Abstract: A lighting device includes a light source having a light exit surface, an optical member covering the light exit surface and applying an optical action to light exiting the light source, and a prism sheet coveting the optical member from an opposite side from the light source, and the prism sheet includes prism portions and a light reflecting portion that covers a part of a surface of the prism portions opposite from the optical member.

Abstract: A lighting device includes a light source having a light exit surface, and a prism sheet covering the light exit surface. The prism sheet includes prism portions, a first light reflecting portion that covers a part of a surface of the prism portions opposite from the light exit surface, and a second light reflecting portion that covers the first light reflecting portico from as opposite side from the light exit surface and has light reflectance lower than that of the first light reflecting portion.

Abstract: A lighting device includes light sources arranged in a row direction and a column direction, and a reflector through which at least a part of light rays emitted by the light source. The reflector includes unit light source regions disposed at an interval from the light sources, a light reflecting pattern disposed in the unit light source regions and reflecting light, and a light transmitting pattern disposed in the unit light source regions and transmissive to the part of the light rays. The unit light source regions are disposed such that the unit light source regions adjacent to each other with respect to at least one of the row direction and the column direction have different distributions of at least one of the light reflecting pattern and the light transmitting pattern.

Abstract: A light guide assembly comprises: a first light guide member; and a second light guide member stacked on the first light guide member. The light guide assembly has first and second light incident surfaces located on different sides, and a light emitting surface and a bottom surface which are oppositely disposed in a thickness direction, the first light incident surface and the bottom surface are located on the first light guide member, and the second light incident surface and the light emitting surface are located on the second light guide member, and the bottom surface is provided with first dots having a density increasing in a direction away from the first light incident surface, and the light emitting surface is provided with second dots having a density increasing in a direction away from the second light incident surface.

Abstract: A display device includes a display module and an optical film. The display module has a through hole. At least one optical film is located on the display module and has an alignment through hole aligned with the through hole and an alignment mark surrounding the alignment through hole.

Abstract: The rolled photonic fibers presents two codependent, technologically exploitable features for light and color manipulation: regularity on the nanoscale that is superposed with microscale cylindrical symmetry, resulting in wavelength selective scattering of light in a wide range of directions. The bio-inspired photonic fibers combine the spectral filtering capabilities and color brilliance of a planar Bragg stack compounded with a large angular scattering range introduced by the microscale curvature, which also decreases the strong directional chromaticity variation usually associated with flat multilayer reflectors. Transparent and elastic synthetic materials equip the multilayer interference fibers with high reflectance that is dynamically tuned by longitudinal mechanical strain. A two-fold elongation of the elastic fibers results in a shift of reflection peak center wavelength of over 200 nm.

Abstract: When a grating is inscribed in a section of optical fiber through a coating of the optical fiber, using a light modulation mask to modulate the light beam that writes the grating, a fluid can be situated between the section of optical fiber and the back side of a mask component carrying the light modulation mask (e.g., on its front side) to reduce the refractive-index discontinuity encountered at the surface of the coating. In various embodiments, rather than running the fiber through a vessel containing the fluid, the fluid is run across the back side of the mask component or retained by capillary action between the fiber section and the mask component.

Abstract: A hollow core optical fiber guide is provided that comprises a body for reflecting light comprising a first end, a second end, a longitudinal dimension extending between the first end and the second end, an inner sidewall, an outer sidewall, and a transverse dimension extending radially between the inner sidewall and the outer sidewall, wherein the body comprises a plurality of optically dielectric material and each of the plurality of dielectric material having a different refractive index; and a light guiding core region disposed within the body.

Abstract: The present invention concerns an optical fibre comprising: an optical waveguide comprising a glass core surrounded by a glass cladding; a coating surrounding said optical waveguide comprising a cured polymer material comprising a polyester obtained by polymerization of a monomer selected from an acid, a triglyceride, or a mixture of triglycerides having a C16-C24 aliphatic chain comprising at least two conjugated double bonds. The present invention concerns also a method for coating an optical fibre with said polyester coating. The cured polymer material forming the coating can be prepared by curing the polyester of the invention either thermally or by radiation.

Abstract: The application relates to methods of analyzing luminescent species. A substrate is provided that has a plurality of zero mode waveguides having apertures that extend through an upper non-reflective layer that is disposed on a lower transparent layer of a substrate. The apertures have non-reflective oxide layers on the reflective side walls of the apertures, the side walls having a thickness of greater than 10 nm, and the oxide layer is formed by oxidizing the non-reflective layer. The volume within the oxide layer defines a solution volume, and the volume within the reflective walls defines a ZMW volume. Having such non-reflective layers on the walls of the ZMW usefully decouples the solution volume from the ZMW volume.

Abstract: Grating couplers and methods of fabricating a grating coupler. The grating coupler may include a plurality of grating structures arranged on a substrate and a layer arranged over the grating structures. The grating structures are composed of a first material characterized by a first refractive index with a real part. The layer is composed of a second material characterized by a second refractive index with a real part. The real part of the second refractive index is greater than the real part of the first refractive index of the first material for electromagnetic radiation with a wavelength in a range of 1 micron to 9 microns.

Abstract: A photonic chip includes a device layer and a port layer, with an optical port located at the port layer. Inter-layer optical couplers are provided for coupling light between the device and port layers. The inter-layer couplers may be configured to couple signal light but block pump light or other undesired wavelength from entering the device layer, operating as an input filter. The port layer may accommodate other light pre-processing functions, such as optical power splitting, that are undesirable in the device layer.

Abstract: An optical subassembly includes a planar dielectric waveguide structure that is deposited at temperatures below 400 C. The waveguide provides low film stress and low optical signal loss. Optical and electrical devices mounted onto the subassembly are aligned to planar optical waveguides using alignment marks and stops. Optical signals are delivered to the submount assembly via optical fibers. The dielectric stack structure used to fabricate the waveguide provides cavity walls that produce a cavity, within which optical, optoelectronic, and electronic devices can be mounted. The dielectric stack is deposited on an interconnect layer on a substrate, and the intermetal dielectric can contain thermally conductive dielectric layers to provide pathways for heat dissipation from heat generating optoelectronic devices such as lasers.

Abstract: An optical subassembly includes a planar dielectric waveguide structure that is deposited at temperatures below 400 C. The waveguide provides low film stress and low optical signal loss. Optical and electrical devices mounted onto the subassembly are aligned to planar optical waveguides using alignment marks and stops. Optical signals are delivered to the submount assembly via optical fibers. The dielectric stack structure used to fabricate the waveguide provides cavity walls that produce a cavity, within which optical, optoelectronic, and electronic devices can be mounted. The dielectric stack is deposited on an interconnect layer on a substrate, and the intermetal dielectric can contain thermally conductive dielectric layers to provide pathways for heat dissipation from heat generating optoelectronic devices such as lasers.

Abstract: Systems and methods describe growing RE-based integrated photonic and electronic layered structures on a single substrate. The layered structure comprises a substrate, an epi-twist rare earth oxide layer over a first region of the substrate, and a rare earth pnictide layer over a second region of the substrate, wherein the first region and the second region are non-overlapping.

Abstract: An optical subassembly includes a planar dielectric waveguide structure that is deposited at temperatures below 400 C. The waveguide provides low film stress and low optical signal loss. Optical and electrical devices mounted onto the subassembly are aligned to planar optical waveguides using alignment marks and stops. Optical signals are delivered to the submount assembly via optical fibers. The dielectric stack structure used to fabricate the waveguide provides cavity walls that produce a cavity, within which optical, optoelectronic, and electronic devices can be mounted. The dielectric stack is deposited on an interconnect layer on a substrate, and the intermetal dielectric can contain thermally conductive dielectric layers to provide pathways for heat dissipation from heat generating optoelectronic devices such as lasers.

Abstract: A method for cleaving an optical fiber may include generating a laser beam, such as a CO2 laser beam, for a discrete time period. The laser beam may impact an optical fiber and form a discrete crater extending into the optical fiber from the outer surface thereof. The method may further include pausing generation of the laser beam for a discrete time period, and rotating the optical fiber about a longitudinal axis of the optical fiber. The method may further include repeating generation of the laser beam. A plurality of discrete craters disposed in an annular array about a circumference of the optical fiber may be formed. The method may further include separating the optical fiber into a main optical fiber portion and a cleaved portion after formation of the annular array of discrete craters.

Abstract: Embodiments provide a splice closure and a method for installing an optical cable. The splice closure includes a closure body, a cable accommodating tray, a nut component, an abutting member, and an elastic member. The abutting member is located between an optical cable and the nut component, and the elastic member is located between the optical cable and an installation tube. When the nut component is screwed to an externally threaded section of the installation tube by using threads of an internally threaded section, the abutting member abuts the elastic member, so that the elastic member elastically deforms under an abutting effect of the abutting member, so as to cause an inner circumferential wall of the elastic member that elastically deforms to abut the optical cable, and an outer circumferential wall of the elastic member that elastically deforms to abut an inner circumferential wall of the installation tube.

Abstract: A multi-directional fiber optic connector includes a housing defining therein a mating-connection chamber, a mating-connection portion having an insertion hole in communication with the accommodation chamber and a plurality of guide grooves equiangularly spaced around the insertion hole for guiding a fiber optic lead end connector of a fiber optic cable into the insertion hole in one of a series of angular positions and an accommodation chamber located at an opposite side of said mating-connection chamber, said mating-connection portion comprising, and an optical device mounted in the accommodation chamber for optical communication with the inserted fiber optic cable.

Abstract: A fiber optic cable splice device includes a sleeve, an inner tube received in the sleeve to allow passage of a fiber optic cable, and a limiting member coupled to the sleeve and limiting the limiting member in the sleeve. A casing is connected to the sleeve at a top end thereof, a joining portion extending sideward from a sidewall thereof, and a bent passage extending through the top end and the joining portion. A rotary connection member is rotatably positioned on the joining portion, and has a threaded plug. When the rotary connection member is rotated relative to the casing, the threaded plug is able to be threaded into a fitting device so that the fiber optic cable is connected to the fitting device.

Abstract: A plug-in connection for the transmission of electric current having a male connector and a female connector, wherein the male connector includes a plug-in extension having electrical contacts, and the female connector includes a plug-in extension receptacle having electrical mating contacts, and at least one projection is arranged on one jacket wall, and the other of these jacket walls incorporates at least one receptacle slot which matches the projection. The plug-in extension, with the projection and the receptacle slot in an undamaged state, can only be inserted into the plug-in extension receptacle from an unambiguously defined plug-in position.

Abstract: A fiber optic connector includes a plug body, a rear sleeve unit and a front sleeve unit. The plug body has first and second recesses. The rear sleeve unit is detachably sleeved around a rear part of the plug body, and has a key. The front sleeve unit is sleeved on of the plug body in front of the rear sleeve unit and detachably connected to the rear sleeve unit. The rear sleeve unit is changeable between a first position, in which the rear sleeve unit is attached to the plug body with the key being engaged with the first recess, and a second position in which the rear sleeve unit is attached to the plug body with the key being engaged with the second recess.

Abstract: A light-shielding fiber optic connector includes a housing defining therein a mating-connection chamber, a mating-connection portion at one side of the mating-connection chamber, an accommodation chamber at an opposite side of the mating-connection chamber and a plug hole perpendicularly connected to the mating-connection chamber, an optical device mounted in the accommodation chamber with a light source transceiver thereof facing toward the mating-connection chamber, a light-shielding device mounted in the plug hole and providing a flexible light-shielding portion for blocking between the mating-connection chamber and the accommodation chamber to prevent light leakage and to prohibit external dust from contaminating the optical device, and a position-limiting member mounted to the housing to hold down the light-shielding device in the plug hole.

Abstract: A fiber optic ferrule includes a body extending from a first end to a second opposite end, with the body including an axial passage extending between the first and second ends. The axial passage includes a first diameter portion having a diameter of at least 125 microns, and a second diameter portion having a diameter of at least 250 microns and less than a diameter of the buffer, the second diameter portion positioned between the first diameter and the second end. The axial passage further defines a tapered shape at the second end extending inward from the second end to the second diameter portion. A hub holds the ferrule. A method of assembling a terminated fiber optic cable is also provided.

Abstract: A fiber optic connector sub-assembly includes a ferrule having a front end, a rear end, and a ferrule bore extending between the front and rear ends along a longitudinal axis. The fiber optic connector sub-assembly also includes a bonding agent disposed in the ferrule bore and having first and second ends along the longitudinal axis. The bonding agent has been melted and solidified at the first and second ends without there being an optical fiber present in the ferrule bore.

Abstract: The present disclosure relates to optical fiber plugs, optical fiber adapters, and optical fiber connector assemblies. One example optical fiber plug includes a ferrule, a sleeve, and a lock cap. At least one lock block is disposed on an inner wall of the lock cap. The at least one lock block is configured to be engaged and locked with a lock slot on an optical fiber adapter. Two stop blocks are disposed on the inner wall of the lock cap. A stop rod is disposed on an outer wall of the sleeve. The stop rod is located between the two stop blocks. The lock cap rotates relative to the sleeve within an angle range limited by the two stop blocks.

Abstract: A connector assembly includes a coaxial connector module and a fiber optic module coupled to the coaxial connector module. The coaxial connector module includes a connector body and coaxial contacts in contact channels. The connector body has a mating interface and fastener openings open at the mating interface to receive fasteners and a window at the mating interface. The fiber optic module includes a housing coupled to the mating interface of the connector body having a cavity and fastener openings receiving the fasteners to couple the housing to the connector body at the mating interface. The fiber optic module includes a fiber optic connector received in the cavity having a mating end and a fiber optic cable extending therefrom. The fiber optic connector is received in the window for mating with a mating fiber optic connector of the mating connector assembly.

Abstract: Described herein are photonic systems and devices including a optical interface unit disposed on a bottom side of a photonic integrated circuit (PIC) to receive light from an emitter of the PIC. A top side of the PIC includes a flip-chip interface for electrically coupling the PIC to an organic substrate via the top side. An alignment feature corresponding to the emitter is formed with the emitter to be offset by a predetermined distance value; because the emitter and the alignment feature are formed using a shared processing operation, the offset (i.e., predetermined distance value) may be precise and consistent across similarly produced PICs. The PIC comprises a processing feature to image the alignment feature from the bottom side (e.g., a hole). A heat spreader layer surrounds the optical interface unit and is disposed on the bottom side of the PIC to spread heat from the PIC.

Abstract: An optical module includes a housing, a printed circuit board, an optical assembly, an optical interface joined with the optical assembly, the printed circuit board, the optical assembly, and the optical interface being disposed in the housing, an adapter to be mated with an external optical connector and disposed on an end of the housing, and first and second connecting part disposed on the adapter and the housing, respectively. The adapter and the housing are secured together through the first and second connecting parts. The optical interface and the adapter are configured to correspond to each other.

Abstract: An optical fiber cable includes: a core comprising gathered optical fibers; an inner sheath housing the core; a wire body embedded in the inner sheath; tension members embedded in the inner sheath, wherein the core is interposed between the tension members; a reinforcing sheet that covers the inner sheath; and an outer sheath that covers the reinforcing sheet, wherein in the inner sheath, ti<Ti and to<To are satisfied, where a thickness of a radially inner portion between the core and the wire body is ti, a thickness of a radially inner portion between the core and each of the tension members is Ti, a thickness of a radially outer portion between the wire body and the reinforcing sheet is to, a thickness of a radially outer portion between each of the tension members and the reinforcing sheet is To.

Abstract: The present disclosure relates to a re-enterable enclosure for a fiber optic network. The enclosure can include features such as a low compression-force perimeter gasket, cable seals constructed to seal effectively seal triple points, multi-function port size reducer plugs and multi-function blind plugs.

Abstract: A communication system may include a first chassis having first and second side walls and adapted to slidably receive therein a plurality of cassettes. A first cable hanger assembly may have a first side edge hingedly coupled to the first side wall of the first chassis, the first cable hanger assembly including a plurality of first hangers adapted to support cables thereon. An axis of rotation of the first cable hanger assembly may be substantially orthogonal to a direction in which the plurality of cassettes are slideable. The cable hanger assembly may be rotatable from a first position to a second position so that during rotation from the first position to the second position, the plurality of first hangers move toward front faces of the plurality of cassettes.

Abstract: An optical component includes an active optical surface, a back surface opposite the active optical surface, and an installation surface connecting the active optical surface and the back surface. At least one of the active optical surface or the back surface is formed with a metal layer on at least a portion of an area located away from a center of the at least one of the active optical surface or the back surface.

Abstract: A lens driving device includes a lens frame that holds a lens, a rack provided pivotally with respect to the lens frame around a pivot shaft along an optical axis of the lens, a lead screw provided along the optical axis, a spring that makes the rack pivot around the pivot shaft, pushes the rack against the lead screw, and engages a tooth of the rack with a tooth of the lead screw, a driving unit that rotates the lead screw, and a nut that includes an end surface facing the rack along the optical axis with a gap C being included therebetween, that engages with the lead screw with backlash being included therebetween, and that is provided un-rotatably with respect to the lens frame. In a case where a half pitch of the tooth of the lead screw is A and the backlash along the optical axis between the lead screw and the nut is B, A>B+C is satisfied.

Abstract: An optical element driving mechanism is provided. The optical element driving mechanism includes a fixed portion, a movable portion, a plurality of first elastic elements, and a first driving assembly. The movable portion is movably connected to the fixed portion, and includes a holder to hold an optical element, wherein the optical element has an optical axis. The first elastic elements are elastically connected to the fixed portion and the movable portion. The first elastic elements extend in a first direction, and the first direction is perpendicular to the optical axis. The first driving assembly drives the movable portion to move relative to the fixed portion in a direction that is perpendicular to the first direction. The first driving assembly is electrically connected to the first elastic elements.

Abstract: A telescope includes a monocular assembly, an optical lens assembly, and a transparent focus sheet. The monocular assembly includes a monocular and a light-shielding tube movably sleeving around the monocular. The optical lens assembly is disposed in the light-shielding tube and is fixed on the monocular. The focus sheet corresponds in position to an end portion of the light-shielding tube. The focus sheet has a first surface and a second surface opposite to and parallel to the first surface. The focus sheet includes a plurality of straight-shaped focus thru-holes, and the focus thru-holes include at least one first thru-hole, at least one second thru-hole and at least one third thru-hole. A longitudinal direction of the first thru-hole and that of the second thru-hole jointly define an angle less than 90 degrees, and a longitudinal direction of the third thru-hole is parallel to an angle bisector of the angle.

Abstract: A driving mechanism is provided, including a base unit, a frame, a holder, a first driving assembly, a sensing magnet, and a magnetic field sensor. The base unit has a polygonal structure. The frame is connected to the base unit. The holder is connected to the frame for holding an optical element, wherein the optical element defines an optical axis. The first driving assembly is disposed on the base unit and the frame, close to a first side of the base unit for driving the holder and the frame to move relative to the base unit along a horizontal direction perpendicular to the optical axis. The sensing magnet is disposed on the holder and close to a second side of the base unit, opposite to the first side. The magnetic field sensor is disposed on the base unit for sensing the sensing magnet.

Abstract: An optical element driving mechanism is provided. The optical element driving mechanism includes a carrier, a base, and a first driving assembly. The carrier holds an optical element with an optical axis. The carrier is movably connected to the base. The first driving assembly drives the carrier to move relative to the base. The first driving assembly includes a driving coil disposed on the carrier, and the direction of the winding axis of the driving coil is different from the direction of the optical axis. The carrier has an abutting surface, which faces and is in direct contact with the driving coil. The maximum size of the abutting surface is greater than the maximum size of the driving coil in the direction of the optical axis.

Abstract: A lens unit with a central axis is provided. The lens unit includes a fixed portion, a movable portion, and a first driving assembly. The fixed portion includes an outer frame and a bottom combined with the outer frame. The outer frame and the bottom are arranged along the central axis. The movable portion is movably connected to the fixed portion, and carries a lens with an optical axis. The central axis is not parallel to the optical axis. The first driving assembly is connected to the movable portion, and drives the movable portion to move relative to the fixed portion. The first driving assembly also includes a biasing element made of a shape memory alloy.

Abstract: An optical system is provided and includes a fixed assembly, a movable member, a driving assembly and a buffering member. The movable member is movably connected to the fixed assembly and is configured to hold an optical member having an optical axis. The driving assembly is for driving the movable member to move relative to the fixed assembly. The buffering member is disposed on a first surface of the fixed assembly. The buffering member, the movable member and the fixed assembly are arranged along the optical axis. The buffering member includes a soft resin material. The buffering member is disposed to surround the optical axis.

Abstract: An optical system is provided, including a holder, a fixed module, a driving assembly, and a first resilient member. The holder is used for holding an optical element that defines an optical axis. The fixed module is movably connected to the holder and has a housing and a base connected to the housing. The base has a bottom surface parallel to the optical axis and a first pillar forming a first surface that is not parallel to the optical axis. The driving assembly drives the holder to move relative to the fixed module. The first resilient member is disposed on the first surface and movably connects the holder with the fixed module.

Abstract: Provided are a lens driving device capable of miniaturizing the entire configuration, and a camera device and an electronic apparatus provided with the lens driving device. The lens driving device of the present disclosure includes: a lens support; a main body for supporting the lens support; a guide mechanism for guiding forward and backward movement of the lens support along an optical axial direction of the lens; and a driving mechanism for generating a driving force for driving the forward and backward movement of the lens support along the optical axial direction. The main body, the guide mechanism, and the driving mechanism are all provided only on one side in a first direction orthogonal to the optical axis direction of the lens with respect to the center of the lens.

Abstract: A multi-axis gimbal actuator includes a first tilt frame tiltably coupled to a second tilt frame. The second frame is tiltably coupled to a reference frame. The first tilt frame is offset from the second tilt frame and approximately parallel to the second tilt frame while in a neutral position. An optical element is mounted on the first tilt frame.

Abstract: An optical imaging system includes a first lens group having a first group of lenses. A foremost lens of the first group of lenses is a lens closest to an object side and has a positive refractive power. The optical imaging system also includes a second lens group having a second group of lenses. A rearmost lens of the second group of lenses is a lens closest to an imaging plane and has convex surfaces. The first and second lens groups are sequentially disposed from the object side to an imaging plane. An expression TL/f1<2.0 is satisfied, where TL represents a distance from an object-side surface of the foremost lens to the imaging plane and f1 represents a focal length of the foremost lens.

Abstract: A zoom lens including, in order from an object side: a first positive lens unit; a second negative lens unit; a third positive lens unit; a fourth negative lens unit; and a fifth positive lens unit, wherein during zooming from a wide angle end, intervals between the adjacent lens units are changed in such a way that the second lens unit is configured to move from the object side to the image side and the third lens unit and the fourth lens unit are configured to move, and a focal length of the third lens unit, a focal length of the fourth lens unit, a movement amount of the second lens unit during zooming from the wide angle end to the telephoto end, and a movement amount of the third lens unit during zooming from the wide angle end to the telephoto end are appropriately set.

Abstract: The present disclosure discloses a camera optical lens. The camera optical lens including, in an order from an object side to an image side, a first lens, a second lens having a positive refractive power, a third lens having a negative refractive power, a fourth lens, a fifth lens, and a sixth lens. The first lens is made of glass material, the second lens is made of plastic material, the third lens is made of glass material, the fourth lens is made of plastic material, the fifth lens is made of plastic material, and the sixth lens is made of plastic material. The camera optical lens further satisfies specific conditions.

Abstract: The present disclosure discloses a camera optical lens. The camera optical lens includes, in an order from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens. The first lens is made of glass material, the second lens is made of plastic material, the third lens is made of plastic material, the fourth lens is made of plastic material, the fifth lens is made of plastic material, the sixth lens is made of plastic material, and the seventh lens is made of plastic material. The camera optical lens further satisfies specific conditions.

Abstract: A multi-axis MEMS assembly includes a micro-electrical-mechanical system (MEMS) actuator configured to provide linear three-axis movement. The micro-electrical-mechanical system (MEMS) actuator includes: an in-plane MEMS actuator, and an out-of-plane MEMS actuator. An optoelectronic device is coupled to the micro-electrical-mechanical system (MEMS) actuator. The out-of-plane MEMS actuator includes a multi-morph piezoelectric actuator.

Abstract: The presently disclosed subject matter includes a mobile electronic comprising an integrated camera, comprising a Wide camera unit comprising a Wide lens unit, and a Telephoto camera unit comprising a telephoto lens unit, the telephoto lens unit and the wide lens unit having respectively TTL/EFL ratios smaller and larger than 1 and defining separate telephoto and wide optical paths.

Abstract: An electronic device includes at least one optical lens assembly. The optical lens assembly includes four lens elements. The four lens elements are, in order from an outside to an inside, a first lens element, a second lens element, a third lens element and a fourth lens element. The first lens element has an outside surface being concave in a paraxial region thereof and an inside surface being convex in a paraxial region thereof. The fourth lens element has an inside surface being convex in a paraxial region thereof.