Excitation and detection apparatus for remote sensor connected by optical fiber

Claim 2

Apparatus for excitation and detection of luminescence comprising: a phosphorescent material which emits a relatively long-lived luminescence when exposed to energy in a predetermined wavelength range; source means coupled to said phosphorescent material for generating an incident pulsed energy signal within said predetermined wavelength range to cause said phosphorescent material to generate said long-lived luminescence; and detector means coupled to said phosphorescent material for selectively detecting the long-lived luminescence from said phosphorescent material when said incident pulsed energy signal has substantially ceased and any relatively short-lived background luminescence generated in the apparatus has substantially ceased, said detector means comprising a first detector channel for detecting a first wavelength of said long-lived luminescence and a second detector channel for detecting a second wavelength of said long-lived luminescence, said first detector channel including first detection means for producing a first signal responsive to the first wavelength of said long-lived luminescence and first circuit means for storing said first signal when said incident pulsed energy signal has substantially ceased and said second detector channel including second detection means for producing a second signal responsive to the second wavelength of said long-lived luminescence and second circuit means for storing said second signal when said incident pulsed energy signal has substantially ceased.

Claim 3

Apparatus as defined in claim 1 further including an optical fiber for coupling the incident pulsed energy signal from the source means to the phosphorescent material and for coupling the long-lived luminescence from the phosphorescent material to the detector means, the phosphorescent material being disposed at one end of said fiber and said source means and said detector means being coupled to the other end of said fiber along a common optical path.

Claim 4

Apparatus as defined in claim 2 further including beam splitter means positioned in said optical path for directing said pulsed energy signal from said light source to said optical fiber and for transmitting said long-lived luminescence from said optical fiber to said detector means and alignment means for varying the orientation of said beam splitter relative to the axis of said optical fiber to permit alignment of said pulsed incident energy signal with said optical fiber.

Claim 5

Apparatus as defined in claim 3 wherein said alignment means comprises adjustable mounting means for said beam splitter, said mounting means including means for rotating said beam splitter about two perpendicular axes.

Claim 6

Apparatus as defined in claim 2 further including calibration source means for supplying a first calibration signal at said first wavelength to said first detector channel and a second calibration signal at said second wavelength to said second detector channel for calibration of said first and second detector channels.

Claim 7

Apparatus as defined in claim 5 wherein said calibration source means includes a calibration light source for providing the first and second calibration signals and control means for controlling said calibration light source to provide said first and second calibration signals within predetermined intensity limits.

Claim 8

Apparatus as defined in claim 6 wherein said control means includes means for sensing said first and second calibration signals, means for comparing said calibration signals with respective predetermined intensity limits and means for providing first and second error signals respectively, to said calibration light source when either of said calibration energy signals is outside its respective predetermined intensity limit.

Claim 9

Apparatus as defined in claim 7 wherein said calibration source comprises a first light emitting diode providing said first calibration signal and a second light emitting diode providing said second calibration signal.

Claim 10

Apparatus as defined in claim 2 wherein said detector means includes spurious signal detecting means for determining that said detector means is receiving spurious light signals on said optical fiber.

Claim 11

Apparatus as defined in claim 9 wherein said spurious signal sensing means includes shutter means for selectively blocking said optical path from said optical fiber and means for comparing the light signals received by said detector means in the blocked and unblocked conditions when said source means is deenergized.

Claim 12

Apparatus as defined in claim 10 wherein said shutter means includes a shutter positioned adjacent the other end of said optical fiber and movable to a position where it blocks the optical path between said optical fiber and detector means.

Claim 13

Apparatus as defined in claim 1 wherein said first circuit means includes first integrator means for storing said first signal and first gating means for coupling said first signal to said first integrator means only when said source means is off and wherein said second circuit means includes second integrator means for storing said second signal and second gating means for coupling said second signal to said second integrator means only when said source means is off.

Claim 14

Apparatus as defined in claim 12 wherein said first and second circuit means each include means for averaging said first and second signals, respectively, over multiple incident pulsed energy signals.

Claim 15

Sensing apparatus comprising: an optical fiber; a phosphorescent material coupled to one end of said optical fiber, said phosphorescent material emitting a relatively long-lived luminescence when exposed to energy in a predetermined wavelength range, said long-lived luminescence including a measuring wavelength having an intensity responsive to a quantity being sensed and a reference wavelength having a relatively constant intensity; source means coupled to the other end of said optical fiber for generating an incident pulsed energy signal within said predetermined wavelength range to cause said phosphorescent material to generate said long-lived luminescence; and detector means coupled to the other end of said optical fiber for selectively detecting the long-lived luminescence from said phosphorescent material, said detector means including a first detector channel for detecting the measuring wavelength and providing a first signal responsive to the intensity of the measuring wavelength, a second detector channel for detecting the reference wavelength and providing a second signal responsive to the intensity of the reference wavelength, and signal processing means responsive to said first signal and said second signal and providing an output representative of the quantity being sensed, said signal processing means including first circuit means for integrating said first signal when said incident pulsed energy signal has substantially ceased and second circuit means for integrating said second signal when said incident pulsed energy signal has substantially ceased.

Claim 16

Sensing apparatus comprising: an optical fiber; a phosphorescent material coupled to one end of said optical fiber, said phosphorescent material emitting a relatively long-lived luminescence when exposed to energy in a predetermined wavelength range, said long-lived luminescence including a measuring wavelength having an intensity responsive to a quantity being sensed and a reference wavelength having a relatively constant intensity; source means coupled to the other end of said optical fiber for generating an incident pulsed energy signal within said predetermined wavelength range to cause said phosphorescent material to generate said long-lived luminescence; and detector means coupled to the other end of said optical fiber for selectively detecting the long-lived luminescence from said phosphorescent material, said detector means including a first detector channel for detecting the measuring wavelength and providing a first signal responsive to the intensity of the measuring wavelength, a second detector channel for detecting the reference wavelength and providing a second signal responsive to the intensity of the reference wavelength, and signal processing means responsive to said first signal and said second signal and providing an output representative of the quantity being sensed, said signal processing means including first circuit means for integrating said first signal when said incident pulsed energy signal has substantially ceased and second circuit means for integrating said second signal when said incident pulsed energy signal has substantially ceased.

Claim 17

Sensing apparatus as defined in claim 14 wherein said first circuit means and said second circuit means include means for integrating said first and second signals, respectively, after multiple incident pulsed energy signals to obtain average values of said first and second signals.

Claim 18

Sensing apparatus as defined in claim 14 wherein said source means and said detector means are coupled to said optical fiber along a common optical path and further including beam splitter means positioned in said optical path for directing said pulsed energy signal from said source means to said optical fiber and for transmitting said long-lived luminescence from said optical fiber to said detector means and alignment means for varying the orientation of said beam splitter relative to the axis of said optical fiber to permit alignment of said pulsed incident energy signal with said optical fiber.

Claim 19

Sensing apparatus as defined in claim 14 further including calibration source means for supplying a first calibration signal at the measuring wavelength to said first detector channel and a second calibration signal at the reference wavelength to said second detector channel for calibration of said first and second detector channels.

Claim 20

A sensing method comprising the steps of: stimulating a phosphorescent material with an incident pulsed energy signal within a predetermined wavelength range to cause emission of a relatively long-lived luminescence including a measuring wavelength having an intensity responsive to a quantity being sensed and a reference wavelength having a relatively constant intensity; detecting the measuring wavelength and providing a first signal responsive to the intensity of the measuring wavelength; detecting the reference wavelength and providing a second signal responsive to the intensity of the reference wavelength; and processing the first signal and the second signal and providing an output representative of the quantity being measured, the step of processing the first signal and the second signal including the steps of integrating the first signal when said incident pulsed energy signal has substantially ceased and integrating the second signal when said incident pulsed energy signal has substantially ceased.

Claim 21

A sensing method comprising the steps of: stimulating a phosphorescent material with an incident pulsed energy signal within a predetermined wavelength range to cause emission of a relatively long-lived luminescence including a measuring wavelength having an intensity responsive to a quantity being sensed and a reference wavelength having a relatively constant intensity; detecting the measuring wavelength and providing a first signal responsive to the intensity of the measuring wavelength; detecting the reference wavelength and providing a second signal responsive to the intensity of the reference wavelength; and processing the first signal and the second signal and providing an output representative of the quantity being measured, the step of processing the first signal and the second signal including the steps of integrating the first signal when said incident pulsed energy signal has substantially ceased and integrating the second signal when said incident pulsed energy signal has substantially ceased.

Claim 22

A sensing method as defined in claim 18 wherein the step of processing the first signal and the second signal includes the step of inhibiting the first signal and the second signal from being integrated during said incident pulsed energy signal.

Claim 23

A sensing method as defined in claim 19 wherein the step of processing the first signal and the second signal includes repeating the integration of said first signal and said second signal after multiple incident pulsed energy signals so as to obtain average values of said first and second signals.

Claim 24

A sensing method as defined in claim 18 further including the steps of coupling the incident pulsed energy signal to the phosphorescent material through an optical fiber, coupling the long-lived luminescence through the optical fiber for detection and detecting spurious light signals on said optical fiber by comparing a detected light signal when said optical fiber is blocked with a detected light signal when said optical fiber is unblocked, spurious light signals being detected when the detected signals in blocked and unblocked conditions differ by more than a predetermined amount.