A light pulse detection circuit for connection to a photodiode, the detection circuit comprising an integration capacitor, discharge means, and comparator means adapted to compare an integration voltage across the terminals of the integration capacitor with a reference voltage threshold in order to produce a light pulse detection signal. The reference voltage threshold is a self-adaptive threshold depending on a level of light background noise. A detection device comprising a photodiode and such a detection circuit. A detection matrix comprising a plurality of such detection devices.

A system for generating clock signals for a photonic quantum computing system includes a pump photon source configured to generate a plurality of pump photon pulses at a first repetition rate, a waveguide optically coupled to the pump photon source, and a photon-pair source optically coupled to the first waveguide. The system also includes a photodetector optically coupled to the photon-pair source and configured to generate a plurality of electrical pulses in response to detection of at least a portion of the plurality of pump photon pulses at the first repetition rate and a clock generator coupled to the photodetector and configured to convert the plurality of electrical pulses into a plurality of clock signals at the first repetition rate.

A light sensor having an adaptively controlled gain includes a photoelectric element, an operational amplifier, a comparator, an adaptive gain control circuit, a variable capacitor and a pulse accumulator circuit. The photoelectric element converts light energy into a photocurrent. The operational amplifier outputs an error amplified signal based on a gain multiplied by a voltage difference between an input voltage and a reference voltage. The comparator compares the error amplified signal with a voltage of a reference voltage source to output a comparison signal. The adaptive gain control circuit includes a pulse detector circuit and a gain control circuit. The pulse detector circuit detects the comparison signal and a clock signal to output a pulse detected signal. The adaptive gain control circuit outputs a capacitance modulating signal according to the pulse detected signal. A capacitance of the variable capacitor is modulated according to the capacitance modulating signal.

A non-transitory computer readable medium including computer executable instructions for performing a method that includes locating a pulsing laser on an imaging array, defining a sub-region array smaller than the imaging array based on a location of the located pulsing laser such that the pulsing laser is at least partly within the sub-region, and sampling the sub-region array at a sub-region sampling rate that is higher than a remainder region sampling rate.

Various embodiments may include a method for fire detection comprising: radiating light at a first wavelength into a scattered light volume and measuring a radiation intensity generated by forward scattering; radiating light at a second wavelength and measuring a second scattered radiation intensity generated by forward scattering; determining a first quotient from the scattered radiation intensities and comparing it to a first and second value; and if the first quotient lies between the first and the second value; radiating pulses at the second wavelength into and measuring a third intensity generated by backward scattering; determining a second quotient from the first and third scattered radiation intensity and comparing the second quotient with a third value; and generating a fire alarm if the second quotient exceeds the third comparison value.

Systems and methods for preventing high-radiant-flux light, such as laser light or a nuclear flash, from causing harm to imaging devices, such as a camera or telescope. The optical components of the imaging device have first and second foci. The second focus forms an image on an array of photodetectors and occurs at a large f-number. The first focus occurs at a small f-number in a gas that is dense enough to dissipate most of a femtosecond laser pulse of potentially damaging intensity and conditioned to easily undergo dielectric breakdown when exposed to high-radiant-flux light that is less intense than a femtosecond laser pulse. Dielectric breakdown forms a conductive arc that dissipates or scatters light, blocking high-radiant-flux light from reaching the array of photodetectors. Several methods may be used for conditioning the gas to break down quickly when exposed to laser attack.

A system and method for enhancing laser contrast on a remote target utilizing an image processor and a laser power controller is provided. An image processor in an imaging device manipulates a laser power controller in a laser system so that a laser beam emitted from a laser system is ultimately synchronized with the imaging device. Firstly, the original laser signal is shifted one time frame relative to the plurality of time frames to create a shifted laser signal. Secondly, the shifted laser signal is subtracted from the original laser signal. Thirdly, the subtracted laser signal is magnified by a frequency band pass filter. The filtered laser signal is added to the original signal to become the finalized laser signal which has better contrast than the original signal.

A light receiver (100), comprising: a plurality of avalanche photodiode elements (10) each being biased with a bias voltage above a breakdown voltage and thus operated in a Geiger mode in order to trigger a Geiger current upon light reception and a plurality of readout circuits (42, 44, 46) associated with individual avalanche photodiode elements (10) or a group of avalanche photodiode elements (10) for reading out a Geiger current generated upon light reception, wherein the readout circuits (42, 44, 46) each comprise a measurement path (42) and a blanking path (46) as well as a switching element (44) for selectively supplying the Geiger current, or a measurement current corresponding to the Geiger current, to the measurement path (42) or the blanking path (46).

A system for generating clock signals for a photonic quantum computing system includes a pump photon source configured to generate a plurality of pump photon pulses at a first repetition rate, a waveguide optically coupled to the pump photon source, and a photon-pair source optically coupled to the first waveguide. The system also includes a photodetector optically coupled to the photon-pair source and configured to generate a plurality of electrical pulses in response to detection of at least a portion of the plurality of pump photon pulses at the first repetition rate and a clock generator coupled to the photodetector and configured to convert the plurality of electrical pulses into a plurality of clock signals at the first repetition rate.

A system includes a switch-mode power supply for drawing low and constant current from a power source. The switch-mode power supply may charge an energy storage element with low and constant current. In a normal condition, a current driver may cause the illuminator to emit electromagnetic radiation as a plurality of flashes. In the normal condition, the system may include an average power that is less than or equal to a threshold value associated with the illuminator. In a fault condition, the illuminator may continuously emit electromagnetic radiation, at low current. In the fault condition, the switch-mode power supply may supply low and constant current to the illuminator. Similarly, in the fault condition, the system may include an average power that is less than or equal to a threshold value associated with the illuminator.