Optical: systems and elements – Absorption filter
Reexamination Certificate
2001-09-07
2002-06-25
Dang, Hung Xuan (Department: 2873)
Optical: systems and elements
Absorption filter
Reexamination Certificate
active
06411450
ABSTRACT:
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may used by or for the Government of the United States of America without the payment of any royalties therefor.
REFERENCE TO COMPUTER PROGRAM LISTING APPENDIX
A Computer Program Listing Appendix is hereby expressly incorporated by reference. The Computer Program Listing Appendix includes two duplicate compact discs. The files on each compact disc, their size in bytes, and the date created are:
File Name
Size
Date Created
A LEP
1,281
07-03-00 11:51 a a.lep
AGVIEWER C
13,459
07-03-00 11:51 a agviewer.c
AGVIEWER H
3,642
07-03-00 11:51 a agviewer.h
ANASAL LEP
1,284
07-03-00 11:51 a aNasal.lep
ATEMP~14 LEP
1,283
07-03-00 11:51 a aTemporal.lep
B LEP
1,281
07-03-00 11:51 a b.lep
C LEP
1,304
07-03-00 11:51 a c.lep
DEFAULT DAT
12,788
07-03-00 11:51 a default.dat
DEFAULT LEP
1,281
07-03-00 11:51 a default.lep
DEMO CPP
104,107
08-10-00 4:04 p demo.cpp
DEMO TCL
32,104
08-10-00 4:04 p demo.tcl
DWBOG~28 C
1,922,441
07-03-00 11:51 a DwbOglmodel.c
DWBOG~30 H
2,725
07-03-00 11:51 a DwbOglmodel.h
DWBTOOGL H
403
07-03-00 1:20 p dwbtoogl.h
GENER~34
48
07-03-00 11:51 a GENERATE_CODE
GLUTDEFS
1,155
07-03-00 11:51 a glutdefs
IMAGE H
222
07-03-00 11:51 a image.h
INFO TCL
9,131
07-03-00 11:51 a info.tcl
INFO1 TCL
8,441
07-03-00 11:51 a infol.tcl
INFO2 TCL
3,179
07-03-00 11:51 a info2.tcl
INTER~46 CPP
10,912
07-03-00 11:51 a interpolation.cpp
INTER~48 H
1,723
07-03-00 11:51 a interpolation.h
LIMIT~50 TCL
4,065
07-03-00 11:51 a limitedFloatSpinner.tcl
MAKEFILE
1,608
07-03-00 11:51 a Makefile
MATRIX3D C
18,500
07-03-00 11:51 a matrix3d.c
MATRIX3D H
2,770
07-03-00 11:51 a matrix3d.h
MODEL DWB
324,946
07-03-00 11:51 a model.dwb
MODEL~60 VAR
2,600
07-03-00 11:52 a model.vars
MULTI~62 TCL
2,521
07-03-00 11:51 a multipleLimitedFloatDialog.tcl
OD_BAD DAT
16,854
07-03-00 11:51 a od_bad.dat
OD_GOOD DAT
12,788
07-03-00 11:51 a od_good.dat
PIC1 BMP
30,056
07-03-00 11:51 a pic1.bmp
PRECI~70 H
68
07-03-00 11:51 a precision.h
SURFACE DWB
37,069
07-03-00 11:51 a surface.dwb
TKFONT H
6,932
07-03-00 11:51 a tkFont.h
TKINT~76 H
26,402
07-03-00 11:51 a tkInt4.0.h
TKINT~78 H
29,681
07-03-00 11:51 a tkInt4.1.h
TKINT~80 H
31,083
07-03-00 11:51 a tkInt4.2.h
TKINT~82 H
36,523
07-03-00 11:51 a tkInt8.0.h
TKINT~84 H
36,416
07-03-00 11:51 a tkInt8.0p2.h
TKPORT H
717
07-03-00 11:51 a tkPort.h
TKWIN H
1,426
07-03-00 11:51 a tkWin.h
TKWININT H
5,606
07-03-00 11:51 a tkWinInt.h
TKWIN~92 H
2,829
07-03-00 11:51 a tkWinPort.h
TOGL C
93,137
07-03-00 11:51 a togl.c
TOGL H
7,436
07-03-00 11:51 a togl.h
VFN H
3,079
07-03-00 1:13 p vfn.h
XVIRIS H
1,870
07-03-00 1:13 p xviris.h
48 files
2,871,176
bytes
BACKGROUND OF THE INVENTION
The invention is a software based model for the design and assessment of laser eye protection and in particular interference filter type laser eye protection.
Interference based filter technology has been under development in all branches of the Department of Defense since the 1980s. By creating square or sinusoidal gratings in a material layer through either controlled exposure to mutually interfering laser beams in appropriate photographic media or by depositing multiple layers of material with alternating refractive indices, light rays whose wavelength is the same as the path length between the refractive interfaces are preferentially reflected rather than transmitted.
There are basically three different manufacturing processes under development to produce the requisite interference layers to provide adequate laser eye protection. All three technologies reject narrow “notches” of the spectrum by design. The peak wavelength rejected (i.e. the exact spectral location) is dependent upon the fringe spacing and incident angle of the impinging radiation with respect to the fringe gradient (i.e. the direction perpendicular to the plane of refractive index fringes at any location). This requires that the filter be carefully designed to reject anticipated incident wavelengths at angles determined by the relative location of the eye behind the laser eye protection (LEP) surface over the range of possible incidence angles.
Prior to the present invention, the inventors were aware of only one other attempt at a similar effort to overlay either predicted or measured angular rejection performance with precise geometric rejection requirements for any eye of a given description and location behind the LEP surface. That effort was solely designed to describe holographic visors and model their predicted performance against eye requirements in Visual Basic.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide an accurate, data-based, three-dimensional representation (graphical) of the protection provided by reflective (i.e., dielectric stacks, holograms, or rugates) or hybrid filters (combination of interference technologies or interference filters and absorptive dyes). The preferred embodiment focuses on modeling the Navy's hybrid spectacles and visors. However, the novel aspects and advantages described herein are applicable to any reflective filter or barrier material.
One aspect of the invention is to assess the effectiveness of an existing LEP device, such as a visor or a pair of spectacles. Another aspect of the invention is to develop, evaluate, or modify a proposed filter design.
The present invention generates a graphical three-dimensional representation in real time of the complex geometry of interference filters. The three-dimensional graphic and assessment features permit the user to completely model the protection for any desired choice or combination of eye parameters or incident laser direction. The invention displays protection based on the actual optical density recorded across a number of locations on an actual filter surface over a range of incident angles. These features are combined with real time response to user inputs through a graphical user interface (GUI) resulting in a powerful new tool for assessing the degree of protection provided by interference based laser eye protection.
The risk assessment features of the invention allow the user to quickly see which portions of the interference filter fail to protect the retina and more specifically the user defined areas around the central fovea. The ability to view which eye and laser incidence angles produce hazards in user defined regions of the retina is an important feature. With this feature, the user can weigh the likelihood of injury against other important aspects of the filter such as overall transmittance (i.e. visibility through the LEP device) or transmittance of key phosphors or displays.
The invention provides a method of assessing the effectiveness of a laser eye protection (LEP) device having an interference filter surface (IFS), comprising (A) specifying optical densities at a number of points on the IFS for a user specified range of incident angles of a given wavelength of laser light at each of the number of points; (B) entering the specified optical densities into a computer; (C) entering properties of the IFS into the computer; (D) entering properties of an eye into the computer; (E) entering properties of the given wavelength of laser radiation into points on the computer; (F) defining a grid using for the IFS and assigning values of optical densities to points to different optical densities, respectively; (H) generating and displaying a three-dimensional image of the eye and IFS using a graphical user interface (GUI), (I) using the GUI, selecting an incident angle orientation for the given wavelength of laser light and coloring the IFS as a function of optical density on the IFS; (J) using the GUI, selecting an eye orientation and projecting a pupil surface onto the IFS at a point of interest along the incident angle selected in step (I); and (K) determining an average optical density for that portion of the IFS intersected by the projected pupil surface of step (J) and coloring the portion in accordance with the determined average optical density.
In one aspect of the invention, the specified optical densities of step (A) are obtained
Gatewood, Jr. Walter P.
Sheehy James B.
Tribble Jerri A.
Billi Ron
Dang Hung Xuan
The United States of America as represented by the Secretary of
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