Note: Descriptions are shown in the official language in which they were submitted.
:~2~
;-.
PORTABLE LUMINESCENCE SENSOR
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to light sensing instruments.
More particularly, the present invention relates to
means and method for sensing and measuring luminescence and
reflectance.
Jn a further and more specific aspect, the instant
invention concerns a portable device for sensing and mea-
suring luminescence and reflectance of selected targets in
the presence of sunlight.
Prior Art
It is generally well recognized that a ray or line of
light is actually a continuously moving stream of energy
particles termed "photons". ~he photons are emitted from
the light source in pulses. Traveling at incomparable speed
and being almost immeasurably diminutive, a stream of
photons assumes wave-like characteristics.
Analogous to other wave forms, light has the properties
of speed, fregue~cy and wavelength. The speed is a constant,
being the speed of light. Both fre~uency and wavelength are
variable. Accordingly, properties for any type of light can
be delineated by the fonmula:
c = f x ( ~ )
where:
c = speed of light
: f ~ freguency; and
~ = wavelength.
Types of light are generally referenced with respect to
the correspondinq wavelength. The known types of light are
jux~aposed along a continuum ranging from the short qamma
rays, having wavelengths in the range of lxlO 4-Angstroms,
to the long radio waves, having wavelengths in the range of
~Q2087 ~
9~1
1x1017 A. Apparatus for producing light within a specific
narrow band, such as an X-ray machine, are well known. The
sun emits the full spectrum of light.
However, it is now recognized that light from the sun
is not uniformly intense along the wavelength gradient.
Throughout the spectrum are instances of the absence or
diminishing of light, causing a dip in a plot of spectral
energy against freguency. A number of these dips are known
as Fraunhofer Lines, and numerous Fraunhofer Lines, or
absorption bands, can be found along the light spectrum. As
is well known in the art, Fraunhofer Lines result from
selective absorption of narrow light fre~uencies by gases
surrounding the sun.
Light falling upon a body is either reflected or
absorbed. Photons striking a surface and not absorbed,
leave the surface at a substantially identical wavelength.
This photon behavior is ordinarily called "reflection".
Reflected light emulates the source light. Thus, in the
case of reflected sunlight, the Fraunhofer absorption bands
are present.
The behavior of a photon being absorbed by material and
causing the reemittance of light is referred to as "lumi-
nescence". Luminescent light is at another, usually longer
wavelength than the excitation source light and does not
contain the Fraunhofer 1ines or dips. Solar-stimulated
luminescence is a naturally occurring phenomenon in various
sources, such as mineral deposits and vegetation.
Recently, it has been discovered that insight into
nature and composition of a luminescent substance can be
achieved by inspection of the emanant light. This is
readily accomplished by employing spectrometer under labo-
ratory conditions. Field exploration for luminescence
materials has been carried out in the past on dark nights by
using ultraviolet lamps to stimulate luminescence and the
human eye as the detector. The severe limitations of such
nighttime field efforts are notoriously well known to
exploration geologists.
Although sunlight excites and stimulates luminescence
in a substance upon which it shines, sunlight simultaneously
masks the relatively faint luminescence of the substance
HQ20a7 - (2)
with a large energy return from reflectance. Thus, sensing
solar stimulated luminescence is a formidable undertaking
which, however, may be accomplished by taking advantage of
the presence of the previously menti~ned Fraunhofer Lines in
the spectrum of sunlight impinging on the object being
observed.
Sunlight generally shows a very sharp Fraunhofer Line
in a measurement of light intensity, whereas a luminescent
substance shows no Fraunhofer Line in its light intensity in
the same spectrum range. Yet, the combination of the
luminescent radiation of the substance and reflected sun-
light will yield a measurement of intensity of a level
nearly equal to that of direct sunlight with a greatly
reduced Fraunhofer Line. Individual substances radiate in
lS differing amounts, thereby reducing the Fraunhofer Line of
reflected sunlight in difference degrees. Charts of the
various luminescent radiations of different substances are
readily available or may be experimentally determined.
Accordingly, by measuring the intensity of direct sunlight
within a given waveband and its corresponding Fraunhofer
Line, and comparing it to the intensity of reflected sun-
light from a luminescent target with its altered Fraunhofer
Line within the same waveband, it is possible to calculate
the change in the dip attributable to the luminescent
radiation of the target and hence the luminescence. Sub-
sequent comparision to a chart of known values will identify
or give insight into the target substance.
A device for this purpose is set forth in United States
Letters Patent No. 3,598,994 upon which is based the famous
FraunhofPr Line Discriminator used for some years by the
United States Geological Survey at Flagstaff, Arizona. The
subject device simultaneously takes a reading of direct
sunlight within a narrow waveband and its spectrally cor-
responding immediately adjacent Fraunhofer Line, and a
reading or reflected sunlight and luminescent radiation of a
substance and that corresponding Fraunhofer Line within the
same waveband as the reading for direct sunlight.
The prior art device, requiring simultaneous readings
of direct sunlight and reflected light, necessitates a
plurality of lenses, filters and prism in an arrangement
requiring an inordinate amount of space, making it impos-
sible for a user to carry the unit in one's hands. Addi-
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tionally, the number and type of lenses and prisms make the
device very heavy and excessively expensive to produce.
Further, the Fabry-Perot type filter, as used in the prior
art device, operate properly only within an exceedingly
narrow temperature range, thereby mandating an adjunct
temperature control unit adding materially to the weight,
bulk and cumbersomeness. It is also noted that the device
is not suitable for rapid, convenient adaptation for oper-
ation in multiple selected wavebands.
It would be highly advantageous, therefore, to remedy
the foregoing and other deficiencies inherent in the prior
art.
Accordingly, it is an object of the present invention
to provide improved means and method for sensing and mea-
suring luminescence emanating from a selected target.
Another object of the invention is the provision ofluminescence sensor of substantially reduced weight and
bulk.
And another object of this invention is to provide a
luminescence sensor which is relatively insensitive to
temperat~re deviations within a range as normally occuring
throughout a typical day.
Yet another object of the invention is the provision of
a luminescence sensor having readily changeable optics to
accommodate a selected luminescent target.
Still another object of the instant invention is to
provide a luminescent sensor which functions independently
of a concurrent reading of direct sunlight.
Yet still another object of the invention is the
provision of a luminescence sensor having conveniently
operable tuning means to adjust for optimum signal input.
Still a further object of the invention is the pro-
vision of a luminescence sensor which is comparatively
inexpensive to fabricate.
Yet a further object of this invention is to provide a
luminescence sensor which is relatively unencumbered and
substantially maintenance free.
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And a further object of the invention is the provision
of a device of the foregoing character which may be assembled
in a manually portable package.
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SUMMARY OF THE INVENTION
Briefly, to achieve the desired objects of the instant
invention, in accordance with a preferred embodiment there-
ofl first provided is a body having a target window for
receiving a composite ray of light emanating from a lumi-
nescent target along a first optical path. A first filter
aligned along the first optical path transmits a first
component of said composite ray of light, including a
selected waveband having an intermediate selected Fraunhofer
Line, and redirects the balance of said composite ray of
light, along a second optical path.
The first component is received by a first sensor which
provides an indication of the energy level. Similarly, the
second component of light is received by a second sensor.
Means are provided to convert the output of the sensor to
sensible indicia.
Further provided is a lens for receiving direct light,
such as sunlight along a third optical path. A diverter,
preferably including a reflective surface, is selectively
positionable to direct light from said third optical path to
travel along said first optical path.
A second filter, aligned along the first optical path
narrows the ray of light from the first filter to a waveband
of selected width in the intermediate range of the selected
Fraunhofer Line. A third filter aligned along the second
optical path narrows the light from the first filter to a
predetermined waveband offset from said Fraunhofer Line by a
selected frequency difference. Each filter is selectively
angularly adjustable relative the respective optical path.
Tuning means for calibrated adjustment are further assoc-
iated with the second filter.
In accordance with a further embodiment, there is
provided a viewing scope for observing the target through
the target window. The filters may be carried by a tray
interchangably receivable within said body. Optical filters
may also be provided to block the entrance of light having
wavelengths lesser or greater than that of visible light.
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BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and further and more specific objects and
advantages of the instant invention will become readily
apparent to those skilled in the art from the following
detailed description of a preferred embodiment thereof,
taken in conjunction with the drawing in which:
Fig. 1 is a perspective view, partially broken away for
purposes of illustration, of a luminescence sensing and
measuring device embodying the principles of the instant
invention;
Fig. 2 is a horizontal sectional view taken along the
line 2-2 of Fig. l;
Fig. 3 is an enlarged fragmentary perspective view of
the lens and filtering portion of the device seen in Fig. 2;
Fig. 4 is a fragmentary vertical sectional view taken
along the line 4-4 of Fig. 3;
Fig. 5 is an enlarged perspective view of an inter-
changeable lens and filter tray assembly usable in connec-
tion with the device of the instant invention;
Fig. 6 is a top plan view of the lens and filter tray
seen in Fig. 5, a portion thereof being broken away to
- reveal additional detail;
Fig 7 is an enlarged bottom plan view of a fragmentary
portion of the tray of Fig. 5, especially illustrating a
preferred means for adjusting the lens holders;
Fig. 8 is further enlarged perspective view of the
portion of the tray seen in Fig. 7, as it would appear when
assembled with the device of Fig. 1, the device being shown
in fragmentary perspective, and further illustrating an
adjusting tool for use in combination therewith;
Fig. 9 is a diagramatic representation of the optical
paths within the device of Fig. l;
Fig. 10 is a graphic representation of sunlight inten-
sity, chosen in a selected band to include a Fraunhofer
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Line, and having a corresponding band as viewed by the
device of the instant ir.vention superimposed thereon; and
Fig. 11 is an illustration, gènerally corresponding to
the illustration of Fig. 10, except having a prior art view
of luminescence light superimposed thereon.
HQ2087 - (8)
41
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A portable luminescence sensor, embodying the princi-
ples of the instant invention, will now be described with
reference to the drawings. First, the structure of a
preferred embodiment will be described in detail. Subse-
quently, the operation and function will be delineated. In
the ensuing narrative, like reference characters will denote
corresponding elements throughout the several views.
Structure
. _
Turning now to the drawings, attention is first directed
to Fig. 1, which illustrates a preferred embodiment of a
portable luminescence sensor constructed in accordance with
the teachings of the instant invention. The body of the
device is in the form of a case, generally designated by the
~, 15 reference character 20, having a base structure 22 and a
removable cover structure 23. With further reference to
Fig. 2, it is seen that the primary support member of base
structure 22 is generally rectangular base plate 24 having
forward edge 25, rearward edge 27, left edge 28, right edge
Z0 29, and top and bottom surfaces 30 and 32, r~spectively.
The terms forward, rearward, left, and right are used herein
for purposes of orientation in the ensuing description.
Similarly, edges 28 and 29 are considered to be longitudinal
while edges 25 and 27 are considered to be lateral. Such
terms are set forth for purposes of convenience and not
limitation.
-
Rear panel 33, having upper edge 34, upright left edge
35 and upright right edge 37, projects upwardly from rear
edge 27 of base plate 24. Seal groove 38, carrying seal 39,
extends continuously along edges 34, 35, and 37. Cover
receiving groove 40, formed in top surface 30 of base plate
24, extends continuously at a location spaced slightly
inboard from edges 25, 28, and 29.
Cover stucture 23, being somewhat in the form of an
inverted box, includes generally rectangular top panel 42,
having integral, depending, continuous left, forward, and
right side panels 43, 44, and 45, respectively. The several
side panels terminate with continuous lower edge 47 which,
in the assembled configuration, is received in groove 40.
Complementary, to provide a light impervious union between
HQ2087 - (9)
4~
base structure 22 and cover structure 23, the continuous
under surface of top panel 42 and side panels 43 and 45 are
received in sealing engagement against seal 39.
A tab 48, projecting inwardly from side panel 43, is
positioned to rest upon top surface 30 of base plate 24 when
edge 47 is fully received within groove 40. Screw 49,
received through a clearance sized opening (not illustrated)
in base plate 24, threadedly engages aperture 50 in tab 48
for detachable securement of cover structure 23 to base
structure 22 in accordance with conventional technique. A
similar tab 52 for a like purpose is seen projecting in-
wardly from side 45 in Fig. 2. As will be apparant to those
skilled in the art, additional attachment structures may ~e
periodically spaced thoughout the arrangement. Similarly,
while screw 49 has been specifically illustrated as a
machine screw, it will be appreciated that other commer-
~, cially available fastening elements may be readily substi-
tuted.
An opening 53, the purpose of which will be discussed
presently, is formed through riqht side panel 45. Cover
plate 54, removably secured to the exterior of right side
panel 4S, as by sheet metal screws 55, normally closes
opening 53. To insure a light impervious assembly, a flat
gasket-type seal may reside between cover plate 54 and right
side panel 55.
,The interior of case 20 is partitioned in for first,
second and third compartments 57, 58, and 59, respectively,
by an arrangem~nt of panels extending upwardly from the top
surface 30 of base plate 24. First panel 60, intermediate
and parallel to left and right edges, 28 and 29, respectively,
extends longitudinally from proximate forward edge 25 to an
intermediate terminal location. Second panel 62 is trans-
verse, extending between first panel 60 and right edge 29.
Third panel 63 is also transverse, extending between first
panel 60 and right edge 29, at an intermediate location
between second panel 62 and forward edge 25. Cover panel
64, having respective edges adjoining the panels 60, 62, and
63, overlays compartment 58. Accordingly, compartment 58
has an open end 65 in substantial alignment with opening 53
through rlght side panel 45 of cover structure 23.
Case 20 may be fabricated of various materials by
respectively suitable manufacturing techniques. For ex-
HQ2087 ~ (10~
ample, case 20 may be structured of metal, such as aluminum,by appropriate stamping technigues. Similarly, the device
may be molded of a plastic material. The several components
may be integrally formed, or alternately, individually
shaped and assembled by bonding with fastening devices or
adhesives compatible with the selected material. Such
devices are well known in the art as are commercially
available cases which may be modified for the immediate
purpose.
In accordance with the immediately preferred embodiment
of the instant invention, the several optical elements are
lined along prescribed interrelated axes. For purposes of
illustration and reference during the ensuing description,
these axes are designated as first, second, third, and
fourth, as represented by the broken lines indicated by the
alphabetic reference characters A, B, C, and D, respectively.
The axes represented by the reference characters A, B, and
C, lie in a single plane with the former two extending in
longitudinal parallelism. The latter is laterally extending,
being a perpendicular bisector of the former. The axis
represented by the reference character D, being perpendic-
ular to the described plane, intersects the axis represented
by the reference character A. Each of the designated axes
is considered the longitudinal axis of an optical path along
which a ray of light moves.
An opening 70 is formed through forward side panel 44
of cover structure 23. An ultra-violet cutoff optical
filter 72, of a standard commercially available type as will
be known to those skilled in the art, is fixed in opening 70
3Q by any suitable lens mounting means, such as a suitable
adhesive. Tubular shield 73 projects forwardly from panel
44. For inclusive reference, opening 70, filter 72, and
shield 73, having axis A as the common center, is termed the
target window.
opening 74, extending through third panel 63, carries
infra-red cutoff optical filter 75. Filter 75, secured
within opening 74 by conventional means in alignment with
axis A, is likewise of standard commercial manufacture.
Aperture 77 is formed through second panel 62. Aper-
ture 78 is similarly formed through first panel 60. Ob-
jective lenses 79 and 80 are mounted within aperture 77 and
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78, respectively. Lens 79 is aligned along axis A. Lens 80
is aligned along axis C. Each of the lens are of the
familiar ~ convex configuration generally referred to
as focusing lens. Hereinafter, lens 79 will be referred to
as first objective lens while lens 80 will be referred to as
second objective lens.
First sensor 82, residing in compartment 57, is aligned
along axis A. A second sensor 83, also residing within
compartment S7, is aligned along axis C. Representative of
the sensor 82 and 83, is the blue enhanced photovoltaic
silicon device distributed by Silicon Detector Corporation,
under the Identification No. sd-200-12-12-241. As supplied
by the manufacturer, the device is provided with outwardly
directed flanges at the base for attachment to base plate 24
by conventional screws. Tubular element 84 provides light
tight communication between lens 79 and sensor 82. Simi-
; ~ larly, tubular element 85 provides a light impervious path
between lens 80 and sensor 83.
Viewing scope 90, having ocular end 92 and objective
end 93, extends through openings 94 and 95 in rear panel 33
and second panel 62, respectively. Field end 93 terminates
in the approximate plane of panel 62. Ocular end 92 is
spaced rearwardly of panel 33. Viewing scope 90 may be of
any commercially available type conventionally used as a
sight for rifles or other firearms. Although a relatively
low magnification in the range of lx to 3x power is pre-
ferred, scopes of greater power or variable power are
contemplated.
A conventional annular lens holder 100 is secured
within an appropriate opening through top panel 42 of cover
structure 23. Diffusing plate 102 is carried by lens holder
100. Lens holder 100 projects upwardly from top panel 42,
and removably receives lens cover 103 in accordance with
standard practice. As a preferred standard, diffusing plate
102 is free from florescence with a twenty percent light
transmission as will be readily understood by those in the
lens making art. Plate 102, the relative position which is
shown in broken outline in Figs. 2 and 3, is aligned along
axis D. The relative positioning of optical filter 72 is
also seen in broken outline in Fig. 3. A second lens cover
104, generally similar to lens cover 103, is detachably
securable to tublar shield 73.
HQ2087 - (12)
~L219~
Diverter means for selectively and optionally receiving
light entering case 20 through lens 102 along the optical
path represented by the broken line D and redirecting the
light along the optical path represented by the broken line
A in a direction toward sensor ~2 resides within compartment
59. As more clearly view~d in Figs. 3 and 4, the immedi-
ately preferred diverter means includes a pair of spaced
apart parallel ways 110 and 112. The ways reside along a
transverse axis, repr~sented by the broken line E which,
when observed in plan view, is perpendicular to the axis
represented by the broken line A. Being generally triangu-
lar in cross-sectlon, and secured to the top surface 30 of
base plate 24 by any convenient expedience, ways 110 and 112
carry elongate guide surfaces 113 and 114, respectively.
Guide surfaces 113 and 114 are in opposition and appear in
cross-section as being mutually, downwardly, outwardly
divergent.
Slide 115 is disposed between ways 110 and 112.
Carried by slide 115 are opposed outwardly, downwardly,
divergent contact surfaces 117 and 118, which are matingly
received against the guide surfaces 113 and 114, respec-
tively. Spring loaded plungers 119, of conventional com-
mercially available configurations, carried by slide 115,
bear against surface 30 of base plate 24, urging slide 115
upwardly in the direction of arrowed line F, maintaining
surfaces 117 and 118 into position, bearing juxtaposition
with the respective guide surfaces 113 and 114. The travel
J of slide 115 in either direction along axis E is limited by
positive stops. In the immediately preferred embodiment,
the stops assume the form of interference tabs 120 carried
at the inner end of ways 110 and 112 and interference tabs
122 affixed to the outer end.
Mirror 123, having reflective surface 124, is supported
at an oblique angle by slide 115. Operating rod 125 projects
from slide 115 parallel to axis E. The fixed end 127, of
operating rod 125, is threadedly engaged within slide 115.
Free end 128 of operating rod 125 resides external of case
120. Hand knob 129 is carried at free end 128.
Mirror 123, in response to manual manipulation of hand
knob 129, is selectively movable in alternate directions
along axis E between a first position and a second position.
The first position is obtained by applying manual pressure
HQ2087 - (13)
1~9~
to hand knob 129 in the direction of arrowed line G, cor-
respondingly moving slide 115 against inner stops 120.
Movement of hand knob 129 in the direction indicated by
arrowed line H, relocates mirror 123 in the second position
wherein slide 115 bears against outer stops 122. With
mirror 123 in the first position, light entering through
filter 72 is free to travel along the axis represented by
the arrowed line A, as previously described. With mirror
123 in the second position, the normal optical path of light
entering through lens 102 along the axis represented by the
bro~en line D, is redirected along the axis represented by
the broken line A in a direction toward sensor 82. For
optimum operation, it is apparent that the physical center
of reflecting surface 124, when in the second position,
should reside at the intersection of axes A and D. Further,
reflective surface 124 should be oriented at forty-five
degrees to each of the associated optical paths.
~ .,
Equivalent structural configurations for achieving the
desired function will readily occur to those skilled in the
art. For example, slide 115 may be movable upon spring
loaded gibs of traditional design. Various detent means may
be substituted for the interference tabs and allow for the
removal of slide 115. Similarly, the movement of slide 115
may be in response to a manually rotated or motor driven
lead screw.
A filter tray 130, detailedly depicted in the enlarged
enhancements of Figs. 5 and 6, removably resides within
compartment 58. Tray 130 includes base 132 which, described
in reference to the assembed relationship with case 20,
includes forward edge 133, rearward edge 134, inner edge
135, outer edge 137, and top and bottom surfaces 138 and
139, respectively. Plunger 140, normally biased in the
direction of arrowed line I by compression spring 142 and
being of known configuration, projects from forward edge
133. Threaded aperture 143 extends through base 132 between
surfaces 138 and 139.
Filter tray 130, along with the associated structure to
be subse~uently described, is removable and replaceable
through opening 53 in right side panel 45 of cover structure
23. The lower portion of the surface of second panel 62
adjacent compartment 58, functions as an alignment surface
for receiving rearward edge 134, which functions as a
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~L~3L9~
complemental alignment surface thereagainst. The surface of
third panel 63, adjacent compartment 58, functions as a
contact surface for receiving the contact end of plunger
140, thereagainst. Plunger 140 and springs 142 function as
biasing means for urging the alignment surfaces into juxta-
position. Accordingly, base 132 is slidable within compart-
ment 58 in selective opposite directions as indicated by the
double arrowed line J. In the inward direction, surface 135
abuts first panel 60 to provide stop means. A bolt, receiv-
able through an opening in base plate 124 and threadedlyengagable within aperture 143, brings surface 139 of base
132 into contact with top surface 30 of base plate 24 to
positionally retain tray 130. The opening through base
plate 24 and the bolt, although not specifically herein
illustrated, are conventional for the intended purpose as
will be appreciated by those skilled in the art.
Supported by base 130 are first, second, and third
filter holders 144, 145, and 147, respectively. For con-
venience of manufacture, each filter holder is identical,
being generally rectangular and including parallel upper and
lower edges 148 and 149, respectively, and parallel upright
edges 150 and 152. Also included are opposing faces 153 and
154. An aperture 155 extends through each filter holder
between faces 153 and 154.
Each filter holder is pivotally supported in a gen-
erally upright position for rotational, angular adjustment.
A stand-off post, having upper end 158 and lower end 159,
rises substantially perpendicularly from top surface 138 of
base 132, proximate the apex of edges 134 and 135. Although
not specifically herein illustrated, lower end 159 is
secured to base 132 by any conventional known means, such as
a bolt extending through base 132 and threadedly engaged
within post 157. Support plate 160, cantileveredly extending
over at lea~t a portion of each of the filter holders, is
secured to the upper end 158 of post 157, as by flat head
machine screw 162.
Filter holder 145 is affixed to tray 132 by pivot means
including bore 163 extending through support plate 160 and
an aligned bore (not illustrated~ extending through base
132. Pin 164, carried proximate upright edge 150, subtends
edges 148 and 149 and is rotatably journaled within respec-
tive bores. In the assembled configuration, as seen in Fig.
HQ2087 - (15)
~9~41
2, the axis of rotation of pin 164 is perpendicular to the
plane defined by the axes A, B, and C. To prevent binding
and insure free rotation of filter holder 154, an auxiliary
stand-off post 165 extends between base 132 and plate 160 at
a location spaced from stand-of:E post 157.
A portion of each of the filter holders 144 and 147,
adjacent the respective upright edge 150, resides between
base 132 and support plate 160. Extending into each filter
holder 144 and 147, from the respective top edge 148 and the
respective upright edge 150, is a threaded aperture (not
specifically illustrated), which receives a respective flat
head machine screw extending through an appropriate sized
countersunk bore 168 in plate 160.
Filter holders 144 and 147 are secured to base 132 as
clearly seen with reference to Fig. 7. An opening 170 is
formed through plate 132 in alignment with countersunk bore
168. Preferably, opening 170 is elongated in a direction
perpendicular to the normal residence direction of lower
edge 149 of the respective filter holder. A bolt 172,
herein illustrated as a socket head cap screw, extends
through opening 170 and is threadedly received within an
opening in the respective filter holder aligned with the
threaded opening receiving the screw 167. Accordingly, each
filter holder 144 and 147 is rotatable about an axis parallel
to the axis of pin 164.
As further seen in Fig. 7, a bore 173 extends through
base 132 along an axis substantially parallel to the axis of
rotation, and spaced from opening 170 in a direction along
the normal residence position of the respective filter
holder. A slot 174, elongated in a dire,ction parallel to
the faces 153 and 154, is formed into the lower edge 149 of
each filter holder 144 and 147.
Referring now to Fig. 8, there is seen driver 175,
including elongate shank 177, terminating with a working end
178 and handle end 179. T-handle 180 is carried proximate
handle end 170. Bearing surface 182, adjacent working end
178, is sized to be matingly and rotatingly received within
bore 173. Perpendicular to cylindrical bearing surface 182
and residing at end 178, is flat bearing surface 183 which
may be receivable against edge 149 of the respective filter
holder 144 or 147. Cylindrical pin 184 projects from
HQ2087 - (16~
bearing surface 183 along an axis spaced from and parallel
to the axis of rotation of cylindrical bearing surface 182.
Pin 184 is receivable within slot 174 when bearing surface
182 is receiYed within bore 173.
With tray 130 positioned within compartment 158,
aperture 155 of filter holder 144 resides at the proximate
intersection of the aces represented by the broken lines A
and C. The aperture 155 of filter holder 147, resides at
the proximate apex of the axes represented by the broken
lines B and C. The elements described with specific refer-
ence to Figs. 7 and 8 provide adjusting means for rotating
the filter holders about an axis of rotation to selective
angular positions relative the above mentioned axes. Bolt
172, and optionally screw 167, function as locking means for
selectively retaining the respective filter holder at a
selected one of the positions.
~,
Slot 174, as will be appreciated by those skilled in
the art, is defined by a continuous side wall. Contained
within the side wall is a pair of spaced parallel sub-sur-
faces. Such are considered camming surfaces. Pin 184functions as a cam to bear against a selected one of the
camming surfaces. In response to rotation of driver 175,
with bearing surface 180 matingly received within bore 173,
the eccentric pin 184 bears against the side wall of slot
174 to angularly direct the selected filter holder about the
respective axis of rotation. Subsequently, bolt 172 is
tightened in the usual manner to immovably fix the filter
holder at the selected position.
With further reference to Fig. 8, there is seen means
for facilitating alignment and adjustment of ~ilter holder
144 and 147 when tray 130 is located within compartment 158.
A pair of threaded apertures 18S extend through base plate
24. Each aperture 185 is of a predetermined si~e and
location to expose the immediately previously described
adjusting and locking means. To maintain the light tight
integrity of case 20, when adjustment of the lens holders
144 and 147 is not desired, each threaded aperture 158 is
provided with a mating threadedly engagable cap 187.
First, second, and third filters are held by the filter
holders 144, 145 and 147, respectively. In each assembly
the filter is held in the respective a~erture 155 by a
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~ ;L91~
cementious material or other means known to those skilled in
the art.
Consistent with an objective function of the instant
invention, first filter 190 is chosen to be of a type having
a light intensity transmission of cpproximately fifty
percent and centered upon a selected Fra~nhofer Line with a
widt~ of 100 Angstroms at forty-five degrees angle of
incidence. Third filter 193 is of a generally similar type,
being centered at approximately 100 Angstroms from the
selected Fraunhofer Line.
Second filter 192 is chosed to have a minimum trans-
mission of approximately forty percent and centered on the
selected Fraunhofer Line with a four Angstrom width at five
degrees incidence. ~he material of fabrication should yield
a maximum shift of approximately ten Angstroms over a five
degree centigrade change in temperature. A representative
material is magnesium fluoride.
For each of the foregoing filters, the given data will
be sufficient for the production of the desired filter by
one skilled in the art of lens ar.d filter making.
The first filter 190 and third filter 193 are angularly
adjustable and l~ckable at the selected angular position
relative the axis of the respective light ray. Second
filter 192 is tunable by the operator during use for selec-
tive angular adjustment relative the optical ~ath of thelight ray extending along the axis A.
As seen in Figs. 5 and 6, filter holder 145 is angu-
larly pivotal about the axis of pin 164 in a re~rward first
direction as designated by the arrowed line K and in a
reciprocal forward second direction represented by the
crrowed line L. Pin 200, projecting upwardly from base
plate 132, limits the angular dis~osition of filter holder
145 in the direction indicated by the arrowed line K.
'pring holder 202 is secured to top surface 138 of bzse 137
ct a location spaced from pin 200 in 2 direction gener211y
indicated by the arrowed line L. Compression spring 2D3,
projecting from holder 202, bears against holder 145 n~rr~211y
biasing same in the directi~n of arrowed line ~ against stop
200.
(18)
121g~
Tuning means for selective angular adjustment of second
filter 192 is best described with reference to Figs. 1 and
2. Adjustment means 204, projecting rearwardly from case
20, is carried proximate the right edge 37 of real panel 33.
Rod 205, extending along an axis substantially parallel to
the axis represented by the broken line A, extends through
aperture 207 in second panel 62 and terminates with end 208,
which contactingly abuts filter holder 145 proximate edge
152.
10Adjusting means 204 may be readily fabricated from a
conventional micrometer head, having barrel 209 and rota-
tably mounted thimble 210. Barrel 209 is stationarily
affixed to panel 33. Thimble 210 is alternately movable in
directions indicated by the arrowed line M and N. In
accordance with conventional practice, rotation of thimble
, 210, in a clockwise direction, results in advancement in the
direction of arrowed line M, while counter-rotation yields
retraction in the direction of arrowed line N. Calibration
indicia 212, cooperating between barrel 209 and 210, micro-
metrically indicates the relative movement.
Rod 205 is an extensible element moving in extending
and retracting directions in response to rotation of thimble
210. Spring 203 reinforces and maintains contact between
filter holder 145 and the free end 208 of rod 205. In
response to extension of rod 205 in the direction indicated
~,by thç arrowed line M, spring 203 is tensioned. In response
to retraction of rod 205, in the direction of arrowed line
N, spring 203 is relaxed.
In accordance with the foregoing description, it is
apparent that a plurality of filter trays 130 can be made to
be interchangeably and replaceably positioned within compart-
ment 58. The tuning means described above insures that each
filter lg2 can be angularly adjusted to a previously cali-
brated position. A prior recording of a read-out of the
calibration indicia 212 will provide a ready reference for
repositioning any given filter.
Optical filter 72 blocks all light having a wavelength
lesser than that of visible light. Similarly, optical
filter 75 blocks all light having a wavelength greater than
that of visible light.
HQ2087 - ~l9)
4~
Those skilled in the electronic arts will understand
that it is a straightforward mat;ter to simply employ a meter
to measure the respective voltage outputs from the photo-
voltaic sensors 82, 83 to obtain the readings from which the
calculations for determining luminescence of the target may
be carried out as set forth in previously mentioned United
States Patent 3,598, 994 and the literature covering the
U.S.G.S. Fraunhofer Line Discriminator. However, it is
desireable to somewhat automate the measuring process to
assist the operator and increase the efficiency of oper-
ation.
It has thus been found that the field operation of the
instrument can be substantially facilitated by employing a
simple microcompùter, such as the Octagon SYS-l ~not shown),
in conjunction with an off-the-shelf low level amplifier
such as the Burr-Brown PGA 100B and commercial analog-to-dig-
ital converter module such as the Intersil lCL7109. The
Octagon SYS-1 uses a National 8073 microprocessor which
features on-board TINY BASIC, a very straightforward lan-
guage for performing the necessary data manipulations andcalculations which result in the direct readout of the
signals sensed by the photovoltaic sensors 83, 83 on a
digital display 300 which may be, for example, a type
PCIM200 ma~ufactured by Printed Circuits International.
Power for the electronics (which, while not shown in
detail, are represented in Fig. 2 by the printed circuit
board 220 plugged into socket 221) is preferably obtained
from a separately housed rechargeable battery pack (not
shown) providing 12 volts ts the on-board power supply 22~
which simply regulates the raw voltage to the close toler-
ance 5 volts standard required by the electronics.
Selecting the information to be displayed on the
readout 300 may be readily accomplished by a knob 302
coupled to a switch (not shown) which selectively connects
the terminals of the sensors 82, 83 (and other sensors-such
a temperature which might be desired~ to the analog-to-dig-
ital converter module.
The electronics package, while entirely optional,
significantly increases the efficiency and flexability of
the instrument and is incorporated in the best embodiment of
the invention.
HQ2087 - (20)
~L2~
Operation
Initially, the device is callbrated under laboratory
conditions. After deciding what substance or target is to
be identified in field use, a lamp having a known lumi-
nescence radiation level with a wavelength similar to that
of the luminescent radiation of the substance to be identi-
fied, is lit in a dark room. Preferably, the room is kept
at a temperature equal to the average temperature antici-
pated in the field, so that the unit may be calibrated at
the mean of the expected variation in temperature during a
normal day of field exposure. The unit should be kept in
the room for a period of time prior to calibration to ensure
that the unit adjusts and stabilizes to the temperature.
A filter tray 130 is selected which has a first filter
190 centered upon the known Fraunhofer Line of the wavelength
of the lamp and having a third filter 193 centered ten
Angstroms from the known Fraunhofer Line. Second filter 192
is centered on the Fraunhofer Line with a four Angstrom
width at five degrees incidence, as previously disclosed.
With the proper filter tray 130 placed within case 20 as
previously described and the unit stabilized to the ambient
temperature, the unit may now be calibrated. Preliminarily,
lens cover 104 is removed from tubular shield 73 to effect
calibration. Concurrently, mirror 123 is positioned along
axis E in the first position, as indicated by the arrowed
line G, and the lens cover 103 positioned over diffusing
plate 102.
On rear panel 3, as shown in Fig. 1, is panel meter 300
and function select knob 302. Panel meter 300 gives a
readout in millivolts corresponding to the energy level of
the luminescent radiation received at sensor 82 or 83,
depending on the position of function select knob 302. It
is known that photons, upon striking a photosensitive
surface, convert the electro-magnetic energy contained
3~ therein to electrical energy which is perceived by the
sensors 82 and 83. In a first position, function select
knob 302 allows no voltage to be read from either sensor.
In a second position, function select knob 302 permits a
readout of the voltage level at sensor 82, and in a third
position permits a readout of the voltage level at sensor
83.
HQ2087 - (21)
With function select knob 302 in the second position,
and the target window aimed at the lamp, the rays of known
luminescent light from the lamp enter along the axis described
by the broken line A, passing through filter 192. The
filter 192 is moved in selective directions and positioned
by rotating adjusting means 204 so that a p~ak reading is
obtained on meter panel 300. This peak reading indicates
that sensor 82 is sensing a peak level of luminescent
radiation. As will be shown with reference to Fig 9, a
peak level of luminescent radiation level is contained in
the Fraunhofer Line of the selected light source.
The peak reading obtained at meter panel 300, in
accordance with the foregoing procedure, is recorded for
further reference. Should the operator be searching for
additional substances with varying wavelengths of lumi-
nescent radiation in the field, trays 130 carrying appro-
priate filters corresponding to the wavelength of the
luminescent radiation of the possible targets can be in-
stalled in successive order, each time obtaining a peak
reading of panel meter 300 by aiming filter 72 at a selected
lamp or light source with a wavelength corresponding to the
anticipated targets. The peak reading for each tray is
recorded. Also, the calibration indicia is recorded.
Field use of the device, having been previously cali-
brated under the foregoing conditions, may be accomplished
in the following manner. First, to ensure that the indoor
calibration will prove correct for outdoor conditions, the
device should initially be used on a totally clear, sunny
day. Use under alternate weather conditions will be dis-
cussed subsequently.
Since the spectra of the sun contains all wavelengths
of light, on a clear day, by removing lens cover 102,
sliding mirror 123 into the second position, adjustment of
second filter 192 until a peak reading is obtained at panel
meter 300 will result in the same peak reading given by the
lamp when previously calibrated. The suspected composition
of the target is now estimated and an appropriate filter
tray 130 is selected and installed. The actual peak reading
at the meter panel 300 may now be compared to that of the
recorded peak reading from the corresponding lamp. On a
clear day, the peaks should match.
HQ2087 - (22)
~2~9~
Continuing, lens cover 103 is placed on diffusing plate
102, mirror 123 moved into the first position and cover 104
removed from filter 72. Filter 72, the target window, is
aimed at the target which is assumed to contain the prede-
termined substance. The light path can be traced withreference to Fig. 9. It is also noted that the operator may
view the target, for accurate alignment, through viewing
scope 90.
Xeflected sunlight, with its corresponding Fraunhofer
Lines, and luminescent radiation, emitted from the target,
enters the unit at the ultra-violet cutoff optical filter
72. Continuing along the optical path, indicated by the
broken line A, the light travels through infrared cutoff
filter 75 to first filter l90 where the light is filtered
and split such that all the reflected sunlight with wave-
lengths differing from the transmission wavelengths of
filter 190 and luminescent radiatior. with wavelengths
differing from transmission range of filter 190 are directed
along the optical path represented by the broken line C
Z0 throuqh lens 193 to sensor 83. Light, having a wavelength
within the passband of filter l90, and containing the
corresponding Fraunhofer Line and the fill-in of that
Fraunhofer Line by luminescent radiation emitted by the
target, will pass through filter l90 in the direction of
sensor 82.
Reflected sunlight that has been redirected by filter
~, 190, and traveling in the direction of sensor 83, is further
split by third filter 193. Light, the wavelength of which
is lO0 Angstroms greater than the wavelength passing through
filter l90, passes through filter 193 and continues in the
direction of sensor 83. All other reflected light is
redirected along the axis indicated by the broken line B, in
a direction toward ocular end 92 of viewing scope 90.
Light passing filter lens 193 and directed toward
sensor 83 continues through lens 80 which further focuses
the light on ~ensor 83. If function select knob 302 is in
the second position, panel meter 300 will give a voltage
reading corresponding to the intensity of the reflected
sunlight 100 ~ngstroms from the known Fraunhofer Line of the
target substance.
Light passing through filter l90 will be futher refined
by filter 190, and focused by lens 79 to concentrate upon
H~2087 - (23)
~2~
sensor 82. Knob 302 may be put in the third position to
obtain a reading of voltage corresponding to the Fraunhofer
Line nearest that of the target substance and the amount the
Fraunhofer Line has been filled in by the fluorescent
radiation of the substance. It will be readily appreciated
by those skilled in the art that by using a known equation,
the amount that the Fraunhofer Line of the reflected sun-
light has been filled in can be calculated. More partic
ularly, the four values necessary for the known equation
are:
A = the direct sunlight intensity in a narrow waveband
proximate a Frau~hofer Line;
B = the direct sunlight intensity in the Fraunhofer
Line;
C = the reflected sunlight intensity in the same narrow
waveband; and
D = reflected sunlight and luminescent radiation of the
target in the Fraunhofer Line.
Accordingly, with reference to a chart of pretermined
values, the target substance can be identified or charac-
teri2ed.
On days of less than clear, bright sunlight, the
previously attained peak readings will not be approached.
This will not, however, prevent use of the luminescence
sensor of the instant invention. By taking a direct sun-
light reading on a less than clear day and comparing it to
the known peak, it is possible to calculate a percPntage
ratio to be applied to all other readings which will still
permit accurate calculation of th~ luminescent radiation
from a target substance. The accuracy obtainable, to some
extent, depends on the operation wavelength range.
~ igs. 10 and 11 compare a time-shifted resultant
obtained with a filtering lens according to the instant
invention with the Fa~ry-Perot type filter of the prior art.
Shown in Fig. 10, in solid line, is a graph of sunlight
intensity with the corresponding Fraunhofer Line centered at
a given wavelength. In comparison to the prior art, the
instant invention utiliæes relatively wide filters. That
is, even though the filters center at a given wavelength,
wavelengths within a few Angstroms range still pass through.
This results in a wide expansion of wavelengths of the
luminescent material being detected. Indicated by broken
line Al in Fig. 10, is the relative increase in intensity at
HQ2087 - (24)
the Fraunhofer Line of reflected liyht caused by the lumi-
nescent radiation of a substance. Broken line A1 represents
the intensity as detected when weather conditions, such as
temperature, are ideal.
Broken line A2 in Fig. 10 shows intensity shifted ~.5
Angstrom, as may be caused by a variation in temperature.
Comparing the intensity levels contained in A1a to that in
A2a, and that of Alb to that of A2b, it is immediately
apparent that a shift of 0.5 Angstrom due to temperature
change will cause ~ relatively minor variation in the
readings. Actual field use has shown that the shift is
significantly minor as to be negligible. An accurate
reading can still be obtained.
By way of comparison, Fig. 11 representing the same
conditions shows a substantially differing result obtained
by the prior art through the use of Fabry-Perot type filters
It is well known that Fabry-Perot type filters are exceed-
ingly temperature sensitive and that 0.5 Angstrom shift will
result from a relatively minor temperature change. As
clearly illustrated in Fig. ll, a 0.5 Angstrom shift will
provide an inaccurate, unusable readout.
Broken line Al in Fig. ll represents a centered reading
of luminescent variation of a given substance. Broken line
A2 represents a shift reading. By comparing the energy
la A2a and Alb to A2b, respectively~ it is seen
that the change in energy reading, under practical field use
conditions, will be rendered useless.
The above descriptions are given by way of example
only. Various changes and modifications to the embodiments
herein chosen for purposes of illustration will readily
occur to those skilled in the art. To the extent that such
modifications and variations do not depart from the spirit
of the invention, they are intended to be included within
the scope thereof which is assessed only by a fair interpre-
tation of the following claims.
Having fully described and disclosed the present
invention in such clear and concise terms as to enable those
skilled in the art to understand and practice the same, the
invention claimed is:
HQ2087 - (25)
