A rain sensor in a vehicle includes a transmitter to implement a pseudorandom modulation of a timing of emission of infrared transmissions toward a windshield of the vehicle. The rain sensor also includes a receiver to be active for only a specified period of time following each emission of the infrared transmissions and to receive a reflection based on the infrared transmission encountering any substance on the windshield.

An open scattered light smoke detector for detecting smoke may include a light transmitter for emitting light, a light receiver spectrally matched to the light transmitter, and a control unit configured to repeatedly actuate the light transmitter, with a pulsed signal sequence, to emit corresponding light pulses, evaluate temporally a signal sequence received by the light receiver, and output a fire alarm if a received signal strength exceeds a minimum value for the smoke concentration. The control unit may be configured to switch the detector from a normal operating mode into a service mode if a phase angle between an emitted and received signal sequence, as determined on the detector side, increases by a minimum angular value which, in terms of the travel time, corresponds technically to an increase in the optical path length from the light transmitter to the light receiver of more than some predefined distance.

An opto-isolator has a light emitter, at least one light guide, a light recorder optically connected to the light emitter via the light guide, an optical signal modulator optically connected to the light emitter, the light guide or the light recorder, and an optical modulator memory connected to the optical signal modulator. The optical signal modulator modulates an optical signal within the opto-isolator, and is controlled by the optical modulator memory.

An apparatus for analog numerical integration having multiple opto-isolators each with an additional level of signal modulation. The opto-isolators are connected in series or in parallel, so as to sum up output signals from all connected opto-isolators. Each opto-isolator has a light emitter, at least one light guide, a light recorder optically connected to the light emitter via the light guide, and an optical signal modulator optically connected to the light emitter, the light guide or the light recorder. The optical signal modulator modulates an optical signal within each opto-isolator.

A system and method evaluate the efficiency of circadian-effective luminaires. Such circadian-effective luminaires affect the master biological clock in the brain, which regulates the daily timings of behavioral activities and physiological functions. Disruption of circadian rhythms can lead to poor performance and poor health, while consistent exposure to bright days and dim nights is necessary for circadian entrainment, and thus for good sleep and good health. The system and method provide a standard test for assessing the efficiency of luminaires for providing circadian-effective light to building occupants. The system and method measure and quantify luminaire efficiency based on the electrical watts needed, termed SOWatt, to reach a circadian stimulus (CS) criterion of 0.3 at the eyes of a standard observer (SO). The system and method can be applied to ceiling mounted, accent, and table-top luminaires.

An optical detecting module includes a housing, a light emitting component, an optical detecting component and an optical signal collecting component. The light emitting component is disposed inside the housing. The optical detecting component is disposed inside the housing to receive an optical detecting signal generated by the light emitting component. The optical signal collecting component is utilized to hold the light emitting component for signal collection. The optical signal collecting component includes an output portion, a bottom portion and at least one lateral portion. The light emitting component is disposed on the bottom portion, and an optical positive signal of the optical detecting signal is projected out of the housing through the output portion. The lateral portion is bent from the bottom portion to reflect an optical lateral signal of the optical detecting signal, and the optical lateral signal is projected out of the housing through the output portion.

To realize collective measurement of ultrawide-band optical signals which have exceeded an electrical band limit. This photodetection device (100) comprises: a time-delay adjustment means (10) into which is input an optical signal that is a detection object; an optical frequency comb generator (20) that generates an optical frequency comb; a photomixer (30) that photomixes optical signal series which are sequentially output from the time delay adjustment means (10) and which were subjected to time adjustment, and the optical frequency comb signal which is output from the optical frequency comb generator (20); and a photodetector (40) that detects the mixed signal output from the photomixer (30). The time delay adjustment means (10) performs time adjustment on the optical signal series so that each of the time adjusted optical signal series is photomixed with the optical frequency comb at different timings in the photomixer (30).

Embodiments of the present disclosure provide systems and methods for providing integrated waveguide-based spectrometer systems. In one aspect, the system includes an optical spectrometer comprising one or more waveguides configured to support propagation of optical radiation (i.e. light) through the waveguides to a photodetector. The spectrometer further includes an input coupler for each waveguide, the input coupler configured to couple the radiation from free space into the waveguide in absence of fiber-optic coupling of the radiation into the waveguide. Because at least a portion of the light propagated through the waveguides has interacted with a sample to be spectroscopically evaluated, the light detected by the photodetector allows to carry out the spectroscopic evaluation of the sample. At least some components of the spectrometer are provided on a single die using conventional CMOS techniques, yielding a compact and low cost device.

In this electric field vector detection method, an electro-optic crystal, where a (111) surface of an optical isotropic medium is cut out, is used as a terahertz wave detection element. The method includes: causing polarization of probe light of ultrashort pulsed light to be circular polarization; allowing the probe light having circular polarization to enter the terahertz wave detection element and probing the terahertz wave; modulating the probe light, having probed the terahertz wave, by a rotating analyzer and detecting the modulated probe light by a photodetector; performing lock-in detection of a detection signal from the photodetector by a lock-in detector using a frequency based on a rotational frequency of the rotating analyzer as a reference signal; and detecting an electric field vector of the terahertz wave based on a detection signal from the lock-in detector.

A gas sensing system includes a signal generator including a wavelength tunable laser, the signal generator providing a first periodic signal and a second periodic signal, wherein the first periodic signal comprises a wavelength scanning signal and the second periodic signal comprises a modulation signal; an optical signal absorption path which is wavelength selective, wherein the generated signal covers at least one of the absorbance band; a signal detector that uses lock-in detection to detect a second harmonic of the second periodic signal after absorption, the signal detector further including a local reference generator, a multiplier, and a low pass filter; a local reference includes a first path (ref1) that outputs sinusoidal signal with frequency equals to that of the second signal in signal generator, and a second path (ref2) that outputs sinusoidal signal of two times ref1 frequency; and a local reference generator having a first phase shifter that is configurable from 0 to 2 and a second phase shifter that shifts 90-degree, wherein the first phase shifter is for an alignment of ref1 with the modulation signal and the second phase shifter provides 90-degree shifts for ref2 from ref1, wherein the first and second paths (ref1 and ref2) are selected by a switch, wherein the switch uses the first path during initialization and the second path for normal operation.