Abstract: The present invention relates to a method for measuring radioactivity of radioactive waste, the method comprising an adsorption step (A) of selectively adsorbing a radioactive substance comprising at least one from among radioactive iodine and radioactive cesium from radioactive waste containing radioactive substances on an adsorption member for adsorbing a radioactive substance, and a measurement step (B) of measuring radioactivity of the radioactive substance.

Abstract: A method of measuring an environmental contaminant includes the steps of dividing a target environment into a plurality of spaces, placing a monitor in each space, uploading device data from each monitor, and processing the device data to determine a level of environmental contamination within each space. Each monitor is configured to measure a level of an environmental contaminant within the space for a sample period. A radon monitor includes a radon sensor configured to detect radon decay events, an environmental sensor configured to measure an ambient condition of air surrounding the radon sensor, a processor configured to record device data including a count of a number of radon decay events and the ambient conditions, and a communication means for transmitting the device data. A system includes a plurality of monitors, a receiving device for receive device data from each monitor, and a cloud computer to process the device data.

Abstract: A scintillator panel 10 includes a substrate 11 having a substrate main surface 11a, a substrate rear surface 11b, and a substrate side surface 11c; and a scintillator layer 12 having a scintillator rear surface 12b formed of a plurality of columnar crystals, a scintillator main surface 12a, and a scintillator side surface 12c. The substrate side surface 11c and the scintillator side surface 12c are substantially flush with each other. In the substrate 11, an angle A1 between the substrate rear surface 11b and the substrate side surface 11c is smaller than 90 degrees.

Abstract: An ion beam profiling system include a beam profiling element, an ion sensitive element electrically isolated from the beam profiling element, an ion source configured to emit an ion beam at the beam profiling element and the ion sensitive element, and a current measuring device coupled to the ion sensitive element. The beam profiling element includes a plate of material having two parallel major surfaces, a first slit aperture extending through the plate of material and having a first longitudinal length extending in a direction parallel to the two parallel major surfaces, and a second slit aperture extending through the plate of material and having a second longitudinal length extending in a direction parallel to the two parallel major surfaces, wherein the first longitudinal length of the first slit aperture is perpendicular to the second longitudinal length of the second slit aperture.

Abstract: A seismic source having two or more operating heads with a firing chamber pressure vessel of compressed air for generating seismic oscillations at low and ultra-low frequencies (ULF) for marine seismic exploration. The multi-headed sound source increases low frequency signal in ranges from below 1 Hz to around 7 Hz to provide greater penetration of the seismic signal through complex overburden such as salt or basalt, improve velocity model building with methods such as Full Wave Inversion, improve the ability to build blocky reservoir models, and improve resolution by reducing side lobes.

Abstract: Techniques for generating a geological model from 3D seismic data and rock property data are disclosed. Rock property data and 3D seismic data are received. Based on the rock property data and the 3D seismic data, an adaptive geological model is generated. The adaptive geological model includes a characteristic geological property. Synthetic seismic data is generated from a first region of interest of the adaptive geological model. The synthetic seismic data is adapted to facilitate a comparison between the first region of interest and a corresponding region of interest of the received 3D seismic data. The characteristic geological property is adjusted until the comparison indicates a result that is within a predetermined threshold region of the corresponding value from the rock properties. A validated geologic model is then generated.

Abstract: System and methods for predicting time-dependent rock properties are provided. Seismic data for a subsurface formation is acquired over a plurality of time intervals. A value of at least one rock property of the subsurface formation is calculated for each of the plurality of time intervals, based on the corresponding seismic data acquired for that time interval. At least one of a trend or a spatio-temporal relationship in the seismic data is determined based on the value of the at least one rock property calculated for each time interval. A value of the at least one rock property is estimated for a future time interval, based on the determination. The estimated value of the at least one rock property is used to select a location for a wellbore to be drilled within the subsurface formation. The wellbore is then drilled at the selected location.

Abstract: A marine seismic data acquisition system includes a streamer spread including plural streamers; a first set of front sources configured to generate seismic waves; a streamer vessel towing the streamer spread and the first set of the front sources, in front of the streamer spread along an inline direction X; a second set of top sources configured to generate additional seismic waves; and first and second source vessels towing the second set of top sources directly above or below the streamer spread. A number NT of the top sources is larger than a number NF of the front sources.

Abstract: Deconvolution-based processing of ultrasonic waveforms enables robust calculation of two-way travel time for an ultrasonic caliper, particularly in the presence of multiple, proximal reflectors (e.g., mud cake, formation, casing, cement, etc.).

Abstract: Techniques for operating a sensor are provided. An example method according to these techniques includes sensing, at the sensor, changes in intensity of a magnetic field of a magnet affixed to a monitored asset to produce sensor data, wherein the monitored asset is disposed in a non-metallic liquid or solid medium, and wherein the sensor is disposed outside of the non-metallic medium; The method also includes analyzing, at the sensor, the sensor data to produce feature information indicative of vibration of the monitored asset. The method also includes providing the feature information to a predictive algorithm to generate prognosis information indicating an occurrence of a known condition of the monitored asset.

Abstract: A metal detector apparatus having a balanced coil system, a receiver unit, a drive coil with at least one capacitor forming a series resonant circuit connected to a transmitter unit having a converter, and a drive controller. The metal detector apparatus configuration generates a first square wave signal set to a fixed/selectable operating frequency which is applied to a first drive switch connected on one side to a first voltage potential and on another side to a centre tap of a half-bridge circuit. A second square wave signal set is generated to the fixed/selectable operating frequency and is applied to a second drive switch connected on one side to a second voltage potential and on another side to the centre tap, via which a drive current is supplied to the drive coil.

Abstract: Techniques for determining an operator position for a hydrocarbon production area include identifying an entity name; determining a plurality of land areas associated with the entity name based on at least one public data set, at least one of the land areas including a hydrocarbon-bearing land area; determining a position associated with the entity name for each of the plurality of land areas based on the at least one public data set and at least one private data set, the position including an operator position or a non-operator position; determining at least a portion of the plurality of land areas in which the determined position associated with the entity name includes the operator position; aggregating the determined portion of the plurality of land areas to generate an operator land area for the entity name; and generating a graphical representation of the generated operator land area to present to a user.

Abstract: Construction and use of an instrument test fixture for capturing performance data for stimulation or fracturing treatments. The test fixture includes a target material, such as concrete, which includes embedded sensors surrounding a casing. An energetic stimulation treatment, such as a dynamic pulse fracturing technique, is applied through the casing to the target material to simulate a treatment that would be performed in a wellbore. During application of the treatment, the sensors capture measurements which are recorded for analysis by a data collection system. The sensors allow for the measurement of key performance indicators including static and dynamic pressure, generated temperature, and resulting strain energy. The captured data can be analyzed and used to design and optimize stimulation treatments for field applications.

Abstract: A method, system, and computer program product for resource management are described. The method includes selecting trouble regions within the service area, generating clustered regions, and training a trouble forecast model for the trouble regions for each type of damage, the training for each trouble region using training data from every trouble region within the clustered region associated with the trouble region. The method also includes applying the trouble forecast model for each trouble region within the service area for each type of damage, determining a trouble forecast for the service area for each type of damage based on the trouble forecast for each of the trouble regions within the service area, and determining a job forecast for the service area based on the trouble forecast for the service area, wherein the managing resources is based on the job forecast for the service area.

Abstract: A storage unit stores ranking information including an index value relating to past rainfall and a corresponding date-time and damage information including details of damage that occurred due to past rainfall and a corresponding date-time. A real-time data reception unit acquires a spot value and a forecast value of current precipitation. Also, a comparison operation unit computes an index value relating to current rainfall using the acquired spot value and forecast value. The comparison operation unit specifies, with reference to the ranking information, the date-time of an index value relating to past rainfall whose similarity to the computed index value relating to current rainfall is not less than a threshold value. An information output unit presents, with reference to the damage information, details of damage that occurred in a period whose difference from the specified date-time of the index value relating to past rainfall is in a predetermined range.

Abstract: An optical member includes a base material containing aluminum or aluminum alloy, a first layer including black porous aluminum oxide provided on the base material, and a second layer including aluminum oxide having a plurality of projection portions provided on the first layer.

Abstract: An anti-glare film including a light reflectance of 3.8% or less and a transmission image clarity of 80% or less. The transmission image clarity of the anti-glare film may be from 5 to 70%. The anti-glare film includes a transparent substrate layer, and an anti-glare layer formed on at least one surface of the transparent substrate layer. The anti-glare layer may be a cured product of a curable composition including one or more types of a polymer component and one or more types of a curable resin precursor component, and in particular, at least two components selected from a polymer component and a curable resin precursor component can be phase separated through liquid phase spinodal decomposition. The anti-glare film can satisfactorily provide anti-reflection properties, anti-glare properties, and transparency.

Abstract: A power semiconductor module includes a first substrate, wherein the first substrate includes aluminum, a first aluminum oxide layer arranged on the first substrate, a conductive layer arranged on the first aluminum oxide layer, a first semiconductor chip, wherein the first semiconductor chip is arranged on the conductive layer and is electrically connected thereto, and an electrical insulation material enclosing the first semiconductor chip, wherein the first aluminum oxide layer is configured to electrically insulate the first semiconductor chip from the first substrate.

Abstract: An inverted nanocone structure of the present disclosure includes a first surface, a second surface spaced apart from the first surface by a predetermined distance and having a greater area than the first surface, and a body having an inverted cone shape between the first surface and the second surface, wherein at least one activated point defect center is provided in the body.

Abstract: A liquid lens architecture includes a transparent substrate, a multilayer thermoplastic polyurethane (TPU)-based membrane overlying at least a portion of the transparent substrate, and a liquid layer disposed between and abutting the transparent substrate and the multilayer thermoplastic polyurethane-based membrane. The TPU-based membrane may exhibit a reversible elastic response to imposed strains of up to approximately 2% and is configured to limit the transpiration of fluid to less than approximately 10?2 g/m2/day.

Abstract: A method for producing a half mirror includes forming a reflection region by which light is reflected and a transmission region through which the light is transmitted on a surface of a transparent plate Only the reflection region is coated with a plating. The coating includes a masking step of coating a position of the transparent plate corresponding to the transmission region with a masking material, a plating step of coating the entire surface which includes the transmission region which has been coated with the masking material and the reflection region with the plating, a plating removing step of removing the plating to a depth in which the masking material is exposed after the plating step, and a masking material removing step of removing the masking material after the plating removing step.

Abstract: An interference filter module comprises two optical fiber collimators arranged on an optical axis so as to be opposed to each other, interference filters, and a casing including a main body portion and filter holding portions to be mounted into the main body portion, which are configured to hold the interference filters. Two interference filters including a kth filter when counted from a front end and a k-th filter when counted from a rear end are determined as a k-th set. The two interference filters of the k-th set are accommodated in two filter holding portions, each of which is a k-th holding portion when counted from the front end and the rear end, respectively. The two filter holding portions have rotation axes in directions orthogonal to a fore-and-aft direction and are rotatably held by the casing. The rotation axes of the filter holding portions are orthogonal to each other.

Abstract: Disclosed is a LiDAR window integrated optical filter that includes a window of a polymer material for absorbing a visible light band and transmitting a near-infrared band; and an upper reflective layer and a lower reflective layer formed on the upper surface and the lower surface of the window. The upper reflective layer and the lower reflective layer may be formed in a thin film including titanium dioxide (TiO2) and silicon dioxide (SiO2).

Abstract: There is provided an optical communication apparatus having high communication stability. An optical communication apparatus of the present invention includes: a signal-transmitting portion; and a signal-receiving portion. The signal-transmitting portion includes a light-emitting element, and a first polarizing plate, which light output from the light-emitting element enters, and which is configured to output polarized light. The signal-receiving portion includes a second polarizing plate, which the light from the signal-transmitting portion enters, and a light-receiving element configured to receive light passing through the second polarizing plate. The first polarizing plate includes a first reflective polarizer.

Abstract: Embodiments described herein relate to a system for positioning indicator lights of a network device. The system may include a circuit board, which may include a circuit board edge positioned behind a front panel of the network device, two surfaces; and a side of the circuit board edge positioned between the two surfaces. The system may also include a hole through the circuit board near the circuit board edge, a cutout extending from a portion of the hole to the side of the circuit board edge, a LED coupled to the surface of the circuit board and adapted to emit light into the hole, and a lightpipe disposed in the hole to receive light emitted from the LED into a first end of the lightpipe. The lightpipe may direct the light from a second end of the lightpipe toward an opening in the front panel of the network device.

Abstract: A single edge lit lighting module is disclosed which produces tailored light distributions valuable in many illumination applications. The lighting module comprises a unique light scattering optical element which is aligned with one or more LED light sources along one of its edges and works in combination with configured reflective surfaces. Light distributions attainable using the invention include, but are not limited to, symmetric and asymmetric bi-lobed “batwing” distributions for wide area direct and indirect lighting, and tilted or asymmetric distributions for perimeter lighting. It is also possible to achieve more rounded and symmetric distributions by an additional diffuser as a cover lens. The invention's unique single edge lit construction provides the means for achieving the lighting distributions without the need for conventional two lit edges and within a compact form factor with narrow width.

Abstract: A light-emitting module includes: a plurality of light sources; and a lightguide plate including a plurality of light source placement sections, in each of which at least one light source is arranged, arrayed in a first direction and a second direction orthogonal to the first direction. The lightguide plate defines at least one first-A light control groove and at least one first-B light control groove that extend parallel to the second direction between a first light source placement section and a second light source placement section adjacent to the first light source placement section in the first direction, and at least one second-A light control groove and at least one second-B light control groove that extend parallel to the first direction between the first light source placement section and a third light source placement section adjacent to the first light source placement section in the second direction.

Abstract: A lightweight stacked optical waveguide using two plastic substrates having nano-structure gratings and a single glass substrate sandwiched between them. The nano-structure gratings face each other, and are each encapsulated within the optical waveguide. The two plastic substrates are each adhesively secured to the central glass substrate rather than to each other to provide sufficient securing strength and precisely establish and maintain an air gap between the substrates. The thickness of the plastic substrates and the glass substrate are selected such that the stacked optical waveguide is lightweight, but also has sufficient drop performance. The stacked optical waveguide can be efficiently manufactured as the adhesive bonds a plastic substrate to a glass substrate.

Abstract: An anti-torsion solid-core polarization-maintaining photonic crystal fiber includes a cladding having an inner layer arranged around the core and an outer layer between the inner layer and the outer wall of the cladding. The inner layer has multi-layer air holes used to construct optical properties and two micron-size air holes arranged along the x-axis extending in the center producing form birefringence. The outer layer includes multi-layer air holes arranged radially along the y-axis. The size and arrangement of the multi-layer air holes in the outer layer cause the bending stiffness of the photonic crystal fiber along the x-axis to be different from that along the y-axis. While meeting the requirements of the optical properties of the fiber, the photonic crystal fiber possesses an anti-torsion ability due to the anisotropy of stress distribution in the radial direction, thereby reducing the non-reciprocal phase difference generated by the magneto-optic Faraday Effect.

Abstract: An optical light package includes an optical output lens, an optical filter located thereunder and between the output lens and LEDS, a tray of LEDs arrayed on a stage mounted on a linear comb based MEMS device that is distributed in such a way that the stage is movable, and a driver that controls movement of the stage.

Abstract: A silicon nitride phased array chip based on a suspended waveguide structure, which includes a silicon nitride waveguide area and a suspended waveguide area. The silicon nitride waveguide area includes a silicon substrate, a silicon dioxide buffer layer, a silicon dioxide cladding layer and a silicon nitride waveguide-based core layer. The silicon nitride waveguide-based core layer includes an optical splitter unit, a first curved waveguide, a thermo-optic phase shifter and a spot-size converter. The suspended waveguide area includes a second curved waveguide and an array grating antenna.

Abstract: A structure for, and method of, forming a first optoelectronic circuitry that generates an optical signal, a second optoelectronic circuitry that receives an optical signal, and a loopback waveguide that connects the output from the first optoelectronic circuitry to the second optoelectronic circuitry on an interposer substrate are described. The connected circuits, together comprising a photonic integrated circuit, are electrically tested using electrical signals that are provided via probing contact pads on the PIC die. Electrical activation of the optoelectrical sending devices and the subsequent detection and measurement of the optical signals in the receiving devices, in embodiments, provides information on the operability or functionality of the PIC on the die at the wafer level, prior to die separation or singulation, using the electrical and optical components of the PIC circuit.

Abstract: An optical assembly may include a waveguide and a Bragg grating configured to couple light into or out of the waveguide. The Bragg grating may include a plurality of layer pairs, wherein at least one layer pair comprises a first material having a first refractive index and a second layer having a second refractive index, and wherein properties of the Bragg grating are selected so that the Bragg grating exhibits a substantially similar diffractive efficiency and diffraction angle for light of at least two colors.

Abstract: An embodiment apparatus comprises an optically transparent substrate having first and second surfaces; a piezoelectric membrane, arranged at the first surface, that oscillates in response to a light beam propagated through the substrate; at least one reflective facet facing the substrate and arranged at the piezoelectric membrane; and an optical element receiving the light beam at an input end and guiding the light beam towards an output end coupled to the second surface. The optical element incorporates a light focusing path focusing the light beam at a focal point at the piezoelectric membrane, and at least one light collimating path collimating the light beam onto the at least one reflective facet. The optical element guides light reflected from the at least one reflective facet to the input end, the reflected light indicating a position of the optical element with respect to the focal point.

Abstract: An ultra-broadband silicon waveguide micro-electro-mechanical systems (MEMS) photonic switch is provided, which is mainly composed of three parts: input waveguides, a waveguide crossing with a nano-gap, and output waveguides. The waveguide crossing is composed of two identical orthogonal elliptical cylinders. Four ports of the waveguide crossing respectively extend to form single-mode strip waveguides to serve as input/output waveguides. The center of the waveguide crossing is fully etched with a nano-gap. The two symmetrical port waveguides are fully etched with nano-grooves. The lower cladding near the waveguide crossing and the nano-grooves is penetrated and etched. The width of the nano-gap is adjusted through adjusting a voltage applied across both ends of the waveguide crossing, so that a guided-mode directly passes through or is totally reflected. In the disclosure, a propagation path of the photonic switch is switched through adjusting the voltage applied to the waveguide crossing.

Abstract: There are provided an optical receptacle having an optical fiber including a first portion on another end surface side, a third portion on one end surface side, and a second portion between the first portion and the third portion; a core diameter at the first portion is smaller than the core diameter at the third portion; the core diameter at the second portion increases from the first portion side toward the third portion side; a first elastic member is provided between the optical fiber and an inner wall of a through-hole; a holder holds the another end surface side of a fiber stub; and the sleeve holds the one end surface side of the fiber stub.

Abstract: A fiber optical connector includes a connector housing and an optical-fiber component. The connector housing comprises a receiving space. One end of the connector housing forms a connector opening communicating with the receiving space. Two side walls of the connector housing comprise a plurality of buckling portions adjacent to the connector opening. The optical-fiber component is positioned in the receiving space. The optical-fiber component comprises a sleeve piece. The sleeve piece comprises a block member and a threaded portion. The block member is assembled in the connector opening and the block member fully received inside the receiving space. Two sides of the block member respectively form an engaging portion. Each of the engaging portions is engaged with the corresponding buckling portion, and the threaded portion is exposed on the peripheral surface of a tail portion of the sleeve piece and out of the connector opening.

Abstract: An optical connector assembly having a connector housing with a first and second end. First end accepts a ferrule assembly, and second end accepts a retention assembly. There is a longitudinal bore from a distal to proximal end of connector. Bore accepts a POF optical fiber therein at distal end and fiber is inserted proximally until fiber bottoms-out at proximal end of ferrule. Retention body accepts one or more retention caps, or retention body contains at least one retention wing set to secure fiber to connector.

Abstract: An optical fiber connector is provided. A receptacle has an angled interior surface that acts to guide an optical fiber into the correct position as a jack is inserted into the receptacle.

Abstract: A cable release system includes a handle. An elongated base extends from the handle and includes a length that allows the handle to be held adjacent a cable connector distal end of a cable connector that is connected to a computing device while the elongated base extends adjacent the cable connector and an elongated base distal end of the elongated base is located adjacent a securing latch on the cable connector. An actuating member is located on the elongated base distal end of the elongated base and is configured to actuate the securing latch on the cable connector when the elongated base distal end of the elongated base is located adjacent the securing latch on the cable connector.

Abstract: An optoelectronic device includes a carrier, an electronic component, a photonic component and a supportive component. The electronic component is electrically coupled to the carrier. The photonic component is electrically coupled to the electronic component. The supportive component is disposed outside the photonic component and the electronic component and configured to support an optical component.

Abstract: Certain aspects of the present disclosure provide techniques for making armored cables. An example method for making an armored cable includes forming a strip stock into an armor tubing; welding a seam of the armor tubing in a welding zone; inserting at least one of a first optical fiber or a first wire into a first end of a first guide tube, wherein: the first guide tube extends through the welding zone; the first guide tube protects the at least one of the first optical fiber or the first wire during the welding of the seam; and the first guide tube is not part of the armored cable after the making of the armored cable; and supporting the first guide tube within the armor tubing by a plurality of support legs such that the first guide tube does not contact the armor tubing.

Abstract: A terminal device includes: a housing; a screen arranged on the housing; a first lens arranged in the housing and disposed on a back of the screen; and a turnover module arranged on the hack of the screen in the housing and configured to change an orientation of the first lens, so that the first lens faces towards a first direction or a second direction of the screen, the second direction being different from the first direction.

Abstract: A liquid lens of the present invention includes a first plate including a cavity in which a conductive liquid and a nonconductive liquid are disposed; a first electrode disposed on the first plate; a second electrode disposed under the first plate; a second plate disposed on the first electrode; and a third plate disposed under the second electrode, wherein the second plate includes a first region having a first thickness, the first region encompassing an optical axis, and a second region extended from the first region and having a second thickness greater than the first thickness, and the location of the upper surface of the first region is lower than the location of the upper surface of the second region.

Abstract: A lens moving apparatus including a housing; a bobbin disposed in the housing; a coil disposed on the bobbin; a magnet disposed on the housing to correspond to the coil; an upper elastic member coupled to an upper portion of the bobbin and an upper portion of the housing; and a damper coupled to the first elastic member and the housing.

Abstract: According to an embodiment, a driving device housing with an axial direction is provided. The driving device housing is made of permeability magnetic material and polygonal in outer shape. The driving device housing includes an outer peripheral side wall and a housing top wall connected to a front side of the outer peripheral side wall. The housing top wall includes an opening allowing light to pass through. The housing further includes at least one step portion at each corner portion thereof. The step portion includes a step horizontal wall extending in a direction intersecting with the axial direction and a step vertical wall extending from the step horizontal wall toward a front side or a rear side. A magnet mounting portion is formed by an inner peripheral wall surface of the step vertical wall and an inner peripheral wall surface of the outer peripheral side wall adjacent thereto.

Abstract: A disclosed lens assembly may include at least four lenses sequentially arranged along an optical axis from a subject to an image sensor. Among the at least four lenses, a first lens disposed closest to the subject may have a visible light transmittance ranging from 0% to 5%, and, among subject-side surfaces and image-sensor-side surfaces of remaining lenses other than the first lens, at least four surfaces may include an inflection point. The lens assembly or an electronic device including the lens assembly may be variously implemented according to embodiments.

Abstract: The present disclosure discloses an optical imaging lens assembly including, sequentially from an object side to an image side along an optical axis, a first lens having positive refractive power; a second lens having negative refractive power; a third lens having refractive power; a fourth lens having refractive power; a fifth lens having refractive power with a convex object-side surface; a sixth lens having positive refractive power with a convex object-side surface a convex image-side surface; and a seventh lens having negative refractive power, wherein a distance TTL along the optical axis from an object-side surface of the first lens to an imaging plane of the optical imaging lens assembly and half of a diagonal length ImgH of an effective pixel area on the imaging plane of the optical imaging lens assembly satisfy ImgH/(TTL/ImgH)>5.0 mm.

Abstract: An imaging optical lens assembly includes nine lens elements which are, in order from an object side to an image side along an optical path: a first lens element, a second lens element, a third lens element, a fourth lens element, a fifth lens element, a sixth lens element, a seventh lens element, an eighth lens element and a ninth lens element. The first lens element has positive refractive power. The eighth lens element with positive refractive power has an image-side surface being convex in a paraxial region thereof. The ninth lens element has an image-side surface being concave in a paraxial region thereof, and the image-side surface of the ninth lens element has at least one convex critical point in an off-axis region thereof.

Abstract: Some embodiments of the disclosure provide an optical imaging lens assembly. From an object side to an image side along an optical axis, the optical imaging lens assembly sequentially includes: a first lens having a refractive power; a second lens having a refractive power, and an object-side surface of the second lens is a convex surface, and an image-side surface of the second lens is a concave surface; a third lens having a refractive power; a fourth lens having a refractive power; a fifth lens having a refractive power; a sixth lens having a positive refractive power, an object-side surface of the sixth lens is a convex surface, and an image-side surface of the sixth lens is a convex surface; and a seventh lens having a negative refractive power, an object-side surface of the seventh lens is a concave surface, and an image-side surface is a concave surface.