Patent US5291013A successfully refreshed from Google Patents.
US5291013A
Expired / Lapsed
US
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Fiber optical monitor for detecting normal breathing and heartbeat motion based on changes in speckle patterns
Assignee: Alamed Corp
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Filing: 1992-11-13
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Granted: 1994-03-01
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Expires: 2012-11-13
Abstract
Abstract A fiber optic body motion monitor in which light is transmitted through an optical fiber waveguide physically coupled to a body being monitored, and modal noise at the output of the optical fiber waveguide is applied to a photodetector filtered, rectified and analyzed to detect breathing and heartbeats. Detection of breathing is performed by low-pass filtering the rectified and filtered signal, and adaptive thresholding of the low-pass filtered signal. A similar but separate technique is used to detect heartbeats. In one embodiment, reliability of detection is enhanced by reducing the number of speckles of light applied to the photodetector to approximately 50%, thereby to maximize modal noise current. In another embodiment the photodetector has two halves separately illuminated by approximately two-thirds of the light from the optical fiber waveguide. Outputs of the photodetector halves are applied to the positive and negative inputs of an operational amplifier, whereby common mode noise is eliminated and modal noise current and therefore sensitivity of modal noise detection increased.
Inventors
- 👤 Antonio B. Nafarrate
- 👤 Eric G. Rawson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:24
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/68; A61B5/6887; A61B5/6892; A61B5/02; A61B5/024; A61B5/02444; A61B5/103; A61B5/11; A61B5/113; G; G01; G01P; G01P13/00; A61B5/72; A61B5/7235; A61B5/7239; Y; Y10; Y10S; Y10S128/00; Y10S128/92; Y10S128/925
Claims Analysis
Total Claims: 65
Claim 1
Independent Claim
292 words
A fiber optic body motion monitor comprising: a light source; an optical fiber waveguide including an input end, an output end, and a sensing section intermediate said input and output ends, said optical fiber being positioned to receive light from said light source at said input end; movable means for transmitting motion of a body being monitored, said sensing section being coupled to said movable means so as to move therewith; photodetector means positioned proximate to said output end for receiving a speckle pattern of light therefrom, which pattern changes in response to movement of said sensing section, said photodetector means generating electrical signals representative of changes in said speckle pattern; and means for identifying electrical signals indicative of normal breathing and heartbeat motion and for differentiating them from electrical signals indicative of deviations from normal breathing and heartbeat motion, comprising, power determination means for producing a power signal indicative of an amount of power in a frequency band relevant to breathing and heartbeat in the signals generated by said photodetector means, breathing extraction means coupled to said power determination means for extracting from said power signal signals indicative of breathing of said body and outputting a signal indicative of the breathing of said body, heartbeat extraction means coupled to said power determination means for extracting from said power signal signals indicative of heartbeat of said body and outputting a signal indicative of the heartbeat of said body, and indicating means for producing at least one of a display indicative of at least one of the extracted breathing signals and the extracted heartbeat signals and an alarm when at least one of the extracted breathing signals and extracted heartbeat signals is indicative of a deviation from normal breathing and heartbeat motion, respectively.
Claim 2
Dependent Claim
292 words
A fiber optic body motion monitor comprising: a light source; an optical fiber waveguide including an input end, an output end, and a sensing section intermediate said input and output ends, said optical fiber being positioned to receive light from said light source at said input end; movable means for transmitting motion of a body being monitored, said sensing section being coupled to said movable means so as to move therewith; photodetector means positioned proximate to said output end for receiving a speckle pattern of light therefrom, which pattern changes in response to movement of said sensing section, said photodetector means generating electrical signals representative of changes in said speckle pattern; and means for identifying electrical signals indicative of normal breathing and heartbeat motion and for differentiating them from electrical signals indicative of deviations from normal breathing and heartbeat motion, comprising, power determination means for producing a power signal indicative of an amount of power in a frequency band relevant to breathing and heartbeat in the signals generated by said photodetector means, breathing extraction means coupled to said power determination means for extracting from said power signal signals indicative of breathing of said body and outputting a signal indicative of the breathing of said body, heartbeat extraction means coupled to said power determination means for extracting from said power signal signals indicative of heartbeat of said body and outputting a signal indicative of the heartbeat of said body, and indicating means for producing at least one of a display indicative of at least one of the extracted breathing signals and the extracted heartbeat signals and an alarm when at least one of the extracted breathing signals and extracted heartbeat signals is indicative of a deviation from normal breathing and heartbeat motion, respectively.
Claim 3
Dependent Claim
62 words
The monitor according to claim 1, wherein said breathing extraction means comprises: low pass filter means for passing signals in a passband in which breathing signals have significant content; threshold means for detecting when signals passed by said bandpass filter means exceed a threshold; and processor means for generating said signal indicative of breathing based on signals detected by said threshold means.
Claim 4
Dependent Claim
40 words
The monitor according to claim 2, wherein said threshold means comprises an adaptable threshold detector which produces a varying threshold as a function of a difference between maximum and minimum levels of signals output by said low pass filter means.
Claim 5
Dependent Claim
72 words
The monitor according to claim 3, wherein said adaptable threshold detector resets said maximum and minimum levels to new levels at the level of the signal output by said low pass filter means whenever said signal output by said low pass filter means exceeds a present maximum level or falls below a present minimum level, respectively, and thereafter decreases said reset maximum level and increases said reset minimum level at predetermined rates.
Claim 6
Dependent Claim
62 words
The monitor according to claim 4, wherein said power determination means comprises a bandpass filter having a center frequency f max at which the breathing signals and heartbeat signals have greatest content and a passband of 0.33 to 3.0 f max , and a rectifier, and the low pass filter of said breathing extraction means has a cutoff frequency of 0.5 Hz.
Claim 7
Dependent Claim
25 words
The monitor according to claim 5, wherein the bandpass filter of said power determination means has a passband of 0.50 to 2.0 f max .
Claim 8
Dependent Claim
61 words
The monitor according to claim 1, wherein said heartbeat extraction means comprises: bandpass filter means for passing signals in a passband in which heartbeat signals have significant content; threshold means for detecting when signals passed by said bandpass filter means exceed a threshold; and processor means for generating said signal indicative of heartbeat based on signals detected by said threshold means.
Claim 9
Dependent Claim
48 words
The monitor according to claim 7, wherein said threshold means comprises: means for averaging the peak amplitudes of a predetermined number of peaks in the signals passed by said bandpass filter means; and means for setting a threshold equal to a predetermined percentage of the averaged peak amplitudes.
Claim 10
Dependent Claim
61 words
The monitor according to claim 7, wherein said power determination means comprises a bandpass filter having a center frequency f max , at which the breathing signals and heartbeat signals have greatest content and a passband of 0.33 to 3.0 f max , and a rectifier, and the bandpass filter means of said heartbeat extraction means has a 0.8-5.0 Hz passband.
Claim 11
Dependent Claim
25 words
The monitor according to claim 9, wherein the bandpass filter of said power determination means has a passband of 0.50 to 2.0 f max .
Claim 12
Dependent Claim
72 words
The monitor according to claim 4, wherein said heartbeat extraction means comprises: bandpass filter means for passing integrated signals in a passband in which heartbeat signals have significant content; threshold means for detecting when signals passed by said bandpass filter means of said heartbeat extraction means exceed a threshold; and processor means for generating said signal indicative of heartbeats based on signals detected by said threshold means of said heartbeat extraction means.
Claim 13
Dependent Claim
55 words
The monitor according to claim 11, wherein said threshold means of said heartbeat extraction means comprises: means for averaging the peak amplitudes of a predetermined number of signals passed by said bandpass filter means of said heartbeat extraction means; and means for setting a threshold equal to a predetermined percentage of the averaged peak amplitudes.
Claim 14
Dependent Claim
79 words
The monitor according to claim 12, wherein said power determination means comprises a bandpass filter having a center frequency f max , at which the breathing signals and heartbeat signals have greatest content and a passband of 0.33 to 3.0 f max , and a rectifier, the low pass filter means of said heartbeat extraction means has a 0.8-5.0 Hz passband, and the low pass filter means of the breathing extraction means has a cutoff frequency of 0.5 Hz.
Claim 15
Dependent Claim
42 words
The monitor according to claims 1, 3, 8 or 13, wherein said photodetector means comprise a single photodetector positioned at a distance from said waveguide output end so as to intercept 24-74% of the speckles of light transmitted at said output end.
Claim 16
Dependent Claim
56 words
The monitor according to claims 1, 3, 8 or 13, wherein said photodetector means comprises a single photodetector, further comprising: filter means coupled to the output end of said optical fiber waveguide for reducing the number of speckles of light applied to said photodetector means to a range of 27-74% of the modes of light transmitted.
Claim 17
Dependent Claim
110 words
The monitor according to claims 1, 3, 8 or 13, wherein said photodetector means comprises: plural photoconductive elements disposed opposite to the end of said optical fiber waveguide so that said elements are illuminated by said speckle pattern of light, said elements producing a pair of outputs each representing approximately half of the speckle pattern of light incident on said elements; and differential amplifier means having a pair of inputs coupled to respective of the outputs produced by said plural photoconductive elements and an output which is a difference signal representing a difference between the *outputs produced by said plural photoconductive elements, said difference signal applied to said identifying means.
Claim 18
Dependent Claim
36 words
The monitor according to claim 16, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 33-100% of the speckles of light transmitted at said output end.
Claim 19
Dependent Claim
36 words
The monitor according to claim 16, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 45-83% of the speckles of light transmitted at said output end.
Claim 20
Dependent Claim
36 words
The monitor according to claim 18, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 60-70% of the speckles of light transmitted at said output end.
Claim 21
Dependent Claim
43 words
The monitor according to claim 16, comprising: filter means coupled to the output end of said optical fiber waveguide for reducing the number of speckles of light applied to said photodetector means to a range of 33-100% of the speckles of light transmitted.
Claim 22
Dependent Claim
24 words
The monitor according to claim 20, wherein said filter means reduces the number of speckles of light applied to said photodetector means to 45-83%.
Claim 23
Dependent Claim
24 words
The monitor according to claim 21, wherein said filter means reduces the number of speckles of light applied to said photodetector means to 60-70%.
Claim 24
Dependent Claim
287 words
A fiber optic body motion monitor comprising: a light source; an optical fiber waveguide including an input end, an output end, and a sensing section intermediate said input and output ends, said optical fiber being positioned to receive light from said light source at said input end; movable means for transmitting motion of a body being monitored, said sensing section being coupled to said movable means so as to move therewith; photodetector means positioned proximate to said output end for receiving a speckle pattern of light therefrom, which pattern changes in response to movement of said sensing section, said photodetector means generating electrical signals representative of changes in said speckle pattern; and means for identifying electrical signals indicative of normal breathing and heartbeat motion and for differentiating them from electrical signals indicative of deviations from normal breathing and heartbeat motion, comprising, power determination means for producing a power signal indicative of an amount of power in a frequency band relevant to breathing in the signals generated by said photodetector means, breathing extraction means coupled to said power determination means for extracting from said power signal signals indicative of breathing of said body and outputting a signal indicative of the breathing of said body, comprising, low pass filter means for passing signals in a passband in which breathing signals have significant content, threshold means for detecting when signals passed by said bandpass filter means exceed a threshold, processor means for generating said signal indicative of breathing based on signals detected by said threshold means, and indicating means for producing at least one of a display of said signal indicative of breathing and an alarm when said signal indicative of breathing is indicative of a deviation from normal breathing.
Claim 25
Dependent Claim
287 words
A fiber optic body motion monitor comprising: a light source; an optical fiber waveguide including an input end, an output end, and a sensing section intermediate said input and output ends, said optical fiber being positioned to receive light from said light source at said input end; movable means for transmitting motion of a body being monitored, said sensing section being coupled to said movable means so as to move therewith; photodetector means positioned proximate to said output end for receiving a speckle pattern of light therefrom, which pattern changes in response to movement of said sensing section, said photodetector means generating electrical signals representative of changes in said speckle pattern; and means for identifying electrical signals indicative of normal breathing and heartbeat motion and for differentiating them from electrical signals indicative of deviations from normal breathing and heartbeat motion, comprising, power determination means for producing a power signal indicative of an amount of power in a frequency band relevant to breathing in the signals generated by said photodetector means, breathing extraction means coupled to said power determination means for extracting from said power signal signals indicative of breathing of said body and outputting a signal indicative of the breathing of said body, comprising, low pass filter means for passing signals in a passband in which breathing signals have significant content, threshold means for detecting when signals passed by said bandpass filter means exceed a threshold, processor means for generating said signal indicative of breathing based on signals detected by said threshold means, and indicating means for producing at least one of a display of said signal indicative of breathing and an alarm when said signal indicative of breathing is indicative of a deviation from normal breathing.
Claim 26
Dependent Claim
39 words
The monitor according to claim 23, wherein said threshold means comprises an adaptable threshold detector which produces a varying threshold as a function of a difference between maximum and minimum levels of signals output by said bandpass filter means.
Claim 27
Dependent Claim
72 words
The monitor according to claim 24, wherein said adaptable threshold detector resets said maximum and minimum levels to new levels at the level of the signal output by said low pass filter means whenever said signal output by said low pass filter means exceeds a present maximum level or falls below a present minimum level, respectively, and thereafter decreases said reset maximum level and increases said reset minimum level at predetermined rates.
Claim 28
Dependent Claim
63 words
The monitor according to claim 25, wherein said power determination means comprises a bandpass filter having a center frequency f max at which the breathing signals and heartbeat signals have greatest content and a passband of 0.33 to 3.0 f max , and a rectifier, and the low pass filter means of said breathing extraction means has a cutoff frequency of 0.5 Hz.
Claim 29
Dependent Claim
38 words
The monitor according to claim 26, wherein said photodetector means comprises plural photoconductive elements positioned at a distance from the waveguide output end so as to intercept 33-100% of the speckles of light transmitted at said output end.
Claim 30
Dependent Claim
42 words
The monitor according to claims 23, 24, 25 or 26, wherein said photodetector means comprise a single photodetector positioned at a distance from said waveguide output end so as to intercept 24-74% of the speckles of light transmitted at said output end.
Claim 31
Dependent Claim
55 words
The monitor according to claims 23, 24, 25 or 26, comprising: said photodetecting means comprising a single photodetector; and filter means coupled to the output end of said optical fiber waveguide for reducing the number of speckles of light applied to said photodetector means to a range of 27-74% of the speckles of light transmitted.
Claim 32
Dependent Claim
105 words
The monitor according to claims 23, 24, 25 or 26, wherein said photodetector means comprises: plural photoconductive elements disposed opposite to said optical fiber waveguide so that said elements are illuminated by said speckle pattern of light, said elements producing a pair of outputs each representing approximately half of the speckle pattern of light incident on said elements; and differential amplifier means having a pair of inputs coupled to respective outputs produced by said plural photoconductive elements and an output which is a difference signal representing a difference between the outputs produced by said plural photoconductive elements, said difference signal applied to said identifying means.
Claim 33
Dependent Claim
36 words
The monitor according to claim 30, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 33-100% of the speckles of light transmitted at said output end.
Claim 34
Dependent Claim
36 words
The monitor according to claim 31, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 45-83% of the speckles of light transmitted at said output end.
Claim 35
Dependent Claim
36 words
The monitor according to claim 32, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 60-70% of the speckles of light transmitted at said output end.
Claim 36
Dependent Claim
43 words
The monitor according to claim 30, comprising: filter means coupled to the output end of said optical fiber waveguide for reducing the number of speckles of light applied to said photodetector means to a range of 33-100% of the speckles of light transmitted.
Claim 37
Dependent Claim
24 words
The monitor according to claim 34, wherein said filter means reduces the number of speckles of light applied to said photodetector means to 45-83%.
Claim 38
Dependent Claim
24 words
The monitor according to claim 35, wherein said filter means reduces the number of speckles of light applied to said photodetector means to 60-70%.
Claim 39
Dependent Claim
286 words
A fiber optic body motion monitor comprising: a light source; an optical fiber waveguide including an input end, an output end, and a sensing section intermediate said input and out ends, said optical fiber being positioned to receive light from said light source at said input end; movable means for transmitting motion of a body being monitored, said sensing section being coupled to said movable means so as to move therewith; photodetector means positioned proximate to said output end for receiving a speckle pattern of light therefrom, which pattern changes in response to movement of said sensing section, said photodetector means generating electrical signals representative of changes in said speckle pattern; and means for identifying electrical signals indicative of normal breathing and heartbeat motion and for differentiating them from electrical signals indicative of deviations from normal breathing and heartbeat motion, comprising, power determination means for producing a power signal indicative of an amount of power in a frequency band relevant to heartbeat in the signals generated by said photodetector means, heartbeat extraction means coupled to said power determination means for extracting from said power signal signals indicative of heartbeat of said body and outputting a signal indicative of the heartbeat of said body, comprising, bandpass filter means for passing signals in a passband in which breathing signals have significant content, threshold means for detecting when signals passed by said bandpass filter means exceed a threshold, processor means for generating said signal indicative of heartbeats based on signals detected by said threshold means, and indicating means for producing at least one of a display of said signal indicative of heartbeats and an alarm when said signal indicative of heartbeats is indicative of a deviation from normal heartbeats.
Claim 40
Dependent Claim
286 words
A fiber optic body motion monitor comprising: a light source; an optical fiber waveguide including an input end, an output end, and a sensing section intermediate said input and out ends, said optical fiber being positioned to receive light from said light source at said input end; movable means for transmitting motion of a body being monitored, said sensing section being coupled to said movable means so as to move therewith; photodetector means positioned proximate to said output end for receiving a speckle pattern of light therefrom, which pattern changes in response to movement of said sensing section, said photodetector means generating electrical signals representative of changes in said speckle pattern; and means for identifying electrical signals indicative of normal breathing and heartbeat motion and for differentiating them from electrical signals indicative of deviations from normal breathing and heartbeat motion, comprising, power determination means for producing a power signal indicative of an amount of power in a frequency band relevant to heartbeat in the signals generated by said photodetector means, heartbeat extraction means coupled to said power determination means for extracting from said power signal signals indicative of heartbeat of said body and outputting a signal indicative of the heartbeat of said body, comprising, bandpass filter means for passing signals in a passband in which breathing signals have significant content, threshold means for detecting when signals passed by said bandpass filter means exceed a threshold, processor means for generating said signal indicative of heartbeats based on signals detected by said threshold means, and indicating means for producing at least one of a display of said signal indicative of heartbeats and an alarm when said signal indicative of heartbeats is indicative of a deviation from normal heartbeats.
Claim 41
Dependent Claim
46 words
The monitor according to claim 37, wherein said threshold means comprises: means for averaging the peak amplitudes of a predetermined number of signals previously passed by said bandpass filter means; and means for setting a threshold equal to a predetermined percentage of the averaged peak amplitudes.
Claim 42
Dependent Claim
60 words
The monitor according to claim 37, wherein said power determination means comprises a bandpass filter having center frequency f max at which the breathing signals and heartbeat signals have greatest content and a passband of 0.33 to 3.0 f max , and a rectifier, and the secondary bandpass filter means of said heartbeat extraction means has a 0.8-5.0 Hz passband.
Claim 43
Dependent Claim
25 words
The monitor according to claim 39, wherein the bandpass filter of said power determination means has a passband of 0.50 to 2.0 f max .
Claim 44
Dependent Claim
41 words
The monitor according to claims 37, 38, or 40, wherein said photodetector means comprise a single photodetector positioned at a distance from said waveguide output end so as to intercept 24-74% of the speckles of light transmitted at said output end.
Claim 45
Dependent Claim
54 words
The monitor according to claims 37, 38, or 40, comprising: said photodetector means comprising a single photodetector; and filter means coupled to the output end of said optical fiber waveguide for reducing the number of speckles of light applied to said photodetector means to a range of 27-74% of the speckles of light transmitted.
Claim 46
Dependent Claim
104 words
The monitor according to claims 37, 38, or 40, wherein said photodetector means comprises: plural photoconductive elements disposed opposite to said optical fiber waveguide so that said elements are illuminated by said speckle pattern of light, said elements producing a pair of outputs each representing approximately half of the speckle pattern of light incident on said elements; and differential amplifier means having a pair of inputs coupled to respective outputs produced by said plural photoconductive elements and an output which is a difference signal representing a difference between the outputs produced by said plural photoconductive elements, said difference signal applied to said identifying means.
Claim 47
Dependent Claim
36 words
The monitor according to claim 43, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 33-100% of the speckles of light transmitted at said output end.
Claim 48
Dependent Claim
36 words
The monitor according to claim 44, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 45-83% of the speckles of light transmitted at said output end.
Claim 49
Dependent Claim
36 words
The monitor according to claim 45, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 60-70% of the speckles of light transmitted at said output end.
Claim 50
Dependent Claim
43 words
The monitor according to claim 43, comprising: filter means coupled to the output end of said optical fiber waveguide for reducing the number of speckles of light applied to said photodetector means to a range of 33-100% of the speckles of light transmitted.
Claim 51
Dependent Claim
24 words
The monitor according to claim 47, wherein said filter means reduces the number of speckles of light applied to said photodetector means to 45-83%.
Claim 52
Dependent Claim
24 words
The monitor according to claim 48, wherein said filter means reduces the number of speckles of light applied to said photodetector means to 60-70%.
Claim 53
Dependent Claim
270 words
A fiber optic motion monitor comprising: a light source; an optical fiber waveguide including an input end, an output end, and a sensing section intermediate said input and output ends, said optical fiber being positioned to receive light from said light source at said input end; movable means for transmitting motion of an object being monitored, said sensing section being coupled to said movable means so as to move therewith; photodetector means positioned proximate to said output end for receiving a speckle pattern of light therefrom, which pattern changes in response to movement of said sensing section, said photodetector means generating electrical signals representative of changes in said speckle pattern; and means for processing said electrical signals to identify predetermined variations in said electrical signals, comprising, power determination means for producing a power signal indicative of an amount of power in a predetermined frequency band in the electrical signals generated by said photodetector means, extraction means coupled to said power determination means for extracting from said power signal signals indicative of said predetermined variations, a signal indicative of the predetermined variations comprising, filter means for passing signals in said predetermined frequency band in which predetermined variations have significant content, threshold means for detecting when signals passed by said filter means exceed a threshold, and processor means for generating said signal indicative of said predetermined variations based on signals detected by said threshold means, and indicating means for producing at least one of a display of said signal indicative of predetermined variations and an alarm when said signal indicative of predetermined variations is indicative of a deviation from a predetermined range.
Claim 54
Dependent Claim
270 words
A fiber optic motion monitor comprising: a light source; an optical fiber waveguide including an input end, an output end, and a sensing section intermediate said input and output ends, said optical fiber being positioned to receive light from said light source at said input end; movable means for transmitting motion of an object being monitored, said sensing section being coupled to said movable means so as to move therewith; photodetector means positioned proximate to said output end for receiving a speckle pattern of light therefrom, which pattern changes in response to movement of said sensing section, said photodetector means generating electrical signals representative of changes in said speckle pattern; and means for processing said electrical signals to identify predetermined variations in said electrical signals, comprising, power determination means for producing a power signal indicative of an amount of power in a predetermined frequency band in the electrical signals generated by said photodetector means, extraction means coupled to said power determination means for extracting from said power signal signals indicative of said predetermined variations, a signal indicative of the predetermined variations comprising, filter means for passing signals in said predetermined frequency band in which predetermined variations have significant content, threshold means for detecting when signals passed by said filter means exceed a threshold, and processor means for generating said signal indicative of said predetermined variations based on signals detected by said threshold means, and indicating means for producing at least one of a display of said signal indicative of predetermined variations and an alarm when said signal indicative of predetermined variations is indicative of a deviation from a predetermined range.
Claim 55
Dependent Claim
38 words
The monitor according to claim 50, wherein said threshold means comprises an adaptable threshold detector which produces a varying threshold as a function of a difference between maximum and minimum levels of signals output by said filter means.
Claim 56
Dependent Claim
68 words
The monitor according to claim 51, wherein said adaptable threshold detector resets said maximum and minimum levels to new levels at the level of the signal output by said filter means whenever said signal output by said filter means exceeds a present maximum level or falls below a present minimum level, respectively, and thereafter decreases said reset maximum level and increases said reset minimum level at predetermined rates.
Claim 57
Dependent Claim
38 words
The monitor according to claim 52, wherein said photodetector means comprises a single photodetector positioned at a distance from said waveguide output end so as to intercept 24-74% of the speckles of light transmitted at said output end.
Claim 58
Dependent Claim
51 words
The monitor according to claim 52, comprising: said photodetecting means comprising a single photodetector; and filter means coupled to the output end of said optical fiber waveguide for reducing the number of speckles of light applied to said photodetector means to a range of 27-74% of the speckles of light transmitted.
Claim 59
Dependent Claim
101 words
The monitor according to claim 52, wherein said photodetector means comprises: plural photoconductive elements disposed opposite to said optical fiber waveguide so that said elements are illuminated by said speckle pattern of light, said elements producing a pair of outputs each representing approximately half of the speckle pattern of light incident on said elements; and differential detector means having a pair of inputs coupled to respective outputs produced by said plural photoconductive elements and an output which is a difference signal representing a difference between the outputs produced by said plural photoconductive elements, said difference signal applied to said identifying means.
Claim 60
Dependent Claim
36 words
The monitor according to claim 55, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 33-100% of the speckles of light transmitted at said output end.
Claim 61
Dependent Claim
36 words
The monitor according to claim 56, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 45-83% of the speckles of light transmitted at said output end.
Claim 62
Dependent Claim
36 words
The monitor according to claim 57, wherein said plural photoconductive elements are positioned at a distance from the waveguide output end so as to intercept 60-70% of the speckles of light transmitted at said output end.
Claim 63
Dependent Claim
43 words
The monitor according to claim 55, comprising: filter means coupled to the output end of said optical fiber waveguide for reducing the number of speckles of light applied to said photodetector means to a range of 33-100% of the speckles of light transmitted.
Claim 64
Dependent Claim
24 words
The monitor according to claim 59, wherein said filter means reduces the number of speckles of light applied to said photodetector means to 45-83%.
Claim 65
Dependent Claim
24 words
The monitor according to claim 60, wherein said filter means reduces the number of speckles of light applied to said photodetector means to 60-70%.
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| 7.5 Years (Year 8) | 2001-02-28 | 2001-08-30 | 2002-03-01 | $3760.00 | Window Closed / Lapsed |
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