MULTISPECTRAL IMAGER WITH HYBRID DOUBLE LAYER FILTER ARRAY

• US 20150144770A1
• Filed: 11/25/2014
• Published: 05/28/2015
• Est. Priority Date: 11/26/2013
• Status: Active Grant

• Current Assignee: Nanolambda Korea
• Original Assignee: Nanolambda Korea
• Inventors: CHOI, Byung Il
• Granted Patent: US 9,645,075 B2
• Time in Patent Office: Days
• US Class Current: 250/208.1
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01N 21/29 using visual detection G01N21/31 takes precedence
• CPC Class Codes: G02B 5/008 Surface plasmon devices diffractive gratings with a pitch less than or comparable to the wavelength G02B5/1809; surface plasmons in integrated optics G02B6/1226; optical analysis of materials by means of surface plasmons G01N21/553
• CPC Class Codes: G02B 5/201 in the form of arrays
• CPC Class Codes: H01L 27/14621 Colour filter arrangements
• CPC Class Codes: H01L 27/14627 Microlenses

Abstract

Hybrid dual layer filter can be employed can be employed as filters. A multispectral imager comprises a two layer filter array monolithically integrated onto detector array, a top layer of pigment based filter and a lower layer of plasmonic nano-optic filter to make a low cost and narrow bandwidth filter without side leaking or side peaks. Multispectral imager comprises a microlens array, a mosaic patterned optical filter array underlying the microlens array and including a two-dimensional repetition of a unit mosaic pattern, and a pixelated detector array underlying the mosaic patterned optical filter array. The unit mosaic pattern comprises an array of composite filter elements having different peaks in a respective transmittance spectrum. Each composite filter element comprises a pigment based filter portion and a plasmonic nano-optic filter portion.

Claims

1. A multispectral imager comprising:

a microlens array;

a mosaic patterned optical filter array underlying the microlens array and including a two-dimensional repetition of a unit mosaic pattern; and

a pixelated detector array underlying the mosaic patterned optical filter array, wherein;

the unit mosaic pattern comprises an array of composite filter elements having different peaks in a respective transmittance spectrum; and

each composite filter element comprises a pigment based filter portion and a plasmonic nano-optic filter portion.

2. The multispectral imager of claim 1, wherein said unit mosaic pattern is an m×

n rectangular pattern, wherein m and n are independent integers greater than 1.

3. The multispectral imager of claim 1, wherein said unit mosaic pattern comprises a combination of multiple hexagonal patterns.

4. The multispectral imager of claim 1, wherein each plasmonic nano-optic filter comprises a conductive material layer including a periodic pattern of geometric shapes.

5. The multispectral imager of claim 1, wherein the plasmonic nano-optic filter portions within the unit mosaic pattern comprise a same conductive material having different periodic patterns of geometrical shapes.

6. The multispectral imager of claim 5, wherein the conductive material is an elemental metal or an intermetallic alloy of at least two elemental metals.

7. The multispectral imager of claim 5, wherein shapes and sizes of the geometrical shapes are configured such that a transmittance spectrum of each plasmonic nano-optic filter portion has at least one pass band within a pass band of the respective pigment based filter portion within a same composite filter element.

8. The multispectral imager of claim 1, the multispectral imager is configured to generate a multispectral image employing said mosaic patterned optical filter array.

9. The multispectral imager of claim 1, wherein each pigment based filter portion in the unit mosaic pattern has a different composition from other pigment based filter portions in the unit mosaic pattern.

10. The multispectral imager of claim 1, a transmission spectra of each composite filter element is the same as the product of a transmission spectra of a respective pigment based filter portion in the composite filter element and a transmission spectra of a respective plasmonic nano-optic filter portion in the composite filter element.

11. The multispectral imager of claim 1, further comprising at least one metal interconnect layer overlying the pixelated detector array.

12. The multispectral imager of claim 1, further comprising at least one metal interconnect layer underlying the pixelated detector array.

13. The multispectral imager of claim 1, wherein each pigment based filter portion overlies a respective plasmonic nano-optic filter portion within each composite filter element.

14. The multispectral imager of claim 1, wherein each composite filter element comprises:

a portion of an upper transparent material layer overlying a respective plasmonic nano-optic filter portion; and

a portion of a lower transparent material layer underlying the respective plasmonic nano-optic filter portion.

15. The multispectral imager of claim 1, wherein the pixelated detector array comprises semiconductor photodetectors.

16. A method of interpreting bio-chemical contents of an organism, comprising:

providing the multispectral imager of claim 1;

taking a multispectral image of an organism; and

identifying health condition of the organism by correlating the multispectral image with spectral distribution data from organisms with previously characterized health conditions.

17. The method of claim 16, wherein the organism is a human, and the multispectral image is taken from a part of a human body.

18. A method of acquire a multispectral image, comprising:

providing the spectral imager of claim 1; and

taking a multispectral image employing the spectral imager.