COATINGS FOR USE WITH LONG WAVELENGTH DETECTION, OPTICAL SYSTEM INCLUDING THE SAME, AND ASSOCIATED METHODS
An imaging lens for use with an operational waveband over any subset of 7.5-13.5 μm, may include a first surface and a second surface, at least one of the first and second surfaces having optical power; an anti-reflection coating on one of the first and second surfaces; and a short wave cut filter on another one of the first and second surfaces, the short wave cut filter blocking wavelengths in a short wave infrared region. Details of the anti-reflection coating and the short wave cut filter are also provided.
1 . An imaging lens for use with an operational waveband over any subset of 7.5-13.5 μm, the imaging lens comprising:
a first surface and a second surface, at least one of the first and second surfaces having optical power;
an anti-reflection coating on one of the first and second surfaces; and
a short wave cut filter on another one of the first and second surfaces, the short wave cut filter blocking wavelengths in a short wave infrared region.
2 . The imaging lens as claimed in claim 1 , wherein the imaging lens includes:
a first optical element, the first surface being on the first optical element; and
a second optical element, the second surface being on the first optical element.
3 . The imaging lens as claimed in claim 2 , wherein the first surface has the anti-reflection coating thereon and the second surface has the short wave cut filter thereon.
4 . The imaging lens as claimed in claim 3 , wherein the first optical element includes a third surface, opposite the first surface, the third surface having the anti-reflection coating thereon.
5 . The imaging lens as claimed in claim 4 , wherein the second optical element includes a fourth surface, opposite the second surface, the fourth surface having the short wave cut filter thereon.
6 . The imaging lens as claimed in claim 1 , wherein the anti-reflection coating has a thickness between 1 and 4 microns.
7 . The imaging lens as claimed in claim 1 , wherein the anti-reflection coating includes five layers.
8 . The imaging lens as claimed in claim 7 , further comprising at least one binding layer between a first layer and the one of the first and second surfaces and adjacent ones of first to fifth layers.
9 . The imaging lens as claimed in claim 1 , wherein the short wave cut filter has a thickness between 3 and 5.5 microns.
10 . The imaging lens as claimed in claim 1 , wherein the short wave cut filter has more than ten layers.
11 . The imaging lens as claimed in claim 1 , wherein the anti-reflection coating includes a plurality of layers, wherein a top and bottom layer of the plurality of layers is a same material.
12 . The imaging lens as claimed in claim 11 , wherein the material includes zinc.
13 . The imaging lens as claimed in claim 12 , wherein the material is zinc sulfide.
14 . The imaging lens as claimed in claim 1 , wherein the first and second surfaces are silicon.
15 . The imaging lens as claimed in claim 1 , wherein the imaging lens has a transmission of greater than 70% in the operational waveband and less than 1% over a wavelength region between 1.1 and 2 microns.
16 . The imaging lens as claimed in claim 15 , wherein the imaging lens has a transmission less than 1% over a wavelength region between 1.1 and 5 microns.
17 . The imaging lens as claimed in claim 15 , wherein the imaging lens has a transmission of less than 0.5% over a wavelength region between 1.1 and 2 microns.
18 - 40 . (canceled)
41 . An imaging system for use with an operational waveband over any subset of 7.5-13.5 μm, the imaging system comprising:
a sensor; and
an imaging lens including:
a first surface and a second surface, at least one of the first and second surfaces having optical power;
an anti-reflection coating on one of the first and second surfaces; and
a short wave cut filter on another one of the first and second surfaces, the short wave cut filter blocking wavelengths in a short wave infrared region.
42 . The imaging system as claimed in claim 41 , wherein the imaging lens is silicon.
43 . The imaging system as claimed in claim 42 , further comprising an additional imaging lens that is not silicon.