Abstract: An intrusion sensor which includes a first light guide arrangement and a second light guide arrangement for detecting the severity of an accident in a vehicle. An interval having a width is positioned between the two light guide arrangements. In this case, the first light guide arrangement is positioned in the direction of an intrusion side. The second light guide arrangement is positioned in the direction of the vehicle interior side.

Abstract: Overlapping range rings from a pair of non-scanning radar or sonar transducers creates a grid structure within a surveillance area defined by their overlapping beam widths. Using PN coded transmission signals and doppler signal processing, intruder targets are detected, located, and tracked as they move throughout the grid structure. Intruders are identified by comparing their movement pattern to those of known intruders. Three dimensional surveillance areas can be monitored using three or more transducer sites.

Abstract: A multifunctional photoelectric switch comprises a display section for displaying a first display information and a second display information. The first display information includes a plurality of items concerning a threshold value and the second display information includes a plurality of items concerning functions of the photoelectric switch. A switch is provided for switching information to be displayed on the display section between each type of display information. A selection menu for the user to select either “Easy” or “Pro” is displayed in the progress of making a transition from a “light reception amount and/or threshold value display” mode of the basic display information to an “operation function setting” mode of the second display information. The user selects and sets either “Easy” or “Pro” on the selection screen. In the “Pro” mode, the set items concerning all functions are displayed; in the “Easy” mode, only the basic items are displayed.

Abstract: A device for a motor vehicle includes at least one laser sensor. The laser sensor includes a device configured to sweep a scanning area with at least one laser beam emitted by the laser sensor and a power supply device for the laser sensor. In a method for operating a laser sensor in a scanning area with at least one laser beam, the power of the laser beam emitted by the laser sensor is varied in accordance with its direction of radiation.

Abstract: A method and apparatus for guiding a vehicle into an optimal position within a parking space. A first linear ray of light is projected along the centerline of a parking space. A second linear ray of light is projected at an angle to and intersecting the first linear ray within the parking space. The first linear ray of light guides the driver while moving into and through the space when the driver aligns an indicator on the vehicle with the first linear ray of light. As the driver nears the optimal position, the second linear ray of light will move towards the indicator. When the indicator coincides with the intersection of the first and second linear rays of light, the vehicle is in the optimal position.

Abstract: Methods and devices are provided for the detection of bacterial agents such agents as Bacillus anthracis and Clostridium botulinum with high sensitivity and selectivity. More specifically, methods and devices are based on a phosphorescence-emission detection system using chelate-stabilized lanthanides (e.g, Eu(III), Tb(III), and Sm(III)) to detect various spore-specific small organic molecules (e.g., dipicolinic acid, diaminopimelic acid, n-acetlymuramic acid, and the like). By careful selection of the chelating agent or ligand coordinated to the lanthanide, both high specificity and selectivity can be obtained. Examples of suitable and preferred sensor systems include N-(2-hydroxyethyl)ethylenediaminetriacetic acid (HEDTA) and N-(2-hydroxyethyl)iminodiacetic acid (HEIDA) combined with europium (III) and/or terbium (III). The chelate-stabilized lanthanides react with the spore-specific “target” molecules to form a characteristically phosphorescent product which can then be detected.

Abstract: A mailbox operated signal device has a motion detector that is attached to the inside of a conventional mailbox and activates a light and a speaker to alert residents that the mail has been delivered to their mailbox. A wireless transmitter is electrically connected to the motion detector. The wireless transmitter is capable of transmitting a motion detected signal. A wireless receiver is capable of receiving the transmitted motion detected signal. A light is electrically connected to the wireless receiver. The light is for indicating when the motion detected signal is received by the wireless receiver.

Abstract: A very reliable alarm system is comprised of transceiver node devices interconnected via infrared links forming a secure perimeter, whereby each transceiver node in the perimeter receives an infrared transmission from a previous transceiver node, and itself transmits an infrared signal to the next transceiver node in the perimeter. If a break of an infrared link occurs, such as would happen if an intruder enters the perimeter area, an indication of the break is communicated around to a base unit device either by each subsequent node device inhibiting its infrared transmission, or changing its transmission to that of a special alarm signal. Upon receiving an indication of a perimeter break the base unit device alerts alarm signaling devices such as audible or visual alarm indicators.

Abstract: A security system employs a plurality of towers for detecting an intruder. A detection beam extends between adjacent towers, and a breach in the detection beam detects the presence of intruders. The solar tower includes a solar panel, a solar mounting bracket, a swivel clamp, a swivel solar bracket, a solar cap opening mechanism, a solar base cap, and a top plate. The solar tower further includes a base unit, frame support rods extending from the base unit, a frame unit having face shield slots, and opposing face shields mounted in the face shield slots. The top plate is secured to the frame support rods with suitable fasteners.

Abstract: A device for supporting an optical fibre in a perimeter barrier is disclosed. The device has a pair of arms (207) and (208) which are pivotally mounted on a pivot pin (225) and which are biased into a predetermined orientation by springs (210, 211/302, 310). The arms (207) and (208) support a fibre (250) which is connected to the arms in a predetermined configuration. The arms carry support portions (200, 201) which connect to wires (12a) and (12b) of the perimeter. If the wires are pulled apart, one of the arms (207) or (208) moves relative to the other arm against the bias of the spring (213, 214) or (302, 310) to move the fibre supported on the arms to cause an alarm to be generated. If the wire is cut, the spring biases one of the arms into moving relative to the other arm to also cause the alarm to be generated.

Abstract: A method of controlling at least one safety-specific function of a machine. The method includes monitoring a monitoring region with at least one location-resolving and time-resolving sensor, where the monitoring region includes a safety boundary which separates off a danger region and defines a safe distance from a danger zone of the machine. The method also includes detecting at least one of a position, a movement direction and a movement speed of an object. The method also includes establishing a position of the safety boundary in a variable manner depending on the at least one of a detected position, movement direction and movement speed of the object. The method also includes triggering the safety-specific function of the machine when entry into the danger region by the object is detected. An apparatus corresponding to the method is also described.

Abstract: A detecting device applied to a vehicle door has a signal transceiver placed above the vehicle door to monitor by downward signals if any passenger or obstacle is near the door. A control circuit is connected to and controls the signal transceiver to emit detecting signals when the vehicle door is opened. Based on the reflected signals, the detecting device judges if any passenger is near the door, and controls the closing/opening movements of the door to avoid any possible injury to passenger.

Abstract: A vehicle door stop safety system for preventing closure of a vehicle door when an object moves between an open door and body of the vehicle. The system includes field producing device for producing a field adjacent to a latch end of the door, when the door is open; and sensing device for sensing an interruption of the field and for producing a block or stop signal when the interruption is sensed. Blocking device is provided for blocking closure of the door upon an interruption of the field. Alternatively, braking device is provided for stopping the door's movement at a position when an interruption of the field is sensed. A controller is provided for actuating the blocking or braking device upon sensing by the sensing device of an interruption of the field.

Abstract: An apparatus is provided for detecting a shopping cart used to bring items to a checkout location, and inspecting its bottom tray for the presence of items. The apparatus includes a cart-detector to detect the presence of the cart at a pre-determined location; and an item-detector to detect the presence of items placed on the lower tray of the cart. The cart detector includes an arrangement of three optical sensors and corresponding retro-reflective targets; and finite state-machine processing logic to discriminate a specific sequence of sensor responses.

Abstract: Device for guiding flows of individuals in mass transportation systems, containing at least the following components: A) a guidance system in embarking and disembarking areas interacting with at least one of the following devices: a) a guidance system in the means of transportation. b) a blocking device between the embarking/disembarking areas and the means of transportation.

Abstract: An apparatus and method for detecting an object approaching a vessel at rest on a water surface include a laser light curtain comprising at least one pulsed laser light beam extending radially from the ship toward a perimeter thereabout, the laser light curtain positioned spaced apart from and approximately parallel to an approach surface for detecting an object interrupting the light curtain; at least one pulsed laser rangefinder connected to the ship and positioned outboard therefrom to generate the laser light curtain; a power source connected to the pulsed laser rangefinder to supply power thereto; a processor connected to the pulsed laser rangefinder to process data therefrom; and at least one display connected to the processor to display information obtained from the processed data.

Abstract: A repellent laser beam device for preventing pests, such as birds, from feeding on fruits in a field. The device is mounted on a tripod and housed in a weather-protected box. It is mounted so as to be adjustable in height and angle. A control unit causes a laser beam to sweep a field in vertical and horizontal patterns, frightening birds and other pests away. The laser beam is of a wavelength seen by birds or other animals and merely frightens them away rather than blinding them. The patterns and speed of the scanning device are variable. The device is powered by a rechargeable battery and includes a solar panel system for recharging the batteries. The system is operable by photocell controlled switches, eliminating the need for human, manual on-off switching.

Abstract: An apparatus which provides a visual indication to the operator of a forklift that the forks are properly vertically aligned, the apparatus having a laser module which produces a visible light beam at the same height as the forks creating a focused dot or similar shape on a solid object. The laser module is retained in a laser housing which is preferably mounted onto the carriage of the forklift between the forks. Vibration-responsive, height-responsive, distance-to-load-responsive and temperature-responsive actuation means, alone or in combination, control the operational state of the laser module.

Abstract: To provide an anti-thief security sensor assembly wherein an optical axis adjustment of a beam projector can be accurately achieved merely by physically opening a cover of a beam projecting unit while a cover of a beam receiving unit is not opened physically, the anti-thief security sensor assembly includes a beam projecting unit (1) for emitting an infrared beam IR and having a projector cover (21A) mounted on a projector base (20A) so as to cover and protect a sensor circuit. This beam projecting unit (1) includes an opening detecting switch (7) for detecting the physical opening of the projector cover (21A) and a transmission request generating circuit (8) operable in response to the detection by the opening detecting switch (7) to output a received beam level transmission request signal B to the beam receiving unit (2).

Abstract: Apparatus in one example comprises first and second fence posts that cooperate to represent a subportion of a perimeter to be secured. The first fence post comprises a first motion sensor and a first laser sensor. The second fence post comprises a second motion sensor and a second laser sensor. Upon physical movement in a region outside the subportion of the perimeter, one or more of the first and second motion sensors serve to automatically perform a detection of the physical movement in the region outside the subportion of the perimeter. Upon the detection of the physical movement in the region outside the subportion of the perimeter the one or more of the first and second motion sensors serve to automatically cause the first and second laser sensors to monitor for physical movement at the subportion of the perimeter.

Abstract: A vehicle door stop safety system for preventing closing of a door of a vehicle when an object moves between the open door and the body of the vehicle. The vehicle door stop safety system includes a field producing assembly for producing a field adjacent to the latch end of the door. The field producing assembly is mountable on the latch end of the door, and the field producing assembly is adapted for operatively connecting to the switch of the vehicle such that the field producing assembly produces the field when the switch is actuated by opening of the door. A sensing assembly produces a block signal when an interruption of the field is sensed. The sensing assembly is mountable on the latch end of the door of the vehicle. A blocking assembly is provided for blocking closure of the door when the sensing assembly detects an interruption of the field produced by the field producing assembly. The blocking assembly is mountable on the body of the vehicle adjacent to the door opening.

Abstract: A perimeter monitoring system is arranged to detect passage across a perimeter of an area. The system primarily includes an emitter, a retroreflector, a detector and an alarm. The emitter provides a modulated visible laser beam. The retroreflector is arranged to direct the beam along a segment of the perimeter and return the beam along the segment. The detector includes a device that blocks reception of light outside an angle of less than 5 degrees. One or more local or remote alarms are activated in response to the signal. For example, a remote alarm is located on the inside of a residence window where it is activated by another visible laser beam. Alignment of the peripheral monitoring system is less costly and false alarms are less likely than with known systems.

Abstract: A repellent laser beam device for preventing pests, such as birds, from feeding on fruits in a field. The device is mounted on a tripod and housed in a weather-protected box. It is mounted so as to be adjustable in height and angle of the device. A control unit causes a laser beam to sweep a field in vertical and horizontal patterns, frightening birds and other pests away. The laser beam is of a wavelength seen by birds or other animals and merely frightens them away rather than blinding them. The patterns and speed of the scanning device is variable. The device is powered by a rechargeable gel pack battery. The range of wavelengths of the laser light beam is preferably from about 432 nanometers to about 633 nanometers. It is known that birds' eyes are sensitive to both ultraviolet light and human-visible light.

Abstract: A method and apparatus for locating various entities, including animate human beings and animals, as well as inanimate objects, such as, for example, certain types of plastics, observes and detects a force and subsequent resulting torque, acceleration, vibration or other measurable quantifiable manifestation of the force created by the non-uniform three-dimensional electric field spatial gradient pattern exhibited uniquely by the entity or object. Incorporation of laser energy enhances detection. Specifically, the inclusion of laser radiation enhances a dielectrokinetic effect by creating a localized region of significantly higher dielectric constant via absorption of the laser radiation by the air, and other properties which in turn significantly increases the dielectrophoretic force and resulting torque, and lowers the response time by preferentially directionally orienting or channeling the non-uniformity of the electric field line generated by the entity or object target towards the laser beam region.

Abstract: An apparatus and method for detecting an object approaching a vessel at rest on a water surface include a laser light curtain comprising at least one pulsed laser light beam extending radially from the ship toward a perimeter thereabout, the laser light curtain positioned spaced apart from and approximately parallel to an approach surface for detecting an object interrupting the light curtain; at least one pulsed laser rangefinder connected to the ship and positioned outboard therefrom to generate the laser light curtain; a power source connected to the pulsed laser rangefinder to supply power thereto; a processor connected to the pulsed laser rangefinder to process data therefrom; and at least one display connected to the processor to display information obtained from the processed data.

Abstract: A parking alignment system utilizing a laser to properly align a vehicle within a garage. The alignment system includes a laser emitter which emits a downwardly pointing laser beam. A driver of the vehicle enters the enclosure and stops the vehicle in a specified position providing proper alignment of the vehicle within the garage when the laser beam strikes a specified target indication position located on the vehicle. The parking alignment system may be actuated by a motion detector detecting motion within the garage.

Abstract: A vehicle traffic detecting device is provided with an automatic cleaning device. The detecting device has an emitter and a receiver facing each other and respectively emitting and receiving a beam of electromagnetic radiation along opposite ends of a beam path. The cleaning device has first and second cleaning units for respectively cleaning the emitter and the receiver. Each cleaning unit includes a fastener fastening the cleaning unit to a casing of the detecting device, a dispenser dispensing a transparent film, a contoured guide defining a film path along which the dispensed film resides, and an actuator for moving the dispensed film along the defined film path. A portion of the defined film path is located in front of the emitter/receiver of the detecting device and thereby positions a portion of the dispensed film in front of the emitter/receiver of the detecting device.

Abstract: A laser lighting assembly, mounted on a forklift, will be projecting a light beam parallel to and in the same plane as a fork, which itself is parallel to a floor or ground level. Until the forks are parallel to the floor or ground level the laser light will not be continuously on. When an operator of the forklift is adjusting the forks to be level, and then parallel to the floor or ground level, as the level positions are being approached, the laser light appears in a blinking sequence with the off periods initially being longer and then becoming shorter as the level positions are approached. Then when the level positions of the forks are reached the laser light is on full time.

Abstract: A cost-effective transmission line safety monitoring system which detects and tracks acoustic and chemical anomalies along a transmission line to determine if a destructive event is present. One or more sensors, each enclosed in a weather-resistant container, are attached to an antenna and installed as part of the antenna transmitting system on a tower, building top or hill. The acoustic signatures and gas purity deviations are detected and transmitted to a remote master processing center where, via the use of packaged software, the signals are continuously compared to an existing library of acceptable and non-acceptable signatures for pattern matches. An operator, using a PC in a simple WINDOWS® format, may assign newly acquired signatures to the library for future operation.

Abstract: A vehicle door stop safety system for preventing closing of a door of a vehicle when an object moves between the open door and the body of the vehicle. The vehicle door stop safety system includes a field producing assembly for producing a field adjacent to the latch end of the door. The field producing assembly is mountable on the latch end of the door, and the field producing assembly is adapted for operatively connecting to the switch of the vehicle such that the field producing assembly produces the field when the switch is actuated by opening of the door. A sensing assembly produces a block signal when an interruption of the field is sensed. The sensing assembly is mountable on the latch end of the door of the vehicle. A blocking assembly is provided for blocking closure of the door when the sensing assembly detects an interruption of the field produced by the field producing assembly. The blocking assembly is mountable on the body of the vehicle adjacent to the door opening.

Abstract: The present invention is a vehicle traffic measurement system designed to accurately count and record the number of vehicles passing through a selected location, to more accurately determine and record the velocity at which the individual vehicles travel through that location, and to accurately determine and record in which relative direction the vehicles are traveling as they pass that location. The basic physical principle is of a moving object interrupting two parallel light beams a known reference distance apart, and information extracted from the interruptions sensed and electronically processed into count, direction, and velocity being recorded for subsequent data analysis.

Abstract: A perimeter monitoring system is arranged to detect passage across a perimeter of an area. The system primarily includes an emitter, a retroreflector, a detector and an alarm. The emitter provides a modulated visible laser beam. The retroreflector is arranged to direct the beam along a segment of the perimeter and return the beam along the segment. The detector includes a device that blocks reception of light outside an angle of less than 5 degrees. One or more local or remote alarms are activated in response to the signal. For example, a remote alarm is located on the inside of a residence window where it is activated by another visible laser beam. Alignment of the peripheral monitoring system is less costly and false alarms are less likely than with known systems.

Abstract: An optical intrusion detection system including a light source, an optical splitter for splitting light emitted from the light source and transmitted via an optical fiber, a plurality of detectors for detecting light power values split by the optical splitter, and a determiner for determining intrusion or non-intrusion by performing a predetermined operation on the output of each of the detectors. According to this system, light having mode coupling while traveling through a multi-mode optical fiber is split, and the split light power values are measured and compared to each other, so that a dynamic change of an optical signal and a static change in light loss due to the physical disturbance from an intruder can be simultaneously measured. Also, an optical splitter can be designed in consideration of the external environment.

Abstract: A laser intrusion system for detecting motion in a swimming pool for detecting a person entering a swimming pool. The laser intrusion system for detecting motion in a swimming pool includes a swimming pool. The swimming pool has a peripheral wall. The peripheral wall has a top edge. A motion detection apparatus is mounted in the peripheral wall of the pool such that emitted light travels over water in the pool. The motion detection apparatus is operationally coupled to a power source and an alarm device. The alarm device is adapted to produce a sound.

Abstract: A laser security fence apparatus is disclosed for providing a warning signal in response to an intrusion by an intruder of a restricted area. The apparatus includes a laser generator for generating a laser beam and a first mirror aligned with the laser beam for reflecting the beam. A second mirror is aligned with the first mirror for reflecting the beam reflected by the first mirror and a collector is aligned with the second mirror for collecting the beam reflected by the second mirror. A microprocessor is associated with the collector and the generator for sensing when the beam is broken by the intruder so that the beam is not received by the collector. An alarm is connected to the microprocessor for actuation by the microprocessor when the microprocessor senses that the beam is broken so that the alarm provides the warning signal.

Abstract: An optoelectric safety system which protects a free entrance or access opening in a machine's protective housing or protective cage at all times during operation. The system includes a reflection light scanner on the machine frame above and adjacent the floor at the front of the machine in the vicinity of the entrance or access opening, which emits a scanning beam covering a horizontal or inclined area and which generates an inner permanent protective field and an outer dynamic protective field.

Abstract: The present invention relates to a method of word screen formation by laser light projection and the structure of word formation by laser light projection, and in particular, relates to a plurality of laser production devices arranged in a single column and by rapid reciprocating action of the devices to project multiple columns of light track and form word arrays.

Abstract: An intruder detection system for detecting the presence of an intruder in a protected area. A light beam, preferably from a laser, is reflected from a target, which is a potential intruder. The time period required for the beam to return to a light detector, as well as the intensity of the reflected light, is recorded. The system includes a computer and software for analyzing the measurements of distance and intensity of reflected light. The algorithm for detecting the presence of an intruder is based on changes in the measured distance and/or intensity of reflected light from initial measurements made during a “learning” period. The system tacks targets using data collected in consecutive searches of the area to be protected. Preferably, an alarm is sounded and/or a video camera is slaved to the system.

Abstract: A laser irradiation unit for projecting a laser beam onto a target for reference comprises a remote receiving unit for receiving an operation light signal from a remote controller, a buzzer or a lamp for confirming operation, and a control unit for operating the buzzer for confirming operation or lighting up the lamp for confirming operation in case the operation light signal is received by the remote receiving unit, and the condition of the remote control operation is conveyed to an operator or the remote controller by sound of the buzzer for confirming operation or by lighting of the lamp for confirming operation.

Abstract: A method of determining distances and angular positions of stationary and moving objects (3), for example in an area to be monitored in connection with for instance swing doors. The determination is done by means of triangulation where light, which in the main part is collimated, is transmitted (1) into the area at different angles and in a certain sequence. The reflected light is correspondingly registered on a position-sensitive sensor (5) which is positioned at a certain distance from the transmitter (1). The position (5a, 5b), where the reflected light falls on the sensor (5), represents the distance, and the moment when the light is received represents the angular position of the detected object. The values are compared to stored reference values which change when the angle of the door's opening is changed.

Abstract: A laser lighting assembly, or another type of a directed high intensity collimated beam of light assembly, mountable on a forklift, or like purpose lifting and carrying equipment, to project at least one light beam, which is always directed parallel to and in the same plane as a fork or pair of forks, which are movably mounted on the lifting and carrying equipment for being raised and lowered. The projected light beam, during operations of the forklift, reflects from a changeable spot location on a load to be lifted, which is supported on a pallet, or is supported on a like fork receiving structure. When the fork is being either raised or lowered to be inserted, for example, in a fork receiving volume of a pallet, an operator of the forklift is observing the changeable spot location.

Abstract: A set of sensors or sensor pairs capable of detecting the presence of a person passing through a portal is used for monitoring the portal. In one embodiment the portal has spaced apart upright supports. On one of the upright supports is mounted the sensors and the other upright support is used as a surface for reflection of the wave energy transmitted. When a person is present in the portal the person reflects the wave energy. The receiver is capable of detecting the time duration between transmission and receipt of the wave energy signal. In a second embodiment, the sensors are mutually inductively coupled in pairs. When a person is present within the portal the mutual inductance is changed in one or more of the sensor pairs. This change in mutual inductance is sensed and used as a means for determining which person is present in the portal. For example, a family may comprise two adults, a teenager, a preteen and a small child.

Abstract: An apparatus for detecting the presence or absence of an object within a monitor zone includes a sensor (12) operative to sense a condition of the monitored zone (Z) and provide a sensor signal indicative thereof. The sensor signal is processed, preferably according to two different transfer functions, to provide first and second signals that vary based on the sensor signal. A comparator (46) provides a comparator signal that varies as a function of the first and second signals. Additional circuitry (58) is operative to provide an indication of the presence or absence of an object within the monitored zone (Z) as based on the comparator signal.

Abstract: A portable, low cost, laser detection system which generates an alarm signal that can be used to produce visual and/or audible warnings indicating the range, location and type laser energy detected. Such laser detection system utilizes a cooperating quadraplex sensor assembly, to provide a complete 360 degree laser detection coverage, mounted on a helmet assembly which includes a helmet shell, a cushioned impact liner coextensive with the interior surface of the helmet shell and a suspended crown support liner the combination of which provides enhanced protection of the user and stabilization of the laser detection system.

Abstract: A light beam, preferably from a laser, is reflected from a target, which is a potential intruder. The time period required for the beam to return to a light detector, as well as the intensity of the reflected light, is recorded. The system includes a computer and software for analyzing the measurements of distance and intensity of reflected light. The algorithm for detecting the presence of an intruder is based on changes in the measured distance and/or intensity of reflected light from initial measurements made during a "learning" period. The system tracks targets using data collected in consecutive searches of the area to be protected. Preferably, an alarm is sounded and/or a video camera is slaved to the system.

Abstract: A storage structure is composed of a storage rack having a plurality of storage bays, each of which is adapted to store a bundle, such as a food-related bundle having a pallet and a number of boxes of food items positioned on the pallet. The storage bays are disposed in a plurality of rows between a first end of the storage rack and a second end of the storage rack, the rows including an upper row and a lower row. The storage structure has a transmitter for transmitting a beam of radiation and a receiver for receiving the beam of radiation. The transmitter is associated with the first end of the storage rack and is positioned to transmit the radiation beam in a direction substantially parallel to the side of the storage rack, and the receiver is associated with the second end of the storage rack. The storage structure has an alarm generator coupled to the receiver for generating an alarm when the radiation beam is interrupted by one of the bundles located on the storage rack.

Abstract: The multiple scattering of coherent radiation in an inhomogeneous medium is used to detect attempted intrusions into a protected area or into a tamper-proof package for such purposes as preventing the unauthorized detection and copying of electronic information used for authentication and coding in electronic commerce, communications, command, and control systems. A key advantage is that any intrusion into the sensed volume will produce a detected change in the measured intensity which will be equal to the full amplitude range if the intrusion is into a cylinder with radius comparable to the wavelength of the sensing radiation. The response of the medium can also be used to provide a unique identity key.

Abstract: A crosswalk warning light system for warning drivers that a pedestrian has entered a crosswalk by shining a light onto the crosswalk and any pedestrians in the crosswalk. The crosswalk warning light system detects a pedestrian entering the crosswalk and activates the light so that a driver can see and avoid the pedestrian in the crosswalk. The crosswalk warning light system is timed so as to deactivate the light after a predetermined interval of time. The light source is selected from any conventional light source such as a scanning laser, a focused strobe light, or a focused incandescent light. The light source is supported above the crosswalk and aimed down toward the crosswalk so that the entire area defined by the crosswalk is illuminated. Further, by aiming the light source down on the crosswalk, the pedestrians are also illuminated.

Abstract: The present invention relates to an apparatus and method for detecting when an object is in a path of a vehicle by transversely transmitting a light beam from the uppermost portion of the vehicle towards the object. The light beam contacts the object when the distance to the object from the ground is smaller than the height of the vehicle and the object is in the path of the vehicle. The reflected beam can be observed by a person in the vehicle alerting the person of insufficient clearance for the vehicle. Preferably, the light beam is a collimated beam emitted from a semiconductor laser diode.

Abstract: A high speed secure fiber optic communication system that includes a coherent alarm system utilizes a pair of single mode fiber optic cables in combination with one or more light sources, phase modulators, detectors and polarization scrambling elements to form a Sagnac interferometer. The phase modulator is driven so that counter propagating light beams in the Sagnac loop experience a different optical path as they pass through the loop. When the two beams are recombined on the central beamsplitter of the Sagnac loop, the two beams interfere with each other and the data impressed as phase modulation on the light beams by the phase modulator is recovered as amplitude modulation on the output detector of the Sagnac interferometer. The coherent alarm system applies a relatively low frequency background signal to the Sagnac interferometer and watches for changes occurring to the background signal that indicate the presence of an intruder.