Abstract: The present invention enables the detection of light using an APD that has high gain and/or a wide range of operating temperature. A first APD is biased with a voltage bias that is controlled based on the breakdown voltage of a second APD, which is thermally coupled with the first APD. Changes in the breakdown voltage of the second APD due to aging, temperature chances, and the like, are reflective of changes in the breakdown voltage of the first APD. As a result, the first APD can be operated with greater stability and reliability at high gain and over larger temperature excursions than APDs known in the prior art.

Abstract: A light sensing device has a first filter to block visible light in a light path. The light sensing device also has a first color sensor and a clear sensor, to detect light in the light path after the first filter. A light intensity calculator computes a measure of the intensity of visible light in the light path, based on a difference between (a) an output signal of the first color sensor, and (b) an output signal of the clear sensor. Other embodiments are also described and claimed.

Abstract: A probe card for wafer-level testing a plurality of optoelectronic devices on a wafer is provided. The probe card has both electrical and optical functionality. The probe card comprises a plurality of lenslets aligned with the plurality of optoelectronic devices to improve the optical coupling efficiency between each of the plurality of optoelectronic devices and a plurality of optical waveguides located on a probe head.

Abstract: Energy harvesting devices include a substrate coupled with a photovoltaic material and a plurality of resonance elements associated with the substrate. The resonance elements are configured to collect energy in at least visible and infrared light spectra. Each resonance element is capacitively coupled with the photovoltaic material, and may be configured to resonate at a bandgap energy of the photovoltaic material. Systems include a photovoltaic material coupled with a feedpoint of a resonance element. Methods for harvesting energy include exposing a resonance element having a resonant electromagnetic radiation having a frequency between approximately 20 THz and approximately 1,000 THz, absorbing at least a portion of the electromagnetic radiation with the resonance element, and resonating the resonance element at a bandgap energy of an underlying photovoltaic material.

Abstract: A light sensor system includes at least one light emitter, a light sensor unit and a processing unit. The light sensor unit is arranged to receive reflected light from an object in accordance with a time sequence in which the at least one light emitter is activated, and accordingly output a plurality of reflected signals. The processing unit is arranged to receive the reflected signals, identify a signal function of time by referring to occurrence sequence of local peak levels of the reflected signals, and determine motion of the object according to the signal function of time. Another light sensor system is proposed. The major difference between the two light sensor systems is that the processing unit of the another light sensor system is arranged to identify the signal function of time by comparing a predetermined threshold with signal levels of the reflected signals.

Abstract: A photosensitive device (100), the photosensitive device (100) comprising a substrate (101) and a plurality of vertically aligned nanowire diodes (102 to 105) provided on and/or in the substrate (101).

Abstract: A person location detecting apparatus according to the present invention includes a light emitting section for radiating a projection light and a TOF method distance image sensor for receiving a reflected light from a room space of the projection light to output distance information in accordance with a distance to an object in the room space from each of a plurality of light receiving sections, and further includes a distance change detecting section for detecting a distance change to the object in the room space based on the distance information from the TOF method distance image sensor and a person distinguishing section for distinguishing a person by specifying a shape of a detected distance change area to detect a direction and distance to the distance change area that is specified as a shape of a person as a location of a person.

Abstract: The invention relates to an optical detector device (1) for generating at least one electrical output signal in response to a received beam of light, comprising an optical band-pass filter (3a), adapted to receive the beam of light and to provide a filtered beam of light, which filter (3a) has a transmission wavelength which increases in direction of at least one axis (4) and an array of detector elements (2) arranged in direction of the axis (4) to receive the filtered beam of light for generating the electrical output signal.

Abstract: An embodiment relates to a device comprising a substrate having a front side and a back-side that is exposed to incoming radiation, a nanowire disposed on the substrate and an image sensing circuit disposed on the front side, wherein the nanowire is configured to be both a channel to transmit wavelengths up to a selective wavelength and an active element to detect the wavelengths up to the selective wavelength transmitted through the nanowire.

Abstract: The present invention regards methods and devices for detecting plaque on a surface in the oral cavity to which a fluorescent agent capable of binding to plaque has been applied, whereby a radiation source emits incident radiation for contacting the surface, reflected light and fluorescent emission resulting from contact of the radiation with the surface is collected by an optical collector and conveyed by an optical pathway in the device, where the optical light signal of the reflected light and fluorescent emission is converted to an electrical signal, and where the electrical signals of the fluorescent emission and the reflected light are then mathematically manipulated to provide a compensated plaque value as a function of the distance from the optical collector and the surface of the oral cavity to which the fluorescent agent has been applied.

Abstract: A fluorescence detection optical system detects fluorescence beams with two or more different wavelengths and maintains a focal position through an automatic focusing function. A multi-channel fluorescence detection apparatus includes the fluorescence detection optical system. The fluorescence detection optical system includes an automatic focusing unit which receives light reflected off a microfluidic device and determines a focal point by using an astigmatic method or a knife edge method, and an actuator which adjusts a position of an objective lens according to control of the automatic focusing unit. In addition, the fluorescence detection optical system may include a plurality of dual band pass filters, dichroic devices, etc., which provide light beams emitted from at least two light sources and transfer fluorescence generated from the microfluidic device to a photodetector.

Abstract: A display device in which light leakage in a monitor element portion is prevented without increasing the number of steps and cost is provided. The display device includes a monitor element for suppressing influence on a light-emitting element due to temperature change and change over time and a TFT for driving the monitor element, in which the TFT for driving the monitor element is provided so as not to overlap the monitor element. Furthermore, the display device includes a first light shielding film and a second light shielding film, in which the first light shielding film is provided so as to overlap a first electrode of the monitor element and the second light shielding film is electrically connect to the first light shielding film through a contact hole formed in an interlayer insulating film. The contact hole is formed so as to surround the outer edge of the first electrode of the monitor element.

Abstract: The invention relates to a charged-particle multi-beamlet lithography system. The system comprises a beam generator for generating a plurality of beamlets, a beamlet blanker array for patterning the plurality of beamlets, an optical fiber arrangement, and a projection system. The beamlet blanker array comprises a substrate provided with a first area comprising one or more modulators and a second area free of modulators. The beamlet blanker array comprises one or more light sensitive elements, electrically connected to the one or more modulators, and arranged to receive light beams carrying pattern data. The optical fiber arrangement comprises a plurality of optical fibers for guiding the light beams carrying pattern data towards the one or more light sensitive elements. The projection of the optical fiber arrangement onto a surface of the beamlet blanker array in a direction perpendicular to the surface falls entirely within the second area.

Abstract: An optical sensor device for the detection of ambient light is adapted to be coupled to a pane (10), in particular to a windshield of a vehicle. The optical sensor device has a sensor unit which includes at least one light receiver (22) for ambient light and a lens plate (12) for directionally coupling an ambient light beam (26) out of the pane (10) onto the light receiver (22). The lens plate (12) has a surface (18) facing the light receiver (22) and oriented substantially parallel to the pane (10) in the coupled condition of the optical sensor device. The surface (18) includes a prism structure (20) having a plurality of single prisms (24) which are designed to direct the rays of a specific ambient light beam (26) defined by a principal direction (A) and an aperture angle onto the light receiver (22).

Abstract: According to an example embodiment, a light-sensing apparatus may include an array of light-sensing pixels, a first gate driver, and a signal output unit. Each of the light-sensing pixels may include a light sensor transistor configured to sense light, a switch transistor configured to output a light-sensing signal from the light sensor transistor, and a conductive light-shielding film on a light-incident surface of the switch transistor. The light sensor transistor and the switch transistor may have the same oxide semiconductor transistor structure. The first gate driver may be configured to provide a gate voltage and a negative bias voltage to each of the light-sensing pixels. The signal output unit may be configured to receive the light-sensing signal from each of the light-sensing pixels and output a data signal.

Abstract: Provided is a display device that includes an optical sensor having a high sensitivity in which a potential difference of an accumulation node due to an illuminance difference on a light receiving surface after boosting is set greater than a potential difference of the same at an end of an integration period. The display device includes an optical sensor in a pixel region. The optical sensor includes a diode D1; a reset signal line RST for supplying a reset signal; a readout signal line RWS for supplying a readout signal; an accumulation node having a potential (VINT) that varies with an amount of light received by the diode D1 during a period from supply of the reset signal to supply of the readout signal; an amplifying element C1 for amplifying VINT according to the readout signal; and a sensor switching element M2 for reading out the amplified potential and outputting the same to an output line.

Abstract: Methods, devices and systems for harvesting energy from electromagnetic radiation are provided including harvesting energy from electromagnetic radiation. In one embodiment, a device includes a substrate and one or more resonance elements disposed in or on the substrate. The resonance elements are configured to have a resonant frequency, for example, in at least one of the infrared, near-infrared and visible light spectra. A layer of conductive material may be disposed over a portion of the substrate to form a ground plane. An optical resonance gap or stand-off layer may be formed between the resonance elements and the ground plane. The optical resonance gap extends a distance between the resonance elements and the layer of conductive material approximately one-quarter wavelength of a wavelength of the at least one resonance element's resonant frequency. At least one energy transfer element may be associated with the at least one resonance element.

Abstract: The invention relates to a plurality of light sources to power a variety of applications including microarray readers, microplate scanners, microfluidic analyzers, sensors, sequencers, Q-PCR and a host of other bioanalytical tools that drive today's commercial, academic and clinical biotech labs.

Abstract: Coherent optical signal processing is performed in a coherent receiver (or diagnostic/testing apparatus) that converts an amplitude and/or angle-modulated optical signal into two electrical signals. A simple receiver can only detect one phase of the signal and only the polarization that is aligned with a local oscillator laser polarization. To detect both phases and both polarizations, two sets of two interferometers, one each with a ?/2 phase shift are required. Coherent optical signal processing methods, apparatus, techniques, etc. are disclosed that include individual components comprising a polarization combiner, a Savart device and photodetection apparatus with substantially reduced temperature and alignment sensitivity operating in optical communication systems and/or subsystems. The various embodiments can be used alone or in such combinations to provide improved coherent optical signal processing in a receiver.

Abstract: First, second, and third image planes are obtained from at least one image sensor. The first image plane is formed from light of a first spectral distribution. The second image plane is formed from light of a second spectral distribution. The third image plane is formed from light of a spectral distribution which substantially covers the visible spectrum. First spatial frequency components are generated from the first, second and third image planes. A second spatial frequency component is generated from the third image plane. A color transform is applied to the first spatial frequency components from the first, second, and third image planes to obtain at least first, second and third transformed first spatial frequency image planes. The at least first, second and third transformed first spatial frequency image planes are combined with the second spatial frequency component from the third image plane to form an image.

Abstract: A portable electronic device, for example an electronic card, includes at least one electronic unit associated to an optical switch which can be actuated by a user and which includes two photo-detectors arranged sufficiently far from each other in the electronic device to enable the user to cover only one of the two photo-detectors with one finger. The switch includes a logical circuit to which are provided a first and a second light reception signal respectively coming from the two photo-detectors. The logical circuit is arranged to supply a signal which only indicates actuation of the optical switch when the first and second light reception signals correspond to two different logical states for the logic circuit.

Abstract: A detector contains a housing with at least one window for allowing radiation to enter, at least one outlook sensor for sensing entered radiation, a unit for processing outlook sensor signals, and outlook mirrors that are shaped and mounted in the housing for reflecting onto the outlook sensor radiation from outside detection zones better than radiation from elsewhere. At least some of the outlook mirrors face the window and in operative orientation neighbor each other vertically. The detector further contains one or more window sensors for sensing radiation indicative of the window being masked or having been damaged and a unit for processing window sensor signals. A gap between at least two of the outlook mirrors allows radiation to travel between the window and at least one window sensor or accordant window sender or both.

Abstract: The invention relates to a charged particle multi-beamlet lithography system for exposing a target using a plurality of beamlets. The system has a beam generator, a beamlet blanker, and a beamlet projector. The beam generator is configured to generate a plurality of charged particle beamlets. The beamlet blanker is configured to pattern the beamlets. The beamlet projector is configured to project the patterned beamlets onto the target surface. The system further has a deflection device. The deflection device has a plurality of memory cells. Each memory cell is provided with a storage element and is connected to a switching electrode of a deflector.

Abstract: A light sensor including a substrate and one or more low profile baffle plates, the baffle plates including collimator holes to allow intended light to strike the light detector of the substrate while preventing extraneous light from striking the detector. The baffle plates are disposed above the substrate, on a shroud, which covers a portion of the substrate but allows intended light to pass through the collimator holes onto the light detector. By stacking baffle plates having a thin, low profile, one on top of another upon the shroud, extraneous light striking the material at an angle between the collimator holes cannot enter the sensor while intended light in the substantial front of the sensor enters the sensor through the collimator holes and can be detected by the light detector.

Abstract: A light-field pixel for detecting a wavefront, the light-field pixel comprises an aperture layer, a light detector layer, and a processor. The aperture layer has a non-conventional aperture and a non-conventional aperture. The non-conventional aperture has a higher gradient of transmission at normal incidence than the conventional aperture. The light detector is configured to measure a first intensity of light through the non-conventional aperture and a second intensity of light through the conventional aperture. The processor is configured to detect the wavefront based on the first intensity normalized by the second intensity.

Abstract: In an embodiment, a DP-QPSK demodulator includes first, second and third polarization beam splitters (“PBSs”) and first, second and third half waveplates (“HWPs”). The first HWP is positioned to receive an output of the first PBS. The second PBS is positioned to receive an output of the first HWP. The second HWP is positioned to receive an output of the second PBS. The third PBS is positioned to receive an output of the second HWP. The third HWP is positioned to receive an output of the third PBS.

Abstract: A light condensing member focuses light, which is incident upon a first area of the light condensing member corresponding to an opening portion of an insulation film, in an upper portion region of a light path member arranged within the opening portion, the insulation film having an upper face extending from the opening portion, and the light path member having a lower face in a region corresponding to a light receiving face of an photoelectric conversion portion.

Abstract: Briefly, embodiments of an optical micro-sensor are described.

Abstract: The invention relates to a device (1) for characterizing a two-phase flow in a channel (11), and to a related method.

Abstract: Embodiments of the present invention provide an optical module, including an MT-Ferrule and a photoelectric conversion unit. The MT-Ferrule is configured to connect multiple channels of optical channels outside the optical module with multiple channels of optical channels of the photoelectric conversion unit, and implement coupling and transmission of multiple channels of single-mode optical signals between the two. The photoelectric conversion unit is configured to convert multiple channels of single-mode optical signals input from the MT-Ferrule into multiple channels of electrical signals and output the multiple channels of electrical signals, and generate, driven by multiple channels of input electrical signals, multiple channels of single-mode optical signals and output the multiple channels of single-mode optical signals to the MT-Ferrule.

Abstract: Described herein are flexible and stretchable LED arrays and methods utilizing flexible and stretchable LED arrays. Assembly of flexible LED arrays alongside flexible plasmonic crystals is useful for construction of fluid monitors, permitting sensitive detection of fluid refractive index and composition. Co-integration of flexible LED arrays with flexible photodetector arrays is useful for construction of flexible proximity sensors. Application of stretchable LED arrays onto flexible threads as light emitting sutures provides novel means for performing radiation therapy on wounds.

Abstract: A novel parallel optical module having combined optical signal transmit and receive function for high-speed performance. The optical module includes a plurality, e.g., sixteen 10-Gb/s transmitter and receiver channels for a 160-Gb/s bidirectional aggregate data rate. The module utilizes a single-chip CMOS optical transceiver containing both transmitter and receiver circuits. 16-channel high-speed photodiode (PD) and VCSEL arrays are flip-chip attached to the low-power CMOS IC. The substrate emitting/illuminated VCSEL and PD arrays operate at 985 nm and include collimating lenses integrated into the backside of the substrate. The IC-OE assembly is then flip-chip attached to a high density organic package forming the transceiver optical module. The exclusive use of flip-chip packaging for both the IC-to-optoelectronic (OE) devices and for the IC-to-organic package minimizes the module footprint and associated packaging parasitics.

Abstract: Computational load is shifted into or out of a computational array based on one or more metrics associated with power generation associated with power used by the computational array. The computational load is shifted by supplying data associated with the computational load into or away from the computational array. The one or more metrics include change in amount of available power for the computational array. The computational load is shifted from the computational array to a second computational array supplied with power from a different power generation facility, based on an indication of a reduction of the available power for the computational array and sufficient computational capacity of the second computational array.

Abstract: Methods and systems for providing a light device that can emit light and sense light are disclosed. In one embodiment, a lighting device includes a light guide having a planar first surface, the light guide configured such that at least some ambient light enters the light guide through the first surface and propagates therein, and at least one light detector disposed along an edge of the light guide, the at least one detector optically coupled to the light guide to receive light propagating therein. The light detector can be configured to produce a control signal. In some embodiments, the lighting device also includes at least one light turning feature disposed on the first surface, the at least one light turning feature configured to direct light incident into the light guide through the first surface.

Abstract: In order to improve resolution to the illuminance of light, the present invention comprises a photoelectric conversion circuit for generating a first current in accordance with illuminance of incident light, a charge/discharge circuit whose electrical capacitance changes in accordance with the first current, a first switching element which is turned on or off so as to control conduction between the photoelectric conversion circuit and the charge/discharge circuit, a current circuit for generating a second current with a constant amount, a second switching element which is turned on or off so as to control conduction between the charge/discharge circuit and the current circuit, and a comparator including a first input terminal and a second input terminal, wherein a signal with a reference potential is input to the first input terminal and the second input terminal is electrically connected to the charge/discharge circuit are provided.

Abstract: A photodetecting circuit includes an adder that selectively adds outputs of a plurality of circuits for photodetection. Each of the circuits for photodetection includes: a element for photodetecting; a transimpedance amplifier for photodetection, with a first input terminal connected to the photodetecting element; a transconductance amplifier, with a first input terminal connected to an output terminal of the transimpedance amplifier; and a feedback circuit, connected between the output terminal of the transimpedance amplifier for photodetection and the first input terminal of the transimpedance amplifier for photodetection and applying feedback to keep fixed an output voltage of the transimpedance amplifier for photodetection.

Abstract: By reducing the potential drop of a storage node that occurs due to feedthrough, the capacitance of a storage capacitor is reduced and sensor sensitivity is improved. In a photosensor, the first terminal of a storage capacitor (C2) and the gate of a MOS transistor (M1), which outputs a signal in accordance with the potential of a storage node (N2), are connected to the storage node (N2). A forward biased pulse voltage is supplied to the anode of a first photodiode (DS) in a reset period, and a reverse biased voltage is supplied to the anode of the first photodiode in a storage period and a readout period. A reverse biased voltage is supplied to the anode of a second photodiode (DM) in all operation periods.

Abstract: The present invention provides methods and systems for particle detection and analysis using two-dimensional optical imaging to access enhanced detection sensitivity and expanded sensing functionality relative to conventional point and array detection-based optical particle counters. Methods and systems of the present invention provide a two-dimensional optical imaging-based particle sensing platform wherein system components and specifications are selected to generate reproducible and readily identifiable signals, including particle detection signatures, from optical scattering or emission from particles provided to the system. Systems and methods of the present invention are capable of accurately and sensitively detecting, identifying, and characterizing (e.g., determining the size of) particles in liquid phase or gas phase samples.

Abstract: A sensor array microchip apparatus includes a substrate and a lens positioned over the substrate. A plurality of radiation sensor elements are formed on the substrate in an array format and spatially separated from each other. The substrate further includes power supply circuitry (generating power for the radiation sensor elements) and processing circuitry (operable to control and process information from the radiation sensor elements). The power supply circuitry and said processing circuitry are positioned on the substrate within the array between two or more of the radiation sensor elements. The lens, in combination with the spatial separation of the radiation sensor elements in the array format, defines a relatively wide (30-80 degrees) field of regard for the sensor.

Abstract: A radiation sensor is provided comprising: one or more first pixels and one or more second pixels. A first optical element is provided over the first and second pixels, having a first field of view. A second optical element is provided over the one or more second pixels, having a second field of view. The second optical element is positioned between the first optical element and the one or more second pixels, wherein the first field of view is substantially narrower than, and lies substantially within, the second field of view.

Abstract: This invention provides an apparatus for estimating change of status of a plurality of particle beams, the apparatus includes a plurality of particle detectors and an estimating unit, wherein the one or the plurality of particle beams is projected to a substrate. The particle detectors detect the one or the plurality of particle beams reflected from the substrate to generate one or a plurality of detector signals. The estimating unit estimates change of the status of the one or the plurality of particle beams by executing a mathematical programming method according to the one or the plurality of detector signals. By such arrangement and monitoring method, the apparatus could estimate the drift of beams.

Abstract: This invention provides a system for estimating change of status of one or a plurality of particle beams, the system comprises a plurality of particle detectors and an estimating unit, wherein one or a plurality of particle beams is being projected to a substrate. The particle detectors detect the one or the plurality particle beams reflected from the substrate to generate one or a plurality of detected signals. The estimating unit estimates change of the status of the one or the plurality of particle beams according to the one or the plurality of detected signals. By such arrangement and estimating method, the system could estimate multiple beams and achieve beam placement accuracy.

Abstract: A system for calibrating a spectrometer includes wide field-of-view (WFOV) optics providing a first light path to a WFOV spectrometer, and narrow field-of-view (NFOV) optics providing a second light path to a NFOV spectrometer. A de-focusing optic is selectively positioned in the first or second light paths. A scan controller selectively controls the WFOV or NFOV optics to scan a celestial body. A processor is configured to calibrate the de-focusing optic, while the WFOV optics scan the celestial body. First, the WFOV optics scan the celestial body without the de-focusing optic positioned in the first light path. Second, the WFOV optics scan the celestial body with the de-focusing optic positioned in the first light path. Next, the processor calibrates the NFOV spectrometer, while the NFOV optics and the de-focusing optic scan the celestial body. After the NFOV spectrometer is calibrated, the NFOV spectrometer may be used to measure the albedo of the earth.

Abstract: The invention relates to a charged particle multi-beamlet lithography system for exposing a target using a plurality of beamlets. The system has a beam generator, a beamlet blanker, and a beamlet projector. The beam generator is configured to generate a plurality of charged particle beamlets. The beamlet blanker is configured to pattern the beamlets. The beamlet projector is configured to project the patterned beamlets onto the target surface. The system further has a deflection device. The deflection device has a plurality of memory cells. Each memory cell is provided with a storage element and is connected to a switching electrode of a deflector.

Abstract: Apparatus, sensor chips and techniques for optical sensing of substances by using optical sensors on sensor chips.

Abstract: A configurable photo detector circuit comprises a photo detector array including a plurality of photo detectors coupled to a plurality of amplifiers. A method for programming a detection pattern of the configurable photo detector circuit comprises selecting a first detection pattern for the photo detector array, generating first signals to create the first selected detection pattern, and applying the first generated signals to the photo detector circuit to implement the first selected detection pattern.

Abstract: A driving method for a photosensor array panel including a plurality of photosensor strips, a plurality of scan lines, at least a dummy photosensor strip, and at least a dummy scan line is provided. The photosensor strips are arranged side by side and located beside the dummy photosensor strip. The scan lines are electrically connected to the photosensor strips, and the dummy scan line is electrically connected to the dummy photosensor strip. The driving method includes the following steps. First, the photosensor strips are turned on in sequence through the scan lines. When none of the photosensor strips is turned on, the dummy photosensor strip will be turned on through the dummy scan line.

Abstract: Provided are an optical sensor having a wider dynamic range with reduced temperature dependence, and a display apparatus in which these optical sensors are used. An optical sensor includes an accumulation node (INT); a reset signal line (RST); a readout signal line (RWS); a photodiode (D1) (photodetecting element); a photodiode (D2) (reference element) that has a light-shielding layer; a thin-film transistor (M1) (first switching element) that outputs a potential of the accumulation node (INT) in response to the readout signal during a sensing period; and a thin-film transistor (M2) (second switching element) that is provided between the accumulation node (INT) and the photodiode (D2), and that electrically separates the accumulation node (INT) from the photodiode (D2) when the potential of the accumulation node (INT) upon supply of the readout signal is higher than a potential on a side of the photodiode (D2) opposite to the accumulation node (INT).

Abstract: The invention provides imaging apparatus and methods useful for obtaining a high resolution image of a sample at rapid scan rates. A rectangular detector array having a horizontal dimension that is longer than the vertical dimension can be used along with imaging optics positioned to direct a rectangular image of a portion of a sample to the rectangular detector array. A scanning device can be configured to scan the sample in a scan-axis dimension, wherein the vertical dimension for the rectangular detector array and the shorter of the two rectangular dimensions for the image are in the scan-axis dimension, and wherein the vertical dimension for the rectangular detector array is short enough to achieve confocality in a single axis.

Abstract: A laser receiver detects a thin beam of laser light and distinguishes between the beam of laser light and an omni-directional pulse of light from a strobe by the use of an additional photo-detector. The device takes into account the possibility that the additional photo-detector could be illuminated simultaneously with the main photo-detectors at the end of the main photo-detectors closest to the additional photo-detector.