Apparatus and method for calibration of fluorescence detectors
First Claim
1. An apparatus for calibration of fluorescence detectors using non-visible light, comprisinga) a housing impervious both to said non-visible light and to said fluorescence to be detected,having at least one opening means to admit passage of said non-visible light and of said fluorescence,b) a standard target element enclosed within said housing, comprisinga predetermined combination of one or more predetermined fluorescent substances with one or more other substances,c) an aperture element enclosed within said housing and disposed between saidstandard target element and said at at least one opening means,d) adapting means for adapting said housing to fit a fluorescence detector, ande) means for adjusting the distance between said adapting means and saidstandard target element, so that a predetermined intensity of said fluorescence is presented to a detector to be calibrated.
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Abstract
The response of a fluorescence detector is calibrated using apparatus and methods for both static and dynamic calibrations. The apparatus and methods are especially suited for portable use in field calibration of fluorescence detectors of authentication systems that use non-visible light. The calibration apparatus incorporates standard target elements (20) comprising predetermined fluorescent substances with known emission spectra, and either non-fluorescent substances or fluorescent substances with other known emission spectra. The substances are either mixed in predetermined proportions, or one substance is arranged in a predetermined pattern (170), such as a bar code, on the other substances. An aperture (30) exposes a predetermined surface area of a standard target element to the view of the fluorescence detector. The distance of the standard target element from the optical front end (70) of the fluorescence detector to be calibrated is adjustable (50). For dynamic calibration, the standard target element is moved from one position to another in the apparatus in a predetermined time. Multiple standard target elements are substituted individually into the apparatus or are carried together on a carrier (80) that is indexed to present each standard target element in turn. Additional light can be admitted to the apparatus through a port (200) to simulate the ambient light encountered in normal use of the fluorescence detector. Standardized quick-disconnect couplings (220, 230) provide for easy exchange of the calibration apparatus among various fluorescence detectors.
136 Citations
34 Claims
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1. An apparatus for calibration of fluorescence detectors using non-visible light, comprising
a) a housing impervious both to said non-visible light and to said fluorescence to be detected, having at least one opening means to admit passage of said non-visible light and of said fluorescence, b) a standard target element enclosed within said housing, comprising a predetermined combination of one or more predetermined fluorescent substances with one or more other substances, c) an aperture element enclosed within said housing and disposed between said standard target element and said at at least one opening means, d) adapting means for adapting said housing to fit a fluorescence detector, and e) means for adjusting the distance between said adapting means and said standard target element, so that a predetermined intensity of said fluorescence is presented to a detector to be calibrated.
- 25. A standard target element for calibration of fluorescence detectors using non-visible light, comprising a predetermined combination of one or more predetermined fluorescent substances with one or more other substances in fixed proportions, having at least one first side without said fluorescent substances, at least one second side with a predetermined fixed surface area of said combination of substances to be exposed to said detectors during calibration, said combination comprising a first fluorescent substance arranged in a predetermined pattern on a background comprising one or more substances selected from a group consisting of a nonfluorescent substance and a second fluorescent substance having a fluorescent emission spectrum differing from that of said fluorescent substance.
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28. A method for calibrating fluorescence detectors, comprising the steps of
a) preparing a standard target element by the substeps of i) mixing a predetermined amount of a predetermined first fluorescent substance having a first fluorescent emission spectrum with one or more substances selected from the group consisting of A) a non-fluorescent substance and B) a second fluorescent substance having a second fluorescent emission spectrum differing from said first fluorescent emission spectrum and ii) if desired, covering the resultant mixture with material transparent both to non-visible light and to said first fluorescent emission spectrum to complete the preparation of said standard target element, and b) covering a first portion of said standard target element to expose a second portion having a predetermined area, c) adjusting the distance between said standard target element and a fluorescence detector to a predetermined distance, d) illuminating the exposed second portion of said standard target element with said non-visible light, e) measuring the response of said fluorescence detector to fluorescence from said standard target element, and f) adjusting said fluorescence detector response to equal a predetermined value, thus achieving the detector calibration.
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33. A method for preparing a standard target element for calibrating fluorescence detectors, comprising the steps of
a) combining a predetermined amount of a predetermined first fluorescent substance having a first fluorescent emission spectrum with one or more substances selected from the group consisting of A) a non-fluorescent substance and B) a second fluorescent substance having a second fluorescent emission spectrum differing from said first fluorescent emission spectrum, in a mixture, b) forming the resultant mixture into a predetermined shape having at least one first side, c) if desired, covering said first side of said shape with material transparent both to non-visible light and to said first fluorescent emission spectrum, and d) covering a first portion of said first side to expose a second portion having a predetermined area, to complete the preparation of said standard target element.
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34. A method for preparing a standard target element for calibrating fluorescence detectors, comprising the steps of
a) arranging a predetermined amount of a predetermined first fluorescent substance having a first fluorescent emission spectrum into a predetermined pattern on a background comprising one or more substances selected from the group consisting of A) a non-fluorescent substance and B) a second fluorescent substance having a second fluorescent emission spectrum differing from said first fluorescent emission spectrum, b) forming the resultant patterned combination into a predetermined shape having at least one first side including said pattern, c) if desired, covering at least said first side of said shape with material transparent both to non-visible light and to said first fluorescent emission spectrum, and d) covering a first portion of said first side to expose a second portion having a predetermined area, to complete the preparation of said standard target element.
Specification