Abstract: A tool for tuning the pitch of blades on a model propeller with pivoting blades, the tool comprising a mount for the model propeller and a calculation module. The mount allows the propeller to be positioned such that the axis of the propeller coincides with a fixed reference axis of the mount and to place each blade of the propeller, successively, in a measurement position. The calculation module determines the angle between a chord of a blade in the measurement position and a fixed reference plane of the tool, the fixed reference plane being orthogonal to the fixed reference axis, based on optical sightings by the calculation model on a suction face of the blade in the measurement position.

Abstract: The invention relates to a tool for tuning the pitch of the blades of a model propeller (50) with pivoting blades, characterized in that it comprises: means (2, 13-16) for mounting the model propeller in the tool, able to make it possible to position the propeller in such a way that its axis of rotation coincides with a fixed reference axis (3) of the tool, and to place each blade of the propeller successively in a measurement position, optical means (4, 8-11) for determining the angle between a chord of a blade (51) in measurement position and a fixed reference plane of the tool orthogonal to the reference axis on the basis of two points (5, 6), referred to as measurement points, sighted by the said optical means on the suction face of the said blade in measurement position. The invention extends to a tool set additionally comprising at least one standard propeller provided with fixed blades of different pitches, and to a tuning method using the tool or the tool set according to the invention.

Abstract: A progressive ophthalmic lens with a continuous progressive surface comprises a substantially constant power first area matched to far vision. It also has a substantially constant power second area matched to near vision. Between the first and second areas is a progressively varying power third area. This is defined by a central part extending to both sides of the main progression meridian. In this central area each line on the progressive surface parallel to the main progression meridian substantially satisfies at every point the following equation:1/R1-1/R2=constantwherein R1 and R2 are the principal radii of the surface at the point concerned.

Abstract: In this lens, the curvature of the main meridian curve of power progression (MP) begins to vary from a point (A3) situated within the intermediate vision zone (VI) at a predetermined distance d1 from the point (A1) on the main meridian curve (MP) situated at the bottom of the far vision zone (VL), and it continues to vary down to a point (A4) situated in the near vision zone (VP) on an extension (MP') of the main meridian curve (MP), and at a predetermined distance d2 from the point (A2) on the main meridian curve (MP) situated at the top of the near vision zone (VP), with the curvature difference between the points (A2 and A4) having a predetermined value .DELTA.C. The values of d1, d2, and .DELTA.C are decreasing functions of the power addition A between the points (A1 and A2).

Abstract: A progressive lens with a continuous surface comprises three substantially constant power areas. A first such area is mathced to far vision, a second to near vision and a third, between the first and second areas, to intermediate vision. Respective progressively varying power areas lie between the first and third areas and between the third and second areas. A predetermined progress meridian passing through these substantially constant power areas may have substantially umbilical parts between the substantially constant power areas.