Diffractive multifocal optical device
OwnerAllen L. Coheninventor
Life of this patent
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Abstract
A diffractive multifocal optical element comprising a phase zone plate containing annular concentric zones in which the zones are spaced substantially proportional to .sqroot.n, the zones possess stepped facets that introduce a discontinuity in optical path length of less than .lambda./2.
Claims27
A diffractive multifocal optical element comprising a phase zone plate containing a plurality of annular concentric zones which are spaced substantially proportional to .sqroot.n, where n is the zone number, and each of the zones including at least one stepped facet for introducing a discontinuity in optical path length of less than .lambda./2, where .lambda. is the design wavelength of the phase zone plate.
A bifocal optical element of Cohen lens design, having a phase zone plate with odd and even zones, wherein the odd and even zones of the phase plate
- a. conform to full period spacing wherein r.sub.n .perspectiveto..sqroot.2 n d .lambda., where r is the zone radius, n is the zone number, d is the focal length of the phase zone plate and .lambda. is the design wavelength of the phase zone plate,
- b. include steps between adjacent zones, the steps having a depth of an optical path length less than about .lambda./2, and
- c. the design wavelength and depth of step is chosen so that zones direct light of the design wavelength to at least two primary focal points in at least adequate intensity for visual usage at each such primary focal point.
A bifocal optical element of Cohen lens design comprising a faceted step phase zone plate containing an alternating profile wherein:
- a. the phase zone plate includes a plurality of substantially concentric zones and conforms to r.sub.n .perspectiveto.2 n d .lambda., where r is the zone radius, n is the zone number, d is the focal length of the phase zone plate and .lambda. is the design wavelength;
- b. the alternating profile occurs within the full-period spacing;
- c. steps are provided between adjacent zones, the steps having an optical path length of less than about .lambda./2;
- and
- d. the zones of the zone plate are formed so that the zone plate directs to direct light of the design wavelength to at least two primary focal points in at least adequate intensity for visual usage at each such primary focal point.
An optical element comprising a plurality of concentric zones, each of said plurality of zones including optically diffractive facets providing two different curved profiles that are joined at radii r.sub.n, where n is the zone number, through transition profiles located about such radii, which transition profiles have profile curvatures that are different from said two different curved profiles to form annular and concentric zones which zones are spaced substantially proportional to .sqroot.n and the zones direct light of the design wavelength to at least primary focal points in at least adequate intensity for visual usage at each such primary focal point.
Dependencies are inferred from the claim text.