US 8,300,313 B2 · Method for manufacturing an optical transmission filter with extended out-of-band blocking

Abstract

In accordance with the invention, a filter is fabricated to take into account the effect of absorption by filter material. The method is exemplified by the fabricating of an ultraviolet light transmission filter for transmitting a band within the range 230-320 nanometers. The resulting filter comprises plurality of hard-coating, thin-film layers of alternating high and low index of refraction. The improved filter provides high transmission, sharp edge slopes, and deep and extended out-of-band blocking. As compared with currently available filters, the filter provides transmission up to three or more times greater, edge slopes up to four times sharper, and deep extended out-of-band blocking extending further, even through the visible range.

A method of making an optical bandpass filter for transmitting a band of ultraviolet light within the range of 230 nanometers to 320 nanometers and with extended out-of-band blocking comprising the steps of:

providing a substrate having front-side and backside surfaces;
forming a transmission filter on at least one of said surfaces, said transmission filter consisting of alternating layers of at least two hard coating materials of a higher refractive index and a lower refractive index respectively;
wherein each individual layer of the alternating layers is deposited by a data processor controlled process comprising the steps of:
calculating with the data processor, a theoretical transmission (Ti) of ultraviolet light through the individual layer,
calculating with the data processor an expected deposition time (ti) of the individual layer,
measuring, during the deposition of the individual layer for a period of time less than (ti), a measured transmission (Tm) of light through the layer,
determining with the data processor when deposition of the individual layer is to terminate based upon the theoretical transmission (Ti) and the measured transmission (Tm);
and
wherein the calculation of (ti) and (Ti) accounts for absorption of ultraviolet light by the layer by defining the transmission of UV light within the individual layer as
T
=
4
⁢
n
a
⁢
n
s
H
where T is a level of a monitoring signal within the individual layer,
where na and ns are the refractive indices of the individual layer and substrate, respectively,
where H is defined as
H
=
[
β
1
′
+
β
2
′
⁢
cos
⁡
(
2
⁢
⁢
θ
m
+
1
)
+
β
3
′
⁢
sin
⁡
(
2
⁢
⁢
θ
m
+
1
)
]
/
[
1
+
D
⁢
⁢
θ
m
+
1
)
with
β
1
′
=
[
β
1
⁢
δ
+
(
1
-
α
)
2
⁢
R
bR
T
b
]
/
(
1
-
α
)
β
1
=
n
a
2
+
n
m
+
1
2
2
⁢
(

p

2
+

q

2
n
m
+
1
2
)
+
2
⁢
n
a
⁢
Re
(
pq
*
)
β
2
′
=
β
2
⁢
δ
1
-
α
β
2
=
n
a
2
-
n
m
+
1
2
2
⁢
(

p

2
+

q

2
n
m
+
1
2
)
β
3
′
=
β
3
⁢
δ
1
-
α
β
⁢
⁢
3
=
(
n
a
2
n
m
+
1
-
n
m
+
1
)
⁢
Im
⁡
(
p
*
q
)
δ
=
γ
+
(
2
⁢
α
-
α
2
)
⁢
(
1
-
A
fR
)
⁢
R
bR
T
b
γ
=
1
+
A
fR
⁢
R
bR
+
A
bR
T
b
where Re(pq*) is a real part of a product of a complex number p and a complex conjugate of a complex number q, defined as
[
p
q
]
=
∏
l
=
1
m
⁢
⁢
[
cos
⁢
⁢
θ
l
(
-
i
⁢
⁢
sin
⁢
⁢
θ
l
n
l
)
-
in
l
⁢
sin
⁢
⁢
θ
l
cos
⁢
⁢
θ
l
]
⁡
[
1
n
s
]
where θl is an accumulated phrase in an Ith deposited layer,
where D is an in-situ fitted parameter which models a decrease in transmission due to extinction in the UV spectrum for any previously-deposited layers on the front-side and backside surfaces and in the substrate,
where Tb is the transmittance through any previously deposited back-side layers,
where RbR is the substrate to backside surface reflectance,
where AfR is the absorption of any previously-deposited layers on the front-side surface of the substrate,
where α is the substrate single-pass absorption value, and
where AbR is the absorption of any previously-deposited layers on the backside surface of the substrate.

317 more elements

Facts

Application

13/097,392Filed 29 Apr 2011 · division

Priority

1 Sep 2006

Published

US 2011/0216399 A18 Sep 2011

Granted

30 Oct 2012

Term ends

Not estimatedThe source records don’t support an estimate.

Classification8 codes

G02B 5/283
Interference filters: designed for the ultraviolet
G01J 3/10
Details: arrangements of light sources specially adapted for spectrometry or colorimetry
G01J 3/4406
Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry: fluorescence spectrometry
G01J 2003/1213
Generating the spectrum; Monochromators: filters in general, e.g. dichroic, band

Family

Application60/841,552Us provisional application · filed 1 Sep 2006

Application60/841,551Us provisional application · filed 1 Sep 2006

Application60/875,359Us provisional application · filed 18 Dec 2006

Application11/849,026Parent of this division · filed 31 Aug 2007

US 2011/0216399 A1Pre-grant publication · published 8 Sep 2011

US 2008/0055584 A1Published application

US 8,300,313 B2This patent

From the US filing history. Foreign family members aren’t listed.

Method for manufacturing an optical transmission filter with extended out-of-band blocking

Life of this patent

Method for manufacturing an optical transmission filter with extended out-of-band blocking

Life of this patent

Abstract

Claims19