Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Patent
1999-07-22
2000-08-01
Epps, Georgia
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
359620, 359621, 359622, G02B 2710
Patent
active
060975415
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to lens arrangements, more particularly for forming three-dimensional images.
BACKGROUND OF THE INVENTION
Lens arrangements are known comprising input and output macrolenses or macrolens arrays with intermediate so-called double-integral transmission microlens screens. In all of these arrangements, the input macrolenses cast an image on to the microlens screen arrangement which transmits rays to the output lenses for reconstitution as a pseudoscopic image that can be captured via a decoding screen on to a sensitised screen such as a photographic plate or film or an electronic arrangement such as a charge coupled device (CCD) screen.
In order to cast an image on to the screen, the input array lenses are, of course, positive, or convex lenses, and the output lenses are, naturally, similar.
The input and output lenses must be spaced about the equivalent of their focal lengths from the central microlens screen, which makes the arrangement somewhat more than two focal lengths long.
Problems arise with such lens arrangements that require more or less expensive measures for their solution or alleviation. One such problem is that the input lenses cast an image of the microlens screen as well as of the image cast on that screen, and graininess in the final images is dependent upon the pitch of the microlens screen. Fine pitch screens are clearly desirable, but correspondingly expensive.
BRIEF SUMMARY OF THE INVENTION
The present invention provides lens arrangements which do not suffer from the problem of graininess yet which a re not expensive and which incidentally have advantages in other ways over the conventional arrangements.
The invention comprises a lens arrangement comprising: correspondingly to those of the input array, and
The input and output arrays may be of plano-concave lenses arranged with their plane faces facing each other and the double convex microlens array having the convex microlens faces contiguous with the plane faces of the input and output arrays.
The input and output arrays may be of equal focal length--giving unit magnification--or they may have different focal lengths and have the principal axes of corresponding macro lenses displaced from each other proportionately to their distance from the principal axis of the arrangement as a whole.
With such arrangements it is possible to correct for chromatic and other aberrations by using glass of different refractive indices and dispersion for the various elements.
Embodiments of lens arrangements according to the invention will now be described with reference to the accompanying drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-section of a first embodiment;
FIG. 2 is a ray tracing through one pair of input and output macrolenses;
FIG. 3 is a sample ray tracing from the output lens array;
FIG. 4 is a face-on-view of one arrangement of macrolenses;
FIG. 5 is a face-on-view like FIG. 4 of a second arrangement;
FIG. 6 is a face-on-view like FIG. 4 of a third arrangement;
FIG. 7 is a face-on-view like FIG. 4 of a fourth arrangement; and
FIG. 8 is a cross-section through a second embodiment.
DETAILED DESCRIPTION OF THE INVENTION
The drawings illustrate lens arrangements 11 comprising: correspondingly to those 12a of the input array 12; and array 14.
The input and output arrays 12, 13 are of piano-concave lenses 12a, 13a arranged with their plane faces 12b, 13b facing each other and the double convex microlens array 14 having its convex microlens faces 14a contiguous with the plane faces 12b, 13b of the input and output arrays 12, 13.
In the embodiment of FIGS. 1 to 7, the input and output arrays 12, 13 are of equal focal lengths, that is to say, all the lenses of each array 12, 13 are of the same focal length.
In a typical arrangement, the focal lengths LA of the input and output macrolenses are--80 mm, the macrolens apertures are 21 mm, the microlens pitch (aperture) p is 915 microns, and the distance `d` between the plane surfaces 12b, 13b of the macrolens arrays 12,
REFERENCES:
patent: 5850310 (1998-12-01), Schweizer
Davies Neil
McCormick Malcolm
De Montfort University
Epps Georgia
Gunter Jr. Charles D.
Lucas Michael A
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