Abstract: A pair of windshield eyeglasses (101) comprises: lenses (106) and a frame (102) for holding the lenses. Each of the lenses or the frame includes an edge formed with a windshield (107) for sealing a gap between the edge and a face of a user. The windshield extends from the edge and ranges from laterally inward side of the face to an upper intermediate portion and to a lower intermediate portion of the frame. By providing the windshield, the airflow along the user's face is changed to flow along the outside of the windshield. Therefore, the airflow along the face is prevented from entering between the eyeglass inner surface and the user's face. In particular, the airflow is effectively prevented from affecting the eyes from medial angles of eyes toward lateral angles of eyes. This eliminates interference with the natural flow of tears on the eye surface, making it possible to effectively prevent drying and inflammation in the eyes, or prevent foreign materials from coming into the eyes.

Abstract: In safety goggles, in particular industrial safety goggles, comprising a curved sight piece and a soft frame between the sight piece and face contact area, it is provided that the frame is designed in the way of a bellows frame, having at least one fold.

Abstract: A multi-purpose goggle for protecting the eyes of the wearer in industrial and sporting environments and against glare when the wearer is viewing a computer screen for extended periods of time, for housing a virtual reality display and for use by pilots engaged in training for their instrument flight rating. The goggle housing is comprised of a downwardly extending upper surface with a first end and a second end, a viewing area operatively configured in some embodiments for receiving an insert, a centrally disposed nose bridge and a first and second lower panel disposed opposite the nose bridge and a securing means comprised of rearward extensions of the upper surface and lower panels.

Abstract: Anti-fog visors assembly comprising at least an external visor (5) and at least an internal visor (6) at least partially kept in abutment on the internal surface of said external visor by way of mechanical retaining means. Said mechanical retaining means comprise at least two retainers (1, 1?) coupled to the external visor, wherein the internal visor is lodged, and is retained. Advantageously, at least one of the two retainers is a pin (1) rotatable with respect to the internal visor, and which comprises a portion (4) for the engagement with the same internal visor, which has at least a region for the loose engagement and at least a region for the tight engagement (15), depending on the rotation angle reached by the rotatable pin. Moreover, the aforesaid rotatable pin is jointed to means (3) for imposing its rotation which extend to the outside of the external visor.

Abstract: A method for assembly of an eyewear and an eyewear structure are provided to incorporate preferred properties into the eyewear. A lens is encircled by a rim element having the preferred properties thereby forming a lens unit which is removably attached to the eyewear structure. Therefore, the lens can be better retained within the eyewear structure. Such lens units can be made interchangeable one to another, and with a variety of individual properties such that replacement of the lens unit attached to the eyewear structure with a selected one of the interchangeable lens units, will change the properties of the eyewear as per user's preferences.

Abstract: The invention provides light-blocking air vents for eyewear. A frame for the eyewear has a brow web that extends approximately horizontally from a top portion of the frame. The brow web includes at least one ventilation aperture having a internal side that is substantially sloped with respect to a top surface of the brow web. One or more lenses are mounted to the frame. Air is allowed to pass through the aperture. However, by providing that the internal side of the aperture is substantially sloped, light is blocked from entering through the aperture. The brow web may include a plurality of ventilation apertures for each of two lenses mounted to the frame. The apertures for each lens are arranged substantially equally-spaced in a row. A lower web may also be provided that includes one or more ventilation apertures. Side lenses may also be provided along with apertures for ventilating the side lenses.

Abstract: The present invention is a lightweight frame formed of layers of neoprene or other suitable material in which the layers are connected in such a way as to form lens receiving pockets on the frame. The lens receiving pockets enable different kinds of lenses to be easily inserted and removed from the frames. Another feature of the invention is a fastening system that uses Velcro™ which can be locked in place using a locking band. In another embodiment of the invention, a threaded coupler is used. The invention also provides for vented cushions which both protect the user from wind so that the eye socket does not become dry, but also allows the protected chambers in which the eyes reside by venting the chamber through these cushions. Another feature of the invention is a vertical strap which can be used to firmly secure the frame in the vertical direction.

Abstract: A face shield for headgear comprises a generally transparent main lens, adapted for engagement to the headgear. The main lens comprises a curved inner and outer main lens surfaces and has a central recessed portion with a curved recessed inner lens surface and a curved recessed outer lens surface. The recessed inner lens surface and the recessed outer lens surface are respectively offset from the curved inner and outer main lens surfaces. The recessed portion is adapted to receive a secondary lens such that a sealed air gap is formed between the secondary lens and the main lens, thereby forming a sealed double pane lens having condensation reduction properties.

Abstract: A pair of fog-free protective glasses has a frame and a lens. The frame has an embedded portion and a pair of temples pivotally connecting to two ends of the embedded portion. The embedded portion has upper and lower embedded plates to define an embedded groove therebetween, and two sides of the embedded portion are respectively formed with at least one guiding structure. Each guiding structure has at least one drainage hole. The lens is embedded in the embedded groove of the frame, and is respectively formed with a guiding portion. A leading airflow is thus produced from the guiding portion through the drainage hole for reducing fog formation on the lens.

Abstract: A goggle resistant to fogging is provided. The goggle consists of a water wicking and thermal transfer face gasket combined with heat transfer inlets and outlets optimized for heat transfer to air flow through the goggle. With low airflow resistance in the vertically oriented inlets and outlets, the goggle ventilates by natural convection removing moisture and keeping the goggle from fogging. Simultaneously, the present goggle results in greater comfort for the user.

Abstract: The present invention relates to a breath guard assembly for a helmet which is capable of effectively preventing a formation steam in a helmet shield, removing any inconvenience when wearing a helmet and capable of implementing an easier attaching and detaching operation of a breath guard from a helmet body.

Abstract: A flexible, auxiliary frame mounted on a flexible frame of a pair of eyeglasses is disclosed. The frame includes, at its back, a hole in a center of a bridge, two protrusions having a larger bottom at both sides of the hole, and two slots at endpieces. The auxiliary frame comprises a forward tab at a bridge, two grooves at both sides of the tab, two projections having a larger outer end disposed at endpieces, and a rear pad. The projections are matingly fitted in the slots, the tab is fitted in the hole, and the protrusions are fitted in the grooves respectively. Further, the frame together with the auxiliary frame are adapted to flexibly expand with the fastening of the projections in the slots being maintained in response to the wearer's larger head.

Abstract: A projection 1 mounted onto, or produced as an integral part of a roll holder cover 3 which is part of eye safety wear (goggles) suitable for use in motocross and other activities, which enables the use of both rip off sheets and roll on strips on a single set of goggles in a single use. Two roll holder covers are mounted to each side of the goggles. Each projection has an upstanding tab 18 for receipt of a rip off sheet which spans the corresponding two projections.

Abstract: Swimming goggles comprising a rigid frame (2) for supporting a pair of glass-shaped transparent members (1), each formed by a flat lens (1a) and a flanged bush (1b) for the connection to the frame, the bush being made of a mouldable thermoplastic material. The flat lenses are made of a plastic material different from that of the bushes and having a softening temperature higher than that of the material of the bushes and no-mist and/or no-scratch properties. The lenses are perimetrically fixed to the bushes within grooves (6) formed on the respective bushes.

Abstract: A heated visor system for providing a user with a visor that will not fog up when used in cold weather. The heated visor system includes a helmet that has an opening. A visor is coupled to the helmet for covering the opening. A heating element is coupled to an interior face of the visor for heating the visor to prevent fogging of the visor during use of the helmet in cold weather. A power source is for the heating element. The power source is coupled to the visor whereby the visor, heating element, and power source are removable from the helmet.

Abstract: Protective eyewear of the invention includes at least one lens and a frame securing the lens. Temples or a retention strap are provided for attaching the protective eyewear to the head of a user. The frame includes a seal member around the lens with ventilation channels formed in the seal member on its surface for contacting the face of the user. Thus, the seal member forms a substantial enclosure between the lens and the face of the user when the eyewear is worn. The ventilation channels extend into the seal member towards the lens to a depth not reaching the lens and ensure free passage of air from the enclosure to the atmosphere so that moisture condensation on the lens is reduced or eliminated.

Abstract: In a sight piece, in particular for skiing goggles or the like, comprising a distal and a proximal sheet united by a flexible seal and spacer element that encircles along the edge, it is provided that the sheets are glued together by means of the seal and spacer element without the use of additional adhesive.

Abstract: Disclosed is a helmet or a safety cap for protecting the rider's head and a method of manufacturing the same, in which the main body of the helmet has a dual-structure so as to reduce work process when an outer surface of the helmet is painted, and weight thereof. The main body of the helmet has a dual-structure in that an outer surface thereof is formed of a thermoplastic for an aesthetic enhancement and an inner surface thereof is formed of FRP or a mixture of aramide fiber, polyethylene fiber, vinylon, carbon fiber. Thus-formed dual structure of the helmet body contributes to enhancement in impact resistance and convenience in painting, decreasing an overall weight of the helmet.

Abstract: Improved eyewear designs allow for circulation of air between the eyes and lenses to prevent fog from appearing on the lenses, the eyewear utilized in a host of sporting activities and work areas that require glasses or goggles for safety purposes. A first embodiment of the invention teaches the use of beveled members affixed to the interior portion of the frames of the glasses or goggles, such that the spaced apart members come in direct contact with the user's forehead, allowing for continuous air flow between the beveled members to the user's eyes. The spacers may be placed on the inside of the frames, attached to the frames by simple adhesives. The distance between the spacers may be of a range of one-quarter to three-eighths inches, and the spacers may be of a similar width as the outside frame. The edges may be rounded or beveled for user comfort.

Abstract: A projection 1 mounted onto, or produced as an integral part of a roll holder cover 3 which is part of eye safety wear (goggles) suitable for use in motocross and other activities, which enables the use of both rip off sheets and roll on strips on a single set of goggles in a single use. Two roll holder covers are mounted to each side of the goggles. Each projection has an upstanding tab 18 for receipt of a rip off sheet which spans the corresponding two projections.

Abstract: Swimming goggles comprising a rigid frame (2) for supporting a pair of glass-shaped transparent members (1), each formed by a flat lens (1a) and a flanged bush (1b) for the connection to the frame, the bush being made of a mouldable thermoplastic material. The flat lenses are made of a plastic material different from that of the bushes and having a softening temperature higher than that of the material of the bushes and no-mist and/or no-scratch properties. The lenses are perimetrically fixed to the bushes within grooves (6) formed on the respective bushes.

Abstract: The description relates to a double lens (1) for skiing goggles with a curved outer lens (2) and an equally curved inner lens (3) made of a cellulose propionate foil, arranged at a distance from the outer lens (2), which is connected with the outer lens (2) via a sealing tape (4) at the edge. To ensure a favorable fogging behaviour it is suggested that both the outer lens (2), made of injection-molded polycarbonate, and the inner lens (3), made of a vacuum-formed cellulose propionate foil, are curved spherically and that the outer lens (2) is provided with a hygroscopic coating (7) at its inner side.

Abstract: The present invention relates to; resin molded articles having on one side of the resin substrate thereof, such as polycarbonate, a scuff resistant organic hard coat layer and on the other surface of the substrate an antifogging organic hard coat layer; resin shaped articles such as into helmet shields, goggles, and the like, in which the organic hard coat layer will not peel off the substrate when molded into a curve-shaped article having a radius of curvature of 50 mm or less and which will cause no optical distortions; a process for the manufacture thereof; and the covering materials for forming each hard coat layer.

Abstract: A diving mask fog wiping device and method which allows fog on the inside of the viewing face plate to be wiped by a slave unit which is magnetically coupled to a master unit on the opposite side of said viewing face plate. Further, the slave unit is magnetically coupled to a resting unit which keeps it out of the line of sight and near the surface of the viewing face plate while it is not being used for wiping. A porous and nonabrasive surface on the slave unit may be soaked in an antifog agent, allowing the agent to be applied and re-applied every time fog is wiped.

Abstract: In one embodiment of the present invention a water activity mask has a transparent visor and a pliable frame defining an interior volume. One end of the frame rests flush against the wearer's face, forming a substantially watertight seal. The interior of the mask contains a fluid directing member extending towards the visor from the inner surface of the mask. In use the fluid directing member normally retains and prevents liquid in the mask from coming into contact with the wearer's face. The liquid is generally used to defog the mask as necessary.

Abstract: Disclosed are sportsman's eye wear designed to overcome the difficulties and problems associated with conventional eye wear designs. The sporting eyeglasses are specially designed to afford the serious hunter, fisherman or outdoorsman superior eye protection in a stylish manner while providing a effective means by which to secure them to the user's head and maintain their position. The eyeglasses also include anti-fogging ventilation, a camouflaging veil and allow for the incorporation of prescription lenses.

Abstract: A facial sun block mask having a lens that is resistant to ultraviolet radiation. The lens is formed to protect most, if not all, of the face of the wearer. The lens is attached to a main body or visor that seat firmly against the upper forehead region of the wearer. The main body may also have vents.

Abstract: A face shield for a helmet. The face shield having a weather lens and a face lens spaced from the weather lens so as to form an air gap, is characterized in that an electroconductive film is attached to the air gap side of the weather lens, in that upper and lower electrodes are printed on upper and lower sides of the electroconductive film, receptively, and in that the weather lens is made from a material such as a polycarbonate, butyrate, or an acrylic, and the face lens from an anti-fog sheet.

Abstract: Sunglasses are formed by an elongated curved frame with a temple hinged at each end of the frame for engaging a user's ears when the frame is in front of the user's face, and a single-piece wraparound double curvature spherical lens secured at its upper edge to the frame and depending in front of the eye portion of a user's face when the frame is supported by the temples on the user's ears. The lens is a double curvature single piece spherical lens. A nosepiece notch is formed in the center of the lower edge of the lens and a nosepiece pad is formed integrally with the lens along the notch. Rearwardly extending rounded peripheral vision shields are formed integrally with the lens on the ends thereof adjacent to and below the frame ends. The shields extend rearwardly of the frame ends for peripherally shielding the user's eyes.

Abstract: A face shield for a helmet. The face shield having a weather lens and a face lens spaced from the weather lens so as to form an air gap, is characterized in that an electroconductive film is attached to the air gap of the weather lens, in that upper and lower electrodes are printed on upper and lower sides of the electroconductive film, respectively, in that a plurality of dot electrodes which are uniformly spaced from each other are printed on the entire part of the electroconductive film, and in that the weather lens is made from a material such as a polycarbonate, butyrate, or an acrylic, and the face lens from an anti-fog sheet.

Abstract: A breath deflector sealed across the bridge of the nose and extending forwardly therefrom, such as to the inside portion of a helmet and downwardly beyond the mouth, to prevent the fogging of glasses or the visor of the helmet. The seal of the breath deflector extends from the outside corner of one eye, across the bridge of the nose, and to the outside corner of the other eye to minimize a direct upward flow of moisture from one's breath to the area of vision in front of one's eyes. The breath deflector is resilient to form fit to the bridge of the nose even at temperatures below freezing, moisture-resistant, and insulative.

Abstract: A face shield is disclosed that includes a headband with an inner and outer surface, first and second ends and a visor between a portion of the inner and outer surfaces that tapers from a maximum width at the midpoint between the first and second ends to a minimum at a first point spaced a distance from the first end and at a second point spaced a distance from the second end, a flexible fluid impervious transparent cover removably attached to the outer edge of said headband, and means for adjustably securing the shield to a wearer's head. This face shield permits a wearer to comfortably wear eye glasses and/or breathing apparatus under the shield. Also, the flexible cover can be readily removed and replaced if damaged.

Abstract: An anti-condensation visor comprises an outer visor which, relative to the user, is situated on the outermost peripheral surface of a helmet or hood to which the visor belongs. The outer visor is provided with openings for fitting on the helmet and with at least one lip for the user to fold the outer visor away. An inner visor is detachably fitted against the inside wall of the outer visor and is held against via at least one mechanical retaining element, while the inner visor rests over essentially its entire surface against the inside wall of the outer visor, and the inner visor is made of hydrophilic material.

Abstract: A face shield assembly for a snowmobile or motorcycle helmet has a ventilation system for cold-weather face shield defogging. The face shield has a face shield frame, lower and upper face shield frame vents, and lower and upper air guides to direct the flow of air flowing through the lower and upper vents. The face shield may be a heated double lens shield having a weather lens, a face lens and an air gap in between the weather lens and the face lens. The assembly may also include an electric face shield defogging system having first and second electrodes extending along the upper and lower edge portions, respectively, of the air gap-facing surface of the face lens. Side areas of the face shield are substantially free of visual obstruction so as to enhance the rider's field of vision. There is a separate electric connector at an end of each electrode, with each connector extending through at least one lens and coming into direct contact with its respective electrode.

Abstract: A pair of goggles that are worn by an active sports participant which enhances the person's ability to see and protect his eyes during active sport activities. The goggles have a double lens assembly that is removably received in the front wall frame of the goggles. One or more metal heat sinks are secured to the goggle structure to dissipate the heat within the chamber between the goggles and the face of the person wearing the goggles.

Abstract: A face shield for a helmet comprises a body with an opening, an inner lens mounted in the body opening and a weather lens releasably mountable over the inner lens. The weather lens has a gasket around its perimeter which spaces the weather lens from the inner lens to form an insulating air gap between the inner lens and the weather lens. The weather lens is made of translucent material to selectively filter the light passing through the lens. The inner lens is recessed in the body so that the weather lens is generally flush with the outer surface of the body. Each side edge of the weather lens is provided with one of a hook and loop fastener and the inner lens has the complimentary fastener portion for mounting the weather lens to the inner lens.

Abstract: Multilayer lens particularly usable for sunglasses, having a main layer made of polycarbonate, cellulose acetate, or similar materials. A mirror reflecting layer is possibly coupled to the main layer or deposited thereon in vacuum by sublimation of appropriate substances, with the optional interposition of a layer of paint. The multilayer lens furthermore includes an outer layer that partially affects the outer surface of the lens. The lens may also include an inner antifogging layer that does not absorb moisture. This multilayer lens allows optimum vision to the user, eliminating or attenuating spurious incident rays at the lateral ends of the lens.

Abstract: A non-fogging goggle assembly comprises a transparent film of polyester or polycarbonate coated with a hydrophilic composition that lowers the surface tension of water droplets, causing them to spread rather than form vision-obstructing beads. The film is applied against the inner face of the goggle lens and releasably held in place without any adhesive by pressure-fitting the edge of the film or parts thereof into peripheral slots or grooves cut into the section of the frame surrounding the lens.

Abstract: Disclosed is a dual-lens vented eyeglass. In one embodiment, each lens is provided with a plurality of apertures extending therethrough, at the junction between the lens and the surrounding frame. In another embodiment, a plurality of apertures are provided in the frame, surrounding the lens. The apertures optimize ventilation, with minimal intrusion into the optical zone.

Abstract: Protective eyeglasses (e.g., sunglasses) for use in high-speed outdoor sports activities, the lenses thereof being resistant to condensation, is achieved by air circulation created by venturi effects. The glasses comprise a frame front having middle portions over the wearer's eyes which support protective lenses, and having endpiece portions near the wearer's temples, the outboard edges of which attach temples which hold the glasses in place. A chamber is defined by the volume between the lenses and the wearer's face, and gaps are defined by the distance between the middle portions of the frame front and the wearer's face. Apertures in each of the endpiece portions of the frame front define an entrance of a ventilation channel for air flow through the frame front, adjacent to the respective chamber. Venturi forces are created within the ventilation channels to facilitate circulation of air.

Abstract: A non-fogging athletic goggle or mask assembly, comprising an athletic goggle or mask in combination with a desiccant assembly, is disclosed. According to one embodiment, an athletic mask or goggle is provided with at least one desiccant chamber formed in a portion of the mask or goggle so as not to obstruct vision. The desiccant chamber includes a gate that can be deployed or retracted to close off or expose the interior of desiccant chamber. The desiccant chamber is provided with a tablet or pre-packaged desiccant, which is retained within the desiccant chamber during use of the goggle or mask and can be replaced upon saturation. When the mask is worn, water vapor in the air trapped by the goggle or mask is absorbed by the desiccant, thereby preventing fogging of the goggle or mask. The desiccant capsule or the desiccant chamber may be further provided with a water vapor permeable membrane that allows water vapor to pass but excludes liquid water.

Abstract: A goggle (11) that includes an electrical defogging system includes a frame (13) and a transparent lens (15). The transparent lens includes an outside layer(51 or 61) and inside layer(53 or 63) spaced from the outside layer by a peripheral gasket (55 or 65). The inside layer has an indium tin oxide (ITO) coating. The ITO coating includes an interior heating zone (33) that is electrically isolated from the edge of the inside layer. Silver bus bars (45, 47) are printed atop the ITO coating along the opposing edges of the interior heating zone adjacent the top and bottom of the goggle lens. The edge isolation regions and the bus bars are positioned and oriented such that the region (48) where the bus bars cross the nose area(41) of the goggle lens is isolated from the interior heating zone(33). Further, the bus bar that passes along the bottom of the goggle lens extends upwardly along one side of the lens. The side section of this bar is electrically isolated (39 ) from the interior heating zone.

Abstract: Known protective helmets used for motorcycle riding, flying and snowmobiling employ transparent visors that have heating elements to reduce and attempt to eliminate the build-up of ice, condensation and fog. A double-lensed face shield is provided with a pair of electrodes formed on an inner face lens, in the air pocket formed between the inner face lens and the outer weather lens. Substantially across one entire surface of the inner face lens is formed an electroconductive film. An upper electrode extends from a first end along an upper margin of the inner face lens on the film to a second end. On the opposite lower margin extends on the film a lower electrode from a first end to a second end. An insulated contact passes from one side of the inner lens to the other and connects the first end of the lower electrode with a conductor which extends on the opposite side of the inner lens towards the first end of the upper electrode.

Abstract: An eye protection device in one embodiment composed of a foam rubber-like member having a front portion, first and second side portions, and first and second apertures therein for receipt of the lenses and frame of a pair of eyeglasses with the side earpieces of the pair of eyeglasses being passed through the first and second apertures in the first and second side portions. When worn, the foam rubber-like member is compressed against the wearer's face to create a seal between the device and the user's face.

Abstract: A spacer is slidably mounted to the headband of a goggle. The spacer comprises a block formed of a body which in use is captured between the headband and the head of the user. The block has an elongated contoured inboard head engaging surface and an outboard frame engaging portion spaced therefrom. In a forward position, adjacent the goggle, the block supports the goggle in spaced relation with the face or head of the wearer to thereby allow ventilation thereof. When the block is in a retracted position the goggle rests against the face or head of the user.

Abstract: A face mask used by a firefighter and/or miner includes a seal between the mask interior surfaces and skin on the face of a user. A port on the sealed visor receives a hose for supplying a regulated amount of air from a compression air tank carried by the user. A portion of the mask in the form of a visor covering the eyes of the user is transparent to visible optical energy. The mask has a tendency while used to have condensate formed thereon, causing the transparent portion to be fogged. An electrically activated device in the form of a heater and/or fan, on the mask prevents formation of and/or removes the condensate. A battery in a housing carried by the user activates the electrically activated device. The housing includes heat insulation to prevent the battery from being damaged by high temperatures in the vicinity of the user. The power supply for the transparent visor energizes a temperature sensor for enabling a firefighter to be warned that he/she is in an unsafe, excessively hot environment, i.e.

Abstract: Protective eyewear is disclosed which comprises a sheet of transparent synthetic plastics material with means for attaching to the wearer's head with a viewing area of said sheet extending across the wearer's eyes. A protrusion extends along the top edge of the sheet, contacts the wearer's forehead in use and holds the viewing area away from the wearer's eyes. Slits are provided in the sheet to improve ventilation and the plastics material is coated with anti-fogging material to prevent misting-up. The slits also make it possible to use the protective eyewear over spectacles.

Abstract: Ski goggles are provided having circuitry for heating the lens by means of at least one solar cell held by the headband of the goggles to prevent or eliminate fogging and condensation on the surface of the lens of the goggles facing the wearer.

Abstract: An improved ski goggles is provided and includes a protective lens that has a fine grid of heat generating wire with sufficient resistance to produce enough heat to remove frost and fog from the lens. An external of self contained battery pack and switching device supplies electricity to the resistance wire grid.

Abstract: A shield comprising a thin elongated transparent flexible member having an upper flat edge, a pair of spaced convex edges spaced apart and located opposite the flat edge for forming a pair of spaced planar portions. The planar portions extend between the flat edge and the convex edges, with the convex edges being joined by a concave edge located opposite the flat edge and between the convex edges which defines a narrowed webbed portion extending integrally between the planar portions. An elongated deformable flexible sealing member extends along the flat edge between the distal ends of the flexible member and a second elongated deformable flexible sealing member extends continuously along the convex edges and the concave edge between the distal ends of the flexible member.

Abstract: An optical preform is prepared first by depositing soot about a glass subate rod (22) to form a boule. Then the soot boule is sintered to consolidate the material and provide a preform from which optical fiber is drawn. The boule is relatively large so that the resulting preform is capable of providing more optical fiber than those used in the past. In order to be able to sinter successfully the enlarged boule, microwave energy from a furnace (60) is coupled to the glass rod so that the sintering proceeds from the rod radially outwardly thereby allowing gases readily to escape and rendering the process highly efficient.