Optical: systems and elements – Single channel simultaneously to or from plural channels – By surface composed of lenticular elements
Patent
1994-09-30
1997-03-25
Epps, Georgia Y.
Optical: systems and elements
Single channel simultaneously to or from plural channels
By surface composed of lenticular elements
359619, G02B 2710
Patent
active
056150482
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to imaging systems.
BACKGROUND OF THE INVENTION
The invention comprises an imaging system forming a pseudoscopic image in focus throughout extended depth of field comprising an input relay lens array, a double integral microlens screen having a median plane on to which the input lens array images an object scene and, on the opposite side of the screen and the same distance therefrom as the input array, an output relay lens array similar to the input lens array.
The relay lenses are substantially larger than the screen microlenses.
The double integral microlens screen may comprise a monolithic screen having back to back plano-convex lens arrays either side of the median plane each of focal length equal to half the screen thickness.
The double integral microlens screen may however comprise two similar contiguous screens each comprising double convex microlenses each having a thickness equal to the focal length.
An optical instrument comprising such an imaging system may have fixed components for dedicated use or may be adjustable, the input and output relay lens arrays being mounted for equal and opposite adjustment with respect to the double integral microlens screen.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of imaging systems according to the invention will now be described with reference to the accompanying drawings, in which:
FIG. 1 is an axial section through one embodiment, showing rays and images;
FIG. 1A is an enlargement of a circled portion at the center bottom of FIG. 1;
FIG. 2 is an axial view of the input relay lens array of FIG. 1;
FIG. 3 is an axial section on a larger scale of a double integral microlens screen as may be used in the embodiment of FIG. 1;
FIG. 4 is an axial section like FIG. 3 of another double integral microlens screen as may be used in the embodiment of FIG. 1;
and FIG. 5 is an axial section through an optical instrument embodying the imaging system of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The drawings illustrate an imaging system 11 (FIG. 1) forming a pseudoscopic image 12 of an object 13. The image 12 is in focus throughout an extended depth of field and is in direct 1:1 correlation with the object 13. The system 11 comprises an input relay lens array 14 (see also FIG. 2 where the array is seen to be a circular array of circular lenses 14a of millimetric diameter), a double integral microlens screen 15 having a median plane on to which the input lens array 14 images the object 13 as illustrated in the scaled-up fragment in FIG. 1, and, on the opposite side of the screen 15 and at the same distance D therefrom as the input array 14, an output lens array 16 similar to the input relay lens array 14.
With millimetric dimensions, the relay lens array lenses are substantially larger than the lenslets of the microlens screen, which are of micrometric dimensions.
Two forms of microlens screen 15 are shown in FIGS. 3 and 4. In FIG. 3, the screen 15 comprises a monolithic screen having back to back plano-convex microlens arrays either side of the median plane 15a. Each microlens has a focal length f equal to its thickness, i.e. equal to half the screen thickness.
The screen 15 illustrated in FIG. 4 comprises two similar contiguous screens 15b,15c each comprising double convex microlenses each having a thickness equal to its focal length f. As depicted within the box B this forms an array of micro field lens systems, which image the aperture A.sub.1 on to the aperture A.sub.2 on the opposite face. This reduces vignetting and cross-talk between adjacent entrance and exit lenses of the relay arrays 14,16.
The microlens array of FIG. 4 is more efficient than that of FIG. 3. In either case, as illustrated, the screens translate all impinging ray directions to transmitted ray directions which subtend the same angle to the screen. This not only images the aperture of the input relay lens on to the aperture of the output relay lens but also ensures complete angular parity between rays emanating from the input rela
Davies Neil
McCormick Malcolm
Bey Dawn-Marie
De Montfort University
Epps Georgia Y.
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