JP5522769B2 - Optical measuring device - Google Patents

Description

  The present invention relates to an optical measurement device, and more particularly to an optical measurement device that suitably controls laser light applied to a subject.

  Today, positron emission tomography (PET) and functional nuclear magnetic resonance tomography (fMRI) are widely used for the purpose of non-invasive measurement of living bodies. While these devices have the advantage of being able to image a wide area inside the living body, they have the disadvantage of increasing the size of the device.

  On the other hand, near-infrared spectroscopy (for example, see Non-Patent Document 1) that separates and measures oxygenated hemoglobin and deoxygenated hemoglobin in blood, or a tomographic detection method for living tissue using laser light (for example, An optical measurement technique such as Non-Patent Document 2) is known.

  In an optical measurement technique used for flow velocity measurement or the like, a probe that irradiates and receives a laser beam on a subject is used. In order to control the laser light emitted from the probe, for example, a mechanical mechanism for controlling the laser light such as a deflection lens, a prism, a slit, and a filter is provided (for example, see Patent Document 1).

  When the probe is a measurement system having such a mechanism, a certain degree of experience is required for the measurer to perform measurement with high accuracy. In addition, when the measurement system performs measurement with the probe fixed to the subject, only a limited depth, direction, and range from the surface of the subject can be irradiated with laser light, and measurement performance There were limits. In addition, with these methods, for example, even when the subject is an infant or an adult, it is difficult to perform high-precision measurement while performing some operation.

  Therefore, in the measurement using the probe and the laser beam, light that has been able to measure a sufficient range of the tomographic portion of the subject and that has been reduced in weight and size without any special mechanical mechanism. Measuring devices were desired both academically and socially.

Heretofore, a liquid crystal optical element that suitably controls the deflection and focal position of laser light and a particle movement control device including the same have been disclosed (see Patent Documents 1 and 2). In this liquid crystal optical element, laser light can be condensed with a simple device by controlling the orientation of liquid crystal molecules by applying a voltage between electrodes provided in the liquid crystal optical element.
JP-A-8-206101 JP 2006-91826 A JP 2006-235319 A F. F. Jobis, “Non inspiratory, inframonitoring of cerebral and myocardial oxygen safety and circuit parameters,” Science 198, 1264 (77). Sato, Maki: “Measurement of higher brain functions by optical topography”, Applied Physics, Vol. 76, 4 (2007) 369

  While the above-described problems existing in conventional optical measurement devices that irradiate and receive laser light exist, high accuracy of various data such as image data obtained from measurement results is also desired.

  Here, it is conceivable to use the above-described liquid crystal optical element for controlling laser light emitted from a probe used in optical measurement technology.

  In other words, by applying the liquid crystal optical element to the optical measurement technology, it is possible to control the laser light without the need for a mechanical mechanism, so it is possible to realize a suitable laser light deflection and focus position control, It is considered that a wide range of measurements can be performed on the subject. In addition, it is considered that operability is improved by controlling the liquid crystal optical element smoothly, and a highly accurate result can be obtained as a measurement result.

  In addition, no technology relating to optical measurement technology in which laser light is controlled by using a liquid crystal optical element is disclosed, and it is considered a new attempt and originality.

  The present invention has been made in consideration of such circumstances, and an optical measurement device that does not require a mechanical mechanism and that can obtain a highly accurate measurement result by suitably controlling laser light. The purpose is to provide.

In order to solve the above-described problem, an optical measurement device according to the present invention irradiates a subject with laser light having at least one predetermined wavelength irradiated from a laser light source, and is irradiated by the irradiation unit and In an optical measurement apparatus comprising a light receiving means for receiving the laser light transmitted through a subject and a measurement means for measuring the laser light received by the light receiving means, the irradiation means is configured to apply liquid crystal molecules by applying voltage. A liquid crystal optical element that changes the focal position of the laser light emitted from the laser light source and irradiates the subject by varying the effective refractive index distribution characteristics of the liquid crystal by controlling the orientation of the liquid crystal; The optical elements are arranged in an array, and the laser light source is a two-dimensional surface-emitting laser array stacked on the liquid crystal optical elements arranged in the array. The laser light source and the child is characterized in that it has an integral-type probe.

  The optical measuring device according to the present invention can suitably control the laser light without using a mechanical mechanism.

  An embodiment of an optical measurement device according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a diagram showing a schematic configuration of an embodiment of an optical measurement device according to the present invention. In this embodiment, the skin of the head, which is an example of the subject 10, is irradiated with laser light emitted from a near-infrared semiconductor laser element, and imaging data of oxygen concentration and blood flow distribution of a living tissue is acquired. A description will be given by applying an optical measurement technique. In addition, this invention is applicable not only to a head but to other parts, and also to flow measurement other than a living body.

  The laser light source 11 is composed of a semiconductor laser element that emits laser light having a predetermined wavelength in a visible to infrared wavelength region, for example, a wavelength of 830 nm.

  The laser light emitted from the laser light source 11 is guided to the irradiation optical fiber 12. The irradiation optical fiber 12 is connected to the optical switch 13.

  The optical switch 13 branches the laser beam supplied from the irradiation optical fiber 12 to each channel. In the present embodiment, the optical switch 13 branches the guided laser light into 16 channels, guides it to the irradiation optical fibers 121 to 1216 (hereinafter referred to as the irradiation optical fiber 12), and performs multipoint measurement. Make it. This multi-point measurement is effective in that measurement results can be obtained from a large number of points in one measurement. Note that the measurement points may be not only multi-point measurement but also single point measurement, or may have a larger number of points.

  The irradiation units 141 to 1416 (hereinafter referred to as the irradiation unit 14) irradiate a predetermined laser beam irradiation position of the subject 10 with the laser beam guided from the irradiation optical fiber 12. Liquid crystal optical elements 151 to 1516 (hereinafter referred to as liquid crystal optical elements 15) are connected to the irradiation unit 14.

  The liquid crystal optical element 15 is controlled to be either a convex lens characteristic or a concave lens characteristic by applying a voltage between the electrodes to control the optical characteristic, and the focal position of the liquid crystal optical element 15 is three-dimensionally adjusted. The laser beam is deflected by controlling the movement. Details of the liquid crystal optical element 15 will be described later.

  The light receiving units 171 to 1716 (hereinafter referred to as the light receiving unit 17) receive the laser light reflected in the subject 10 and passed through the subject 10 from a predetermined laser light receiving position. The received laser light is guided to light receiving optical fibers 181 to 1816 (hereinafter referred to as light receiving optical fiber 18).

  The irradiation unit 14 and the light receiving unit 17 constitute a probe, and their end surfaces are in light contact with the surface of the subject 10. Further, the interval between the adjacent laser light irradiation position and the laser light receiving position is, for example, approximately 30 mm, but is not limited to this, and can be appropriately changed according to the measurement site.

  The detector 20 detects laser light for each assigned light receiving position among the laser light received from the light receiving unit 17 and converts the detected laser light into electric signals. The detector 20 includes, for example, a photodiode, an avalanche diode that can realize highly sensitive optical measurement, an avalanche diode array, and the like. A photomultiplier tube may be used as the detector 20.

  The electrical signal converted by the detector 20 is a modulation signal selective detection circuit, for example, a multi-channel lock-in amplifier 21 composed of a plurality of lock-in amplifiers, and selects a modulation signal corresponding to the light irradiation position and wavelength. Detect. In the present embodiment, the multi-channel lock-in amplifier 21 as a modulation signal detection circuit corresponding to the case of analog modulation is shown. However, when digital modulation is used, a digital filter or digital signal processor is used to detect the modulation signal. Is used.

  The computing device 22 computes the measurement result based on the electrical signal transmitted from the multi-channel lock-in amplifier 21. The arithmetic unit 22 images, for example, the oxygen concentration from the measurement result of the subject 10. The computing device 22 analyzes blood flow, for example, using the frequency component of the fast Fourier transform on the transmitted electrical signal.

  The display device 23 includes an LCD (Liquid Crystal Display), a CRT (Cathode Ray Tube), and the like, and displays analysis results such as a flow velocity distribution imaged by the arithmetic device 22.

  Next, a detailed configuration of the liquid crystal optical element 15 will be described.

  2A and 2B are diagrams showing the liquid crystal optical element 15 attached to the tip of the laser light irradiation unit 14 in FIG. 1, where FIG. 2A is a side view of the liquid crystal optical element 15, and FIG. 3 is a plan view of a second electrode 33. FIG.

  The first substrate 30 of the liquid crystal optical element 15 is a substrate made of transparent glass and having a rectangular shape. A first electrode 31 made of, for example, an ITO (indium tin oxide) material is disposed on the upper surface of the first substrate 30.

  The second substrate 32 is a substrate made of transparent glass having substantially the same shape as the first substrate 30. The first substrate 30 and the second substrate 32 are arranged to face each other in parallel with the first electrode 31 in between. A second electrode 33 made of, for example, aluminum is disposed on the upper surface of the second substrate 32. As shown in FIG. 2B, the second electrode 33 has a round hole 35 having a diameter of 3.8 mm, for example.

  The third electrode 36 is disposed on the upper surface of the second electrode 33 via an insulating layer 38 made of, for example, thin glass and a spherical spacer 37 having a diameter of 40 μm. The third electrode 36 is made of, for example, an ITO material. A protective layer 40 made of glass is disposed on the upper surface of the third electrode 36.

  Between the surface of the first substrate 30 where the first electrode 31 is disposed and the second substrate 32, a liquid crystal layer 41 in which liquid crystal molecules are aligned in one direction has a thickness of, for example, 110 μm. It consists of Further, the liquid crystal layer 41 is sealed by a spherical spacer 42 having a diameter of, for example, 110 μm.

  The surfaces of the first substrate 30 and the second substrate 32 sandwiching the liquid crystal layer 41 are coated with polyimide. Also, rubbing is performed in the x-axis direction.

  The voltage supply unit 45 applies a voltage between the first electrode 31 and the second electrode 33, and the voltage supply unit 46 applies a voltage between the first electrode 31 and the third electrode 36. A control unit (not shown) controls the voltage when a voltage is applied between the electrodes.

  Here, the second electrode 33 is divided into eight as shown in FIG. Different voltages are applied to the electrodes 33a to 32h, which are the eight voltages of the second electrode 33, based on the control of the control unit. FIG. 3 is a diagram illustrating a specific configuration example of the second electrode 33.

  The voltages applied to the electrodes 33a to 32h of the second electrode 33 are respectively applied from the voltage supply units 45a to 45h, and different voltages can be applied independently.

  Next, the operation of the optical measurement device in this embodiment will be described.

  The irradiation optical fiber 12 and the light receiving optical fiber 18 constituting a probe (not shown) are mounted on the skin of the subject 10 such as the head. The interval between the adjacent laser beam irradiation position and the laser beam receiving position is, for example, approximately 30 mm, but is not limited to this.

  Laser light is irradiated from the laser light source 11 of the optical measuring device and guided to the irradiation optical fiber 12. The laser light guided to the irradiation optical fiber 12 is guided to the optical switch 13. The optical switch 13 splits the laser light into a predetermined number of channels. In the present embodiment, the optical switch 13 branches the guided laser light into 16 channels, and the laser light is guided to the irradiation optical fiber 12, respectively.

  The laser beam guided to the irradiation unit 14 which is the end of the irradiation optical fiber 12 enters the liquid crystal optical element 15. In the liquid crystal optical element 15, a predetermined voltage (first voltage) Vo is applied between the first electrode 31 and the second electrode 33 by the voltage supply unit 45. In addition to the voltage supply unit 45, a predetermined voltage (second voltage) Vc is applied between the first electrode 31 and the third electrode 36 by the voltage supply unit 46. The liquid crystal optical element 15 to which a voltage is applied between the electrodes can function as a liquid crystal lens to control the optical characteristics. The detailed description of the liquid crystal optical element 15 will be described later.

  The laser beam refracted through the liquid crystal optical element 15 of the irradiating unit 18 irradiates a predetermined laser beam irradiation position of the subject 10. After entering the subject 10, the laser light reflected within the subject 10 and further passing through the subject 10 is received by the light receiving unit 17 from a predetermined laser light receiving position. The received laser beam is guided to the light receiving optical fiber 18.

  Since the laser light is branched into 16 channels by the optical switch 13, the laser light is incident on the inside of the subject from 16 laser light irradiation positions located on the surface of the subject 10. Further, the laser light reflected in the subject 10 and passed through the subject 10 is received by the light receiving unit 17 from 16 laser light receiving positions located on the surface of the subject 10.

  This multi-point measurement is effective in that measurement results can be obtained from a large number of points in one measurement. In addition, as for the measurement points, not only multipoint measurement but also measurement of only one point can be performed, or more measurement points may be provided.

  The detector 20 detects a laser beam for each assigned laser beam receiving position among the laser beams received from the light receiving unit 17, and converts each detected laser beam into an electrical signal.

  The electrical signal converted by the detector 20 is guided to a multi-channel lock-in amplifier 21 which is a selective detection circuit for a modulation signal. A modulation signal corresponding to the light irradiation position and wavelength is selectively detected from the derived electrical signal. This signal is guided to the arithmetic unit 22.

  The computing device 22 that has received the signal computes the measurement result based on the electrical signal transmitted from the multi-channel lock-in amplifier 21. The arithmetic unit 22 images, for example, the oxygen concentration from the measurement result of the subject 10. The arithmetic unit 22 analyzes the flow rate, for example, the blood flow, using the frequency component of the fast Fourier transform on the transmitted electrical signal.

  Analysis results such as flow velocity distribution imaged by the arithmetic device 22 are displayed on the display device 23.

  Next, the operation of the liquid crystal optical element 15 as the irradiation unit 18 will be described.

  FIG. 4 is a diagram conceptually showing a case where the liquid crystal optical element 15 irradiates laser light.

  4A shows the case where the liquid crystal optical element 15 having concave lens characteristics irradiates the subject 10 with laser light, and FIG. 4B shows the case where the liquid crystal optical element 15 having convex lens characteristics lasers the subject 10. It is a figure explaining the case where light is irradiated. FIG. 4C shows the case where the liquid crystal optical element 15 having concave lens characteristics irradiates the subject 10 while deflecting the laser beam, and FIG. 4D shows the case where the liquid crystal optical element 15 having convex lens characteristics shows the subject. 10 is a diagram illustrating a case where laser beam 10 is irradiated while being deflected.

  The optical measurement device in the present embodiment has a concave lens function and a convex lens function, and is configured to be able to control the concave lens characteristic and the convex lens characteristic, which are optical characteristics of the liquid crystal optical element 15. The concave lens characteristic and the convex lens characteristic are respectively determined by a predetermined first voltage Vo between the first electrode 31 and the second electrode 33 of the liquid crystal optical element 15 and between the first electrode 31 and the third electrode 36. Control is performed by applying the second voltage Vc. A method for controlling the concave lens characteristic and the convex lens characteristic of the liquid crystal optical element 15 and the operation thereof are described in, for example, Japanese Patent Application Laid-Open No. 2006-91826.

  Thus, by suitably controlling the first voltage Vo and the second voltage Vc, as shown in FIGS. 4A and 4C, the irradiation width of the laser light can be controlled. Further, when the laser beam is illuminated using the concave lens characteristic, the laser beam emitted from the liquid crystal optical element 15 is emitted to a wide area, so that the measurement range can be expanded.

  Furthermore, the liquid crystal optical element 15 can control the optical characteristics so as to move the focal position in a three-dimensional direction (X, Y, Z axis directions in FIG. 4A) in order to deflect the laser light. .

  For example, by changing the second voltage Vc, the optical characteristics of the liquid crystal optical element 15 are changed, for example, from a very small focal length in the Z-axis direction to a nearly infinite state. The optical characteristics of the liquid crystal optical element 15 are varied in this way when the second voltage Vc applied to the second electrode 33 divided into a plurality is uniformly changed. is there.

  Further, the liquid crystal optical element 15 can change the focal position of the laser light in the X and Y axis directions in addition to the Z axis direction. The second electrode 33 is divided into eight as shown in FIG. 2B, and the second voltage Vc applied to each of the electrodes 33a to 33h is variably controlled by a control unit (not shown). Thus, the focal position can be changed.

  For example, Japanese Patent Application Laid-Open No. 2006-235319 describes a method of individually controlling the second voltage Vc and its operation in order to change the focal position in accordance with the change in the optical characteristics of the liquid crystal optical element 15.

  By controlling the second voltage Vc and moving the focal position in the three-dimensional direction in this way, for example, laser light can be freely radiated to a desired measurement range as shown in FIGS. 4C and 4D. Can be made. Further, it is possible to irradiate a desired region with laser light without moving the probe.

  According to this optical measuring device, the optical measuring device used for measuring the concentration in blood or blood flow is equipped with a liquid crystal optical element, and a mechanical mechanism is used by suitably controlling this optical characteristic. Optical measurement can be performed without any problems.

  Specifically, by controlling the voltage applied between the electrodes of the liquid crystal optical element to suitably control the optical characteristics, it has both a convex lens function and a concave lens function, and the focal position is three-dimensional. Can be controlled. Therefore, it is possible to realize the deflection of the laser beam, which has conventionally been realized by providing a plurality of mechanical mechanisms, with a single liquid crystal optical element.

  Further, since the mechanical mechanism can be omitted, the entire optical measuring device can be reduced in size and simplified.

  Further, in the present embodiment, the second electrode of the liquid crystal optical element is divided into eight and can be controlled independently, so that the optical characteristics can be controlled more precisely and measurement with high resolution can be performed. . Furthermore, more accurate results can be obtained for imaging data based on measurement data obtained in this way.

  In this embodiment, the measurement is performed using the single-wavelength laser light emitted from the laser light source in FIG. 1. However, the present invention is not limited to this, and a laser light source having a plurality of wavelengths may be used. Good. FIG. 5 is a diagram showing an outline of an optical measuring device configured with laser beams having a plurality of wavelengths as laser light sources.

  As an example, this optical measuring device includes two laser light sources, a laser light source 11A and a laser light source 11B. Other configurations are substantially the same as those of the optical measurement device in FIG.

  In this optical measuring device, for example, the laser light source 11A is constituted by a near infrared semiconductor laser that irradiates laser light having a wavelength of 780 nm, and the laser light source 11B is constituted by a near infrared semiconductor laser that emits laser light having a wavelength of 830 nm. . The laser beams irradiated from the laser light sources 11A and 11B are mixed, sent to the irradiation optical fiber 12, and irradiated onto the subject 10.

  Thus, by providing a laser light source having a plurality of wavelengths, it is possible to measure blood flow concentrations of oxygenated hemoglobin and deoxygenated hemoglobin having different absorbances.

  Further, as shown in FIG. 6, the probe 62 portion in the optical measuring device according to the present invention can be configured by integrating the two-dimensional surface emitting laser array 60 and the liquid crystal optical element array 61. By arranging the liquid crystal optical elements 15 in an array, a wider range can be measured in a short time, and the optical measuring device can be further reduced in size.

  Furthermore, noise light from the surface of the subject 10 can be obtained by being attached to the light receiving optical fiber 18 that is the light receiving unit 17 so as to be orthogonal to the polarization direction of the laser light emitted from the liquid crystal optical element 15. It is also possible to block the surface reflected light. Thereby, the S / N of the scattered light signal in hemoglobin can be improved.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment.

  For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  The shape of the third electrode 36 may be given by either a sine wave function, a superposition function of the sine wave function, or a power function. Further, although one liquid crystal lens is shown, a configuration in which a plurality of liquid crystal lenses are arranged may be used. Further, it may be a two-dimensional array such as a compound eye.

The figure which shows schematic structure of the optical measuring device which concerns on this invention. It is a figure which shows the liquid crystal optical element of the optical measuring device based on this invention, (A) is a side view of a liquid crystal optical element, (B) is a top view of the 2nd electrode of a liquid crystal optical element. The figure which shows the specific structural example of the 2nd electrode of the liquid crystal optical element of the optical measuring device which concerns on this invention. The figure which shows notionally the case where the liquid crystal optical element of the optical measuring device which concerns on this invention irradiates a laser beam. The figure which shows the outline of the structure which used the laser beam of several wavelengths in the optical measuring device which concerns on this invention. The figure which shows the probe comprised by integrating the two-dimensional surface emitting laser array and the liquid crystal optical element array in the optical measuring device which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Subject 11, 11A, 11B Laser light source 12 Irradiation optical fiber 13 Optical switch 14 Irradiation part 15 Liquid crystal optical element 17 Light reception part 18 Light reception optical fiber 20 Detector 21 Multichannel lock-in amplifier 22 Arithmetic device 23 Display device 30 One substrate 31 First electrode 32 Second substrate 33 Second electrode 35 Round hole 36 Third electrode 38 Insulating layer 40 Protective layer 41 Liquid crystal layer 45 Voltage supply unit 46 Voltage supply unit

Claims (3)

Irradiation means for irradiating a subject with laser light of at least one predetermined wavelength emitted from a laser light source, light receiving means for receiving the laser light emitted by the irradiation means and transmitted through the subject, and the light reception In an optical measuring device comprising measuring means for measuring laser light received by the means,
The irradiation means includes
Liquid crystal optics for controlling the orientation of liquid crystal molecules by applying voltage and varying the effective refractive index distribution characteristics of the liquid crystal, thereby changing the focal position of the laser light emitted from the laser light source and irradiating the subject. With elements,
The liquid crystal optical elements are arranged in an array,
The laser light source is a two-dimensional surface emitting laser array stacked on the liquid crystal optical elements arranged in the array,
The liquid crystal optical element and the laser light source constitute an integral probe. The liquid crystal optical element according to claim, characterized in by varying the distribution characteristics of the effective refractive index of the liquid crystal subjected to orientation control of the liquid crystal molecules by applying a voltage, further comprising a concave lens function and a convex lens function 1 The optical measuring device described. Means further comprising means for channelizing laser light emitted from the laser light source;
The irradiating means and the light receiving means irradiate and receive the laser beam guided from the corresponding channel in a multipoint manner,
The optical measuring device according to claim 1 , wherein the measuring unit measures the laser light received by the light receiving unit from multiple points.

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