A light detection and ranging (LIDAR) device scans through a scanning zone while emitting light pulses and receives reflected signals corresponding to the light pulses. The LIDAR device scans the emitted light pulses through the scanning zone by reflecting the light pulses from an array of oscillating mirrors. The mirrors are operated by a set of electromagnets arranged to apply torque on the mirrors, and an orientation feedback system senses the orientations of the mirrors. Driving parameters for each mirror are determined based on information from the orientation feedback system. The driving parameters can be used to drive the mirrors in phase at an operating frequency despite variations in moments of inertia and resonant frequencies among the mirrors.

Light steering device with an array of oscillating reflective slats

A sheet includes an optical fiber extending across at least a portion of its surface to detect a breach or nuclear radiation. The sheet can line at least a portion of a container or a fence. A breach of the, sheet or radiation within or near the sheet reduces optical transmissibility of the fiber. The fiber integrates the radiation over time and/or over the length and volumetric mass of the fiber, making the fiber sensitive to even low-level radiation. The optical fiber is monitored for a change in its transmissibility. A reduction in the transmissibility, such as to below a threshold, can trigger an alarm, such as an annunciator, or send a message that includes information about the time or the container's contents or location when the breach or radiation is detected to a central location, such as a ship's control room or port notification system.

Tamper proof container

A friction estimation and compensation technique was implemented on a laboratory apparatus designed to permit the direct measurement of friction. Experimental results are reported for a friction observer which estimates the total friction present, assuming that it is a constant times the sign of velocity. An second observer is used to estimate the velocity using the measured position of the rotating shaft in the apparatus, when the velocity is not measurable. Experimental results show that the friction estimate is consistent with the measured friction, displaying the theoretical hysteresis phenomenon. Moreover, the performance of the system is substantially improved, especially at very low velocity, through the use of the estimated friction to compensate the system.

/pdf/implementation-of-a-friction-estimation-and-compensation-s36nchacke.pdf

Implementation of a friction estimation and compensation technique

The invention relates to the field of fiber optics, and more particularly to birefringence in single-mode fibers. The sensitivity of a fiber optic sensor coil for a current sensor may be incresed by winding the sensing fiber, without torsion, around a current-carrying wire to form the coil, wherein the pitch angle of the fiber (14) may be selected to result in a phase shift due to Berry's phase of circularly polarized light propagating throught the fiber. Preferably, the pitch angle may be approximately 60°.

Decreasing the effects of linear birefringence in a fiber-optic sensor by use of berry's topological phase

The invention is directed to an apparatus and a method for reducing noise, in particular RIN noise, in optical sensors, in particular fiber-optic sensors. The optical sensor produces a sensor output signal representing a physical quantity to be measured and also contains a first noise component, which is detected by a first detector. A separate detector detects an input light noise component of the input light source of the optical sensor and produces a second noise component. The second noise component is electronically processed and time-delayed by a filter by a time delay which substantially corresponds to the time delay experienced by the sensor input light traversing the optical sensor. The time-delayed processed signal is then subtracted from the sensor output signal to produce a reduced noise optical sensor signal corresponding to the measured physical quantity.

Apparatus and method for electronic RIN reduction in fiber-optic sensors utilizing filter with group delay

A ring laser gyro system having at least one fixed mirror, and two movable mirror assemblies, for causing a pair of laser beams to counter-rotate therebetween, including amplitude control circuits and a phase control circuit for causing the movable mirror assemblies to sinusoidally oscillate at the same amplitude and frequency, but 180° out of a phase with one-another, to substantially eliminate lock-in.

System for substantially eleminating lock-in in a ring laser gyroscope

A control system is designed and implemented for a test table the motion of which is to track the output of a gyroscope. The process to be controlled is governed by a third-order differential equation with an important nonlinearity due to static friction. Representing the friction as an independent random walk yields a dynamic process amenable to design by methods of linear control theory. An existing design program was used to calculate the compensator transfer function which was realized with standard capacitors, resistors, and operational amplifiers. The compensator was installed in the test table and results in excellent closed-loop system performance.

Design of servo for gyro test table using linear optimum control theory

A precision accelerometer is provided which is capable of measuring linear accelerations along three axes The accelerometer incorporates a self-charging radioactive particle as the inertial acceleration sensing mass The particle is contained in an evacuated cubical chamber, and the position of the particle within the chamber is established by the differential between the mean number of emitted charged particles detected at the opposite walls of the chamber, whenever the particle moves from a central position within the chamber The accelerometer includes an electronic control system which generates feedback signals that tend to maintain the particle centered within the chamber in the presence of accelerations, and at the same time to provide electrical outputs which are measurements of the accelerations along the three coordinate axes

Accelerometer using radioactive pickoff

A ring laser gyro system having at least one fixed mirror (3,4), and two movable mirror assemblies (1,2), for causing a pair of laser beams to counter-rotate therebetween, including amplitude control circuits and a phase control circuit for causing the movable mirror assemblies (1,2) to sinusoidally oscillate at the same amplitude and frequency, but 180° out of a phase with one-another, to substantially eliminate lock-in.

Bo H. G. Ljung

Papers

System for substantially eleminating lock-in in a ring laser gyroscope

Design of servo for gyro test table using linear optimum control theory

Accelerometer using radioactive pickoff

Apparatus for controlling mirrors in a ring laser gyroscope