An object detection system compensates for variations in transmission characteristics within an object passageway caused by, for example, dust or dirt. An object detection device includes a plurality of electromagnetic radiation emitters and detectors arranged in rows on opposite sides of a passageway. First lenses focus radiation from the emitters into a semi-columnated beams of radiation that together create a plane of semi-columnated electromagnetic radiation that spans substantially across a width of the passageway. Second lenses focus the received electromagnetic radiation onto corresponding ones of the plurality of radiation detectors. A controller receives a radiation intensity signal from the detectors, determines that its value is outside of a predetermined range, and adjusts an amount of electrical power supplied to the plurality of radiation emitters so that the value of the radiation intensity signal changes to become within the predetermined range.

The present disclosure relates to a light source system suitable for use in a time of flight camera. The light source system includes a light source, such as a laser, and a driver arranged to supply a drive current to the light source to turn the light source on to emit light. The driver includes two transistors coupled to the light source in series, such that when both transistors are turned on, a drive circuit is completed, current flows and the light source turns on. A very short pulse of light emission may be achieved efficiently by switching one of the transistors to the on-state to complete the drive circuit and a short time later turning off the other transistor in order to break the drive circuit. In this way, a pulse of light in the order of less than 1 nanosecond or less than 500 picoseconds may be achieved.

A circuit comprises an optical coupling including an illuminator optically coupled to an optical sensor to output a voltage from the optical sensor based on intensity of illumination from the illuminator. The circuit includes a voltage input node with a resistance connected in series between the voltage input and a Zener diode. A method includes powering an illuminator with current from a first voltage input node. The method includes sensing illumination level in illumination from the illuminator with a sensor and outputting output proportionate to illumination sensed by the sensor indicative of voltage detected at the voltage input node. The method can include limiting current between the voltage input node and the illuminator.

A circuit comprises an optical coupling including an illuminator optically coupled to an optical sensor to output a voltage from the optical sensor based on intensity of illumination from the illuminator. The circuit includes a voltage input node with a resistance connected in series between the voltage input and a Zener diode. A method includes powering an illuminator with current from a first voltage input node. The method includes sensing illumination level in illumination from the illuminator with a sensor and outputting output proportionate to illumination sensed by the sensor indicative of voltage detected at the voltage input node. The method can include limiting current between the voltage input node and the illuminator.

A method for assigning light sensors for regulating a lighting system includes switching the lighting of the lighting system into a first switching state such that a first lighting group emits light with a predetermined luminous flux, switching the lighting of the lighting system into a second switching state such that the first lighting group emits light with a reduced luminous flux by comparison with the predetermined luminous flux or emits no light, and measuring a luminance of the light reflected by a reference surface respectively assigned to the light sensors with the aid of the light sensors to determine a first measurement value in the first switching state and a second measurement value in the second switching state. The method may further include assigning a sensor to the first lighting group based on a comparison of difference values formed for each of the light sensors, and storing the assignment.

A method for assigning light sensors for regulating a lighting system includes switching the lighting of the lighting system into a first switching state such that a first lighting group emits light with a predetermined luminous flux, switching the lighting of the lighting system into a second switching state such that the first lighting group emits light with a reduced luminous flux by comparison with the predetermined luminous flux or emits no light, and measuring a luminance of the light reflected by a reference surface respectively assigned to the light sensors with the aid of the light sensors to determine a first measurement value in the first switching state and a second measurement value in the second switching state. The method may further include assigning a sensor to the first lighting group based on a comparison of difference values formed for each of the light sensors, and storing the assignment.

An integrated optical linewidth reduction system based on optical feedback and a low-speed electronic control loop to control the optical feedback. Light is tapped and reflected back to the laser with an amplitude, phase or both amplitude and phase adjustment such that the linewidth of the laser is lower than the free-running laser linewidth. The amplitude of the feedback signal may be controlled using an optical attenuator. The phase of the feedback signal may be controlled using a phase shifter. The amplitude of the optical feedback may be monitored by means of a filter and a photodetector, or just a photodetector. The amplitude and/or phase of the optical feedback is monitored by means of a frequency/phase noise discriminator. The phase shifter can be an endless phase shifter

A networked LED lighting system for illuminating plants uses LEDs of different colors each at a respective pre-selected power level, for example corresponding to a power level at which maximum efficiency is achieved, and controlling color ratios and total daily intensity by turning LEDs off or on as needed. To improve longevity of the LEDs, the turning off and on of the LEDs can occur at low frequencies, be implemented in the LED drivers as opposed to switching off the power, and can include a gradual transition between on and off states.

A networked LED lighting system for illuminating plants uses LEDs of different colors each at a respective pre-selected power level, for example corresponding to a power level at which maximum efficiency is achieved, and controlling color ratios and total daily intensity by turning LEDs off or on as needed. To improve longevity of the LEDs, the turning off and on of the LEDs can occur at low frequencies, be implemented in the LED drivers as opposed to switching off the power, and can include a gradual transition between on and off states.

An advanced plant production system comprises a robust and efficient network of lighting, instrumentation and control and data acquisition systems, which are integrated together to maximize plant health, crop production, while conserving resources. The system provides an advanced user interface that can be accessed both locally and remotely. In some embodiments, the lighting can be controlled to mimic the circadian rhythm of the crops or the Sun, and can be matched to a particular type and/or maturity of plant. A sensor node which can be used in the plant production system comprises internal sensors, and can also be connected to other external sensors, to provide detailed environmental information. Several methods are described that can optimize the efficiency of the system, and can be used to improve the yield, value, and/or quality of crops.