Low noise optical probe
First Claim
1. An oximeter sensor for measuring electromagnetic energy which has been attenuated by a living flesh material, said sensor comprising:
- a light source;
a base having a thickness, said base being positioned adjacent said flesh material when said optical probe is positioned for use;
an aperture in said base, said aperture forming an entrance to a chamber which extends into said base, said aperture and chamber having a width of at least 3 mm and, said chamber having a particular depth such that the flesh material which penetrates into the chamber via said aperture is not substantially compressed with change in pressure between said flesh material and a surface defining said aperture typically expected from a patient; and
a detector located within said chamber such that when said oximeter sensor is in use, said detector and light source are generally in axial alignment for transmission, said detector separated from any of said portion of flesh material which has penetrated into said chamber, said detector receiving electromagnetic energy transmitted by said light source and through said flesh material, said detector operative to generate a signal in response to said electromagnetic radiation, said width of said aperture being sized to reduce motion artifacts in said signal due to motion typically expected for a living patient.
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0 Petitions
Accused Products
Abstract
An optical probe for measurements, which is particularly suited to reduce noise in measurements taken on an easily compressible material, such as a finger, a toe, a forehead, an earlobe, or a lip. The probe includes a base having an aperture which leads to a chamber. The base is placed adjacent a portion of the material, the chamber being placed directly adjacent any easily compressible portion of the material. A photodetector is located within the chamber and does not contact the material. A light emitting diode (LED) is affixed to the material, opposite the photodetector and above the chamber. The material which is supported by the aperture and therefore rests above or has intruded into the chamber is inhibited from compression since nothing comes in contact with this portion of the material, even when the material moves. Thus, light from the LED is directed through a stabilized portion of the material, i.e., the optical path length through which light travels is stabilized, even during motion of the material. This reduces noise in the signal measured by the photodetector. A scattering medium is interposed between the LED and the material, between the material and the photodetector, or between the LED and the material as well as between the material and the photodetector. The scattering medium is used to improve the signal-to-noise ratio of the received optical signal.
1135 Citations
9 Claims
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1. An oximeter sensor for measuring electromagnetic energy which has been attenuated by a living flesh material, said sensor comprising:
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a light source; a base having a thickness, said base being positioned adjacent said flesh material when said optical probe is positioned for use; an aperture in said base, said aperture forming an entrance to a chamber which extends into said base, said aperture and chamber having a width of at least 3 mm and, said chamber having a particular depth such that the flesh material which penetrates into the chamber via said aperture is not substantially compressed with change in pressure between said flesh material and a surface defining said aperture typically expected from a patient; and a detector located within said chamber such that when said oximeter sensor is in use, said detector and light source are generally in axial alignment for transmission, said detector separated from any of said portion of flesh material which has penetrated into said chamber, said detector receiving electromagnetic energy transmitted by said light source and through said flesh material, said detector operative to generate a signal in response to said electromagnetic radiation, said width of said aperture being sized to reduce motion artifacts in said signal due to motion typically expected for a living patient. - View Dependent Claims (2, 3)
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4. A method of making a motion artifact resistant oximeter sensor, said method comprising the steps of:
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forming a chamber having an aperture and sizing said aperture with width large enough such that a compressible portion of living tissue material when covering said aperture may enter said chamber when said sensor is in use, said chamber sized to substantially reduce motion artifact with changes in pressure between said tissue material in the area about said aperture expected due to patient movement; locating a detector in said chamber in a position to detect electromagnetic energy which passes through a portion of tissue material covering the aperture of said chamber, said detector positioned so as not to contact said portion of tissue material; and locating an electromagnetic energy source on said oximeter sensor such that it is generally in axial alignment of transmission with said detector when said oximeter sensor is in use. - View Dependent Claims (5, 6, 7, 9)
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8. A method of stabilizing the optical path length through living flesh between a light source and a detector in an optical probe wherein the optical probe has a base and the detector is located in a chamber in the base that opens through an aperture to a surface of the base, said optical probe configure to be attached to flesh of a living subject, the method comprising:
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selecting the size of said aperture so that a portion of the surface of the living flesh through which the light will pass, when said optical probe is attached to flesh of said living subject, will protrude substantially uncompressed into the detector chamber upon motion typically expected for a living patient and so that the size of the aperture substantially reduces motion artifact; and affixing the probe to the living flesh so that the said portion of the surface of the living flesh which protrudes into the chamber and the base moves with the movement, if any, of the adjacent living flesh.
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Specification