Abstract:
A path light that utilizes an ambient light sensor to determine the lighting conditions may experience feedback from its light source if it determines that the lighting conditions are appropriate to illuminate the path light's light source. The path light, as disclosed herein, may compute an offset value to ascertain the amount of feedback from the light source. Upon learning the offset value, the path light may subtract the offset value from a detected amount of light to determine whether the lighting conditions of its surroundings still meet a threshold level of darkness for the path light to illuminate.
Abstract:
The present invention relates to a detection device (6) for detecting photons emitted by a radiation source (2) and capable of adjusting ballistic deficit. The detection device (6) comprises a pre-amplifying unit (11) (such as, e.g., a charge-sensitive amplifier), a shaping unit (60) comprising a feedback discharge unit (13, I) (such as, e.g., a feedback resistor or a feedback current source), and a feedback discharge control unit (50) coupled to the feedback discharge unit (13, I). The feedback discharge control unit (50) is adapted to, e.g., adjust a resistance of a feedback resistor (and/or to adjust the current value of the feedback current source) if an electrical pulse generated by the shaping unit (60) does not exceed at least one energy comparison value (X 1 , X 2 ,..., X N ). The feedback discharge control unit (50) is adapted to not adjust the parameter of the feedback discharge unit (13, I) if the electrical pulse exceeds the at least one energy comparison value (X 1 , X 2 ,..., X N ). By tuning the feedback resistor operating point (or the feedback current source operating point), the ballistic deficit can be adjusted to a predefined expected value.
Abstract:
A method of calibrating an output of a light sensor for use in controlling a lighting system comprising at least one lighting device. The method comprises placing the lighting system into each of a plurality of discrete modes, each mode being configured to output a different respective configuration of light, wherein in operation each mode will automatically vary an output illumination level of the respective configuration based on the output of the light sensor in response to a changing light level in an environment being illuminated. The method further comprises performing a plurality of calibrations by determining a respective calibration setting for calibrating the output of the light sensor in each of the modes, and setting each mode to vary the output illumination level based on the output of the light sensor as calibrated by the respective calibration setting.
Abstract:
An optical measurement apparatus (10) comprises a photon detection unit (12) that detects incident photons, a time signal output unit (14) that outputs a time signal, and a storage unit (16) where the time signal outputted from the time signal output unit (14) is stored when photons are detected by the photon detection unit (12). The photon detection unit (12) comprises an HPD (24) having a photo-cathode (24a) and an APD (24b), a TZ amplifier (26), a peak-holding circuit (28), and an A/D converter (30). The time signal output unit (14) comprises a timer (32) and a counter (34). The storage unit (16) comprises a comparator (36) and a memory (38). When photons impinge on the HPD (24), a trigger signal is outputted from the comparator (36), and the photon count outputted from the A/D converter (30) and the time information outputted from the counter (34) are stored in the memory (38).
Abstract:
Colour changes in a target, such as a chemical sensor using a colour-changing indicator reagent to detect the presence of a poisonous gas, are continuously monitored by reflecting the target (10) on to a sensor (16) light originating from first one and then another light source (12a, 12b, etc), each having a different, known emission wavelength. In each cycle, direct light from the appropriate source is also collected by another sensor (14), connected in a closed loop (26) with circuitry in which the emission intensity is compared with a known reference value (38) and which adjusts the emission intensity so as to stabilise it at this constant reference value. Once this is stabilised, the reflected light intensity signal is passed to a data store (20), after which a divider (22) produces an output signal (36) representing the ratio of the reflected light intensities in two separate cycles originating from two different light sources (12a, 12b, etc). The conduct of each cycle is controlled by timing means (18). Where there are two light sources, the wavelength of the second (12b) is outside the response range of the target, that of the first (12a) being at or near the peak target response, so that all the divider output signals represent successive values of actual reflected light intensity. These signals can be processed to show the rate of colour change in the target and used to operate e.g. an alarm.