U.S. patent number RE43,681 [Application Number 13/274,627] was granted by the patent office on 2012-09-25 for optical detection system.
This patent grant is currently assigned to Retro Reflective Optics, LLC. Invention is credited to Paul M. Leavy, Jr., Norman R. Wild.
United States Patent |
RE43,681 |
Wild , et al. |
September 25, 2012 |
**Please see images for:
( PTAB Trial Certificate ) ** |
Optical detection system
Abstract
The present invention pertains to radiant energy systems and
more particularly to systems exhibiting the retroreflection
principle wherein the system comprises a focusing means and a
surface exhibiting some degree of reflectivity positioned near the
focal plane of the device, and wherein incident radiation falling
within the field-of-view of said system is reflected back in a
direction which is parallel to the incident radiation. The present
invention has great applicability in military optical system
applications for detecting the presence of an enemy employing
surveillance equipment and for neutralizing this surveillance
capability.
Inventors: |
Wild; Norman R. (Nashua,
NH), Leavy, Jr.; Paul M. (Lynnfield, MA) |
Assignee: |
Retro Reflective Optics, LLC
(Portsmouth, NH)
|
Family
ID: |
27623344 |
Appl.
No.: |
13/274,627 |
Filed: |
October 17, 2011 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
12471058 |
May 22, 2009 |
Re. 42913 |
|
|
|
11197731 |
Oct 6, 2009 |
Re. 40927 |
|
|
Reissue of: |
04623186 |
Mar 10, 1967 |
6603134 |
Aug 5, 2003 |
|
|
Current U.S.
Class: |
250/526; 398/170;
89/1.11; 356/141.1; 250/342 |
Current CPC
Class: |
G02B
5/12 (20130101) |
Current International
Class: |
B64D
1/04 (20060101); G01B 11/26 (20060101); G01J
5/02 (20060101); H04B 10/00 (20060101) |
Field of
Search: |
;250/342,493.1,494.1,495.1,496.1,526,580
;340/600,619,825,825.36,982 ;356/3,3.09,124,127,141.1
;359/529,626,627 ;89/1.11 ;398/170 ;342/27,28 ;331/64,65 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Electronics, Nov. 10, 1961, pp. 81-85. cited by other .
Francis Weston Sears, "Principles of Physics Series," Optics, Third
Edition, Fifth Printing, Addison-Wesley Publishing Company, Inc.,
Reading, MA, USA, Apr. 1958, pp. 34-39 and 89-91 (11 pages). cited
by other .
"Reflectorized Sheeting, Adhesive (Retro-Reflective)," Military
Specification, FSC 8305, MIL-R-13689A, Jan. 10, 1956, Superseding
MIL-R-1369 (CD), Oct. 4, 1954, pp. 1-9. cited by other .
"Sheeting and Tape Reflective; Nonexposed Lens, Adhesive Backing,"
Federal Specification, FSC 9390, L-S-300, Sep. 7, 1965, pp. 1-15,
Superceding CCC-S-00320 (Army-MO), Nov. 18, 1963, including the
requirements of MIL1-R-13689A, Jan. 10, 1956. cited by
other.
|
Primary Examiner: Mai; Huy K
Parent Case Text
.Iadd.RELATED APPLICATIONS.Iaddend.
.Iadd.Notice: More than one Reissue Application has been filed for
the reissue of U.S. Pat. No. 6,603,134. The reissue applications
are application Ser. Nos. 13/274,627, 12/471,058 (now U.S. Pat.
No.: RE42,913), and 11/197,731 (now U.S. Patent No. RE40,927), all
of which are divisional reissues of U.S. Pat. No.
6,603,134..Iaddend.
.Iadd.RELATED APPLICATIONS.Iaddend.
.Iadd.There is more than one Reissue Application based on U.S. Pat.
No. 6,603,134. This application is a Divisional of U.S. patent
application Ser. No. 12/471,058 filed May 22, 2009, entitled,
"OPTICAL DETECTION SYSTEM," now U.S. Pat. No. RE42,913, issued Nov.
15, 2011, which is a Divisional of U.S. patent application Ser. No.
11/197,731, filed Aug. 5, 2005, entitled, "OPTICAL DETECTION
SYSTEM," now U.S. Pat. No. RE40,927, issued Oct. 6, 2009, which is
a Reissue of U.S. patent application Ser. No. 04/623,186 filed Mar.
10, 1967, entitled, "OPTICAL DETECTION SYSTEM," now U.S. Pat. No.
6,603,134, issued Aug. 5, 2003, each commonly owned with this
application, the entire disclosures of which are here incorporated
by reference..Iaddend.
Claims
What is claimed is:
.[.1. The method of detecting an uncooperative optical system
including a focusing means and a surface exhibiting some degree of
reflectivity disposed substantially in the focal plane of said
focusing means, said method comprising the step of directing
optical energy at said optical system whereby that portion of said
energy incident upon said optical system is retroreflected with an
optical gain to thereby form a beam of retroreflected optical
energy, and the step of detecting said retroreflected optical
energy having a radiant flux density in excess of a preselected
value to thereby indicate the presence of said optical
system..].
.[.2. The method of claim 1, including the step of scanning a
predetermined geographical area to detect the presence of an
optical system therein..].
.[.3. The method of claim 2, including the step of tracking said
optical system after the presence thereof has been detected..].
.[.4. The method of claim 3, including the step of directing a
weapon at the position of said optical system after the detection
thereof..].
.[.5. The method of claim 1, wherein the radiant energy directed at
said optical system is in the nonvisible region..].
.[.6. The method of claim 1, wherein the radiant energy directed at
said optical system is light energy in the nonvisible
region..].
.[.7. The method of claim 6, wherein the light energy in the
nonvisible region is infrared..].
.[.8. The method of claim 4, wherein said weapon is a laser..].
.[.9. The method of claim 1, wherein the radiant energy is in the
ultraviolet portion of the electromagnetic spectrum..].
.[.10. The method of claim 1, wherein the radiant energy is X-ray
energy..].
.[.11. The method of claim 1, wherein the radiant energy comprises
high energy particles related to quantum mechanics..].
.[.12. The method of claim 1, wherein the radiant energy is
acoustical energy..].
.[.13. The method recited in claim 1 wherein said optical system is
a telescope..].
.[.14. The method recited in claim 1 wherein said optical system is
a binocular..].
.[.15. The method recited in claim 1 wherein said optical system is
a periscope..].
.[.16. The method recited in claim 1 wherein said optical system is
a human eye..].
.[.17. Apparatus for detecting the presence of an uncooperative
optical system including a focusing means and a surface exhibiting
some degree of reflectivity disposed substantially in the focal
plane of said focusing means, said apparatus comprising means for
producing radiant energy, means for directing said energy toward
said optical system whereby said energy is retroreflected with an
optical by said optical system, and means for detecting said
retroreflected energy having a radiant flux density in excess of a
preselected value to thereby indicate the presence of said optical
system..].
.[.18. Apparatus in accordance with claim 17 wherein said means for
producing radiant energy is a radiant energy source operative in
the nonvisible region..].
.[.19. Apparatus in accordance with claim 17, wherein said means
for producing radiant energy is a radiant energy light
source..].
.[.20. Apparatus in accordance with claim 19, wherein said radiant
energy light source is an infrared source..].
.[.21. Apparatus in accordance with claim 17, wherein said means
for producing radiant energy, said means for directing said energy
toward said optical system, and said means for detecting the energy
retroreflected by said optical system, form an optical
transceiver..].
.[.22. Apparatus in accordance with claim 21, wherein said means
for producing rays of radiant energy, said means for directing said
rays toward said optical instrument, and said means for detecting
the rays retroreflected by said optical instrument are
concentrically disposed with respect to one another..].
.[.23. Apparatus in accordance with claim 22, wherein said means
for producing radiant energy, said means for directing said energy
toward said optical system, and said means for detecting said
energy retroreflected by said optical system are concentrically
disposed with respect to one another..].
.[.24. Apparatus in accordance with claim 22, wherein said means
for producing radiant energy comprises a radiant energy source said
means for directing said energy toward said optical system
comprises a primary mirror having a substantially parabolic
configuration, and said means for detecting said retroreflected
energy comprising a detector said primary mirror, and a secondary
mirror having a substantially planar configuration said primary
mirror having an aperture concentric with the principal axis
thereof, said radiant energy source being positioned adjacent the
non-reflecting surface of said secondary mirror, in the focal plane
of said primary mirror, said secondary mirror being positioned
adjacent said primary mirror, and having the reflecting surface of
said secondary mirror facing the reflecting surface of said primary
mirror, and said detector being positioned adjacent the
non-reflecting surface of said primary mirror, being in axial
alignment with the aperture thereof, being positioned in the focal
plane of said detection means..].
.[.25. Apparatus in accordance with claim 22, wherein said means
for producing radiant energy comprises a radiant energy source,
said means for directing said energy toward said optical system
comprises a collecting mirror having a substantially elliptical
configuration a primary mirror having a substantially parabolic
configuration, and a secondary mirror having a substantially planar
configuration, said means for detecting said retorreflected energy
comprising a detector, and said primary mirror, said primary mirror
having an aperture concentric with the principal axis thereof, said
secondary mirror being positioned with the reflecting surface
thereof facing the reflecting surface of said primary mirror, said
radiant energy source being positioned between the reflecting
surfaces of said primary and secondary mirrors, and in axial
alignment with said mirrors, said collecting mirror being
positioned adjacent the non-reflecting surface of said primary
mirror, in axial alignment with the aperture thereof, and said
detector being positioned in the focal plane of said direction
means adjacent the non-reflecting surface of said secondary mirror
in the focal plane of said primary mirror..].
.[.26. Apparatus in accordance with claim 21, wherein said means
for producing incident radiant energy is a radiant energy light
source operative in the nonvisible region..].
.[.27. Apparatus in accordance with claim 23, wherein said radiant
energy light source is an infrared source..].
.[.28. Apparatus in accordance with claim 17, wherein said means
for directing said incident energy towards said optical system
having scanning means operatively associated therewith to cause
said rays to scan a predetermined geographical area to detect and
locate said optical system..].
.[.29. Apparatus in accordance with claim 28, including tracking
means operatively associated with said scanning means to thereby
track the movement of said optical system after detection
thereof..].
.[.30. Apparatus in accordance with claim 28, including weapon
means operatively associated with said tracking means for use
against said optical system after detection thereof..].
.[.31. Apparatus in accordance with claim 30, wherein said weapon
means is high energy source..].
.[.32. Apparatus in accordance with claim 31, wherein said high
energy source is a laser..].
.[.33. The apparatus recited in claim 17 wherein said optical
system is a telescope..].
.[.34. The apparatus recited in claim 17 wherein said optical
system is a binocular..].
.[.35. The apparatus recited in claim 17 wherein said optical
system is a periscope..].
.[.36. The apparatus recited in claim 17 wherein said optical
system is a human eye..].
.[.37. Apparatus for measuring the retroreflective characteristics
of an optical system consisting of at least a focusing means and a
surface exhibiting some degree of reflectivity disposed
substantially in the focal plane of said focusing means, said
apparatus comprising a radiant energy source, detection means,
measuring means connected to said detection means, and means for
directing said radiant energy produced by said source at said
optical system, whereby said radiant energy is retroreflected with
an optical gain by said optical system and detected by said
detecting means and the output thereof is coupled to said measuring
means..].
.[.38. An optical system accordance with claim 37, including means
disposed between said radiant energy source and said optical system
for transmitting a portion of the radiant energy produced by said
radiant energy source toward said optical system, and for
transmitting a portion of said energy retroreflected by said
optical system toward said detecting means..].
.[.39. An optical system in accordance with claim 38, wherein said
directing means and said detecting means are substantially
concentric..].
.[.40. The method of detecting the presence of devices which
exhibit the phenomenon of retroreflection, said method comprising
the step of directing radiant energy at said devices whereby said
radiant energy is retroreflected with an optical gain by said
devices, and the step of detecting said retroreflected radiant
energy which is in excess of a preselected radiant flux density
level to thereby indicate the presence of said devices..].
.[.41. The method of claim 40, including the step of analyzing said
retroreflected radiant energy to thereby determine the spatial and
temporal characteristics of said devices..].
.[.42. Apparatus for detecting the presence of devices which
exhibit the phenomenon of retroreflection, said apparatus
comprising means for producing radiant energy, means for directing
said energy toward said devices whereby said energy is
retroreflected with an optical gain by said devices, and means for
detecting said retroreflected energy which is in excess of a
preselected radiant flux density level to thereby indicate the
presence of said devices..].
.[.43. apparatus for measuring the retroreflective characteristics
of devices which exhibit the phenomenon of retroreflection, said
apparatus comprising means for producing radiant energy, means for
directing said energy toward said devices whereby said energy is
retroreflected with an optical gain by said devices, means for
detecting said retroreflected energy which is in excess of a
preselected radiant flux density level to thereby indicate the
presence of said devices, and means for analyzing said detected
energy to thereby determine the characteristics of said
devices..].
.[.44. The method of detecting an uncooperative and non-radiating
microwave antenna system consisting of at least a microwave
focusing means and a microwave feed horn disposed substantially at
the focal point of said focusing means, said method comprising the
step of directing swept frequency microwave energy at said antenna
system whereby substantially all energy at the operating frequency
of said antenna system which is impingent thereon is focused by
said focusing means and absorbed by said feed horn and energy of
any other frequency is retroreflected by said antenna system with
an energy density gain to thereby form a beam of retroreflected
microwave energy, and the step of detecting said retroreflected
energy having an energy density in excess of a preselected value to
thereby indicate the presence of said antenna system..].
.[.45. The method recited in claim 44 further including the step of
determining the frequency at which the energy density of said
retroreflected energy is of a minimum level to thereby determine
the operating frequency of said antenna system..].
.[.46. The method recited in claim 44 further including the step of
analyzing any temporal characteristics of said energy
retroreflected by said antenna system..].
.[.47. The method recited in claim 44 further including the step of
analyzing any spatial characteristics of said beam of energy
retroreflected by said antenna system..].
.Iadd.48. A method of directing a laser at an object within an
optical system, comprising: transmitting radiant energy at an
object included in an optical system having retroreflective
characteristics, wherein the optical system includes a lens and the
object includes at least a portion exhibiting some degree of
reflectivity disposed substantially in a focal plane of the lens;
receiving reflected radiant energy after retroreflection of the
radiant energy; and directing automatically a laser at the object
based on a characteristic of the at least a portion of the object
determined from the reflected radiant energy..Iaddend.
.Iadd.49. The method of claim 48, comprising causing the laser to
alter the object..Iaddend.
.Iadd.50. The method of claim 48, wherein the characteristic of the
at least a portion of the object is determined from a
characteristic of the reflected radiant energy..Iaddend.
.Iadd.51. The method of claim 50, wherein the characteristic of the
reflected radiant energy is at least one of an optical gain, an
intensity level, a temporal characteristic, a temporal property, a
spectral characteristic, and a spectral property..Iaddend.
.Iadd.52. The method of claim 48, wherein the characteristic of the
at least a portion of the object is at least one of a relative
position, a mechanical characteristic, and an electrical
characteristic..Iaddend.
.Iadd.53. The method of claim 48, wherein the at least a portion of
the object is included in at least a portion of a surface included
in the object..Iaddend.
.Iadd.54. An apparatus for directing a laser at an object within an
optical system, comprising: a radiant energy source configured to
transmit radiant energy at an object included in an optical system
having retroreflective characteristics, wherein the optical system
includes a lens and the object includes at least a portion
exhibiting some degree of reflectivity disposed substantially in a
focal plane of the lens; a detector configured to detect received
reflected radiant energy after retroreflection of the radiant
energy; and a utilization system configured to direct automatically
a laser at the object based on a characteristic of the at least a
portion of the object determined from the reflected radiant
energy..Iaddend.
.Iadd.55. The apparatus of claim 54, comprising a power source
configured to cause the laser to alter the object..Iaddend.
.Iadd.56. The apparatus of claim 54, wherein the characteristic of
the at least a portion of the object is determined from a
characteristic of the reflected radiant energy..Iaddend.
.Iadd.57. The apparatus of claim 56, wherein the characteristic of
the reflected radiant energy is at least one of an optical gain, an
intensity level, a temporal characteristic, a temporal property, a
spectral characteristic, and a spectral property..Iaddend.
.Iadd.58. The apparatus of claim 54, wherein the characteristic of
the at least a portion of the object is at least one of a relative
position, a mechanical characteristic, and an electrical
characteristic..Iaddend.
.Iadd.59. The apparatus of claim 54, wherein the at least a portion
of the object is included in at least a portion of a surface
included in the object..Iaddend.
.Iadd.60. A method of automatically tracking at least a portion of
an object within an optical system, comprising: transmitting
radiant energy at an object included in an optical system having
retroreflective characteristics, wherein the optical system
includes a lens and the object includes at least a portion
exhibiting some degree of reflectivity disposed substantially in a
focal plane of the lens; receiving reflected radiant energy after
retroreflection of the radiant energy; and automatically tracking
the at least a portion of the object based on a characteristic of
the at least a portion of the object determined from the reflected
radiant energy..Iaddend.
.Iadd.61. The method of claim 60, wherein the characteristic of the
at least a portion of the object is determined from a
characteristic of the reflected radiant energy..Iaddend.
.Iadd.62. The method of claim 61, wherein the characteristic of the
reflected radiant energy is at least one of an optical gain, an
intensity level, a temporal characteristic, a temporal property, a
spectral characteristic, and a spectral property..Iaddend.
.Iadd.63. The method of claim 60, wherein the characteristic of the
at least a portion of the object is at least one of a relative
position, a mechanical characteristic, and an electrical
characteristic..Iaddend.
.Iadd.64. The method of claim 60, wherein the at least a portion of
the object is included in at least a portion of a surface included
in the object..Iaddend.
.Iadd.65. An apparatus for automatically tracking at least a
portion of an object within an optical system, comprising: a
radiant energy source configured to transmit radiant energy at an
object included in an optical system having retroreflective
characteristics, wherein the optical system includes a lens and the
object includes at least a portion exhibiting some degree of
reflectivity disposed substantially in a focal plane of the lens; a
detector configured to detect received reflected radiant energy
after retroreflection of the radiant energy; and a utilization
system configured to automatically track the at least a portion of
the object based on a characteristic of the at least a portion of
the object determined from the reflected radiant
energy..Iaddend.
.Iadd.66. The apparatus of claim 65, wherein the characteristic of
the at least a portion of the object is determined from a
characteristic of the reflected radiant energy..Iaddend.
.Iadd.67. The apparatus of claim 66, wherein the characteristic of
the reflected radiant energy is at least one of an optical gain, an
intensity level, a temporal characteristic, a temporal property, a
spectral characteristic, and a spectral property..Iaddend.
.Iadd.68. The apparatus of claim 65, wherein the characteristic of
the at least a portion of the object is at least one of a relative
position, a mechanical characteristic, and an electrical
characteristic..Iaddend.
.Iadd.69. The apparatus of claim 65, wherein the at least a portion
of the object is included in at least a portion of a surface
included in the object..Iaddend.
Description
Applicants herein have made the discovery that any type of focusing
device in combination with a surface, exhibiting any degree of
reflectivity and positioned near the focal plane of the device,
acts as a retro-reflector. A retroreflector is defined as a
reflector wherein incident rays or radiant energy and reflected
rays are parallel for any angle of incidence within the
field-of-view. A characteristic of a retroreflector is that the
energy impinging thereon is reflected in a very narrow beam, herein
referred to as the retroreflected beam. This phenomenon is termed
retroreflection.
It is herein to be noted that the term radiant energy includes
light energy, radio frequency, microwave energy, acoustical energy,
X-ray energy, heat energy and any other types of energy which are
part of the energy spectrum and which are capable of being
retroreflected by the device, instrument or system sought to be
detected.
One type of optical device which exhibits this phenomenon, and thus
is a particular type of retroreflector, is a corner reflector
consisting of three mutually perpendicular reflecting planes,
However, this type of retroreflector is both difficult and
expensive to fabricate.
Due to the applicants discovery, it has now become possible to
accomplish a great many feats heretofore considered impossible, as
will become more apparent from the discussion to follow
hereinafter. In this context it should be noted that the eyes of
human beings, as well as those of animals, operate as
retroreflectors. Also, any optical instrument which includes a
focusing lens and a surface having some degree of reflectivity, no
matter how small, positioned near the focal point of the lens, act
as a retroreflector, whereby any radiant energy from a radiant
energy source directed at these instruments is reflected back
towards the source in a substantially collimated narrow beam.
It is therefore the primary object of the present invention to
provide a method and apparatus for detecting objects exhibiting
retroreflection characteristics.
It is another object of the present invention to provide a method
and apparatus to detect objects having retroreflection
characteristics by illuminating the same with a radiant energy
source.
It is a more particular object of the present invention to provide
a method and apparatus for scanning an area to detect the presence
of optical instruments such as binoculars, telescopes, periscopes,
range finders, cameras, and the like.
It is a further object of the present invention to provide means
and apparatus for determining the characteristics of a device
exhibiting retroreflection characteristics from a remote
location.
It is a further object of the present invention to provide a method
and apparatus for detecting optical instruments for rendering the
instruments ineffective and for neutralizing humans utilizing said
instruments by employing lasers or similar high energy sources.
It is yet another object of the present invention to provide a
method and apparatus for transmitting and receiving radiant energy
utilizing concentric optics.
These and other objects, features and advantages of the present
invention will become more apparent from the following detailed
discussion considered in conjunction with the accompanying
drawings, wherein:
FIG. 1 is a diagram showing a retroreflection system consisting of
a lens and a reflector wherein the source radiation is parallel to
the optical axis of the lens.
FIG. 2 is a diagram of a retroreflection system similar to that of
FIG. 1, wherein the source radiation is not parallel to the optical
axis of the lens.
FIG. 3 is a diagram of a retroreflection system similar to FIG. 1
wherein the lens is imperfect so as to form an image rather than
focusing at a single point.
FIG. 4 is a diagram of a retroreflection system wherein the
reflector is obliquely positioned with respect to the optical axis
of the lens.
FIG. 5 is a diagram of a human eye, wherein there is depicted the
retroreflection characteristics thereof.
FIG. 6 is a schematic representation depicting a beam splitting
optical system for transmitting and receiving radiant energy.
FIG. 7 is a schematic representation depicting a concentric optical
system for transmitting and receiving radiant energy.
FIG. 7a is a schematic representation of another embodiment of the
concentric optical system depicted in FIG. 7.
FIG. 7b is a schematic representation of still another embodiment
of the concentric optical system depicted in FIG. 7.
FIG. 8 is a schematic representation depicting an ordinary
telescope as an image forming system having retroreflection
characteristics.
FIG. 9 is a schematic representation depicting one half of an
ordinary binocular as an image forming system having
retroreflection.
FIG. 10 is a schematic representation depicting an ordinary
periscope as an image system having retroreflection
characteristics.
FIG. 11 is a schematic representation depicting an ordinary camera
as an image forming system having retroreflection
characteristics.
FIG. 12 depicts a system for scanning an area to detect the
presence of optical instruments by utilizing the retroreflection
characteristics thereof and for neutralizing observers using said
optical instruments, and/or rendering the instruments
ineffective.
FIG. 13 is a diagram of a radar system, and more particularly of a
radar antenna which is to be detected in accordance with the
principles of the present invention.
FIG. 14 depicts the waveforms obtained during the detection of the
radar system shown in FIG. 13.
In accordance with the general principles of the present invention
an optical system consisting of a focusing lens and a reflective
surface positioned near the focal plane of said lens has radiant
energy rays supplied thereto by a radiant energy transmitter. The
radiant energy rays reflected by the optical system due to its
retroreflection characteristics are recovered by a radiant energy
receiver to thereby detect the presence and relative position of
said optical system. The output of the radiant energy receiver may
be applied to a utilization means for determining the
characteristics of the retroreflector or for directing a weapon
means.
Referring now to the drawings and more particularly to FIG. 1
thereof, there is shown an optical system consisting of a lens 20
and a reflective surface 22, which herein is a mirror, positioned
in the focal plane 24 of the lens 20. Rays of radiation 26 and 28,
respectively, are directed towards the system, and more
particularly towards the lens 20, from a radiation source (not
shown); the incident rays in the present illustration being
parallel to the optical axis 30 of the lens. It is herein to be
noted that for the purpose of clarity the incident rays are herein
shown as being confined to the top half of the lens 20. The
incident rays 26 and 28 are refracted by the lens 20 and focused at
the focal point 32 of the lens, which focal point lies on the
mirror 22. The rays are then reflected by the mirror so that the
angle of reflection equals the angle of incidence, and are returned
to the lower half of the lens where they are again refracted and
emerge therefrom as retroreflected rays 26R and 28R. The rays 26R
and 28R are returned to the radiation source parallel to the
incident rays 26 and 28 thereof. However, as shown in the drawing,
the relative positions of the rays 26 and 28 are inverted so that
the image returned to the radiation source is also inverted.
In the optical system depicted in FIG. 2, similar parts are
de-noted by similar reference numerals. In this system the rays 34
and 36 are not parallel to the optical axis 30A of both the lens
20A and the mirror 22A, the mirror 22A being positioned in the
focal plane 24A of the lens. The rays 34 and 36 are refracted by
the lens 20A and focused at a point 37 removed from the optical
axis but still on the focal plane. The rays 34 and 36 are reflected
by the mirror. Both of the rays 34 and 36 would normally emerge
from the lens as retroreflected rays 34R and 36R, after refraction
by the lens, and would be returned to the source of the rays 34 and
36 in a direction parallel thereto. However, since the lens 20A is
of finite size, the reflected ray 34R will miss the lens and will
not be retroreflected. The loss of reflected rays in this manner is
called "vignetting".
In the system depicted in FIG. 3 wherein similar parts are de-noted
by similar reference numerals, the lens 20B is assumed to be
imperfect; i.e., it has aberrations. In this case the rays 38 and
40 are parallel to the optical axis 30B but are not focused at a
single point on the focal plane 24B, and instead form an image on
the mirror 22B, which image is referred to as the circle of
confusion. In most practical optical systems there are circles of
confusion and the mirror is normally positioned at the plane of
least circle of confusion, herein depicted by the reference numeral
42. Thus, the image formed on the mirror by means of the rays 38
and 40 can be considered to be a radiant source, and the
retroreflected rays 38R and 40R exit from the lens 20B
substantially parallel to each other. This is possible since each
emerging ray can be paired with a parallel incident ray which
radiates from a common point of the image source located at the
mirror 22B.
In the system depicted in FIG. 4, the reflecting surface or mirror
22C, and its axis 44, is tilted with respect to the optical axis
30C of lens 20C. However, the ray 48 is again retroreflected by the
system and the retroreflected ray 48R is returned parallel to the
incident ray 48. The retroreflected ray 46R, due to the ray 46, is
lost because of vignetting.
The concept set forth herein above in conjunction with FIG. 3, that
the retroreflected rays be considered as radiating from a source on
the image plane, is highly significant. With this concept in mind,
it will be readily apparent that even if the retroreflecting
surface is dispersive, curved, or tilted, (as shown in FIG. 4), the
system will still exhibit retroreflective properties for any and
all rays which are returned to the lens by the reflecting
surface.
The rays retroreflected by the optical systems depicted in FIGS. 1
to 4 are in the form of a narrow, substantially collimated beam
having a high radiant flux density. It is to be noted that there is
an actual increase in the radiant flux density of the
retroreflected beam due to the narrowing thereof. This increase in
radiant flux density is herein termed optical gain.
For example, if the irradiance produced by the radiating source at
the collecting lens in FIG. 3 is 100 watts/cm.sup.2 and the area of
the lens is 100 cm.sup.2, then the radiant flux at the image or
focal plane (circle of confusion) is
.times..times..times..times..times..times..times..times..times.
##EQU00001##
It is a characteristic of a retroreflector to return the
retroreflected energy or rays in a very narrow beam. The dimensions
of the retroreflected beam is a function of the angular resolution
of the retroreflector which includes the lens and the reflecting
surface.
The solid angle into which the incident radiant flux will be
retroreflected is determined by the square of the angular
resolution of the retroreflector. If, for example, the resoltuion
of the optical system is 10.sup.-4 radians, the solid angle into
which the retroreflected beam will be returned is 10.sup.-8
steradians. One steradian being the solid angle subtended at the
center of a sphere by a portion of the surface of area equal to the
square of the radius of the sphere. Thus at a distance of 10.sup.4
cm from the focal plane the area of the retroreflected beam is only
1.0 cm.sup.2. The retroreflector, by radiating into such a small
solid angle, has radiant intensity of
.times..times..times..times..times..times..times..times.
##EQU00002##
In order to obtain a measure of the optical gain we must compare
the retroreflector to a standard or reference. This reference has
been taken to be a diffuse surface known in the art as a Lambertian
radiator. If the 10.sup.4 watts of incident radiant flux were
simply re-radiated in a Lambertian manner; i. e., into a solid
angle of 3.14 (.pi.) steradians, the radiant intensity would be
.times..times..times..times..times..times..times..times..times.
##EQU00003## Thus, the retroreflector has an overall optical gain
equal to
.times..times..times..times..times..times..times..times.
##EQU00004##
Although there is no actual increase in radiant flux, the
retroreflector has a radiant intensity which is 3.14.times.10.sup.8
greater than that of a Lambertain radiator which emits the same
radiant flux. Thus, for example, a telescope having a collecting
area of 100 cm.sup.2 and an angular resolution of 0.1 milliradian
would appear similar in size to about 3.5.times.10.sup.8 cm.sup.2
of a diffuse or Lambertian radiator.
It should be noted that in almost all cases, the retroreflector
will be disposed within an environment that produces background
radiation in a Lambertian manner. Thus, the radiant intensity of
the retroreflector is so much greater than that of a Lambertian
radiator that it is easily discernible from the background, even
when, (as shown in FIG. 2) a large percentage of the retroreflected
radiant flux is lost due to vignetting.
It is herein to be noted that the radiant intensity of the
retroreflected beam is dependent upon the characteristics of the
optical system employed. If an optical system of the type shown in
FIGS. 1, 2, and 4 were possible and there were no loss of energy
(power) entering the system, then the radiant intensity gain would
be almost infinite since the energy would be retroreflected in an
almost perfectly collimated beam, i.e. a retroreflected beam whose
divergence angle is almost zero. However, almost all optical
systems resemble that shown in FIG. 3 and the factor which
determined the divergence angle of the retroreflected beam is the
size of the circle of confusion and more particularly, the least
circle of confusion. The size of the least circle of confusion is
dependent upon the resolution of the system and in particular upon
the resolution of the focusing lens. Thus, the less aberrations in
the lens, the better the resolution, the smaller the circle of
least confusion, the smaller the divergence angle of the
retroreflected beam, and thus the greater the optical gain.
Referring to FIG. 5, there is shown a magnified cross-sectional
view of a human eye denoted generally by the reference numeral 50.
The eye includes a cornea 52, an anterior chamber 54, a lens 56,
and a retina 58. The retina has a small portion or point 60 thereon
termed the yellow spot or macula lutea, which is approximately 2 mm
in diameter. At the center of the macula lutea is the fovea
centralis 62 whose diameter is approximately 0.25 m. The acuity of
vision is greatest at the macula lutea and more particularly at the
fovea centralis. Thus, the eye is always rotated so that the image
being examined or the rays entering thereon fall on the fovea 62.
As seen in FIG. 5, rays 64 and 66 enter the eye and pass through
the cornea 52 and the anterior chamber 54 and are refracted by the
lens 56 and focused on the fovea centralis portion 62 of the retina
58. The rays are then reflected, passing through the lens 56,
anterior chamber 54 and cornea 52 and emerge therefrom as
retroreflected rays 64R and 66R which are parallel to the rays 64
and 66. Thus, it is seen that even the human eye acts as a
retroreflector.
Referring now to FIG. 6, there is shown an optical system for
transmitting and receiving radiant energy, the more particularly a
beam splitter for transmitting radiant energy and for receiving or
recovering a portion of said radiant energy.
The beam splitter includes an optical bench 70 having an optical
system consisting of a lens 72 and a rotating pattern or reticle
74, which may also be a modulator, said system being placed on said
bench. The beam splitter also includes a radiant energy source 76,
a collimator 78, a thin plate of glass 80 having a semi-reflective
coating thereon, a detector 82. In the operation of the beam
splitter, the radiant energy from the source 76 is collimated to
form a beam by the collimator 78 and the beam is directed upon the
glass plate 80, a portion of the energy in the beam being reflected
and a portion of the energy in the beam being transmitted by the
glass plate. The energy is then transmitted down the optical bench
70 where the lens refracts the transmitted energy and focuses the
beam upon the reticle 74 from whence is is retroreflected back to
the glass plate. A portion of the retroreflected energy passes
through the glass plate and is lost, and a portion thereof is
reflected by the glass plate and detected by means of the detector
and the output thereof is then fed to the utilization means 83. The
detector 82 is thus effectively positioned within or concentric
with the retroreflected energy beam without affecting the
transmission of radiant energy from the source to the optical
system. The energy obtained by the utilization means can be used to
obtain the spectral and temporal characteristics of the
retroreflected beam, and may the be compared with the transmitted
beam to determine various characteristics of the optical system
being investigated. It will be apparent that the use of this test
instrument makes possible the investigation and characterization of
optical systems in terms of recording the retroreflective
characteristics thereof.
The rotating pattern or reticle 74 can be replaced with a
reflective surface and a modulator placed on the light incident
side of the lens 72. The modulator can then be tilted so that none
of the light reflected from its surface returns to the beam
splitter 80 to be reflected to the detector 82. The only light then
returning to the detector 82 will be that modulated by the
modulator and reflected back from the reflective surface replacing
the reticle 74.
FIG. 7 depicts a folded concentric optical system for transmitting
and receiving radiant energy--also known as an optical transceiver.
The optical transceiver 84 includes a primary mirror 86 having a
substantially parabolic shape, a secondary mirror 88 having a
planar configuration, a radiant energy source 90, a detector 92 and
a utilization means 94. The primary mirror has an aperature 96
concentric with its principal axis and the principal axis of the
secondary mirror is aligned so as to be coaxial therewith. The
light source and detector are also aligned with the mirrors so that
all of the aforesaid elements are concentrically disposed with
respect to each other. The light source is positioned adjacent to
the nonreflecting surface of the primary mirror while the detector
is positioned adjacent to the nonreflecting surface of the
secondary mirror.
In the operation of the transceiver 84, rays 98 and 100 are emitted
by the radiant energy source 90, and impinge upon the secondary
mirror 88, from whence they are reflected and impinge upon the
primary mirror 86. The rays are then reflected by the primary
mirror and directed towards an optical instrument 102 which
exhibits retroreflective characteristics. The incident rays are
retroreflected by the optical instrument 102 and are returned as
retroreflected rays 98R and 100R. The rays 98R and 100R return in a
direction parallel to the rays 98 and 100 and impinge upon the
primary mirror 86 and are reflected thereby towards the detector 92
where they are detected, and the detector output signal is then fed
to the utilization means 94.
As discussed previously, the term optical instruments exhibiting
retroreflective characteristics include the eyes of animals and
humans.
A second embodiment of a folded concentric optical transceiver is
shown in FIG. 7a, wherein similar parts are denoted by similar
reference numerals.
In this embodiment the light source 90A is positioned adjacent to
the nonreflecting surface of the secondary mirror 88A and the
detector 92A is positioned adjacent to the nonreflecting surface of
the primary mirror 86A.
In the operation of the transceiver 84A, rays 104 and 106 are
emitted by the radiant energy source 90A, and impinge upon the
primary mirror 86A, from whence they are reflected towards the
optical instrument 102A. The rays are retroreflected by the optical
instrument and are returned as retroreflected rays 104R and 106R.
The rays 104R and 106R return in a direction parallel to the rays
104 and 106 and impinge upon the primary mirror and are reflected
thereby towards the secondary mirror through the aperture 96A to
the detector 92A, and the output signal of the detector is then fed
to the utilization means 94A.
A third embodiment of a folded concentric optical transceiver is
depicted in FIG. 7b, wherein similar parts are denoted by similar
reference numerals.
In this embodiment, the detector 92B is once more positioned
adjacent to the nonreflecting surface of the secondary mirror 88B
and the radiant energy source 90B is positioned between the
reflecting surfaces of the primary mirror 86B and the secondary
mirror 88B. There is also included a collector 108, which may be an
elliptically shaped mirror for collecting the spurious radiation
rays from the source 90B and reflecting back upon the source,
wherefrom they are directed upon the secondary mirror and ultimatel
directed toward the optical instrument 102B.
In the operation of the transceiver 84B, energy from the radiant
energy source 90B impinges upon the secondary mirror 88B, and more
particularly rays 110 and 112 so impinge. These rays are reflected
by the secondary mirror towards the primary mirror, from where they
are once more reflected towards the optical instrument 102B. The
incident rays 110 and 112 are then retroreflected by the optical
instrument and returned as retroreflected rays 110R and 112R. The
rays 110R and 112R return in a direction parallel to the rays 110
and 112 and impinge upon the primary mirror and are reflected
thereby towards the detector 92B where they are detected and the
output thereof is then fed to the utilization means 94B.
It is herein to be noted that although the folded optical
transceivers depicted in FIGS. 7, 7a, and 7b have been shown as
being concentric, it is also possible to employ the above type of
transceivers wherein their optical characteristics are not
concentric. However, it has been found from the view-point of
efficiency and efficacy that the concentric optical transceivers
are more desireable.
FIG. 8 is an optical schematic representation of a telescope having
an objective lens 116, a reticle 118, a pair of erector lenses 120
and 122, a field lens 124, and an eyelens 126.
Thus, when rays 128 and 129 are directed towards the objective 20
lens 116, they are focused on the reticle 118 and retroreflected
thereby to produce retroreflected rays 128R and 129R respectively,
whose direction is opposite and parallel to that of the incident
rays 128 and 129. Thus, the combination of the objective lens 116,
and the reticle 118 form a retroreflective optical instrument, in
and of themselves.
It is herein to be noted that even if the reticle 118 is merely
plain glass, as in most cases it is, it still exhibits some degree
of reflectivity, which reflectivity gives rise to the
retroreflected rays 128R and 129R.
It is herein also to be noted that incident rays passing through
the telescope to the eye of the observer are also retroreflected by
the eye of the observer. Thus, there is in effect, two
retroreflective optical systems and thus two retroreflective
signals.
FIG. 9 is an optical schematic representation of one half of a
binocular and comprises an objective lens 132, a first porro prism
134, a second porro prism 136, a reticle 138, a field lens 140, and
an eyelens 142. When a ray such as 144 is incident on the objective
lens 132, it is focused thereby on the reticle 138, after passing
through the porro prisms 134 and 136. It is herein to be noted that
although the ray 144 is directed along a path which is not
straight; i.e., there are several right angle bends therein, the
entire path is still part of the focal path of the instrument.
Thus, the ray 144 is focused on the reticle 138, causing the same
to be retroreflected as ray 144R which then goes through a path
similar to that of ray 144 and emerges from the objective lens 132
in a direction which is opposite and parallel to that of the
incident ray 144. It is to be noted that the description herein
above describing a single ray is for purposes of simplicity of
explanation.
FIG. 10 is an optical schematic representation of a periscope. The
periscope includes a window 146, an objective prism 148, an
objective lens 149, an amici prism 150, an erecting prism assembly
152, a reticle 154, a field lens 156, an eyelens 158, and a filter
160. An incident ray 162 enters the periscope through the window
146, then passes through the prism 148, objective lens 149, amici
prism 150, and erecting prism assembly 152 to the reticle 154
whereon the incident ray is reflected and emerges from the
periscope as retroreflected ray 162R whose direction is opposite
and parallel to the incident ray 162. Again it is to be noted that
the description above describing a single ray is merely for the
purpose of simplicity of explanation.
FIG. 11 is an optical schematic representation of a camera. The
camera includes a lens 164, a shutter 166, and film 168. In the
operation of the camera when a picture is taken the shutter opens
and incident rays 170 and 171 are focused on the film 168 through
an aperture 172 in the shutter, by means of the lens 164. These
rays are then reflected by the film and emerge from the lens as
retroreflected rays 170R and 171R.
It is to be noted that most, if not all, optical systems will have
a reflecting surface such as a reticle, a lens, or a prism in the
focal plane, and the incident radiation will be retroreflected by
any such surface.
Referring now to FIG. 12, there is shown one embodiment of a system
for detecting the presence of an optical instrument, for tracking
said instrument, and for neutralizing observers utilizing said
instrument and/or rendering the instrument ineffective.
The system includes a scanner 180, including an optical searching
means 182, such as a source of infrared light, a detector 184, and
a laser 186. It is herein to be noted that the search means 182 and
the detector 184 may be combined in the form of a transceiver as
described hereinbefore in conjunction with FIGS. 7, 7a, and 7b. The
scanner 182 is controlled by a scanning and positioning means 188,
which includes a servo motor (not shown.) The scanning and
positioning means 188 is powered by a power and control means 190,
which means also supplies power for the scanner 180, and a
utilization system 192.
In the operation of the system, the scanner 180 is caused to scan a
preselected area by means of the scanning and positioning means
188, the means 188 being programmed by the utilization system 192.
The optical searching means emits rays 194 and 195, when these rays
impinge upon an optical instrument 196 exhibiting retroreflective
characteristics, as hereinbefore described, they are retroreflected
as retroreflected rays 194R and 195R respectively, and detected by
the detector 184 and the detector output is then fed to the
utilization system 192. The utilization system may be programmed to
merely track the instrument 196, in which case, this information
would be fed to the scanning and positioning means 188 and thence
to the scanner 180 causing it to track said instrument. However, if
it is desired to neutralize the observer using the instrument, or
to render the instrument ineffective, then the utilization system
192 will feed a signal to the laser 186 activating the same and
causing a high intensity laser beam to be directed at the
instrument, thereby accomplishing the aforementioned objects.
It is herein to be noted that although the present system has been
described as employing a laser, it is also possible to use any
other high energy system, weapon, or weapon system.
With the present system, it will be readily apparent to those
skilled in the art, that a hostile satellite orbiting the earth and
employing optical surveillance equipment to monitor a country's
activities can be detected and its surveillance capability
destroyed.
It is herein again to be noted that the aberrations in almost all
optical instruments cause a small divergence of the retroreflected
rays, the amount of said divergence being governed by the
resolution of the retroreflector. As a practical matter the angular
resolution of optical systems such as binoculars, periscopes,
telescopes, cameras, and optical systems carried by missiles will
be between about 10.sup.-3 and 10.sup.-5 radians which produce
retroreflected beams of 10.sup.-6 to 10.sup.-10 steradians. At a
range of 1,000 feet the area of these beams would be 1.0 and
10.sup.-4 ft.sup.2 respectively. This divergence is so small so
that the retroreflected rays are substantially collimated.
It is herein to be noted that in microwave application corner
reflectors have been utilized for retroreflecting purposes.
However, the present invention enables the detection of microwave
apparatus, such as antennas and the like which do not have a corner
reflector as an integral part thereof, by utilizing the inherent
retroreflection characteristics of the apparatus as hereinbefore
discussed. Thus, this apparatus and systems exhibiting the
retroreflection phenomenon can be similarly detected by the use of
radio frequency, microwave, X-ray, acoustical or any similar types
of energy directed thereat.
In many microwave antenna systems microwave lenses are utilized in
place of reflectors for the purposes of obtaining wide angle
scanning as compared with the system bandwidth. These microwave
lenses exhibit characteristics which are equivalent to the optical
lenses hereinbefore discussed, and thus a detailed explanation of
the retroreflection of microwave and similar types of energy by
these lenses, in conjunction with a reflective surface, will be
readily apparent to those skilled in the art.
In this connection, FIG. 13 is an illustration of a radar system
which is to be detected by means of the retroreflection principles
of the present invention. The radar system is generally indicated
by the reference numeral 200 and includes a parabolic disk antenna
202 having a feed 204 whose impedance mismatch is lowest at the
operating frequency of the radar system 200.
When the radar system 200 is in an off condition, the resonant
frequency of the antenna feed 206 can be detected by beaming swept
frequency microwave energy at the system such as by utilizing a
variable frequency klystron (not shown) or the like.
The pulses produced by the klystron are indicated as 210 in the
waveforms shown in FIG. 14. The wave energy 210 is retroreflected
by the parabolic disk antenna 202 because the parabola focuses the
energy at the feed horn which in turn is mismatched. Hence, the
energy reflected from it is recollimated by the parabola similar to
the optical system described heretofore. The energy is detected in
a suitable manner and produces the waveforms indicated at 212 in
FIG. 14, until such time that the frequency of the klystron is
equal to the operating frequency of the feed 206. When this occurs,
the energy beamed to the radar system is focused on the feed horn,
absorbed by the feed 206 and is therefore not retroreflected. This
results in the waveform indicated as 214 in FIG. 15. The dip or
drop in power level indicates absorption of the beamed energy and
thus the frequency of the operation of the radar system is now
known. By further analysis of the retroreflected waves it is
possible to obtain even more information concerning the electrical
and mechanical characteristics of the radar system 200, such as the
type of antenna system being utilized, its scan angle, its
beamwidth, its gain, etc.
It will be apparent to those skilled in the art that if the antenna
were a sonar disk and acoustical energy were directed threat, the
acoustical energy would be retroreflected and the retroreflected
acoustical energy would be capable of detection.
It is thus again reiterated that although only a few types of
radiant energy have herein been discussed, any type of energy which
can be retroreflected may be employed.
While we have shown and described various embodiments of our
invention, there are many modifications, changes, and alterations
which may be made therein by a person skilled in the art without
departing from the spirit and scope thereof as defined in the
appended claims.
* * * * *