Abstract: An implantable diagnostic device in accordance with the present disclosure includes a probe assembly that can be implemented in a variety of ways. A few example implementations include: a needle inside which is located a bio-sensor chip (the needle being insertable into a human being); a compact package containing the bio-sensor chip (the compact package configured for placement inside a catheter); or a silicon-based bio-sensor package configured for insertion into a vein.

Abstract: An ocular sensor (110) is proposed for verification of at least one analyte in an eye fluid. The ocular sensor (110) is composed of at least one sensor material which is designed to change at least one optical characteristic in the presence of the at least one analyte. Furthermore, the ocular sensor (110) comprises at least one sensor chip which has at least one integrated optical detector (122) for verification of the optical characteristic. A measurement system (166) is also proposed for verification of at least one analyte in an eye fluid, which measurement system (166) comprises an ocular sensor (110) according to the invention as well as an evaluation unit (168) which is designed to interchange information with the sensor chip (118).

Abstract: A device for measuring a hydration status based on an analyte concentration in a subject. The device includes: a light source configured for illuminating at least a portion of an anterior region of an eye of the subject with incident light having a substantially broad illumination spectrum at an angle substantially tangential to the surface of the eye; an optical collector configured for detecting reflected light from the at least a portion of the anterior region of the eye; an analyzer configured for analyzing the detected reflected light; and a processor configured to determine the analyte concentration level in the subject based on the analyzed reflected light, wherein the processor determines a hydration status of the subject based on the analyte concentration level and reference data.

Abstract: A device for measuring an analyte concentration level in a subject. The device includes: a light source configured for illuminating at least a portion of an anterior region of an eye of the subject with incident light having a substantially broad illumination spectrum at an angle substantially tangential to the surface of the eye; an optical collector configured for detecting reflected light from the at least a portion of the anterior region of the eye; an analyzer configured for analyzing the detected reflected light; and a processor configured to determine the analyte concentration level in the subject based on the analyzed reflected light.

Abstract: An embodiment of the invention provides a method that captures a diagnostic image of a retina having at least one lesion, wherein the lesion includes a plurality of spots to be treated. Information is received from a user interface, wherein the information includes a duration, intensity, and/or wavelength of treatment for each of the spots. A real-time image of the retina is captured; and, a composite image is created by linking the diagnostic image to the real-time image. At least one updated real-time image of the retina is obtained using eye tracking and/or image stabilization; and, an annotated image is created by modifying the composite image based on the updated real-time image. A localized laser beam is delivered to each of the spots according to the information, the composite image, and the annotated image.

Abstract: A method includes directing toward a portion of a subject's body a first pulse of electromagnetic energy. While the portion is in a functional state due to the first pulse, a second pulse is directed toward the portion. At a second-pulse time, reflected energy due to the second pulse is detected. While the portion is in a functional state due to the first and second pulses, a third pulse is directed toward the portion. At a third-pulse time, energy of the third pulse, reflected from the portion, is detected. In response to detecting the pulses at the second-pulse time and the third-pulse time, a characteristic of the portion is quantified resulting from (a) the functional state due to the first pulse and (b) the functional state due to the first and second pulses. A clinical state of the subject is identified. Other embodiments are described.

Abstract: Methods, apparatus, and systems for detecting hemozoin and diagnosing malaria infection are disclosed.

Abstract: The present invention provides contact lens with integrated biosensor for the continuous, non-invasive monitoring of physiological glucose by employing biocompatible nanostructure-laden lens materials. These contact lenses can be worn by diabetics who can colorimetrically see changes in their contact lens color or other fluorescence-based properties, giving an indication of tear and blood glucose levels. This invention for the glucose biosensor based on the new disposal contact lens provides a safe, convenient and non-expensive glucose sensing device. The sensing device disclosed herein provides an efficient and noninvasive solution for monitoring blood glucose.

Abstract: A device for measuring an analyte concentration level in a subject. The device includes: a light source configured for illuminating at least a portion of an anterior region of an eye of the subject with incident light having a substantially broad illumination spectrum at an angle substantially tangential to the surface of the eye; an optical collector configured for detecting reflected light from the at least a portion of the anterior region of the eye; an analyzer configured for analyzing the detected reflected light; and a processor configured to determine the analyte concentration level in the subject based on the analyzed reflected light.

Abstract: An apparatus and method for measuring a concentration of a substance in an eye using a retro-reflected measurement light beam having a first wavelength at which the substance has a non-zero first absorption coefficient and a retro-reflected reference light beam having a second wavelength at which the substance has a second absorption coefficient which is substantially equal to zero. The apparatus further includes a detector positionable to receive the retro-reflected measurement light beam and the retro-reflected reference light beam. The detector is responsive to light having the first wavelength by generating a measurement signal and responsive to light having the second wavelength by generating a reference signal. The apparatus further includes an electrical circuit coupled to the detector. The electrical circuit is responsive to the measurement signal and the reference signal to measure the concentration of the substance in the eye.

Abstract: A method determines the concentration of a substance in a subject's blood. The method includes measuring an interaction of at least one light beam with a portion of the subject's body. The method further includes calculating a value of an optically-measured parameter indicative of the interaction of the at least one light beam with the substance in the portion of the subject's body. The method further includes measuring values of one or more temperature-indicative parameters corresponding to a temperature of the portion of the subject's body. The method further includes accessing an empirical correlation of the optically-measured parameter and the one or more temperature-indicative parameters to concentrations of the substance in blood. The method further includes obtaining a concentration of the substance in the subject's blood using the empirical correlation. The concentration corresponds to the value of the optically-measured parameter and the values of the one or more temperature-indicative parameters.

Abstract: Wearable or implantable devices combining microfluidic control of sample and reagent flow and micro-cavity surface plasmon resonance sensors functionalized with surface treatments or coatings capable of specifically binding to target analytes, ligands, or molecules in a bodily fluid are provided. The devices can be used to determine the presence and concentration of target analytes in the bodily fluids and thereby help diagnose, monitor or detect changes in disease conditions.

Abstract: In one aspect the present invention provides methods for assessing a physiological state of a mammalian retina in vivo, the methods of this aspect of the invention each include the steps of (a) irradiating a portion of a mammalian retina, in vivo, with light having a wavelength in the range of from 600 nm to 1000 nm at an intensity sufficient to stimulate two-photon-induced fluorescence in the retina; and (b) assessing a physiological state of the retina by analyzing the fluorescence.

Abstract: Methods, apparatus, and systems for detecting hemozoin and diagnosing malaria infection are disclosed.

Abstract: A noninvasive method and apparatus for determining analyte concentration (e.g., glucose) in a subject that includes measuring light refraction from at least a portion one or more structures. One example of such structure is the subject's iris.

Abstract: The invention provides high speed, low cost scanning suitable for time domain OCT systems. According to the preferred embodiment, the apparatus includes a piezo scanning device and partial reflecting surfaces that simultaneously generate two sets of multiple reference signals at two different wavelengths that can span different regions of a target enabling acquiring target information from a large range within the target. In one embodiment of the invention, information from both the front region and the back region of an eye is acquired in a coordinated manner.

Abstract: A medical diagnostic method utilizes a surface plasmon resonance apparatus provided with a sensing surface. A tear sample from an eye of a patient is placed into contact with the sensing surface. The surface plasmon resonance apparatus is then operated to determine concentrations of solutes such as salt and antigenic analytes in the tear sample.

Abstract: An ophthalmic device which comprises a holographic element comprising a medium comprising a phenylboronic acid group and, disposed therein, a hologram, wherein an optical characteristic of the element changes as a result of a variation of a physical property of the medium, and wherein the variation arises as a result of interaction between the medium and an analyte present in an ocular fluid.

Abstract: A method determines the concentration of a substance in a subject's blood. The method includes noninvasively irradiating an eye with a measurement light beam having a first wavelength and a first power and with a reference light beam having a second wavelength and a second power. The second wavelength is different from the first wavelength. The method further includes measuring at least one of a body temperature of the subject and an ambient temperature of the subject. The method further includes detecting a power of the measurement retro-reflected light beam and detecting a power of the reference retro-reflected light beam. The method further includes calculating a measurement ratio of the detected power of the measurement retro-reflected light beam and the first power and calculating a reference ratio of the detected power of the reference retro-reflected light beam and the second power.

Abstract: A method and system for non-invasively measuring the concentration of an optically-active substance in a subject are provided. The system includes a light source adapted to transmit light towards a subject or object having a concentration of an optically-active substance, a polarizer positioned between the light source and the subject, an image capturing device, and a processor. The image capturing device is positioned to receive light reflected from the subject and create a measured image therefrom. The measured image defines measured light intensity data. The processor is configured to calculate a concentration of the optically-active substance based on a selected portion of the measured light intensity data.

Abstract: Methods, apparatus and systems for measuring pressure and/or for quantitative or qualitative measurement of analytes within the eye or elsewhere in the body. Optical pressure sensors and/or optical analyte sensors are implanted in the body and light is cast from an extracorporeal light source, though the cornea, conjunctiva or dermis, and onto a reflective element located within each pressure sensor or analyte sensor. The position or configuration of each sensor's reflective element varies with pressure or analyte concentration. Thus, the reflectance spectra of light reflected by the sensors' reflective elements will vary with changes in pressure or changes in analyte concentration. A spectrometer or other suitable instrument is used to process and analyze the reflectance spectra of the reflected light, thereby obtaining an indication of pressure or analyte concentration adjacent to the sensor(s).

Abstract: An ophthalmic device which comprises a holographic element comprising a medium comprising a phenylboronic acid group and, disposed therein, a hologram, wherein an optical characteristic of the element changes as a result of a variation of a physical property of the medium, and wherein the variation arises as a result of interaction between the medium and an analyte present in an ocular fluid.

Abstract: A device for measuring a hydration status based on an analyte concentration in a subject. The device includes: a light source configured for illuminating at least a portion of an anterior region of an eye of the subject with incident light having a substantially broad illumination spectrum at an angle substantially tangential to the surface of the eye; an optical collector configured for detecting reflected light from the at least a portion of the anterior region of the eye; an analyzer configured for analyzing the detected reflected light; and a processor configured to determine the analyte concentration level in the subject based on the analyzed reflected light, wherein the processor determines a hydration status of the subject based on the analyte concentration level and reference data.

Abstract: A device for measuring an analyte concentration level in a subject. The device includes: a light source configured for illuminating at least a portion of an anterior region of an eye of the subject with incident light having a substantially broad illumination spectrum at an angle substantially tangential to the surface of the eye; an optical collector configured for detecting reflected light from the at least a portion of the anterior region of the eye; an analyzer configured for analyzing the detected reflected light; and a processor configured to determine the analyte concentration level in the subject based on the analyzed reflected light.

Abstract: Utilization of a contact device placed on the eye in order to detect physical and chemical parameters of the body as well as the non-invasive delivery of compounds according to these physical and chemical parameters, with signals being transmitted continuously as electromagnetic waves, radio waves, infrared and the like. One of the parameters to be detected includes non-invasive blood analysis utilizing chemical changes and chemical products that are found in the conjunctiva and in the tear film. A transensor mounted in the contact device laying on the cornea or the surface of the eye is capable of evaluating and measuring physical and chemical parameters in the eye including non-invasive blood analysis. The system utilizes eye lid motion and/or closure of the eye lid to activate a microminiature radio frequency sensitive transensor mounted in the contact device. The signal can be communicated by wires or radio telemetered to an externally placed receiver.

Abstract: Utilization of a contact device placed on the eye in order to detect physical and chemical parameters of the body as well as the non-invasive delivery of compounds according to these physical and chemical parameters, with signals being transmitted continuously as electromagnetic waves, radio waves, infrared and the like. One of the parameters to be detected includes non-invasive blood analysis utilizing chemical changes and chemical products that are found in the conjunctiva and in the tear film. A transensor mounted in the contact device laying on the cornea or the surface of the eye is capable of evaluating and measuring physical and chemical parameters in the eye including non-invasive blood analysis. The system utilizes eye lid motion and/or closure of the eye lid to activate a microminiature radio frequency sensitive transensor mounted in the contact device. The signal can be communicated by wires or radio telemetered to an externally placed receiver.

Abstract: Utilization of a contact device placed on the eye in order to detect physical and chemical parameters of the body as well as the non-invasive delivery of compounds according to these physical and chemical parameters, with signals being transmitted continuously as electromagnetic waves, radio waves, infrared and the like. One of the parameters to be detected includes non-invasive blood analysis utilizing chemical changes and chemical products that are found in the conjunctiva and in the tear film. A transensor mounted in the contact device laying on the cornea or the surface of the eye is capable of evaluating and measuring physical and chemical parameters in the eye including non-invasive blood analysis. The system utilizes eye lid motion and/or closure of the eye lid to activate a microminiature radio frequency sensitive transensor mounted in the contact device. The signal can be communicated by wires or radio telemetered to an externally placed receiver.

Abstract: An ocular sensor (110) is proposed for verification of at least one analyte in an eye fluid. The ocular sensor (110) is composed of at least one sensor material which is designed to change at least one optical characteristic in the presence of the at least one analyte. Furthermore, the ocular sensor (110) comprises at least one sensor chip which has at least one integrated optical detector (122) for verification of the optical characteristic. A measurement system (166) is also proposed for verification of at least one analyte in an eye fluid, which measurement system (166) comprises an ocular sensor (110) according to the invention as well as an evaluation unit (168) which is designed to interchange information with the sensor chip (118).

Abstract: A method and apparatus for measuring an apparent depth (1) of a section of an eye (30) are disclosed. Light is focused to a measurement location (15) proximate or within the eye. The measurement location is scanned through the section and upon passing through first and second refractive index interfaces defining the section, a respective reflected light signal is detected, from which apparent positions of the first and second interfaces may be derived. Preferably, a confocal scanning arrangement is employed. Preferably, the section is the aqueous humor (34) of the eye (30). From changes in its refractive index (n) corresponding changes in glucose concentration in the aqueous humor and, in turn, in the bloodstream of a patient may be derived, offering a non-invasive monitoring means for diabetic patients. The apparatus may be a hand-held device, employing microelectromechanical systems.

Abstract: Utilization of a contact device placed on the eye in order to detect physical and chemical parameters of the body as well as the non-invasive delivery of compounds according to these physical and chemical parameters, with signals being transmitted continuously as electromagnetic waves, radio waves, infrared and the like. One of the parameters to be detected includes non-invasive blood analysis utilizing chemical changes and chemical products that are found in the conjunctiva and in the tear film. A transensor mounted in the contact device laying on the cornea or the surface of the eye is capable of evaluating and measuring physical and chemical parameters in the eye including non-invasive blood analysis. The system utilizes eye lid motion and/or closure of the eye lid to activate a microminiature radio frequency sensitive transensor mounted in the contact device. The signal can be communicated by wires or radio telemetered to an externally placed receiver.

Abstract: In one aspect the present invention provides methods for assessing a physiological state of a mammalian retina in vivo, the methods of this aspect of the invention each include the steps of: (a) irradiating a portion of a mammalian retina, in vivo, with light having a wavelength in the range of from 600 nm to 1000 nm at an intensity sufficient to stimulate two-photon-induced fluorescence in the retina; and (b) assessing a physiological state of the retina by analyzing the fluorescence.

Abstract: The invention provides a method of diagnosing, prognosing, staging, and/or monitoring a mammalian amyloidogenic disorder or a predisposition thereto by detecting a protein or polypeptide aggregate in the cortical and/or supranuclear regions of an ocular lens of the mammal.

Abstract: An apparatus and method for measuring a concentration of a substance in an eye using a retro-reflected measurement light beam having a first wavelength at which the substance has a non-zero first absorption coefficient and a retro-reflected reference light beam having a second wavelength at which the substance has a second absorption coefficient which is substantially equal to zero. The apparatus further includes a detector positionable to receive the retro-reflected measurement light beam and the retro-reflected reference light beam. The detector is responsive to light having the first wavelength by generating a measurement signal and responsive to light having the second wavelength by generating a reference signal. The apparatus further includes an electrical circuit coupled to the detector. The electrical circuit is responsive to the measurement signal and the reference signal to measure the concentration of the substance in the eye.

Abstract: Methods, apparatus, and systems for detecting hemozoin and diagnosing malaria infection are disclosed.

Abstract: A method for detecting disease in a patient includes providing infrared (IR) light and coupling the IR light through direct lens coupling or through a first group of one or more optical fibers. IR light is reflected from a portion of the patient and collected by a lens arrangement or a second group of one or more optical fibers. The reflected IR light is dispersed into its spectrum which is detected and analyzed. An apparatus suitable for diagnosing a disease in a patient includes an IR light source and optical fiber or direct lens coupling of IR light onto a body part or fluid of the patient. Reflected light from the patient is optically dispersed using a prism or grating. An IR focal plane array receives the optically dispersed light. The spectrum of the reflected IR light is used to provide a diagnosis of disease in the patient by identifying various disease markers or chemical fingerprints. The method and apparatus are capable of non-invasively detecting disease markers in a patient.

Abstract: A method of performing a diagnostic characterization and assessment of a patients' eye is provided. The method comprising the extraction of measurement data relating to a predetermined portion of the eye, for example the fovea, at a plurality of wavelengths and fitting the extracted measurement data to a model of the eye, for example a linear adaptive model. The data subsequently analyzed to determine at least one of a common retinal behavior, a deviation from the common retinal behavior, and an oximetry value. In the case of the measurement data relating to the fovea of the eye then the oximetry value is indicative of the blood oxygen saturation of the choroid vasculature of the eye. Further analysis based upon storing the measurement data and/or analysis from each test allows for the changes within the patients eye to be established unlike prior art solutions, and identifying the changes with an element of the eye such as the retina, cornea, crystalline lens, etc.

Abstract: Retinal metabolism is analyzed with a retinal function camera over at least a portion of a cardiac cycle by first illuminating a portion of a retina of an eye 10 with light of a first wavelength and producing a first image. The portion of the retina is subsequently illuminated with light of a second wavelength, the first and second wavelengths being selected such that absorptivity of light of the first wavelength by oxygenated blood is greater than absorptivity of light of the second wavelength and the absorptivity of light of the first wavelength by deoxygenated blood is less than absorptivity of light of the second wavelength, to produce a second image. The first and second images are processed to map relative oxygenation of the portion of the retina as an indication of retinal metabolic function of the portion of the retina.

Abstract: Utilization of a contact device placed on the eye in order to detect physical and chemical parameters of the body as well as the non-invasive delivery of compounds according to these physical and chemical parameters, with signals being transmitted continuously as electromagnetic waves, radio waves, infrared and the like. One of the parameters to be detected includes non-invasive blood analysis utilizing chemical changes and chemical products that are found in the conjunctiva and in the tear film. A transensor mounted in the contact device laying on the cornea or the surface of the eye is capable of evaluating and measuring physical and chemical parameters in the eye including non-invasive blood analysis. The system utilizes eye lid motion and/or closure of the eye lid to activate a microminiature radio frequency sensitive transensor mounted in the contact device. The signal can be communicated by wires or radio telemetered to an externally placed receiver.

Abstract: Biosensor, communicator, and/or controller apparatus, systems, and methods are provided for monitoring movement of a person's eye. The apparatus includes a device configured to be worn on a user's head, a light source for directing light towards one or both eyes of the user, one or more image guides on the device for viewing one or both eyes of the user, and one or more cameras carried on the device and coupled to the image guides for acquiring images of the eyes and/or the user's surroundings. The apparatus may include a cable and/or a transmitter for transmitting image data from the camera to a remote location, e.g., to processor and/or display for analyzing and/or displaying the image data. A system including the apparatus may be used to monitor one or more oculometric parameters, e.g., pupillary response, and/or to control a computer using the user's eyes instead of a mouse.

Abstract: Disclosed is an automated method which can detect images containing red lesions. First, each image is preprocessed; next, candidate objects that may represent red-lesions are extracted; and in the final stage the probability for each candidate to represent a red-lesion is estimated using a classifier and a large set of specifically designed features.

Abstract: A medical diagnostic method utilizes a surface plasmon resonance apparatus provided with a sensing surface. A tear sample from an eye of a patient is placed into contact with the sensing surface. The surface plasmon resonance apparatus is then operated to determine concentrations of solutes such as salt and antigenic analytes in the tear sample.

Abstract: An apparatus for measuring a blood component using the trans-reflectance of light irradiated to a transflective member disposed behind a test site. The apparatus includes an optical source unit irradiating light to the test site of a test subject; a transflective unit transflecting light transmitted through the test site; a detection unit detecting the transflected light; and an analysis unit analyzing the transflected light detected in the detection unit. A related method includes irradiating the light to the test site; transflecting light through the test site, detecting the transflected light, and analyzing the detected light. Blood component measurement can be easily performed without collecting blood by analyzing the transflected light with a high optical power containing much information about a blood component.

Abstract: Embodiments of the present invention relate to a system and method of detecting or monitoring macular degeneration in a patient. One embodiment of the present invention includes emitting a first light into the patient's retinal tissue at a first wavelength, emitting a second light into the patient's retinal tissue at a second wavelength, detecting the first and second lights after dispersion by the retinal tissue, and determining an amount of lipid proximate the retinal tissue based on the detected first and second lights.

Abstract: The present invention provides a spectroscopic apparatus, a method and a computer program product for determining the concentration of an analyte of a fluid that flows through a capillary vessel of a biological sample. The spectroscopic apparatus makes use of an imaging system for determining the position of at least one biosensing substrate that has been implanted into the biological sample in the proximity of the capillary vessel but outside the capillary vessel. The biosensing substrate is capable of inducing surface-enhanced spectroscopic effects and is preferably adapted to reversibly and selectively bind a certain analyte or molecule of the fluid, to which the vessel wall of the capillary vessel is at least semi-permeable.

Abstract: The present invention relates to a hand-held fluorescence photometer and method for measuring an analyte level, preferably a blood glucose level, from an ocular fluid. The photometer is based on a dual beams measuring system and it is capable of defining the correct positioning for the measurement. Only when the apparatus is correctly positioned the actual analyte measurement automatically takes place.

Abstract: Utilization of a contact device placed on the eye in order to detect physical and chemical parameters of the body as well as the non-invasive delivery of compounds according to these physical and chemical parameters, with signals being transmitted continuously as electromagnetic waves, radio waves, infrared and the like. One of the parameters to be detected includes non-invasive blood analysis utilizing chemical changes and chemical products that are found in the conjunctiva and in the tear film. A transensor mounted in the contact device laying on the cornea or the surface of the eye is capable of evaluating and measuring physical and chemical parameters in the eye including non-invasive blood analysis. The system utilizes eye lid motion and/or closure of the eye lid to activate a microminiature radio frequency sensitive transensor mounted in the contact device. The signal can be communicated by wires or radio telemetered to an externally placed receiver.

Abstract: A non-invasive method for analyzing the blood-brain barrier includes obtaining a Raman spectrum of a selected portion of the eye and monitoring the Raman spectrum to ascertain a change to the dynamics of the blood brain barrier. Also, non-invasive methods for determining the brain or blood level of an analyte of interest, such as glucose, drugs, alcohol, poisons, and the like, comprises: generating an excitation laser beam at a selected wavelength (e.g., at a wavelength of about 400 to 900 nanometers); focusing the excitation laser beam into the anterior chamber of an eye of the subject so that aqueous humor, vitreous humor, or one or more conjunctiva vessels in the eye is illuminated; detecting (preferably confocally detecting) a Raman spectrum from the illuminated portion of the eye; and then determining the blood level or brain level (intracranial or cerebral spinal fluid level) of an analyte of interest for the subject from the Raman spectrum.

Abstract: A medical diagnostic method utilizes a surface plasmon resonance apparatus provided with a sensing surface. A tear sample from an eye of a patient is placed into contact with the sensing surface. The surface plasmon resonance apparatus is then operated to determine osmolarity of the tear sample.

Abstract: An apparatus for measuring a concentration of a substance in an eye (13) includes a measurement light source (4) producing a measurement light beam having a first wavelength at which the substance has a non-zero first absorption coefficient. The apparatus further includes a reference light source (6) producing a reference light beam having a second wavelength at which the substance has a second absorption coefficient which is substantially equal to zero. At least a portion of the measurement light beam retro-reflects from the retina (17) and at least a portion of the reference light beam retro-reflects from the retina (17). The apparatus further includes a detector (9) responsive to light having the first wavelength by generating a measurement signal and responsive to light having the second wavelength by generating a reference signal.

Abstract: The concentration of glucose in the anterior chamber of an eye is non-invasively measured by guiding a beam through a polarizer (4), a quarter wave plate (6), a polarization modulator (20), and an analyzer (7). After initializing the polarizer and the analyzer to extinguish the beam, it is guided parallel to the iris (56) of the eye (50) and introduced into the anterior chamber (57), wherein it is refracted, impinges on and is reflected from the iris, and exits the anterior chamber approximately collinear with the portion (55A) of the beam incident on the anterior chamber. The beam then is guided onto a detector (10), and a sufficient signal is applied to the polarization modulator to extinguish the beam. The signal represents the glucose concentration in the patient's blood.