Real-time method and apparatus for measuring the decay-time constant of a fluorescing phosphor
First Claim
1. A method for determining the decay-time constant of a fluorescing phosphor, said method comprising the steps of:
- irradiating a phosphor with an excitation pulse;
detecting light emitted by the phosphor in response to irradiation with the excitation pulse;
converting the detected light into an electrical signal;
differentiating the electrical signal;
discriminating the zero-crossing point of the differentiated electrical signal; and
outputting a pulse signal having a pulse width corresponding to the time period between the start of the excitation pulse and the time when the differentiated electrical signal reaches zero, wherein the pulse width is proportional to the decay-time constant of the phosphor.
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Abstract
A method for determining the decay-time constant of a fluorescing phosphor is provided, together with an apparatus for performing the method. The apparatus includes a photodetector for detecting light emitted by a phosphor irradiated with an excitation pulse and for converting the detected light into an electrical signal. The apparatus further includes a differentiator for differentiating the electrical signal and a zero-crossing discrimination circuit that outputs a pulse signal having a pulse width corresponding to the time period between the start of the excitation pulse and the time when the differentiated electrical signal reaches zero. The width of the output pulse signal is proportional to the decay-time constant of the phosphor.
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Citations
9 Claims
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1. A method for determining the decay-time constant of a fluorescing phosphor, said method comprising the steps of:
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irradiating a phosphor with an excitation pulse; detecting light emitted by the phosphor in response to irradiation with the excitation pulse; converting the detected light into an electrical signal; differentiating the electrical signal; discriminating the zero-crossing point of the differentiated electrical signal; and outputting a pulse signal having a pulse width corresponding to the time period between the start of the excitation pulse and the time when the differentiated electrical signal reaches zero, wherein the pulse width is proportional to the decay-time constant of the phosphor. - View Dependent Claims (2, 3, 4)
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5. An apparatus for determining the decay-time constant of a fluorescing phosphor, said apparatus comprising:
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a photodetector for detecting light emitted by a phosphor irradiated with an excitation pulse and for converting the detected light into an electrical signal; a differentiator for differentiating the electrical signal; and a zero-crossing discrimination circuit that outputs a pulse signal having a pulse width corresponding to the time period between the start of the excitation pulse and the time when the differentiated electrical signal reaches zero, wherein the width of the output pulse signal is proportional to the decay-time constant of the phosphor. - View Dependent Claims (6, 7, 8, 9)
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Specification