Abstract: A system for detecting a gas may include a first laser having a wavelength overlapping with two or more absorption features in a spectrum of the gas, a second laser having a wavelength centered away from absorbing features in the spectrum of the gas, and at least one sensor to determine a received power of the first laser and a received power of the second laser.

Abstract: A method for controlling a furnace for reheating iron and steel products, comprising forming an infrared image, using an infrared camera, of an upper face of a product over the width and at least partially over the length thereof when said product is arranged on a predetermined discharging surface; digital processing comprising binarization of the infrared image into two classes of pixels, one class that corresponds to the pixels associated with the presence of scale that is bonded on the face of the product and one class that corresponds to the pixels associated with the presence of scale that is not bonded on the face of the product; determining the amounts of non-bonded scale and of bonded scale on the upper face of the product on the basis of the binarized image; modifying furnace control parameters on the basis of the determined amounts of non-bonded scale and of bonded scale.

Abstract: An absorption spectrometer with self-referencing calibration takes two measurements along a first and second path having different distances through a sample while largely preserving all other aspects of the optical path and system constant. Comparing these two measurements allows extraction of the spectrum largely free from instrument-specific artifacts.

Abstract: A plasma processing apparatus having an improved yield includes a metal base member having a disk shape or a cylindrical shape arranged inside a sample table; a refrigerant flow path arranged multiple times in a concentrical shape around a center of the base member; at least one temperature sensor; and a controller configured to detect a temperature of the base member or the wafer using the temperature sensor. The controller is configured to detect the temperature of the base member or the wafer based on one of a plurality of linear functions indicating a relation between an error and a set temperature of the refrigerant, and the linear functions are different corresponding to regions of a plurality of continuous temperature ranges within an adjustable temperature range of the refrigerant, and the plurality of linear functions include the same coefficient and have a point where the error is 0.

Abstract: An apparatus includes at least one Terahertz (THz) device that transmits or receives THz radiation or transmits and receives THz radiation. The apparatus also provides a flow of protective gas in at least one portion of the beam path of the THz radiation.

Abstract: An analysis device including a flow channel member, a suction mechanism, and a measurement unit. The flow channel member includes a flow channel; The suction mechanism is connected to a first end of the flow channel member and is configured to introduce a liquid sample from a second end of the flow channel member to the flow channel and hold the liquid sample between fluid layers in a part of the flow channel. The measurement unit includes a light irradiation unit a light reception unit configured to receive light from the part of the flow channel and the contents of the part of the flow channel when irradiated by the light irradiation unit. The measurement unit includes an aperture member to limit light from the light irradiation unit and includes an opening having an opening width shorter than the length of the part of the flow channel.

Abstract: A gas detection that includes a projector including a light source that emits laser light having a wavelength at which an absorption rate by a detection target gas is high and a spatial light modulator that modulates the laser light emitted from the light source, a projection control unit that controls projection light to be projected toward a retroreflector by causing the light source to emit the laser light and setting a pattern of a modulation part of the spatial light modulator, a light receiver that receives reflected light of the projection light reflected by the retroreflector and measures an intensity of the received reflected light; and a leakage determination unit that acquires the intensity of the reflected light from the light receiver and determines leakage of the detection target gas in a detection space with the retroreflector based on the intensity of the reflected light.

Abstract: A device and a spectrometer for quantitatively detecting carbon 14 isotope by a dual-wavelength method. Two mid-infrared lasers with different wavelengths are locked in an optical cavity of a sample chamber, to ensure the two lasers are collinear. The cavity length of the optical cavity is adjusted by a cavity length adjusting unit, to tune the mode frequency of the optical cavity, and then tune the frequencies of the two mid-infrared lasers, so that the frequencies of the two mid-infrared lasers match with different energy levels of the target isotope molecule simultaneously. After the frequencies of the mid-infrared lasers match with the energy levels of the target isotope molecule simultaneously, the target isotope molecule is excited by two mid-infrared lasers simultaneously, and the optical cavity output signal of the second mid-infrared laser passing through the optical cavity is detected.

Abstract: A method for determining a measure of a gas concentration from a group of at least two non-dispersive infrared. NDIR. gas sensors (S1-SN) is described. The method comprises the steps of obtaining. at a processing unit (1), from each NDIR gas sensor (S1-SN) a measure of a gas concentration as a belief function Pi(x), which provides a probability as a function of the sensed light intensity at a specific wavelength, merging. in the processing unit, the belief functions Pi(x) to a merged belief function P(x). A computer program performing the method is also described.

Abstract: A system for detecting a gas may include a first laser having a wavelength overlapping with two or more absorption features in a spectrum of the gas, a second laser having a wavelength centered away from absorbing features in the spectrum of the gas, and at least one sensor to determine a received power of the first laser and a received power of the second laser.

Abstract: Optical cells are described for use in spectroscopy applications. The cells include a series of discrete planar reflectors aligned with one another and spaced apart from one another at each end of the sample cavity. The discrete planar reflectors can be surrounded by transparent windows and divergent energy can be removed from the cell cavity via the windows. The cells can define a unique beam path for the energy beam, and there can be no overlapping optical paths through the cell. The cells can provide well-defined detection signals with very high signal-to-noise ratio.

Abstract: An optical measuring device for the spectral measurement of a sample is disclosed. The optical measure device includes an integrating cavity that has a diffusely reflective interior in order to render the light in the integrating cavity diffuse, a light source that is configured to emit light of a predetermined wavelength range into the integrating cavity, and a sensor that is configured to receive light from the integrating cavity, wherein the integrating cavity comprises an optical opening, and wherein the optical measuring device is provided and configured to measure a sample located outside of the integrating cavity directly in front of the optical opening.

Abstract: A device, for emitting and controlling infrared light, comprises a substrate extending between a bottom surface and a top surface. A cavity is provided in the substrate, the cavity opening onto the top surface. A light source extends over the cavity and is able to heat up when passed through by an electric current, so as to emit infrared light. A cover covers the substrate, the cover and the substrate forming a first component enclosing the light source. The light source delineates a first half space comprising the cover, and a second half space comprising the cavity and the bottom surface of the substrate.

Abstract: An aspect of the present disclosure is to provide a washing machine that detects contamination of water due to a dye and prevents contamination of laundry due to the dye. The washing machine includes a tub; a drum configured to be rotatable inside of the tub; a detergent supplier configured to supply a detergent to the tub; a water supplier configured to supply a water to the tub; an optical sensor provided under the tub, wherein the optical sensor includes a light emitting element and a light receiving element configured to selectively receive a plurality of visible rays having different wavelengths and an infrared ray among a light emitted from the light emitting element; and a controller configured to control the water supplier to supply the detergent and the water to the tub and rotate the drum during a washing. In addition, the controller may reduce the washing time based on the sum of the received intensities of the plurality of visible rays and the received intensity of the infrared ray.

Abstract: A beam transmitter, a receiver, and a LIDAR, along with methods to operate each are provided. The beam transmitter comprises a first and a second transmission channel (201a, 201b), each transmission channel including a first online laser, a first offline laser, and a first laser transmission selection switch operable to toggle between including the first online laser signal and the first offline laser signal in a first transmission beam. The beam transmitter further includes at least one light redirection device operable to coalign the first transmission beam with the second transmission beam. The receiver comprises a first splitter (402a, 402b), a first filter (404a, 404b), a first detector channel (406a, 406b), a second splitter (408a, 408b), a second filter (410a, 410b), and a second detector channel (412a, 412b). The LIDAR includes the beam transmitter, the receiver, and a shared telescope.

Abstract: Systems, devices and methods including a handheld sensing device comprising: a sensor configured to measure ambient methane, ethane, propane, butane, and/or pentane concentrations; and a handle, where the sensor is disposed on a first end of the handle; control electronics comprising: a processor having addressable memory, the processor in communication with the sensor, where the processor is configured to: receive the measured ambient gas concentrations; and detect elevated ambient gas concentrations that may be attributed to a natural gas emissions source based on the measured ambient gas concentrations.

Abstract: In a biological component measurement device according to the present disclosure, a modulation unit intensity-modulates excitation light emitted from an excitation light source and the intensity-modulated excitation light is incident to an optical medium. The modulation unit switches a plurality of modulation frequencies in order from a low frequency to a high frequency. The plurality of modulation frequencies include a first frequency and a second frequency higher than the first frequency. A light position detector detects a position of probe light when the sample is irradiated with excitation light intensity-modulated at the first frequency and a position of probe light when the sample is irradiated with excitation light intensity-modulated at the second frequency. The biological component acquisition unit measures a biological component of the sample based on the position of the probe light at the first frequency and the position of the probe light at the second frequency.

Abstract: The invention relates to a method for contactless characterization of a substance (A) using waves (W), wherein the substance (A) comprises a spectral structure (a({tilde over (e)}i)) as a characteristic field (KF) which qualitatively depends on at least one property (ei) of the substance (A), wherein the spectral structure (a({tilde over (e)}i)) is recorded by a measurement (x), and wherein the measurement (x) may comprise an interference structure (s) that depends on the measurement circumstances.

Abstract: An optical sensor and a method of operating the optical sensor are provided. The optical sensor includes a light source configured to emit a light, and a path adjuster configured to adjust a traveling path of the light to reflect the light at a first time, and allow the light to pass through the path adjuster at a second time. The optical sensor further includes a light receiver configured to receive a reference light among the reflected light, and receive, among the light passing through the path adjuster, a measurement light related to a target material.

Abstract: Apparatus and techniques for laser-processing workpieces can be improved, and new functionalities can be provided. Some embodiments discussed relate to use of beam characterization tools to facilitate adaptive processing, process control and other desirable features. Other embodiments relate to laser power sensors incorporating integrating spheres. Still other embodiments relate to workpiece handling systems capable of simultaneously providing different workpieces to a common laser-processing apparatus. A great number of other embodiments and arrangements are also detailed.

Abstract: An infrared (IR) imaging system for determining a concentration of a target species in an object is disclosed. The imaging system can include an optical system including a focal plane array (FPA) unit behind an optical window. The optical system can have components defining at least two optical channels thereof, said at least two optical channels being spatially and spectrally different from one another. Each of the at least two optical channels can be positioned to transfer IR radiation incident on the optical system towards the optical FPA. The system can include a processing unit containing a processor that can be configured to acquire multispectral optical data representing said target species from the IR radiation received at the optical FPA. One or more of the optical channels may be used in detecting objects on or near the optical window, to avoid false detections of said target species.

Abstract: A method of performing spectroscopic measurements provides an optical frequency comb, and directs the comb through or at a sample. The optical frequency comb is generated by gain switching a laser diode constructed from Gallium Nitride and related materials. Various techniques are described for manipulating the comb source to achieve desired benefits for spectroscopy.

Abstract: A respiratory assistance apparatus has a gases inlet configured to receive a supply of gases, a blower unit configured to generate a pressurised gases stream from the supply of gases; a humidification unit configured to heat and humidify the pressurised gases stream; and a gases outlet for the heated and humidified gases stream. A flow path for the gases stream extends through the respiratory device from the gases inlet through the blower unit and humidification unit to the gases outlet. A sensor assembly is provided in the flow path before the humidification unit. The sensor assembly has an ultrasound gas composition sensor system for sensing one or more gas concentrations within the gases stream.

Abstract: A device for the photoacoustic characterisation of a gaseous substance, includes a chamber intended to contain the gaseous substance to characterise and into which a light beam is injected. The chamber is delimited, inter alia, by an inner face, on which a part of the light beam is reflected. This inner face is etched so as to have recesses, each recess being delimited laterally by a lateral surface of which a part at least is tilted, with respect to an average plane of the inner face, by a given tilt angle (?).

Abstract: Disclosed is an optical detection system for detecting a decomposition product of a high-voltage device, including: a measurement gas chamber and a measurement host. The measurement gas chamber is disposed on the high-voltage device and is in communication with a gas chamber of the high-voltage device, a collimator and a reflector are disposed on two sides of the measurement gas chamber respectively, and the measurement host is connected to the collimator. The collimator is used for emitting measurement laser to the measurement gas chamber according to a laser signal sent by the measurement host, and receiving reflected laser from the reflector and transmitting the reflected laser to the measurement host. In the present invention, data collection and backhaul between a measurement host and a measurement gas chamber are implemented through a laser signal, thus avoiding electromagnetic interference and improving the safety of measurement for a high-voltage device.

Abstract: A capnograph system may be used together with a ventilation system for a patient. The capnograph system may include a capnography module with a carbon dioxide detector, which may generate a carbon dioxide signal responsive to an amount of carbon dioxide detected within an air path of the ventilation system. A monitoring circuit may further detect a pressure within the air path. A processing component within the capnography module may generate a pressure signal responsive to the pressure detected in the air path. The pressure signal, alone or in combination with other signals such as the carbon dioxide signal, may be used to detect spontaneous breaths of the patient.

Abstract: A gas detection device and process detect a target gas for monitoring an area for the target gas. A radiation source emits electromagnetic radiation (50) that penetrates the area and impinges on an array of filters (15, 25) that distributes the impinging radiation (50) onto a first gas photosensor (35), a second gas photosensor (37) and a reference photosensor (36). The first gas photosensor (35) is only sensitive to radiation in a first wavelength range, the second gas photosensor (37) is only sensitive to radiation in a second wavelength range and the reference photosensor (36) is only sensitive to radiation in a reference wavelength range. The wavelength ranges are spaced apart from one another. An analysis unit (10) analyzes signals [Sig(35), Sig(36), Sig(37)] from the three photosensors (35, 36, 37) and carries out three pair comparisons to determine whether or not the target gas is present.

Abstract: Provided is a gas sensor comprising first and second light emitting parts, first and second light receiving parts, a first optical path region and a second optical path region, wherein the optical path regions have a common region, an optical path length of the first optical path region is longer than that of the second optical path region, a rate of change of an output signal with respect to a gas to be measured of the first light receiving part is larger than that of the second light receiving part, a rate of change of an output signal with respect to an interference gas of the second light receiving part is larger than that of the first light receiving part, and a sensitivity peak wavelength of the second light receiving part overlaps with an absorption wavelength of water vapor.

Abstract: The present invention relates to a method (1) for determining a content of H2S in a process gas comprising H2S. The method (1) comprises extracting (2) a sample of the process gas, performing oxidation (4) of at least a major portion of H2S of the sample, whereby oxidation products comprising elemental sulfur are formed, analysing (6) the oxidized sample by optical absorption spectroscopy at wavelengths above 310 nm, and determining (8) the content of H2S in the process gas based on the analysing. The invention further relates to a system (100) for determining a content of H2S in a process gas comprising H2S, and use of system (100).

Abstract: A fuel quality sensor can include a pump with a suction side and a pressure side for pumping fuel along a fuel flow path between an underground reservoir and a nozzle of a fuel dispensing unit; a first transmitter disposed at the suction side of the pump on a first side of a bypass plenum in fluid communication with the fuel flow path, the first transmitter configured to transmit a first light signal at a first predetermined frequency in the bypass plenum; a receiver disposed at the suction side of the pump on a second side of the bypass plenum and configured to receive the first light signal; and a control unit electrically connected to the first transmitter and the receiver and configured to determine at least one parameter of the fuel present in the fuel flow path based on the received first light signal at the first predetermined frequency.

Abstract: A measuring device for analyzing a composition of a fuel gas including at least a first gas and a second gas different from the first gas, the first gas and the second gas absorbing an infrared light in at least one common first wavelength range in the electromagnetic spectrum, the measuring device including: an intermittent first infrared emitter; a first sample chamber for receiving the fuel gas; a first detector including at least the first gas and operating according to a photoacoustic effect; and a first filter chamber containing the second gas. The first sample chamber, the first detector, and the first filter chamber are arranged relative to each other such that an infrared light emitted from the first infrared emitter passes through the first sample chamber and the first filter chamber and impinges on the first detector.

Abstract: A method, apparatus and/or system for measuring engine oil consumption using laser induced breakdown spectroscopy.

Abstract: An integrated sensor for detecting gases present in an environment is provided. The integrated sensor comprises a first gas sensor and a second gas sensor. The first gas sensor is configured to measure a first gas and the second gas sensor is configured to measure a second gas. The first gas is different from the second gas. The first gas sensor is an optical sensor and defines an optical cavity. The second gas sensor is disposed within the optical cavity of the first gas sensor.

Abstract: A system, method, and device for simulating an IR signature to test an IR detection device. At least one infrared LED display is provided. Each infrared LED display contains infrared LEDs that emit the desired IR signature. A reflector reflects the IR signature toward the IR detection device. The configuration of the reflector is dependent upon the configuration of the infrared LED display and whether or not some intermediate lens system is used. The IR signature is collimated as it travels to the IR detection device. The IR signature can be collimated by the reflector or by an added lens system. The IR signature fills the field of view associated with the IR detection system. The IR signature comes from a computer-controlled display. As such, the system can simulate various IR signatures and move those IR signatures throughout the field of view of the IR detection system.

Abstract: Methods may include emplacing a downhole tool within a wellbore, sampling a fluid downhole with the downhole tool; analyzing the fluid, and calculating an interfacial tension (IFT), wherein calculating the acid-base IFT contribution comprises measuring a concentration of a surface-active species directly. Apparatuses for measuring an interfacial tension (IFT) in a fluid downhole may be part of a downhole tool and may include a sampling head to sample the fluid; and a downhole fluid analysis module that includes a spectrometer capable of measuring a concentration of a surface-active species in the fluid, and a processor configured to determine the IFT of the fluid downhole based on the measured concentration of the surface-active species.

Abstract: In an embodiment a method for compensating a temperature gradient effect for gas concentration sensors includes variating a temperature gradient, measuring a variation of gas concentration depending on the variation of the temperature gradient, analysing a dependence of the gas concentration and the temperature gradient for setting up an error correction function and applying the error correction function to correct measured values of the gas concentration.

Abstract: An NIR analyzer with the optical probes across a pipe, or in a bypass configuration, after a stabilizer in an oil or condensate production plant. Prior to use, liquid samples from the plant are analyzed in a chemical lab to obtain reference vapor pressure or compositional values. A chemometric model using known techniques is then built with the captured absorption spectra and the reference lab results. Preprocessing methodologies can be used to help mitigate interferences of the fluid, instrument drift, and contaminate build up on the lenses in contact with the fluid. The chemometric model is implemented through the NIR analyzer as the calibration curve to predict the vapor pressure or other values of the flowing fluid in real time.

Abstract: A sample cell includes an annular support surrounding a sample region. A set of reflectors of the annular support define an optical path that reflects a source beam in a sequence of alternating directions through the sample region at a plurality of different angles such that the source beam exits the set of reflectors after having passed through the sample region a plurality of times. A micro-cell is positionable in the sample region including multi-dimensionally distributed nano-pores. A slidingly adjustable lens forms part of source and detector photomixing packages.

Abstract: A device for measuring surface temperature of a turbine blade based on a rotatable prism includes a probe, a prism rotating apparatus and an optical focusing apparatus. The prism rotating apparatus and the optical focusing apparatus are located inside the probe. The probe includes a probe outer casing, a probe inner casing, a water-cooled casing pipe, a sapphire window piece, a quartz prism, a light pipe, a collimating lens, a focusing lens and an infrared array detector. The prism rotating apparatus includes a rotary motor, a worm, a gear and a prism rotary table, the rotary motor rotates to drive the prism rotary table to rotate. The optical focusing apparatus includes a telescopic motor, a coupler, a lead screw and a drive rod, the telescopic motor rotates to drive the lead screw, so as to further drive the drive rod to move along the slot.

Abstract: A device and method for evaluating long-term operation of a transformer oil pump. An inlet of an oil pump is connected to an outlet of an oil tank through an oil pipe, and an outlet of the oil pump is connected to an inlet of the oil tank through an oil pipe. A pressure gauge is provided on the oil pipe to the inlet and the outlet of the oil pump, respectively. An ultra-high-frequency (UHF) sensor is provided on an inner wall of an oil pipe close to the oil pump. A pressure difference between the oil pipes to the inlet and to the outlet of the oil pump is monitored. A three-phase unbalanced current of a stator winding is monitored. The vibration of the oil pump is monitored. The rotor-to-stator rub is monitored. Based on the above inspection, a long-term health status of the oil pump is determined.

Abstract: An optical physiological sensor configured to perform high speed spectral sweep analysis of sample tissue being measured to non-invasively predict an analyte level of a patient. An emitter of the optical physiological sensor can be regulated to operate at different temperatures to emit radiation at different wavelengths. Variation in emitter drive current, duty cycle, and forward voltage can also be used to cause the emitter to emit a range of wavelengths. Informative spectral data can be obtained during the sweeping of specific wavelength regions of sample tissue.

Abstract: An air filter includes filter media, a sensor, and circuitry coupled to the sensor, the circuitry configured to receive data from the sensor representative of the condition of the filter media and wirelessly transmit such data. The data may be received by a device with a display to use the information to present an indication of the filter media condition to a user.

Abstract: A method of detecting the presence of insects, including larvae, in an indoor environment, which includes the steps of (a) obtaining a sample of volatile organic compounds (VOCs); (b) separating the sampled VOCs; (c) detecting the presence or absence of “target” VOCs from at least one category: “category 1 VOCs”—VOCs emitted independently of the support on which the insects develop and emitted only in an insect infestation VOCs, “category 2 VOCs”—VOCs emitted independently of the support but may have biological origins other than insects, and “category 3 VOCs”—VOCs emitted depending on the support and emitted only in an insect infestation; (d) calculating both an insect infestation index (“3I”) and a limit value (“VL”) based on the presence or absence of the target VOCs; and (e) comparing the “3I” and “VL” values. The environment is infested for a “3I” value strictly greater than the “VL” value.

Abstract: A breath analyte capture device includes a breath input port into which a user exhales a breath sample, and a cartridge insertion port for receiving a disposable cartridge containing an interactant. During exhalation of a breath sample, at least a portion of the breath sample is routed through the cartridge such that the analyte (such as breath acetone) is captured by the interactant. In some embodiments, the concentration of the analyte in the breath sample is measured by monitoring a chemical reaction that occurs in the disposable cartridge. The chemical reaction may be monitored by illuminating the cartridge at each of multiple light wavelengths while measuring reflected light.

Abstract: A flow cell assembly (16) for a fluid analyzer (14) that analyzes a sample (12) includes (i) a base (350) that includes a base window (350B); (ii) a cap (352) having a cap window (352B) that is spaced apart from the base window (350B); and (iii) a gasket (360) that is secured to and positioned between the base (350) and the cap (352), the gasket (360) having a gasket body (360A) that includes a gasket opening (360B). The gasket body (360A), the base (350) and the cap (352) cooperate to define a flow cell chamber (362). Moreover, an inlet passageway (366) extends into the flow cell chamber (362) to direct the sample (12) into the flow cell chamber (362); and an outlet passageway (368) extends into the flow cell chamber (362) to allow the sample (12) to exit the flow cell chamber (362).

Abstract: A detection assembly and a method for producing a detection assemblies are disclosed. In an embodiment a detection arrangement includes an emitter configured to generate radiation having a peak wavelength in an infrared spectral range, a detector configured to receive the radiation, a mounting surface comprising at least a first contact surface and a second contact surface for external electrical connection of the detection arrangement, a form body adjoining the emitter and the detector at least in places and deflection optics, on which the radiation impinges during operation of the detection arrangement so that an optical path is formed between the emitter and the detector by the deflection optics, wherein the deflection optics include a scattering body into which the radiation enters during the operation through a surface of the scattering body facing the emitter.

Abstract: A device that is configured to detect spectrally resolved emission from a material is disclosed. The device includes an optical cavity comprising a pair of substrates separated by a distance defined to restrict a photonic density of states (DOS) of the material to be detected, a detector oriented with respect to the optical cavity to receive emission from the optical cavity and a controller configured to control the distance. The pair of substrates includes facing reflective surfaces.

Abstract: Various embodiments may relate a chemical sensor. The chemical sensor may include a substrate including a first sealed (or isolated) cavity and a second sealed (or isolated) cavity separate from the first sealed (or isolated) cavity. The chemical sensor may also include an emitter in the first sealed (or isolated) cavity, the emitter configured to emit infrared light. The chemical sensor may further include a detector in the second sealed (or isolated) cavity. The chemical sensor may also include a waveguide configured to carry the infrared light from the emitter to the detector. The waveguide may include a sensing portion configured such that a property of the infrared light carried through the sensing portion changes in response to a chemical entity in contact with the sensing portion. The detector may be configured to detect the change in the property (of the infrared light).

Abstract: Methods, apparatuses, and systems for improving gas detecting devices are provided. An example gas detecting device may include a receiver element. In some examples, the receiver element may include a sample filter component and a reference filter component. In some examples, the sample filter component may be positioned coaxially with the reference filter component.

Abstract: An apparatus includes a substrate, a first patterned layer, and a second patterned layer. The first patterned layer may be coupled to the substrate and may have a first metasurface pattern. The second patterned layer disposed separately from the substrate and the first patterned layer, and may have a second metasurface pattern. Movement of the first patterned layer relative to the second patterned layer may be controllable via control circuitry such that a gap distance of a gap between the first patterned layer and the second patterned layer is changed to cause a transmittance for radiant energy of a selected wavelength passing through the apparatus to change from a first transmittance value to a second transmittance value.