Browse Prior Art Database

SELF-ALIGNED MICROLENS FABRICATION TECHNIQUE USING FRESNEL LENSES

IP.com Disclosure Number: IPCOM000025601D
Original Publication Date: 1986-Aug-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 103K

Publishing Venue

Xerox Disclosure Journal

Abstract

Fresnel microlenses can be fabricated lithographically and have been shown to exhibit excellent image forming properties with resolution down to the diffraction limit. The useful field of these devices is almost identical to conventional lenses of similar numerical aperture. Two types have been made: Zone plates and Phase plates. The phase lates require controlled

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XEROX DISCLOSURE JOURNAL

SELF-ALIGNED MICROLENS Proposed Classification FABRICATION TECHNIQUE USING U.S. C1.350/452 FRESNEL LENSES
Cl. Int. Frank C. Genovese G02b 3/08

/ PHASE

PLATES

(OBJECT AT INFINITY 1 SUBSTWT E

Fresnel microlenses can be fabricated lithographically and have been shown to exhibit excellent image forming properties with resolution down to the diffraction limit. The useful field of these devices is almost identical to conventional lenses of similar numerical aperture. Two types have been made: Zone plates and Phase plates. The phase lates require controlled

than the zone plates (in which an opaque layer is etched away) but offer a distinct improvement in light-collection efficiency.

The principle drawback of Fresnel lenses for any application is their contrast limitation. Because they are a diffraction rather than a refraction device more than one image order is generated at the same time and appears as undesirable background to the image of interest. However if the image area to be exposed is small compared with the area of the lens this background can be acceptably low. In other words these devices are unsuitable for imaging small dark objects in a brightly lighted field but can yield excellent results ifa small illuminated area is to be imaged in an otherwise dark field.

etching OF buildup of transparent material and are s

P ightly harder to fabricate

A practical consideration in designing these lenses is the limitation imposed by the lithogr...