US20180321482A1 - Optical Filter - Google Patents
Optical Filter Download PDFInfo
- Publication number
- US20180321482A1 US20180321482A1 US15/587,919 US201715587919A US2018321482A1 US 20180321482 A1 US20180321482 A1 US 20180321482A1 US 201715587919 A US201715587919 A US 201715587919A US 2018321482 A1 US2018321482 A1 US 2018321482A1
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- US
- United States
- Prior art keywords
- light
- filter
- user
- optical filter
- nvd
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 27
- 230000004297 night vision Effects 0.000 claims abstract description 11
- 230000000007 visual effect Effects 0.000 claims 1
- 238000005286 illumination Methods 0.000 abstract description 9
- 230000004300 dark adaptation Effects 0.000 abstract description 8
- 230000005043 peripheral vision Effects 0.000 abstract description 5
- 210000004027 cell Anatomy 0.000 description 6
- 230000001815 facial effect Effects 0.000 description 6
- 230000006870 function Effects 0.000 description 5
- 208000001140 Night Blindness Diseases 0.000 description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000004438 eyesight Effects 0.000 description 2
- 238000009434 installation Methods 0.000 description 2
- 230000004296 scotopic vision Effects 0.000 description 2
- 238000006748 scratching Methods 0.000 description 2
- 230000002393 scratching effect Effects 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 210000003850 cellular structure Anatomy 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000003333 near-infrared imaging Methods 0.000 description 1
- 210000004279 orbit Anatomy 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000001931 thermography Methods 0.000 description 1
- 230000016776 visual perception Effects 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/20—Filters
- G02B5/208—Filters for use with infrared or ultraviolet radiation, e.g. for separating visible light from infrared and/or ultraviolet radiation
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/12—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices with means for image conversion or intensification
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/12—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices with means for image conversion or intensification
- G02B23/125—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices with means for image conversion or intensification head-mounted
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B25/00—Eyepieces; Magnifying glasses
- G02B25/001—Eyepieces
Definitions
- This invention relates generally to Night Vision Devices, and more specifically to the placement of an optical filter or similarly functional device in relation to the Night Vision Device and to the device user's eye.
- Night Vision Devices refer to a group of electronic devices used to augment the vision of the user in low light and/or dark conditions. There are at least four classes of such devices distinguished by the type of illumination amplified by their respective electronics: image intensifiers, near infrared imaging, thermal imaging and combinations of these called fusion devices. Other types of devices may include infrared sources to illuminate the scene.
- NVDs utilize a display to convert the electronic signals from the detectors into an image visible by the human eye.
- the image display may be an analog phosphor typified by the NVD AN/PVS-14 Image Intensifier P-43 phosphor or a digital display in black & white or color as typified by the RECON III or a display that optically combines the two display types typified by the ENVG.
- dark adaptation time An important factor is the time period required to transition from photopic to scotopic vision, a phenomenon termed dark adaptation time. Depending on prior conditions, this dark adaptation time can be 45 minutes or longer. During this transition, the eye has difficulty detecting objects resulting in a condition called night blindness. Because the NVD display is bright, therefore when the user of the NVD removes the device or looks away from the display, he/she endures night blindness during the dark adaptation time.
- the displays of the NVDs produce a general illumination of the user's face and/or eye socket. Termed facial signature or splash, this is very undesirable because it will disclose the presence and location of the NVD user to hostile persons who happen to be looking in the direction of the NVD user.
- the NVD 2 is utilized by the wearer 1 by holding the NVD up to the eye and viewing through the attached eyepiece 3 but not touching the facial surface surrounding the eye. This existing design results in a portion of the face 4 being illuminated by the display of the NVD which is undesirable.
- the invention comprises the placement of an optical filter internally in the optical train of the eyepiece.
- This optical filter has light transmissive characteristics shown in the accompanying table:
- the user/observer can adequately see the light emitted from the light emitting display.
- that light emitted from the display and passing through the filter is modified so as to reduce splash-back on the observer's face.
- FIG. 1 is a representation of the undesirable facial illumination caused by the Night Vision Device display.
- FIG. 2 is a representation of the rubber eyepiece commonly used to reduce the facial signature but sacrificing the peripheral vision of the user.
- FIG. 3 is a representation of the optical filter placed in the external eyecup of an NVD.
- FIG. 4 is an exploded view of a PVS-14 NVG eyepiece showing the placement of the optical filter and the user's eye.
- the eyepiece cell component is modified to accept the optical filter.
- FIG. 4 diagrams the internal integration of the filter in a typical eyepiece of the NVS-14.
- the user's eye 17 is positioned at the end of the eyepiece assembly.
- the eyepiece assembly is attached to the NVD body by means of the threaded locking ring 14 .
- Element 8 is a threaded retaining ring which is mounted on the optical cell collar 12 .
- Element 9 is a retaining ring.
- Knurled ring 10 is rotated by the operator to achieve focus with fiduciary ring 11 providing indication to the operator of the adjustment.
- the optical cell collar 12 utilizes the grooves on the side of the optical cell 15 to effect longitudinal movement of elements 8 , 9 , 10 , 11 , and 12 .
- the optical cell 15 contains the focusing lens elements.
- Elements 8 , 9 , 10 , 11 , and 12 serve in conjunction to move the eyepiece cell 15 with mounted optical filter 16 longitudinally along the optic axis in order to achieve proper focus of the displayed image to the operator.
- the optical filter 16 is retained in position to the eyepiece cell by an O-ring 13 and the locking ring 14 .
- the filter 16 can have optical properties of the sort disclosed in U.S. Pat. No. 6,158,865.
Abstract
Description
- Not applicable.
- Not applicable.
- Not applicable.
- This invention relates generally to Night Vision Devices, and more specifically to the placement of an optical filter or similarly functional device in relation to the Night Vision Device and to the device user's eye.
- Night Vision Devices (NVDs) refer to a group of electronic devices used to augment the vision of the user in low light and/or dark conditions. There are at least four classes of such devices distinguished by the type of illumination amplified by their respective electronics: image intensifiers, near infrared imaging, thermal imaging and combinations of these called fusion devices. Other types of devices may include infrared sources to illuminate the scene.
- These NVDs utilize a display to convert the electronic signals from the detectors into an image visible by the human eye. Depending on the type of ENVD, the image display may be an analog phosphor typified by the NVD AN/PVS-14 Image Intensifier P-43 phosphor or a digital display in black & white or color as typified by the RECON III or a display that optically combines the two display types typified by the ENVG.
- It is a well-known fact that such displays are sufficiently bright to cause the eye to function in the photopic regime or the mesopic intermediate regime between photopic and scotopic. The human eye has two modes of function depending on the incident illumination levels (e.g. Duplicity Theory as discussed in Graham (Editor) Vision and Visual Perception, John Wiley and Sons, 1966). In this regard, the term “photopic” refers to the eye function at a relatively high level of illumination (daylight) and “scotopic” refers to function at relatively low light levels (night). Acuity and color sensitivity are significantly better for the photopic regime; sensitivity to low illumination is significantly better with scotopic vision.
- An important factor is the time period required to transition from photopic to scotopic vision, a phenomenon termed dark adaptation time. Depending on prior conditions, this dark adaptation time can be 45 minutes or longer. During this transition, the eye has difficulty detecting objects resulting in a condition called night blindness. Because the NVD display is bright, therefore when the user of the NVD removes the device or looks away from the display, he/she endures night blindness during the dark adaptation time.
- Special filters such as that disclosed in Kreutzig U.S. Pat. No. 6,158,865 have been designed to shorten the dark adaptation time and reduce this night blindness.
- It is important that any optical filter employed to reduce the facial signature function to maintain the user's peripheral vision, to reduce the dark adaptation time, and yet work properly with all types of image displays.
- The displays of the NVDs produce a general illumination of the user's face and/or eye socket. Termed facial signature or splash, this is very undesirable because it will disclose the presence and location of the NVD user to hostile persons who happen to be looking in the direction of the NVD user. As illustrated in
FIG. 1 , the NVD 2 is utilized by thewearer 1 by holding the NVD up to the eye and viewing through the attached eyepiece 3 but not touching the facial surface surrounding the eye. This existing design results in a portion of the face 4 being illuminated by the display of the NVD which is undesirable. - Attempts to reduce this facial signature by placement of standard accordion rubber eyecups on the eyepiece that interface tightly to the user's eye essentially eliminate the user's peripheral vision. This result significantly and detrimentally compromises the user's situational awareness when using an NVD with such an eyecup. In
FIG. 2 , a flexible eyecup 5 made of pleated rubber is frequently attached to the eyepiece 3 in order to block this illumination of the face. Note that because the flexible eyecup 5 touches the face, the peripheral vision of the use is significantly reduced. This is undesirable. - Some previous designs have placed filters over the final optical element of the eyepiece. In
FIG. 3 , an optical filter 6 is attached to the eyepiece 3 which reduces the illumination 7 on the user's face. These filters are described in Kreutzig U.S. Pat. No. 8,226,251. - While this succeeds in a major objective as described above, placement of the filter in this location subjects the filter to scratching, difficulty of field installation and outright loss of the filter.
- It is the object of this invention to provide a system that utilizes placement of the filter or similarly functional device in the interior of the NVD eyepiece optical train and therein obviates scratching, difficult field installation and loss of the filter.
- Furthermore, it is the object of this invention to disclose the use of specific optical filters for all types of Night Vision Devices. These filters will significantly reduce the dark adaptation time of the user and therefore improve the ease and safety of use of the filtered NVD without degradation of the NVD performance.
- To accomplish these objects, the invention comprises the placement of an optical filter internally in the optical train of the eyepiece. This optical filter has light transmissive characteristics shown in the accompanying table:
-
TABLE 1 Wavelength (nm) % Transmission Ranges from about 390 to about 410 0.1 Ranges from about 410 to about 415 10 Ranges from about 420 to about 430 27 Ranges from about 445 to about 455 15 Ranges from about 460 to about 475 9 Ranges from about 490 to about 505 6 Ranges from about 510 to about 525 7 Ranges from about 540 to about 550 18 Ranges from about 560 to about 576 50 Ranges from about 590 to about 606 87 Ranges from about 690 to about 707 90 Ranges from about 750 to about 1000 90 - When a filter having such characteristics is provided, the user/observer can adequately see the light emitted from the light emitting display. However, in accordance with the invention, that light emitted from the display and passing through the filter is modified so as to reduce splash-back on the observer's face.
- Furthermore when using the Night Vision optical filter, the time required for the user's eyes to dark adapt is reduced as reported in THOMAS et. al., “Optical Filter Effects on Night Vision Goggle Acuity and Preservation of Dark Adaptation”, Aviation and Space Environ Med 2010; 81: 869-72.
-
FIG. 1 is a representation of the undesirable facial illumination caused by the Night Vision Device display. -
FIG. 2 is a representation of the rubber eyepiece commonly used to reduce the facial signature but sacrificing the peripheral vision of the user. -
FIG. 3 is a representation of the optical filter placed in the external eyecup of an NVD. -
FIG. 4 is an exploded view of a PVS-14 NVG eyepiece showing the placement of the optical filter and the user's eye. The eyepiece cell component is modified to accept the optical filter. - While the invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to this embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
-
FIG. 4 diagrams the internal integration of the filter in a typical eyepiece of the NVS-14. The user's eye 17 is positioned at the end of the eyepiece assembly. The eyepiece assembly is attached to the NVD body by means of the threaded locking ring 14. Element 8 is a threaded retaining ring which is mounted on the optical cell collar 12. Element 9 is a retaining ring. Knurledring 10 is rotated by the operator to achieve focus with fiduciary ring 11 providing indication to the operator of the adjustment. The optical cell collar 12 utilizes the grooves on the side of the optical cell 15 to effect longitudinal movement ofelements 8, 9, 10, 11, and 12. The optical cell 15 contains the focusing lens elements.Elements 8, 9, 10, 11, and 12 serve in conjunction to move the eyepiece cell 15 with mounted optical filter 16 longitudinally along the optic axis in order to achieve proper focus of the displayed image to the operator. The optical filter 16 is retained in position to the eyepiece cell by an O-ring 13 and the locking ring 14. - The filter 16 can have optical properties of the sort disclosed in U.S. Pat. No. 6,158,865.
Claims (2)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US15/587,919 US10101573B1 (en) | 2017-05-05 | 2017-05-05 | Optical filter |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US15/587,919 US10101573B1 (en) | 2017-05-05 | 2017-05-05 | Optical filter |
Publications (2)
Publication Number | Publication Date |
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US10101573B1 US10101573B1 (en) | 2018-10-16 |
US20180321482A1 true US20180321482A1 (en) | 2018-11-08 |
Family
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Application Number | Title | Priority Date | Filing Date |
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US15/587,919 Expired - Fee Related US10101573B1 (en) | 2017-05-05 | 2017-05-05 | Optical filter |
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US (1) | US10101573B1 (en) |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6158865A (en) * | 1999-10-29 | 2000-12-12 | Kreutzig; Kirk | Color enhancing filter and method of employing a color enhancing filter to improve human eye vision |
US8699158B1 (en) * | 2012-05-30 | 2014-04-15 | Spectrum Technologies, Inc. | Night vision filter for use with computer monitor screens and the like |
-
2017
- 2017-05-05 US US15/587,919 patent/US10101573B1/en not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6158865A (en) * | 1999-10-29 | 2000-12-12 | Kreutzig; Kirk | Color enhancing filter and method of employing a color enhancing filter to improve human eye vision |
US8699158B1 (en) * | 2012-05-30 | 2014-04-15 | Spectrum Technologies, Inc. | Night vision filter for use with computer monitor screens and the like |
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US10101573B1 (en) | 2018-10-16 |
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AS | Assignment |
Owner name: SPECTRUM TECHNOLOGIES INTERNATIONAL LTD., ILLINOIS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:KREUTZIG, KIRK;REEL/FRAME:042319/0169 Effective date: 20170505 |
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Free format text: PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.); ENTITY STATUS OF PATENT OWNER: SMALL ENTITY |
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STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
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FP | Lapsed due to failure to pay maintenance fee |
Effective date: 20221016 |