a micrometer alignment section at a fixed height above the physical surfaces when a footing of the support structure is rested upon the physical surfaces. The cup comprises mirroring on a bottom surface thereof; at least one reference feature on the mirroring surface for providing to a user, a visual reference for at least one micrometer grade marker reflected by the mirroring surface, for dialing a micrometer.

A micrometer system and water holding cup and related for use in connection with a hydrostatic level-measuring system for measuring with precision, a level normal to gravitation of physical surfaces, the micrometer system comprising: a micrometer; an elongated micrometer probe tip at a lower extremity of the micrometer; a micrometer dial for extending and retracting the probe tip in response to a dialing thereof; a micrometer alignment section fixed to the micrometer, and a substantially rigid support structure for supporting the a micrometer alignment section at a fixed height above the physical surfaces when a footing of the support structure is rested upon the physical surfaces. The cup comprises mirroring on a bottom surface thereof; at least one reference feature on the mirroring surface for providing to a user, a visual reference for at least one micrometer grade marker reflected by the mirroring surface, for dialing a micrometer.

The objective of the invention is to improve the durability and reduce the weight of a device for measuring the difference between the drafts on the two sides of ship, by making it possible to prevent the occurrence of bubbles in a measuring liquid and prevent leakage of the measuring liquid. In order to measure the difference between the drafts on the two sides of a ship, a measuring device (1) is provided with: two liquid level measuring tubes (11) attached respectively to the port and starboard sides of the ship; a communicating hose (41) which causes the two liquid level measuring tubes (11) to communicate with one another; and a drum (51) to which a central portion of the communicating hose (41) is secured, and onto which a left hose section (41a) and a right hose section (41b) are wound simultaneously. In order to bend the central portion of the communicating hose (41) into a U-shape to catch said central portion, the measuring device (1) includes a hose catching projection (51c) which protrudes from an outer peripheral surface of a shaft member (51a) of the drum (51), and a resin coil spring (42) mounted on the central portion of the communicating hose (41).

A water-holding cup for use in connection with a hydrostatic system for measuring with precision, a level normal to gravitation of a surface, said cup comprising: a cup height h thereof from a bottom to a top of said cup when said cup is resting upon the surface, which cup height h is known a priori within acceptable measurement errors; mirroring on a bottom surface of said cup; and at least two water outlets for fluidically interconnecting said cup with other like-cups, said outlets oriented at a fitting angle of at least five (5) degrees downward.

A water-holding cup for use in connection with a hydrostatic system for measuring with precision, a level normal to gravitation of a surface, said cup comprising: a cup height h thereof from a bottom to a top of said cup when said cup is resting upon the surface, which cup height h is known a priori within acceptable measurement errors; mirroring on a bottom surface of said cup; and at least two water outlets for fluidically interconnecting said cup with other like-cups, said outlets oriented at a fitting angle of at least five (5) degrees downward.

A hydrostatic level-measuring system and related apparatus and method for measuring with precision, a level normal to gravitation of a physical surface, comprising: a plurality of N water-holding cups containing water and fluidically interconnected with one another and resting upon the physical surface, where N is greater than or equal to 2; each of the water-holding cups of comprising a cup height h.sub.n thereof from a bottom to a top of the cup which cup height h.sub.n is known a priori within acceptable measurement errors; and a micrometer system for measuring on an absolute or relative scale, a distance d.sub.n between the top of each the cup and the top surface of the water wherein a meniscus visible to a user is formed when the contact occurs and the meniscus is used to guide the measurement precision.

A hydrostatic level-measuring system and related apparatus and method for measuring with precision, a level normal to gravitation of a physical surface, comprising: a plurality of N water-holding cups containing water and fluidically interconnected with one another and resting upon the physical surface, where N is greater than or equal to 2; each of the water-holding cups of comprising a cup height h.sub.n thereof from a bottom to a top of the cup which cup height h.sub.n is known a priori within acceptable measurement errors; and a micrometer system for measuring on an absolute or relative scale, a distance d.sub.n between the top of each the cup and the top surface of the water wherein a meniscus visible to a user is formed when the contact occurs and the meniscus is used to guide the measurement precision.