Diffractive/refractive lenslet array

• US 5,696,371 A
• Filed: 05/23/1996
• Issued: 12/09/1997
• Est. Priority Date: 05/23/1996
• Status: Expired due to Term

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Meyers, Mark Marshall
• Primary Examiner(s): LE, QUE TAN
• Application Number:
  US08/652,735
• Time in Patent Office: 565 Days
• Field of Search: 250/208.1, 250/216, 250/226, 250/239, 250/237 R, 359/819, 359/822, 359/823, 257/432-433
• US Class Current: 250/208.1
• CPC Class Codes: G02B 3/0043 Inhomogeneous or irregular arrays, e.g. varying shape, size, height
• CPC Class Codes: G02B 3/0056 arranged along two different directions in a plane, e.g. honeycomb arrangement of lenses G02B3/0043 takes precedence; miniaturised objectives for electronic devices employing wafer level optics G02B13/0085
• CPC Class Codes: G02B 3/0075 characterized by non-optical structures, e.g. having integrated holding or alignment means
• CPC Class Codes: G02B 5/003 Light absorbing elements
• CPC Class Codes: G02B 5/005 Diaphragms for cameras G03B9/02
• CPC Class Codes: G02B 5/18 Diffraction gratings holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44

Abstract

A short focal length image sensor is formed with an array of photosensor sites and a lenslet array. The lenslet array is comprised of a number of abutting lenslets corresponding in number to the number of photosensor sites. Each lenslet has its optical axis decentered as a function of its radial position in the lenslet array so that each lenslet views a different segment of a total field of view. A field limiting baffle, comprised of one or more separated aperture plates, is included with the center of the apertures in each aperture plate being positioned to lie along the optical axis of a respective lenslet.

Claims

1. A short focal length image sensor comprising:

a photosensor array comprised of number of photosensors;

a lenslet array comprised of a number of abutting lenslets corresponding in number to the number of photosensors each lenslet having a decentration corresponding to its radial position in the lenslet array so that each lenslet views a different segment of a total field of view; and

a field limiting baffle comprised of at least one aperture plate which may be a lenslet aperture stop where the center of the apertures are each positioned to lie along the optical axis of a respective lenslet optical axis.

2. A short focal length image sensor comprising:

a color photosensor array comprised of number of sets of three photosensors;

a lenslet array comprised of a number of abutting lenslets corresponding in number to the number of sets of three photosensors each lenslet having a decentration corresponding to its radial position in the lenslet array so that each lenslet views a different segment of a total field of view; and

a field limiting baffle comprised of at least one aperture plate which may be a lenslet aperture stop where the center of the apertures are each positioned to lie along the optical axis of a respective lenslet optical axis.

3. The short focal length image sensor according to claim 2 wherein said lenslets have an aspherical surface.

4. The short focal length image sensor according to claim 3 wherein said lenslets additionally have an aspherical surface whose profile varies as a function of its radial position in the lenslet array.

5. The short focal length image sensor according to claim 2 and further comprising:

a plurality of baffles extending between each lenslet and a corresponding set of three photosensors so as to prevent stray light from one lenslet impinging on one or more of the three photosensors in an adjacent set of photosensors.

6. The short focal length image sensor according to claim 2 wherein each of said lenslets has a surface that is a diffractive/refractive hybrid to eliminate chromatic aberration.

7. The short focal length image sensor according to claim 6 wherein said lenslets have a diffractive/refractive surface whose profile varies as a function of it radial position in the lenslet array.