U.S. patent number RE37,136 [Application Number 09/275,895] was granted by the patent office on 2001-04-17 for tunable high intensity forensic light.
This patent grant is currently assigned to Instruments SA, Inc.. Invention is credited to Nicholas Vezard.
United States Patent |
RE37,136 |
Vezard |
April 17, 2001 |
Tunable high intensity forensic light
Abstract
In accordance with the present invention an improved forensic
light source comprising a source of light and support structure for
supporting the source of light is provided. A light guide having
first and second ends is coupled to the source of light at the
first end to receive light from the source of light and transmit
the light to the second end. The light guide is mounted on the
support structure. A filter support member supports a plurality of
filters. A movable light directing assembly is mounted on the
second end of the light guide for movably supporting the filter
support member for movement to a plurality of positions. Each of
the positions corresponds to the coupling of a selected one of the
filters to the second end, whereby the light is filtered by the
selected filter. A heat sink may be coupled to the first end of the
light guide.
Inventors: |
Vezard; Nicholas (Metuchen,
NJ) |
Assignee: |
Instruments SA, Inc. (Edison,
NJ)
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Family
ID: |
23068155 |
Appl.
No.: |
09/275,895 |
Filed: |
March 24, 1999 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
279229 |
Jul 22, 1994 |
05613752 |
Mar 25, 1997 |
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Current U.S.
Class: |
362/583; 362/284;
362/293; 362/294 |
Current CPC
Class: |
G02B
6/0006 (20130101); G02B 6/32 (20130101); G02B
6/4296 (20130101); G02B 6/4298 (20130101); G02B
6/3814 (20130101) |
Current International
Class: |
F21V
8/00 (20060101); G02B 6/32 (20060101); G02B
6/42 (20060101); G02B 6/38 (20060101); F21V
008/00 () |
Field of
Search: |
;356/419
;362/282,284,293,322,324,393,552,572,573,574,575,577,583,294 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Quach; Y.
Attorney, Agent or Firm: Handal & Morofsky
Claims
I claim:
1. A forensic light source, comprising:
(a) a source of light;
(b) support structure for supporting said source of light;
(c) a light guide having first and second ends, said light guide
being coupled to said source of light at said first end to receive
light from said source of light and transmit said light to said
second end, said light guide being mounted on said support
structure;
(d) a filter support member supporting a plurality of filters;
and
(e) a portable hand holdable and movable light directing assembly
mounted on said second end of said light guide, said light
directing assembly supporting said filter support member and
providing for movement of said filter support member to a plurality
of positions, each of said positions corresponding to a coupling of
a selected one of said filters to said second end, whereby said
light emitting from said second and is filtered by said selected
filter while the emitted light is directed to various locations
through movement of said light directing assembly.
2. A forensic light source as in claim 1, wherein said filter
support member comprises a wheel with a plurality of filters
mounted around a point of rotation and said filter support members
further comprises a mounting structure configured to rotatably
mount said wheel about said point of rotation, and said wheel is
positioned to be rotated by a finger of a user.
3. A forensic light source, as in claim 1, wherein said filter
support member defines a plurality of detentes and a spring member
is mounted on said light directing assembly and positioned to
releasably engage one of said detentes, each of said detentes being
positioned to correspond to alignment between its respective one of
said filters and said second end, when a respective detente is
engaged by said spring member, each of said detentes corresponding
to a respective one of said filters.
4. A forensic light source as in claim 1, wherein said source of
light is a xenon lamp.
5. A forensic light source as in claim 1, wherein said source of
light is a tungsten lamp.
6. A forensic light source as in claim 1, wherein said source of
light is a metal halide lamp.
7. A forensic light source as in claim 1, further comprising a heat
sink coupled to said first end of said light guide.
8. A forensic light source as in claim 7, wherein said light guide
is a liquid light guide.
9. A forensic light source as in claim 7, further comprising a
lens, said lens positioned to focus said light from said second end
through a selected filter.
10. A forensic light source as in claim 1, wherein said light guide
is a liquid light guide providing light from said second end
through a selected filter.
11. A forensic light source as in claim 10, further comprising a
lens positioned to focus light from said second end through a
selected filter.
12. A forensic light source as in claim 11, further comprising a
heat sink coupled to said first end of said light guide.
13. A forensic light source as in claim 1, wherein said light guide
is a fiber optic light guide.
14. A forensic light source as in claim 13, further comprising a
heat sink coupled to said first end of said light guide.
15. A forensic light source as in claim 1, further comprising a
lens, said lens being positioned to focus said light from said
second end through a selected filter.
16. A forensic light source as in claim 15, further comprising a
securing member, said securing member providing for an adjustable
setting of a position of said second end of said light guide
relative to said lens.
17. A forensic light source as in claim 1, wherein said movable
light directing assembly comprises a housing portion and a handle
portion, said housing portion containing said filter support member
and said handle portion being configured and dimensioned to be
grasped by a hand of a user.
18. A forensic light source as in claim 17, further comprising a
lens positioned to focus light from said second end through a
selected filter.
19. A forensic light source as in claim 17, further comprising a
securing member, said securing member providing for an adjustable
setting of a position of said second end of said light guide
relative to a lens.
20. A forensic light source as in claim 17, wherein said housing
portion allows the user to rotate said filter support member with
the user's thumb while gripping said handle portion and directing
the filtered light.
21. A forensic light source, as in claim 20, wherein said filter
support member defines a plurality of detentes and a spring member
is mounted on said light directing assembly and positioned to
releasably engage one of said detentes, each of said detentes being
positioned to correspond to alignment between its respective one of
said filters and said second end, when a respective detente is
engaged by said spring member, each of said detentes corresponding
to a respective one of said filters.
22. A forensic light source as in claim 1, wherein said movable
light directing assembly comprises a housing portion and a handle
portion, said housing portion containing said filter support member
and said handle portion being configured and dimensioned to be
grasped by a hand of a user.
23. A forensic light source as in claim 22, wherein said housing
portion is configured to allow the user to rotate said filter
support member while gripping said handle portion and directing the
filtered light.
24. A forensic light source, comprising:
(a) a source of light;
(b) a support structure for supporting said source of light;
(c) a light guide having first and second ends, said light guide
being coupled to said source of light at said first end to receive
light from said source of light and transmit said light to said
second end, said light guide being mounted on said support
structure;
(d) a filter support member supporting a plurality of filters;
(e) a portable hand holdable and movable light directing assembly
coupled to said second end of said light guide, said light
directing assembly supporting said filter support member and
providing for movement of said filter support member to a plurality
of positions, each of said positions corresponding to a coupling of
a selected one of said filters to said second end, whereby said
light emitting from said second end is filtered by said selected
filter while the emitted light is directed to various locations
through movement of said light directing assembly; and
(f) a heat sink coupled to said first end of said light guide.
25. A forensic light source as in claim 24, wherein said light
guide is a liquid light guide for providing light from said second
end through a selected filter.
26. A forensic light source as in claim 25, further comprising a
lens, said lens positioned to focus said light from said second end
through a selected filter.
27. A forensic light source as in claim 24, further comprising a
lens positioned to focus light from said second end through a
selected filter.
28. A forensic light source as in claim 24, wherein said filter
support member comprises a wheel with a plurality of filters
mounted around a point of rotation and said filter support member
further comprises a mounting structure configured to rotate said
wheel about said point of rotation.
29. A forensic light source as in claim 28, wherein said movable
light directing assembly comprises a housing portion and a handle
portion, said housing portion being substantially circular in shape
to contain said wheel and said handle portion being configured and
dimensioned to be grasped by a hand of a user.
30. A forensic light source as in claim 29, further comprising a
securing member, said securing member providing for an adjustable
setting of a position of said second end of said light guide
relative to a lens..Iadd.
31. A forensic light source comprising:
(a) a source of light;
(b) a support structure for supporting said source of light;
(c) a light guide having first and second ends, said light guide
being coupled to said source of light at said first end to receive
light from said source of light and transmit said light to said
second end, said light guide being mounted on said support
structure;
(d) a filter support member supporting a plurality of filters, said
filter support member being coupled to receive light from said
source of light; and
(e) a portable hand holdable and movable light directing assembly
mounted on said second end of said light guide, said light
directing assembly including a hand or finger operable control
member coupled to said filter support member and controlling the
movement of said filter support member to a plurality of positions,
each of said positions corresponding to a coupling of a selected
one of said filters to said source of light, whereby said light
emitted from said second end is filtered by said selected filter
and the emitted light can be directed to a desired location through
movement of said light directing assembly by the same hand which
operates said control member. .Iaddend..Iadd.
32. A forensic light source, as in claim 31, wherein said filter
support member defines a plurality of detents and a spring member
mounted to act on said detents and positioned to releasably engage
one of said detents, each of said detents being positioned to
correspond to alignment between its respective one of said filters
to said source of light. .Iaddend..Iadd.
33. A forensic light source as in claim 31, further comprising a
heat sink coupled to said first end of said light guide. .Iaddend.
Description
TECHNICAL FIELD
The present invention relates to light sources for illuminating
forensic depositions or other evidence with an improved light cable
for transmitting selectable wavelength ranges.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to U.S. patent application of Purcell
Ser. No. 08/076,916, filed Jun. 14, 1993, U.S. Pat. No. 5,515,162
and entitled "LOW NOISE LIGHT SOURCE FOR FORENSIC EXAMINATION", and
U.S. patent application Ser. No. 08/227,962, which is abandoned,
the subject matter of which are hereby incorporated herein by
reference.
BACKGROUND
Starting at the end of the nineteenth century, crime fighters began
to use and develop what has grown into a substantial body of
technological tools designed to detect and/or enhance physical
evidence. One of the earliest techniques of this kind to receive
widespread application is the dusting of fingerprints. Light
sources were also among the first tools used in this field. Hence
the classic icon of the gumshoe, flashlight in hand, searching for
evidence at the dimly lit crime scene.
When a fingerprint is fresh, the oil which forms the print
generally follows the pattern of the fingerprint ridges in the
finger which made the print. If a fine dust is applied to the
surface of a fresh print, the dust tends to adhere to the oils in
the fingerprint, thus forming a pattern which generally reveals the
pattern of the fingerprint.
Fingerprint dusts were initially selected for their color
contrasting qualities as compared to the background. Thus white
dust was used to enhance a fingerprint on a black object and vice
versa. Even where the oils of a fingerprint have lost their
tackiness due to aging or other phenomena, the amino acids into
which they break down do cause a minute etching of many surfaces.
While this etching is often not visible to the naked eye, and may
not become visible with the application of a colored powder,
extremely fine fluorescent dusting powders will reveal the
fingerprint pattern when illuminated under high intensity
light.
Today, many materials, such as dyes, in addition to fluorescent
dusting powders are used. Inspection of the evidence is done with
specialized light sources. These light sources usually comprise a
high intensity source and a filter which passes light having a
limited range of wavelengths. Depending upon the material used,
which material may be either a fluorescent dusting powder, dye, or
other marker material, light having a wavelength which
substantially coincides with a known excitation wavelength of the
marker is employed. The characteristic of the marker is that, upon
illumination with light at one of its excitation wavelengths, it
will fluoresce, or emit light. Such fluorescence is typically at a
longer wavelength as compared to the excitation wavelength.
Examination of evidence is also enhanced through the use of color
filtering glasses or barrier filters, whose color filtering
characteristics are tuned to maximize the image to be detected. As
noted above, the excitation wavelength is varied through the use of
filters at the source. While such devices are very efficient in
filtering light, every filter has its own fixed characteristics.
These include its center wavelength, bandwidth and transmission
coefficient. Thus, if one wishes to have flexibility, it is
necessary to have a wide range of filters having different center
wavelengths and different bandwidths. This is both cumbersome and
expensive. Moreover, as new dyes and powders are introduced, old
filters can become obsolete or unnecessary.
In an attempt to provide convenience and flexibility, some light
sources used for forensic examination come with a mechanical filter
assembly, which allows the introduction of one of about a half
dozen filters into the path of the light source to provide the
desired wavelength illumination. While this does solve the problem
of providing a convenient and easy way to use a light source,
obsolescence and limited wavelength and bandwidth selection
remain.
In an attempt to overcome some of these disadvantages, earlier
forensic illumination systems have attempted to achieve a measure
of tunability by mounting an interference filter for angular
rotation. Generally, such angular rotation results in a change in
angle of incidence with respect to the filter input and a
relatively small variation in the encountered path length between
the functional layers in the interference filter for light passing
through the filter in a fixed direction. In accordance with Bragg's
Law, this results in different wavelengths being passed by the
filter.
In the above-referenced disclosure of Purcell, a system is
disclosed which provided a high intensity light source which is
continuously adjustable to vary the center frequency of a band of
wavelengths. At the same time, the flexibility of varying the
bandwidth of this band was also possible. The same was done with a
single light source and a single filtering apparatus. At the same
time that was achieved with a mechanical configuration that is both
reliable and rugged. Finally, that system was easily portable, and
capable of outputting light sufficient for close up analysis of
surfaces bearing such material as oils, semen, blood and so
forth.
In that system, a method and apparatus for illuminating a
deposition of organic material such as, blood, sweat or oil for
forensic examination was also provided. A light source emitted
light having a range of wavelengths. A first optical coupler or
light pipe was positioned and configured to reflect the light
toward a reflective diffraction grating. A supportable structure
supported, at a selectable relative position, an exit slit and the
grating to pass a desired band of wavelengths of output light from
portions of the light reflected by the grating. A bendable second
optical coupler was coupled to the exit slit and directed the
output light toward the deposition to be examined. The bendable
second optical coupler comprised a liquid fiber optic member. The
support structure rotated the grating. An electronic control and a
hand held remote control pad was coupled to the support structure
and controlled the support structure.
As can be seen from the above, numerous advantages are provided in
such a continuously adjustable diffraction grating based system.
Naturally, it is desirable to have the possibility of the highest
possible intensity output light at the selected wavelength.
However, such a brute force approach results in increased power
consumption and excessive heat energy, stressing the rest of the
system. In an attempt to achieve better results without aggravating
this problem, the above disclosure of Purcell utilizes an infrared
blocking filter to filter the light source thus allowing only
filtered and relatively low intensity light to fall on the grating.
This, however, also has an adverse impact on the amount of energy
output by the forensic light source, particularly in the
ultraviolet range. In addition, the use of the filters, because
they are exposed to a high intensity source, results in there being
another element subject to deterioration and replacement.
In accordance with the latter of the two above applications, a
filter is used to achieve maximum throughput of energy. Improved
signal-to-noise ratio is achieved using other filters at the
detection end. In order to protect the filters at the light output
side, protection is provided by infrared reflecting filters which
reflect unwanted infrared radiation away from the bandpass filters
used in the system. However, they also attenuate the desired output
light. These bandpass filters are located in the housing and
relatively proximate to the source of light which is filtered to
output the desired filtered light at the selected wavelength.
SUMMARY OF THE INVENTION
In accordance with the present invention an improved forensic light
source comprising a source of light and support structure for
supporting the source of light is provided. A light guide having
first and second ends is coupled to the source of light at the
first end to receive light from the source of light and transmit
the light to the second end. The light guide is mounted on the
support structure. A filter support member supports a plurality of
filters. A movable light directing assembly is mounted on the
second end of the light guide for movably supporting the filter
support member for movement to a plurality of positions. Each of
the positions corresponds to the coupling of a selected one of the
filters to the second end, whereby the light is filtered by the
selected filter.
The filter support member comprises a wheel with a plurality of
filters mounted around a point of rotation. Mounting structure is
provided for rotatably mounting the wheel for rotation about the
point of rotation.
The filter support member defines a plurality of detentes and
further comprises a spring member mounted on the movable light
directing assembly. It is positioned to releasably engage the
detentes. The detentes are positioned to correspond to alignment
between one of the filters and the second end, when engaged by the
spring member, each of the detentes corresponding to a respective
one of the filters.
The source of light may be a xenon lamp, a tungsten lamp or a metal
halide lamp. A heat sink may be coupled to the first end of the
light guide. The light guide may be a liquid light guide or a fiber
optic light guide. A lens for focussing light from the second end
through a selected filter may be provided and a securing member may
be used to adjust the position of the second end relative to the
lens.
BRIEF DESCRIPTION OF THE DRAWINGS
One way of carrying out the invention is described in detail below
with reference to drawings which illustrate only one specific
embodiment of the invention and in which:
FIG. 1 is a schematic view of a forensic light source constructed
in accordance with the present invention;
FIG. 2 is a detailed view of the coupling between the fiber optic
light guide and the light source;
FIG. 3 is a view along lines 3--3 of FIG. 2 illustrating the heat
sink of the system of the present invention;
FIG. 4 is a view partially in cross section of a hand-held light
directing assembly constructed in accordance with the
invention;
FIG. 5 is a view along lines 5--5 of FIG. 4;
FIG. 6 is a top plan view of the filter wheel of the present
invention;
FIG. 7 is a top plan view of the filter wheel of the assembly of
the present invention with the cover of the housing removed;
FIG. 8 is a side view along lines 8--8 of FIG. 6;
FIG. 9 is a front view of the light directing assembly head of the
present invention;
FIG. 10 is a top view along lines 10--10 of FIG. 9;
FIGS. 11 and 12 are views similar to the views of FIGS. 4 and 10 of
the embodiment of FIGS. 1-10 of an alternative embodiment; and
FIG. 13 is a view of yet another alternative embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1, a forensic deposition illumination system 10
constructed in accordance with the present invention is
illustrated. System 10 generally comprises a light source 12
contained in a housing 20, a hand held light directing assembly 14,
and a fiber optic cable 16 optically coupling the light source 12
to the hand-held light directing assembly 14.
Light is supplied to the system by a lamp 18 located within housing
20 of light source 12. Light from lamp 18 is focused by a parabolic
reflector 22 also contained within housing 20. In accordance with
conventional technology, housing 20 may also contain a fan for
cooling the assembly and an appropriate power supply for lamp 18.
In this respect, reference is made to the above-identified patent
applications.
Housing 20 of light source 12 is provided with a flange 24 which is
secured to housing 20 by a pair of screws 26, as illustrated in
FIG. 1. Mounted to flange 24 is a heat sink 28 which comprises a
main body 30 and heat dissipating fins 32, as can be seen most
clearly in FIGS. 2 and 3.
Hand-held light directing assembly 14 includes a handle portion 34
and a filter housing portion 36. Protruding from filter housing
portion 36 is a rotatable filter wheel 38.
During use, a user 40 grasps the handle portion 34 in his hand 42
and aims the light at a deposition 44 to be examined. Deposition 44
may be located on a surface 46.
Referring to FIGS. 2 and 3, the construction of the heat sink 28
may be more clearly understood. In particular, heat sink 28 may be
machined out of a single piece of aluminum. Heat sink 28 may be
finished with a black anodized finish. Heat sink 28 includes a
tubular forward portion 48 which mounts into flange 24 and may be
permanently secured thereto using set screws 50. Heat sink 28
includes an inner bore 52 which communicates optically with light
from lamp 18 as reflected by reflector 22. Lamp 18 may be of any
conventional type such as of the incandescent, metal halide, or
xenon type.
A larger bore 54 is located at the opposite end of heat sink 28 and
is sufficiently large to accommodate the fiber optic cable 16.
Generally, fiber optic cable 16 includes an inner fiber optic
member 56 and a sheathing 58. The diameter of the inner fiber optic
member 56 substantially equals the diameter of smaller bore 52,
while the outside diameter of sheathing 58 substantially matches
the inside diameter of bore 54. Fiber optic cable 16 is maintained
and positioned in bore 54 by a set screw 60 which has a large
knurled head 62 (FIG. 3) which allows set screw 60 to be easily and
conveniently grasped by the fingers of a user. During use, fiber
optic cable 16 is inserted into bore 54 and set screw 60 is
tightened in position thereby securing fiber optic cable 16 in
position.
Referring to FIG. 4, the construction of the hand-held
light-directing assembly 14 may be most clearly understood. In
particular, assembly 14 comprises a handle portion 34. Handle
portion 34 includes a light guide receiving bore 64 which is in
optical communication with a central bore 66. Central bore 66 is of
a diameter which matches the diameter of inner fiber optic member
56. This enables the handle to communicate substantially all of the
light conducted by fiber optic cable 16. Fiber optic cable 16 is
maintained in position by a hand adjustable set screw 68 with a
knurled head 70. During use, fiber optic cable 16 is inserted into
bore 64 and held in position by set screw 68.
Handle portion 34 also includes a lens receiving bore 72. A lens 74
is mounted on an annular shoulder 76 in bore 72. Lens 74 focusses
the output light at the output end 78 of fiber optic cable 16.
During use, selective focussing of the output from end 78 of fiber
optic cable 16 may be achieved by varying the position of end 78 in
the directions shown by arrow 80 and setting the position of fiber
optic cable 16 using set screw 68. For example, end 78 may be
brought to the position shown in phantom lines in FIG. 4. Variation
of the position of end 78 will result in varying light output cone
diameters and varying intensities. High intensity corresponds to
smaller diameter light outputs, while larger diameter outputs will
result in lower intensity. The advantage of the lower intensity
outputs is that wider areas may be illuminated and the same may be
particularly useful in searching operations. On the other hand,
minute examination of a deposition may require use of a relatively
small diameter high-intensity spot of illumination.
Handle portion 34 is secured to filter housing portion 36 by a
plurality of screws 26 which are disposed in holes 82 in flange 84,
and which threadedly engage tapped holes in main housing 86 of
filter housing portion 36, as can be seen in FIG. 5. Filter housing
portion 36 houses rotatable filter wheel 38. Rotatable filter wheel
38 is rotatably mounted within main housing 86 by being supported
on a post 88. Rotatable filter wheel 38 is maintained in spaced
relationship to the rear wall 90 of main housing 86 by a washer
92.
Referring to FIG. 6, the construction of the rotatable filter wheel
38 may be seen. In particular, rotatable filter wheel 38 comprises
a plurality of filter receiving openings 94 within which filters 96
are located. The circumferential edge of wheel 38 may be smooth as
illustrated in FIG. 6 or may include a knurled surface as is shown
in dotted lines in FIG. 6. Such a knurled surface 98 would be
disposed around the entire periphery of rotatable filter wheel 38.
Rotatable filter wheel 38 also includes a plurality of detentes 100
which are adapted to be engaged by a detente engaging spring member
102, as can be seen most clearly in FIG. 7. Detente engaging spring
member 102 is secured by a screw 104 to the inside side wall 106 of
main housing 86. It is maintained in place at a location from the
inside side wall 106 through the use of a washer 108.
As can be seen in FIG. 7, the circumferential edge 110 of rotatable
filter wheel 38 extends through a hole 112 defined in main housing
86 allowing a user to engage the same with his thumb and rotate the
rotatable filter wheel to cause engagement with the detente 100
associated with a selected filter 96, by rotation of wheel 38 in
the direction indicated by arrow 114.
As can be seen most clearly in FIG. 8, spacing from the forward
portion of filter housing portion 36 is maintained by an integral
central annular shoulder 116 on the rotatable filter wheel. The
forward surface 118 of shoulder 116 bears against front plate 120
of housing portion 36. Front plate 120 defines a hole 122 through
which light filtered by a selected filter 96 is allowed to pass to
illuminate the forensic deposition 44 under examination. As can be
seen in FIG. 9, front plate 120 also includes a hole 124 for
receiving post 88. Likewise, a plurality of screws 126 are used to
secure front plate 120 to the side walls 106 of main housing
86.
As can be seen in FIG. 10, circumferential edge 110 of rotatable
filter wheel 38 is easily accessible through window 112 for
adjustment of a desired filter. The same is of particular interest
because during use, the user using a single hand may hold and
direct the light source while, at the same time adjusting the
filter through which light can pass. In addition, the inventive
design is of particular value because the use of a single hand-held
light directing assembly frees up the other hand either to hold the
light source or to do other tasks such as adjust viewing filters,
cameras, painting with developing agents, dusting with appropriate
print revealing powders, or the like.
An alternative embodiment is illustrated in FIGS. 11-12. Generally,
similar parts or parts performing analogous, corresponding or
identical functions to those of the FIGS. 1-10 embodiment are
numbered herein with numbers which differ from those of the earlier
embodiment, by multiples of one thousand.
An alternative embodiment of the invention is illustrated in FIG.
11. Generally, in this embodiment the hand-held light directing
assembly 1014 of system 1010 is of similar construction except that
a viewing filter 1128 is secured to the front plate 1120 of filter
housing portion 1036 by a supporting bracket 1130 having aperture
1122. During use, as illustrated in phantom lines in FIG. 1, a
viewer looks through filter 1128 when inspecting the deposition. In
addition, provision may be made for adjustable angular positioning
of filter 1128, also as illustrated in phantom lines in FIG. 1.
Otherwise operation of the system illustrated in FIG. 11 is
identical to that of the system illustrated in FIGS. 1-10. The
construction of the filter may be more clearly seen in FIG. 12.
As alluded to the above, the inventive system has numerous
advantages. In addition to the flexibility provided to the user
through the use of the rotatable filter wheel housing which may be
operated to adjust the filter and position of the output light
beam, the design also accommodates the variation of the intensity
and size of the output light beam. In addition, the system of the
present invention has superior intensity output on account of the
fact that the filters in the rotatable filter wheel do not have to
be protected by heat absorbing filter or heat reflecting mirror as
used in conventional forensic light sources. In particular, in
conventional sources, the output light from the lamp is reduced in
intensity by removal of the infrared portion of the source. This is
necessary in order to prevent excessive heat buildup in the filter,
which would destroy the filter in a relatively short time.
Another important aspect of the invention is the fact that because
the light is first passed through the fiber optic wave guide, no
such protective filter is required and the light may be caused to
fall directly upon the filters which, instead of being located
adjacent to the lamp in the optical wave train, are located at the
far end of the fiber optical or liquid optical wave guide. As can
be readily understood by those of skill in the art, the flexible
optical wave guide does have an attenuation factor. However,
because of the placement of the filters at the far output end of
the optical wave guide, the additional attenuation factor of the
infrared protective filters is avoided. However, because of the
fact that light, including a great deal of infrared energy, is
passed into the flexible optical wave guide, excessive heat may be
caused to be built up within the wave guide, particularly near its
input end. Accordingly, the input end is provided with
heat-dissipating heat sink.
In accordance with yet another alternative embodiment illustrated
in FIG. 13, the heat sink 2028 is provided with a housing 2132
housing a fan 2134 which blows air over the fins 2032. This results
in extreme cooling which of particular value when very high
intensity lamp sources are used.
With respect to a possible flexible fiber optic wave guides, a
liquid light guide such as one of the type made by Lumatec of
Germany is preferred. This particular light guide will absorb
infrared rays to a very great extent (almost 100%) while only
attenuating the ultraviolet and visible spectrum to the extent of
about 50 or 60%. However, a conventional fiber optic wave guide
will provide exceptional performance in the case of lower intensity
lamps inasmuch as infrared radiation is reduced by approximately
50%. In the case of lower intensity lamps, this reduction is
sufficient to prevent damage to the filters in the rotatable filter
wheel. However, if high intensity lamps are used, close to 100%
attenuation which is substantially an action of infrared radiation
will be necessary to prevent damage to the filters and the use of a
liquid light guide is required in order to obtain reasonable filter
life.
While an illustrative embodiment of the invention has been
described above, it is, of course, understood that various
modifications will be apparent to those of ordinary skill in the
art. Such modifications are within the spirit and scope of the
invention, which is limited and defined only by the appended
claims.
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