CA1219141A - Portable luminescence sensor - Google Patents
Portable luminescence sensorInfo
- Publication number
- CA1219141A CA1219141A CA000457932A CA457932A CA1219141A CA 1219141 A CA1219141 A CA 1219141A CA 000457932 A CA000457932 A CA 000457932A CA 457932 A CA457932 A CA 457932A CA 1219141 A CA1219141 A CA 1219141A
- Authority
- CA
- Canada
- Prior art keywords
- light
- optical path
- optical filter
- filter
- ray
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Abstract
ABSTRACT OF THE DISCLOSURE
Apparatus is provided to sense and measure solar-induced lumi-nescence, as well as reflectance, within the field of view of a target window for receiving a composite ray of light from the target. A first filter within the path of the composite ray of light transmits a first narrowband component thereof, including a predetermined Fraunhofer Line frequency, to a first sensor. A
second narrowband component thereof, proximate the Fraunhofer Line frequency, is directed to a second sensor such that ratios of the electromagnetic energy impinging, respectively, on the first and second sensors may be determined. A removable filter tray carrying the narrowband filters and fine tuning means is employed to facilitate the selection of the predetermined Fraunhofer Line frequency.
Apparatus is provided to sense and measure solar-induced lumi-nescence, as well as reflectance, within the field of view of a target window for receiving a composite ray of light from the target. A first filter within the path of the composite ray of light transmits a first narrowband component thereof, including a predetermined Fraunhofer Line frequency, to a first sensor. A
second narrowband component thereof, proximate the Fraunhofer Line frequency, is directed to a second sensor such that ratios of the electromagnetic energy impinging, respectively, on the first and second sensors may be determined. A removable filter tray carrying the narrowband filters and fine tuning means is employed to facilitate the selection of the predetermined Fraunhofer Line frequency.
Description
:~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-HQ2087 - (3) 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.
HQ2087 - (4) ~2~
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.
HQ2087 - (5) 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.
HQ2087 - (6) 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 HQ2087 - (7) 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) 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 HQ2087 - (11) 1~iL9~
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 HQ2087 - (14) ~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
;-.
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-HQ2087 - (3) 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.
HQ2087 - (4) ~2~
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.
HQ2087 - (5) 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.
HQ2087 - (6) 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 HQ2087 - (7) 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) 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 HQ2087 - (11) 1~iL9~
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 HQ2087 - (14) ~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 HQ2087 - (17) ~ ;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
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 HQ2087 - (17) ~ ;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)
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)
Claims (18)
1. An apparatus for receiving a composite ray of light from a target, which composite ray of light includes reflected light having at least one Fraunhofer Line and may include solar induced luminescent radiation and for sensing and measuring the relative value of the luminescent radiation if present, said apparatus comprising:
a. a body;
b. a target window carried by said body for receiving said composite ray of light therethrough along a first optical path;
c. a first optical filter aligned along said first optical path for:
i. transmitting therethrough a first fraction of said composite ray of light along said first optical path, and ii. redirecting the balance of said composite ray of light along a second optical path;
d. a second optical filter aligned along said first optical path for limiting the light energy content of light passing therethrough to a selected waveband including, but wider than, a selected Fraunhofer Line;
e. tuning means for effecting selective angular adjustment of said second optical filter relative said first optical path;
f. first sensor means aligned along said first optical path for receiving light in said selected waveband and for sensing the electro-magnetic energy level contained therein;
g. a third optical filter aligned along said second optical path for transmitting a narrowed waveband in the continuum offset from said selected Fraunhofer Line by a selected frequency difference:
h. second sensor means aligned along said second optical path for receiving said light in said narrowed waveband in the continuum and for sensing the electro-magnetic energy level contained therein;
and h. indicator means for providing a sensible readout of the energy level sensed by said first and said second sensor means.
a. a body;
b. a target window carried by said body for receiving said composite ray of light therethrough along a first optical path;
c. a first optical filter aligned along said first optical path for:
i. transmitting therethrough a first fraction of said composite ray of light along said first optical path, and ii. redirecting the balance of said composite ray of light along a second optical path;
d. a second optical filter aligned along said first optical path for limiting the light energy content of light passing therethrough to a selected waveband including, but wider than, a selected Fraunhofer Line;
e. tuning means for effecting selective angular adjustment of said second optical filter relative said first optical path;
f. first sensor means aligned along said first optical path for receiving light in said selected waveband and for sensing the electro-magnetic energy level contained therein;
g. a third optical filter aligned along said second optical path for transmitting a narrowed waveband in the continuum offset from said selected Fraunhofer Line by a selected frequency difference:
h. second sensor means aligned along said second optical path for receiving said light in said narrowed waveband in the continuum and for sensing the electro-magnetic energy level contained therein;
and h. indicator means for providing a sensible readout of the energy level sensed by said first and said second sensor means.
2. The apparatus of Claim 1 in which said first fraction of said composite ray of light is limited by said first optical filter to a selected waveband containing said selected Fraunhofer Line and in which the transmissive bandwidth of said first optical filter is wider than the transmissive bandwidth of said second optical filter.
3. The apparatus of Claim 1 further including a first focusing lens aligned along said first optical path intermediate said second optical filter and said first sensor means for concentrating the electro-magnetic energy contained within said selected waveband for receipt by said first sensor means.
4. The apparatus of Claim 3 further including a second focusing lens aligned along said second optical path intermediate said third optical filter and said second sensor means for concentrating the electromagnetic energy contained within said narrowed waveband in the continuum for receipt by said second sensor means.
5. The apparatus of Claim 1 further including means for angularly adjusting said first optical filter relative said first optical path.
6. The apparatus of Claim 5 further including means for angularly adjusting said third optical filter relative said second optical path.
7. The apparatus of Claim 1 further including viewing scope means carried by said body, said viewing scope means having an ocular lens for receiving at least a portion of the composite ray of light received through said target window.
8. The apparatus of Claim 1 further including a fourth optical filter aligned along said first optical path intermediate said target and said first optical filter for blocking from said first optical filter a selected waveband of said composite ray of light having a wavelength shorter than the wavelength of visible light.
9. The apparatus of Claim 1 further including a fifth optical filter aligned along said first optical path intermediate said target and said first optical filter for blocking from said first optical filter a selected waveband of said composite ray of light having a wavelength longer than the wavelength of visible light.
10. The apparatus of Claim 1 further including viewing scope means carried by said body for receiving light redirected from said second optical path by said third optical filter.
11. The apparatus of Claim 1 further including:
a. a direct light receiving lens carried by said body for receiving a ray of direct light therethrough along a third optical path; and b) diverter means for selectively redirect-ing said ray of direct light along said first optical path in a direction toward said first sensor means.
a. a direct light receiving lens carried by said body for receiving a ray of direct light therethrough along a third optical path; and b) diverter means for selectively redirect-ing said ray of direct light along said first optical path in a direction toward said first sensor means.
12. The apparatus of Claim 11 wherein said diverter means redirects said ray of direct light onto said first optical path at a location intermediate said target window and said first optical filter.
13. The method of determining the presence and relative level of luminescence emanating from a selected target, said method comprising the steps of:
a. receiving a composite ray of light from said target along a first optical path, said composite ray of light comprising reflected light having at least one Fraunhofer Line and possibly including luminescent light;
b. splitting said composite ray of light into i. a first component including a selected waveband of said composite ray of light including, but wider than, a selected Fraunhofer Line, and ii. a second component including the balance of said composite ray of light; and c. correlating the electro-magnetic energy level contained in said first component with the electro-magnetic energy level contained in said second component.
a. receiving a composite ray of light from said target along a first optical path, said composite ray of light comprising reflected light having at least one Fraunhofer Line and possibly including luminescent light;
b. splitting said composite ray of light into i. a first component including a selected waveband of said composite ray of light including, but wider than, a selected Fraunhofer Line, and ii. a second component including the balance of said composite ray of light; and c. correlating the electro-magnetic energy level contained in said first component with the electro-magnetic energy level contained in said second component.
14. The method of Claim 13 wherein the step of splitting includes the sub-steps of:
a. allowing said first component to continue along said first optical path; and b. redirecting said second component along a second optical path.
a. allowing said first component to continue along said first optical path; and b. redirecting said second component along a second optical path.
15. The method of Claim 14 including the further step of narrowing said second component to a waveband of selected width in the continuum offset from said selected Fraunhofer Line by a selected frequency difference.
16. The method of Claim 15 including the additional step of sensing the energy level in said first component.
17. The method of Claim 16 including the further step of concentrating the energy in said first component prior to sensing said energy level.
18. The method of Claim 13 including the further step of alternately directing a ray of direct light along said first optical path.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US50968183A | 1983-06-30 | 1983-06-30 | |
| US509,681 | 1995-07-31 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1219141A true CA1219141A (en) | 1987-03-17 |
Family
ID=24027659
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000457932A Expired CA1219141A (en) | 1983-06-30 | 1984-06-29 | Portable luminescence sensor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1219141A (en) |
-
1984
- 1984-06-29 CA CA000457932A patent/CA1219141A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4345840A (en) | Method and apparatus for instantaneous band ratioing in a reflectance radiometer | |
| US4247202A (en) | Automatic computing color meter | |
| US4165180A (en) | Automatic computing color meter | |
| Horvath | The university of Vienna telephotometer | |
| TW355215B (en) | Method for measuring the optical properties of transparent-reflective and/or reflective objects as well as measuring apparatus for carrying out such method | |
| US3582659A (en) | Spectrophotometer circuit with linear response to absorbance | |
| JPS5873829A (en) | Radiation measuring instrument | |
| US4652761A (en) | Grating ozone spectrophotometer | |
| US4708475A (en) | Portable luminescence sensor | |
| US3601492A (en) | Apparatus for measuring film thickness | |
| US4865424A (en) | Optical device with adjusting means | |
| CA1219141A (en) | Portable luminescence sensor | |
| US3924954A (en) | Heliograph | |
| US4097152A (en) | Spectrophotometer with visual spectrum display | |
| Blackwell et al. | Low Noise Solar and Laboratory Spectroscopy: I. Technique | |
| Pettit et al. | Spectral Energy-Curve of Sun-Spots | |
| GB2096792A (en) | Double monochromator using a concave rotatable diffraction grating | |
| WO1988006279A1 (en) | Ultraviolet radiation detector | |
| McAlister et al. | A Large Recording Spectrograph for the Infra‐Red to 15μ | |
| Matthews et al. | Filter ozone spectrophotometer | |
| US2326007A (en) | Sensitometry | |
| US3891326A (en) | Multi-channel sun photometer | |
| Meaburn | Scanning Fabry-Pérot interferometers for nebular studies | |
| US4035086A (en) | Multi-channel analyzer for liquid chromatographic separations | |
| Sigernes et al. | Absolute calibration of optical devices with a small field of view |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |