Abstract: A photometering apparatus has a photometering apparatus having a plurality of photometering systems for measuring the brightness of an object. photometering system includes:a light receiving device in which different parts of an object are detected by a plurality of split photodetectors whose light receivers each comprise a detection area which is made separate by at least one insensitive area; a photometering optical system for projecting the image of the object onto the light receiving device; wherein the image of the object formed on the at least one insensitive area of one of the plurality of split photodetectors of one of the plurality of photometering systems is formed on the plurality of detection areas of another of the plurality of split photodetectors of another of the plurality of photometering systems.

Abstract: An electro-optic sampling oscilloscope facilitates adjustment of signal-to-noise ratio caused by electrical, optical and temperature factors.

Abstract: An optical analysis system includes an optical filter mechanism disposed to receive light from a light source and configured to optically compress data carried by the light into at least one orthogonal component of the light. A detector mechanism in operative communication with the optical filter mechanism measures a property of the at least one orthogonal component to measure the data.

Abstract: An arrangement for measuring the power or energy of optical radiation of radiation sources, especially laser radiation is disclosed. It comprises a module defining an open or at least partially closed hollow space, wherein the inner walls or outer walls of the module are entirely or partially occupied by detectors for generating measurement signals which are proportional to the measured parameters of the radiation sources. The detectors are connected together in such a way that their generated measurement signals are further processed to form at least one resultant sum signal or the detectors are connected to a downstream processing device to form at least one resultant sum signal. This at least one resultant sum signal is relatively independent from the position, arrangement and radiating characteristic of the examined radiation source in the module. At least one opening or guide-through is provided in the module for inserting the radiation source to be examined.

Abstract: An optoelectronic sensor arrangement comprising a light transmitter for the transmission of sequential operational light pulses into a monitored region and with a light receiver unit for the reception of operational light pulses reflected from an object located in the monitored region, wherein the light receiver unit includes at least two photosensitive elements, with a circuit for the suppression of stray light being associated with each photo-sensitive element.

Abstract: To measure the optical power level of light from an object to be measured, a bias section applies to a photo-detecting section such a reverse bias voltage as makes the current multiplication factor M almost zero to prevent the output current from flowing, and then applies such a reverse bias voltage as makes the M one or more to allow the output current to flow. A processing section determines an offset level from the output of a direct-current amplifying section during an offset data acquisition period that the M is almost zero. The time T0 from when the bias section applies to the photo-detecting section such a reverse bias voltage as makes the M one or more to when the reverse bias voltage is applied to make the M almost zero is determined to be a measurement state. The processing section measures the optical power with a clock faster than time T0.

Abstract: A device detects the times of multiple explosions to within a microsecond thout the need for precise aiming. The device uses a linear array of photodetectors to detect light from the explosions. Each photodetector views a different area, so that explosions occurring in different areas are viewed by different photodetectors. To increase the sensitive area of each photodetector while keeping the device compact, the photodetectors are elongated in a direction orthogonal to the direction in which they are arrayed. A filter is used to transmit only the light produced at the beginning of each explosion.

Abstract: A process and device for continuously measuring the quantity of particles spended in a liquid, which exist in at least two different physical states, such as detached or attached within the paper pulp. A separation assembly separates the particles into divisions depending on their size, and the separation assembly is continuously fed with liquid via an input pipe. A measuring and processing assembly has two channels or ducts coming from the separation assembly and are provided with translucent windows. A measurement and capture unit illuminates the windows, and at least two cameras located opposite each of the respective windows are synchronized with the illumination unit to capture, at regular intervals, an image of the windows. A system for digitizing the captured images and processing them to determine the quantity of particles for each physical states is forwarded to an output unit in a digital or analog form.

Abstract: An arrangement for inspecting the surface of a rotating object (1) which includes object retaining means for retaining whilst rotating the object, means (3) for irradiating the surface of an object when retained and rotated by the object retaining means with a first beam of optical radiation, means (5) for irradiating the surface of an object when retained and rotated by the object retaining means with a second beam of optical radiation detectable as distinct from the first beam, detector means (7) for detecting radiation reflected by the surface of the object from the first beam and for detecting radiation reflected by the surface of the object from the second beam and a signal processor (15) for receiving signals produced by the detector means and for analysing such signals wherein the first beam and the second beam are of different wavelengths or in different wavelength bands and the detector means is capable of simultaneously receiving and detecting radiation received from the same irradiated area of the

Abstract: A beam monitoring assembly (10) that provides near-field imaging, far-field imaging and power measurements of a laser beam (12) in real-time for alignment and performance verification purposes. The monitoring assembly (10) includes a holographic beam splitter (24) that splits the laser beam (12) from the laser resonator cavity into a series of separate split beams (28, 30, 32) having varying beam powers. One of the split beams (28) is directed to a power meter (36) to measure the power of the beam (12). One of the split beams (28) is directed to a near-field camera (42) that provides a near-field image of the beam (12). Another one of the split beams (30) is directed to a heat dump (52) that absorbs and removes the beam's energy from the assembly. Another one of the split beams (32) is directed to a far-field lens (46) that focuses the split beam (32) onto a far-field camera (50) that provides a far-field image of the beam (12).

Abstract: A ratiometric sensor is formed of a first photodiode connected in series with an electronic component, such as a second photodiode or a resistor, between a source of first voltage and a source of second voltage. The ratiometric sensor supplies a "ratiometric voltage" on a ratiometric sensor output line that is connected to a junction between the first photodiode and the electronic component. The ratiometric voltage is proportional to the ratio of the equivalent resistance of the first photodiode to the sum of the equivalent resistances of the first photodiode and the electronic component. A ratiometric sensor that uses a photodiode and a resistance has a large dynamic range because the ratiometric voltage can vary between the first voltage and the second voltage. A ratiometric sensor that uses two photodiodes is less sensitive to noise than a conventional circuit that uses a single photodiode, because noise can get canceled from the numerator and denominator of the ratio.

Abstract: An energy beam threat discrimination system (110) adapted for use with laser beam energy (134). The system (110) includes an first detector (114) for detecting a first laser signal. A second detector (112) detects a coherent laser signal. A timer circuit (124, 126) establishes a time interval between the detection of the first laser signal and the detection of the coherent laser signal and provides an output (130) in response thereto. A control circuit (128, 130) determines, based on the output (130), if the first laser signal and/or the second laser signal is threatening. In a specific embodiment, the first detector (114) provides an event detection flag (118) as an output in response to the detection of a first laser signal. The first detector (114) includes a high sensitivity laser light detector (142), a pre-amplifier (144), and an analog threshold circuit (146). The coherent detector (112) provides a coherent detection flag (116) as an output in response to the detection of the coherent laser signal.

Abstract: The invention provides apparatuses for detecting light from, for example, closely spaced detection sites. In one embodiment, the invention provides an apparatus for measuring the amount of light emitted from or transmitted through two or more detection sites of a first set of detection sites on a planar substrate while spatially resolving the measurements for each detection site of the first set, the apparatus comprising: for each detection site of the first set, an addressable source of a light beam directed to that detection site at a first angle; and an array detector comprising a plurality of light responsive pixels, wherein for each detection site of the first set there is at least one light responsive pixel that receives light emitted from or transmitted through that detection site at a second angle that can be the same as the first angle.

Abstract: A system for the measurement of high bandwidth peak power pulses from laser sources. A laser pulse from a laser is directed onto the surface of a diffuser that replicates the pulse. A linear array of fiber optics of varying fiber length transmits the replicated pulses to a detector. The detector produces n pulses having a pulse width .lambda., each separated in time by a given time delay .DELTA.t which is directly proportioned to the length of each fiber. The output of the detector is fed to a digitizing oscilloscope to produce of digitized average pulse phase output.

Abstract: Photodiodes are situated in a row over a line segment having a predetermined width. Current generated by at least one of the photodiodes is converted into voltage by a resistor. This voltage is amplified by first MOSFETs that are connected at drains thereof in parallel to a source of voltage with a resistor between the adjacent two thereof. This voltage is amplified by second MOSFETs that are connected at drains thereof in parallel to the source of voltage. The first MOSFETs produce a first output signal that id dependent on the position at which the incident light fall on the photodiodes. The second MOSFETs produce a second output signal that is independent from the position of the incident light. A divider calculates a ratio between the first and second output signals. This ratio is indicative of information of the position of the incident light.

Abstract: Two detectors are effectively positioned at a predetermined lateral position in a rectangular illumination field at a wafer plane. The ratio of the signals from the two detectors is calculated. This ratio is indicative of the quality of the illumination field and any lamp instability which may effect the illumination field, and therefore image quality. In a photolithographic device, a short arc mercury xenon lamp provides illumination for projecting the image of a reticle onto a photosensitive resist covered substrate or wafer. The desired illumination intensity profile is sensitive to lamp instability. This instability may alter the desired illumination intensity profile which may adversely effect image quality, and therefore the resulting product. The ratio of the signals received from predetermined locations laterally along the illumination intensity profile improves the detection of unstable lamps.

Abstract: Scene intensity measuring and illumination source detection apparatus for determining scene illuminant and appropriate exposure settings for an image capture device is disclosed. The apparatus includes a diffractive optical element including an off-axis segment for dispersing incident scene illumination into its spectral components and for focusing the incident scene illumination, a structure responsive to the spectral intensities of the spectral components of the incident scene illumination for producing detection signals corresponding to such spectral components, a structure coupled to the sensing means for producing digitized detection signals, and a structure responsive to the digitized detection signals for determining the scene illuminant and the appropriate exposure settings for the image capture device.

Abstract: A light meter comprising: a light sensitive charge storage array having at least one charge storage cell, and reading circuit means connected to said array for generating a light reading from charge stored in said array, said light reading being indicative of the quantity of light incident on said array; wherein said reading circuit means collects charge from said array and compares said collected charge to a threshold to generate said light reading.

Abstract: A photometric apparatus is capable of obtaining a precise photometric value without any saturation of a photometric output value even when measuring a light intensity of a flicker light source. The photometric apparatus has a photometric portion for measuring the field by use of a charge type photometric device, and a charge time determining portion for determining a value of a next charge time of the photometric device on the basis of an output value of the photometric portion and a value of the charge time at that time. The charge time determining portion determines the value of the next charge time so that a photometric output value in the next photometric process approximates a predetermined target value.

Abstract: Optical measuring apparatus for determining chromaticity of thin films on a substrate includes a light source for illuminating the substrate and a measuring apparatus for dispersing light into various wavelengths and making wavelength dependent intensity measurements. Radiation from the light source is reflected or transmitted by the substrate to the measuring apparatus along a first beam path having a first diaphragm for cutting off the radiation from the substrate in a leak-tight manner. Radiation from the light source is also transmitted to the measuring apparatus directly along a second beam path having a second diaphragm for cutting off radiation from the light source in a leak-tight manner. The light source (6a) consists of a globe photometer (6a), in which a lamp (4) is provided. A steadily burning light source, especially a halogen lamp, is used as the lamp (4).

Abstract: A position and orientation tracking system presents a laser scanning appaus having two measurement pods, a control station, and a detector array. The measurement pods can be mounted in the dome of a radioactive waste storage silo. Each measurement pod includes dual orthogonal laser scanner subsystems. The first laser scanner subsystem is oriented to emit a first line laser in the pan direction. The second laser scanner is oriented to emit a second line laser in the tilt direction. Both emitted line lasers scan planes across the radioactive waste surface to encounter the detector array mounted on a target robotic vehicle. The angles of incidence of the planes with the detector array are recorded by the control station. Combining measurements describing each of the four planes provides data for a closed form solution of the algebraic transform describing the position and orientation of the target robotic vehicle.

Abstract: A light sensing device including at least one light sensor is provided. The at least one light sensor is configured to be exposed to a light image. In response to the light image, the at least one light sensor is configured to generate a first signal. The light sensing device further includes a measuring device coupled to the at least one light sensor. The light sensing device also includes a sampling generator configured to generate a sampling signal to the measuring device. The sampling signal is inhibited when the first signal is lesser than or equal to a predetermined value. Upon inhibition of the sampling signal, the measuring device retains a measure of the first signal.

Abstract: Disclosed is a light quantity measurement device that can accurately monitor light intensity regardless of the polarized condition of incident light. A light quantity measuring device comprises: a birefringent optical device; transmission means for passing incident light from a light source; and a light-receiving device for receiving an ordinary light beam and an extraordinary light beam from the transmission means. The light-receiving device has at the least two electrically separated light-receiving areas from which currents produced by received light are independently output, and includes first and second variable gain amplification means for amplifying currents, which are produced by received light, from the two electrically separated light-receiving areas, and an addition circuit for adding together those currents that are amplified by the first and the second amplification means.

Abstract: An air conditioning apparatus for a vehicle includes a first sunlight sensor disposed in a driver's seat side and a second sunlight sensor disposed in a passenger seat side space. The sunlight sensors are integrally formed with a filter and a Fresnel lens. When an elevation angle of sunlight is low, an inadequate correction of sunlight amounts is prevented by the Fresnel lens. Further, when sunlight enters the vehicle from the side, detected sunlight amounts detected by the first and second sunlight sensors are corrected so that a ratio or a difference between the detected sunlight amounts becomes large when the ratio or the difference is in a predetermined range. Therefore, when sunlight enters from the side, the correction of the detected sunlight amounts can be performed adequately so that passengers in the passenger compartment of the vehicle feel comfortable.

Abstract: An automatic lighting system simplifies reproduction of desired lighting conditions by use of a computer which compares characteristics of an actual subject to prestored data representing light locations for preferred lighting of a similar mimic subject, and orients mounted lighting fixtures accordingly. A plurality of light fixtures are mounted for movement on frame. Ideal locations of the light fixtures are determined for mimic subjects of various characteristics by a skilled photographer. The location and illumination data are then stored in computer memory. When an actual subject is placed in the same position as the mimic subject for photographing thereof, data for a mimic subject having characteristics closest to the actual subject are selected from the prestored data, and the light fixtures are automatically oriented accordingly in response to computer control.

Abstract: An image information processing apparatus comprising a parallel connection circuit for parallelly connecting a plurality of photo-electric conversion elements, a combined signal read circuit for reading out a combined signal from the plurality of parallelly connected photo-electric conversion elements, an individual signal read circuit for reading out an independent individual signal of each of the plurality of photo-electric conversion elements, a photometry circuit connected to the combined signal read circuit and a distance measurement circuit connected to the individual signal read circuit.

Abstract: A radiometric calibration system is proposed to calibrate the sensor array of a space born optical imaging system. The calibration system comprises an occulting plate with an occulting convolution aperture which executes a relative lateral motion with respect to an image of the sun, to effect a deterministic and continuously varying calibration flux level to the sensor array. The shape, size orientation and apodization of the aperture control the functional form of the temporal irradiance function reaching the sensor being calibrated. Continuous calibration functions covering a range from a minimum to a maximum desired flux level are readily achievable.

Abstract: A ratiometric sensor is formed of a first photodiode connected in series with an electronic component, such as a second photodiode or a resistor, between a source of first voltage and a source of second voltage. The ratiometric sensor supplies a "ratiometric voltage" on a ratiometric sensor output line that is connected to a junction between the first photodiode and the electronic component. The ratiometric voltage is proportional to the ratio of the equivalent resistance of the first photodiode to the sum of the equivalent resistances of the first photodiode and the electronic component. A ratiometric sensor that uses a photodiode and a resistance has a large dynamic range because the ratiometric voltage can vary between the first voltage and the second voltage. A ratiometric sensor that uses two photodiodes is less sensitive to noise than a conventional circuit that uses a single photodiode, because noise can get canceled from the numerator and denominator of the ratio.

Abstract: An illumination measuring device for panoramic picture taking has a first photoelectric illumination intensity receiver which diffusely determines light falling in a first measuring region and illuminating a first panoramic portion, at least one further photoelectric illumination intensity receiver which diffusely determines light falling in a second measuring region and illuminating a further panoramic portion, and an evaluating unit determining a deviation of an illumination intensity determined by the further illumination intensity receiver from an illumination intensity determined by the first illumination intensity receiver.

Abstract: A photometric control device for a camera comprises a light-receiving device 7 for conducting a photometry on a subject field with an accumulation type of photoelectric conversion device to output a photometric signal corresponding to brightness of the subject field, an accumulation time setting unit 13 for controlling an accumulation time of the photoelectric conversion device, a selection unit 14 for selecting any one of a first brightness value calculation mode for suppressing affection of flicker of a light source and a second brightness value calculation mode for taking no consideration of the affection of flicker on the basis of the accumulation time determined in the accumulation time setting unit 13, and a brightness value calculation unit 10 for calculating a brightness value on the basis of the photometric signal from the light-receiving device 7.

Abstract: An automatic lighting system simplifies reproduction of desired lighting conditions by use of a computer which compares characteristics of an actual subject to prestored data representing light locations for preferred lighting of a similar mimic subject, and orients mounted lighting fixtures accordingly. A plurality of light fixtures are mounted for movement on frame. Ideal locations of the light fixtures are determined for mimic subjects of various characteristics by a skilled photographer. The location and illumination data are then stored in computer memory. When an actual subject is placed in the same position as the mimic subject for photographing thereof, data for a mimic subject having characteristics closest to the actual subject are selected from the prestored data, and the light fixtures are automatically oriented accordingly in response to computer control.

Abstract: A technique for performing background suppression in photodiode detectors is disclosed. A first detector measures the light emitted by the source to be measured and the background light, while a second detector simultaneously measures the background light only. The value measured by the second detector is subtracted from the value measured by the first detector, and the difference represents the portion of the first detector's measured value which is attributable to the source to be measured.

Abstract: An optical system for the attenuation of laser light for measurement purposes which includes four logical subassemblies including a first attenuator subassembly for the attenuation of high power laser light, a second attenuator subassembly for lower power attenuation of the laser light, a third lens subassembly for collecting beam size data simultaneously at multiple locations in space, and a fourth logical subassembly including a beam measuring assembly for recording the beam size data received from the lens subassembly for analysis of the beam characteristics. The first attenuator subassembly is provided with a pair of reflecting, opposed facing, fixed wedges. The reflecting wedges are selectively tilted to eliminate interference effects between their inward facing reflecting surfaces. The second attenuator subassembly further includes a pair of opposed facing and movable wedges arranged in series with a fixed filter.

Abstract: A photometering device comprises: a generator for generating an analog voltage output which varies in accordance with a light intensity of an object field and is proportional to an absolute temperature; a reference voltage generator for generating a reference voltage output proportional to an absolute temperature; a switching device for switching the analog voltage output and the reference voltage output; a single output terminal for sequentially outputting the analog voltage output and the reference voltage output switched by the switching device; and an arithmetic operation device having a single analog-digital converter for converting the analog voltage output and the reference voltage output supplied from the single output terminal to digital signals for calculating a photometering value based on the digitally converted analog voltage output and reference voltage output.

Abstract: Primary and secondary mirrors constitute a collimator which permit measurements to be made within a reasonably sized equipment enclosure. An incoming laser beam, from a unit undergoing test, has its light dispersed by an integrating sphere from which radiometric measurements may be made. Further, the output from the sphere passes through an avalanche photo diode for detecting laser beam pulse envelopes. These envelopes may be measured for such parameters as pulse width, and interval. A focal plane array camera is provided to measure boresight deviation from the unit undergoing test.

Abstract: A near-field goniophotometric apparatus and method for measuring the three-dimensional near-field distribution of luminous flux surrounding a light source. The apparatus incorporates an imaging photometer mounted on a rotatable arm. The photometer is designed to measure the helios of a volume of space rather than the luminance of a planar surface, and to simultaneously measure the helios of a plurality of such volumes. A control mechanism is provided to position the arm and to rotate the light source relative to the arm. The method facilitates prediction of the illuminance or irradiance at a point on a plane from the helios measurements.

Abstract: An exposure calculation device comprises: first composite photometered value calculation apparatus means for classifying areas of divisional photometering means to a first pattern and calculating a composite photometered value for each classified area based on the photometered values of the divisional photometering areas contained in each classified area; first exposure value calculation means for calculating a first exposure value based on the calculated composite photometered value; second composite photometered value calculation means for classifying the areas of the divisional photometering means to a second pattern and calculating a composite photometered value for each classified area based on the photometered values of the divisional photometering areas contained in each classified area; second exposure calculation means for calculating a second exposure value based on the calculated composite photometered value; contribution factor calculation means for calculating contribution factors of the first an

Abstract: A dual beam laser array provides two overlapping beams for use in a direct read after write (DRAW) optical data storage system. A first portion of the overlapping beams is directed to a first optical detector and a second portion of the overlapping beams is directed to a second optical detector. A logic circuit connected to the optical detectors generates power signals representative of the power levels of each of the overlapping beams without the need to completely separate the beams.

Abstract: A portable traffic signal photometer is capable of rapidly and effectively measuring the intensity of light emanating from a traffic signal light. The photometer includes a housing member with a circular front opening for engagement with the lens of a traffic signal light. The photometer is pressed against the lens, and the light emanating from the traffic signal light is directed through an optical filter located inside the housing, which permits light from the traffic signal light emanating at a predetermined downward angle to pass through it. The light from the filter is directed onto a light-sensitive device, which produces an output signal proportional to the intensity of the light emitted by the traffic signal lens.

Abstract: In an automatic exposure (AE) controlling method and apparatus according to the invention, a picturing area or a view is divided into a plurality of zones of which the central one is usually used for iris adjustment with the largest weight. The central zone is automatically expanded or reduced in the upper, lower, right-hand or left-hand direction(s) in accordance with differences in average luminance between the central zone and a respective one of the surrounding zones.

Abstract: A light beam is chopped and split into two beams. Intensity of a first beam is changed by using, e.g., an electrooptic material in accordance of a change in a signal to be detected, such as a voltage in an electronic device, and detected by a first photodetector. On the other hand, a second beam is detected by a second photodetector without being subjected to the intensity change. At least one of the outputs of the first and second photodetectors are adjusted so that they become equal to each other when no signal is applied to the light intensity changing means. The difference of the thus adjusted output signals is detected by, e.g., a lock-in amplifier in a narrow band at the chopping frequency.

Abstract: In the present invention there is provided a plurality of photosensitive elements arranged in a symmetrical pattern around a central circular area. The area surrounding the central area is formed of a square area having the circular area at its center with the square area divided into four equal quadrants. The next area is rectangular in shape and surrounds the second area. The rectangular area is formed in four equal sections with each of the corners of the square area lying along two adjacent edges of the rectangular areas. A selection means is provided for selecting the output signal from any one the photodiodes or for selecting the output signals from any combination of two or more of the photodiodes so as to accentuate the responsiveness of the light meter to a selected area or feature of the image to be photographed.

Abstract: Apparatus for determining the energy of single pulses of rapidly pulsing laser radiation including first radiation sensing apparatus for providing a first signal output in response to single pulses of a plurality of pulses of rapidly pulsing radiation; second radiation sensing apparatus for providing a second signal output in response to a plurality of pulses of rapidly pulsing radiation, the second signal output being an indication of the overall average incident optical power of the plurality of pulses; and signal processing apparatus, associated with the first and second radiation sensing apparatus, for receiving and processing the first and second signal outputs so as to determine an average pulse rate of the plurality of pulses and thereby also to provide an output indication of the energy of single pulses of the plurality of pulses of rapidly pulsing radiation.

Abstract: A method and an apparatus for detecting the endpoint in a plasma etching process is disclosed. The invention uses a positive filter and a negative filter simultaneously to generate a first and a second signal respectively. The first and second signals are combined to form a combined signal. A change in the combined signal is indicative of the endpoint.

Abstract: A technique for the simultaneous measurement, in real time, of the changes in mode size, pulse length, and power of a wavetrain of laser pulses delivered by mode-locked or other pulsed laser systems contemplates directing respective portions of the beam along each of three beam paths. The beam portions along the first and second beam paths are subjected to respective, and different, degrees of focusing, and then passed through respective non-linear elements which generate radiation at the second harmonic. The first harmonic components are removed, and the second harmonic components are passed to respective first and second detectors which generate signals representative of the total second harmonic energy along each of the first and second beam paths. The beam portion along the third beam path is passed to a detector which generates a signal representative of the total energy in the beam pulse. The three signals are combined to give values proportional to peak power, pulse length, and mode size.

Abstract: A method and apparatus for measuring the output of the measurement signal output by an optical sensor, for determining the intensity of the lights incident on the sensors. A plurality of setting values corresponding in a functional relationship to a plurality of estimated light intensity values being stored, prior to the measurement, in a memory. An address specifying means for causing the memory to output one of the plurality of setting values prestored therein during the time the address is specified. A count means for counting clock pulses with a predetermined period during the time duration of the measurement signal. A detecting means for detecting a comparison between the count value of the clock pulses and the setting value prestored in the memory and then causing the address specifying means to specify a new address in the memory in response to the detection result.

Abstract: A device for detecting a backlighting condition comprising a light meter of which the image receiving surface is divided into a central area, an intermediate area and a marginal area, and a circuit for discriminating between true and false backlighting conditions in such a way that when the luminance of the marginal area is greater than that of the intermediate area by more than a predetermined value and when the luminance of the intermediate area is greater than that of the central area, the backlighting condition in question is taken as a true one.

Abstract: A light metering device comprises a photometric element for independently metering a plurality of metering areas into which a whole image area is divided to provide weighted average brightness information for a scene to be photographed. The whole image area is divided into a plurality of metering areas including at least a center metering area defined at center of the whole image area, a lower metering area defined right below the center metering area, and two lower metering areas defined by a lower center half of the whole image area excluding the center metering area and the lower center metering area. The lower center metering area is weighted less than the center and lower metering areas by weighting differently the photometric sensitivities of the metering areas.

Abstract: A light metering device includes a light detecting number having a plurality of light detecting elements arranged in a matrix for detecting brightness of smaller divisions into which a whole image field is divided, respectively, to define a plurality of light metering areas different in area in an image field so as to contain a smaller light metering area within a larger light metering area, and a calculating member for obtaining a mean brightness value of each light metering area by calculating an arithmetic mean value of the outputs from the light detecting elements defining each light metering area. The difference of mean brightness values of two adjacent light metering areas is compared with a predetermined critical mean brightness value to determine that lighting condition under which a subject exists is ordinary or unusual.

Abstract: A light source discriminating apparatus includes three photosensors, two of which have similar spectral sensitivity characteristics to each other. The apparatus senses the difference in the energy distribution of light sources by comparing the ratios of the light intensity sensed by these photosensors. In this manner, the type of a light source having a spectrum peak in the energy distribution of the light emanating from the source may be discriminated as a fluorescent light source, for example. The results of discrimination may be used effectively for adjusting white balance or shutter speed of a video or electronic still camera.