Abstract: A progressive ophthalmic lens element having a front surface that includes an upper viewing zone having a surface power suitable for distance vision, a lower viewing zone having a surface power suitable for near vision, and a corridor of relatively low astigmatism connecting the upper and lower viewing zones, the corridor being a part of an intermediate viewing zone having a surface power varying from that of the upper viewing zone to that of the lower viewing zone. The progressive ophthalmic lens element also has a back surface. The invention is then characterized by the front surface including at least one correction to improve optical performance of the lens element by at least partially compensating for a cylinder correction applied to, or to be applied to, the backsurface.

Abstract: A progressive ophthalmic lens element including a lens surface having upper viewing zone providing good optical quality at a predetermined low surface power over a large area of vision; said predetermined power being determined by the viewer's distance prescription (R.sub.x) the horizontal fitting position normally being determined by the inter pupillary distance of the wearer, and the vertical fitting position normally being determined by the vertical frame midpoint; a lower viewing zone of higher surface power providing an enhanced range of vision for intermediate or lesser viewing distances; and a corridor of relatively low astigmatism extending therebetween; wherein the contours of mean surface power and/or surface astigmatism within the lower viewing zone, upper viewing zone and corridor are generally symmetric about a vertical lens meridian.

Abstract: A series of progressive ophthalmic lens elements, each lens element including a lens surface havingan upper viewing zone having a surface power to achieve a refracting power corresponding to distance vision;a lower viewing zone having a greater surface power than the upper viewing zone to achieve a refracting power corresponding to near vision;a corridor of relatively low surface astigmatism connecting the upper and lower zones, said corridor having a surface power varying from that of the upper viewing zone to that of the lower viewing zone;the progressive ophthalmic lens series includinga first set of lens elements having a base curve(s) suitable for use in providing a range of distance prescriptions for a first category of patient; anda second set of lens elements having a base curve(s) suitable for use in providing a range of distance prescriptions for a second category of patient;each lens element within a set differing in prescribed addition power and including a progressive design, in at least one of t

Abstract: A method of producing a microwave resonator comprising a cavity (50) defined, at least in part, by a generally cylindrical wall (64) having an electrically conductive inner surface and containing a generally cylindrical piece of low loss dielectric material (22), characterised by forming a generally cylindrical piece of low loss dielectric material of predetermined size and placing same in a cavity to produce a microwave resonator which operates in a particular mode at a specific frequency at a particular temperature. Microwave radiation corresponding to a further operating mode is then passed into the cavity and then the frequency corresponding to the further operating mode is searched for and measured. A further generally cylindrical piece of dielectric material is produced by scaling from the first piece of dielectric material according to the ratio between the first and second frequencies.

Abstract: A progressive ophthalmic lens including a lens surface having: a lower viewing zone providing good optical quality at a predetermined high surface power over a large area of vision; said predetermined power being determined by the viewer's near prescription (R.sub.x) the horizontal fitting position normally being determined by the near pupillary distance of the wearer, and the vertical fitting position normally being determined by the vertical frame midpoint, an upper viewing zone of lower surface power providing an enhanced range of vision for intermediate or greater viewing distances; and a corridor of relatively low astigmatism extending therebetween; wherein the contours of mean surface power and/or surface astigmatism within the lower viewing zone, upper viewing zone and corridor are generally symmetric about a vertical lens meridian as fitted to the wearer.

Abstract: A series of progressive ophthalmic lens elements, each lens element including a lens surface havingan upper viewing zone having a surface power to achieve a refracting power corresponding to distance vision;a lower viewing zone having a greater surface power than the upper viewing zone to achieve a refracting power corresponding to near vision;a corridor of relatively low surface astigmatism connecting the upper and lower zones, said corridor having a surface power varying from that of the upper viewing zone to that of the lower viewing zone;the progressive ophthalmic tens series includinga first set of lens elements having a base curve(s) suitable for use in providing a range of distance prescriptions for a first category of patient; anda second set of lens elements having a base curve(s) suitable for use in providing a range of distance prescriptions for a second category of patient; each lens element within a set differing in prescribed addition power and including a progressive design, in at least one of

Abstract: A method of producing a microwave resonator comprising a cavity (50) defined, at least in part, by a generally cylindrical wall (64) having an electrically conductive inner surface and containing a generally cylindrical piece of low loss dielectric material (22), characterized by forming a generally cylindrical piece of low loss dielectric material of predetermined size and placing same in a cavity to produce a microwave resonator which operates in a particular mode at a specific frequency at a particular temperature. Microwave radiation corresponding to a further operating mode is then passed into the cavity and then the frequency corresponding to the further operating mode is searched for and measured. A further generally cylindrical piece of dielectric material is produced by scaling from the first piece of dielectric material according to the ratio between the first and second frequencies.