Substance-in-blood concentration measurement device and substance-in-blood concentration measurement method
A substance-in-blood concentration measurement device for measuring concentration of a substance in blood of a living body, including: a target placement unit on which the living body that includes a measurement target portion is placed; a light emission unit that irradiates the measurement target portion with a laser beam; a photodetector that receives reflected light from the measurement target portion and detects intensity of the reflected light; and a condenser lens disposed on an optical path of the reflected light between the measurement target portion and the photodetector. On the optical path from the measurement target portion to the photodetector, in a section from the target placement unit to the photodetector, the reflected light propagates through space, except where transmitted through the condenser lens, and the condenser lens forms an image of the reflected light on the photodetector.
1 . A substance-in-blood concentration measurement device for measuring concentration of a substance in blood of a living body, comprising:
a target placement surface on which the living body that includes a measurement target portion is placed;
a laser configured to irradiate the measurement target portion with a laser beam, wherein the measurement target portion is a portion of the living body inwards of an epidermis;
a photodetector configured to receive a reflected light component of the laser beam reflected from the measurement target portion and detect intensity of the reflected light; and
a first lens disposed on an optical path of the reflected light between the measurement target portion and the photodetector, wherein
on the optical path from the measurement target portion to the photodetector, in a section from the target placement surface to the photodetector, the reflected light propagates through space, except where transmitted through the first lens, and
the first lens is optically conjugated to focus the reflected light from the measurement target portion onto a light receiving surface of the photodetector such that reflected light from a skin surface of the living body is defocused at the light receiving surface or guided outside an area of the light receiving surface on the photodetector.
2 . The substance-in-blood concentration measurement device of claim 1 , wherein
the laser is configured to irradiate the measurement target portion with the laser beam from a back surface side opposite a body placement side of the target placement surface, and
the photodetector is configured to receive the reflected light component of the laser beam reflected from the measurement target portion from the back surface side of the target placement surface.
3 . The substance-in-blood concentration measurement device of claim 1 , further comprising a second lens disposed on the optical path of the laser beam between the laser and the measurement target portion, the second lens condensing the laser beam on the measurement target portion, wherein on the optical path from laser to the measurement target portion, in a section from the laser to the target placement surface, the laser beam propagates through space, except where transmitted through the second lens.
4 . The substance-in-blood concentration measurement device of claim 1 , wherein the light receiving surface of the photodetector is separated from the first lens by a defined distance more than a distance from the first lens to a position to which an image of light reflected from a skin surface of the living body is transferred.
5 . The substance-in-blood concentration measurement device of claim 1 , wherein depth from a skin surface of the living body to the measurement target portion is changed by changing a position of the photodetector.
6 . The substance-in-blood concentration measurement device of claim 1 , wherein an incident angle of the laser beam to the measurement target portion is different from an emission angle of the optical path from the measurement target portion to the photodetector.
7 . The substance-in-blood concentration measurement device of claim 6 , wherein the emission angle of the optical path from the measurement target portion to the photodetector is from 0 degrees to 90 degrees from the normal to a surface of the target placement surface on which the living body is placed, and is different from the incident angle of the laser beam to the measurement target portion.
8 . The substance-in-blood concentration measurement device of claim 6 , wherein the incident angle of the laser beam to the measurement target portion is 45 degrees or more from the normal to a surface of the target placement surface on which the living body is placed, and
the emission angle of the optical path from the measurement target portion to the photodetector is from 0 degrees to 40 degrees from the normal to the surface.
9 . The substance-in-blood concentration measurement device of claim 1 , wherein wavelength of the laser beam is a defined wavelength selected from a range from 2.5 m to 12 m.
10 . The substance-in-blood concentration measurement device of claim 9 , wherein modulating the wavelength of the laser beam allows for detection of different types of blood component.
11 . The substance-in-blood concentration measurement device of claim 9 , wherein the wavelength of the laser beam is a defined wavelength selected from a range from 6.0 m to 12 m, and a blood component to be detected is glucose.
12 . The substance-in-blood concentration measurement device of claim 9 , wherein the wavelength of the laser beam is a defined wavelength selected from a range from 5.0 m to 12 m, and a blood component to be detected is lactic acid.
13 . The substance-in-blood concentration measurement device of claim 1 , wherein the photodetector comprises an infrared sensor that outputs an intensity of the reflected light as a one-dimensional value, and
the substance-in-blood concentration measurement device further comprises a two-dimensional imaging means that may be disposed in a position relative to the measurement target portion that is equivalent to the position relative to the measurement target portion of the photodetector, the two-dimensional imaging means receiving the reflected light reflected from the measurement target portion to detect whether or not a focused image is formed based on the reflected light.
14 . The substance-in-blood concentration measurement device of claim 1 , wherein the photodetector is a two-dimensional infrared sensor array in which a plurality of light receiving elements capable of detecting mid-infrared light are arranged in a matrix on a light receiving surface.
15 . The substance-in-blood concentration measurement device of claim 1 , wherein
the target placement surface is provided with a through hole in an area where a surface of the living body comes into contact with the target placement surface,
the laser beam is configured to irradiate the surface of the living body through the through hole, and
the photodetector is configured to receive the reflected light passing through the through hole.
16 . The substance-in-blood concentration measurement device of claim 1 , wherein
the target placement surface is provided with a concave portion in an area where a surface of the living body comes into contact with the target placement surface,
the laser is configured to irradiate the surface of the living body by passing through the target placement surface, and
the photodetector is configured to receive the reflected light after passing through the target placement surface.
17 . The substance-in-blood concentration measurement device of claim 1 , wherein signal strength detected by the photodetector from reflected light from a skin surface is lower than that from the reflected light from the measurement target portion inward of the epidermis.
18 . A substance-in-blood concentration measurement method for measuring concentration of a substance in blood of a living body, comprising:
placing the living body that includes a measurement target portion;
irradiating the measurement target portion with a laser beam from a laser, wherein the measurement target portion is a portion of the living body inwards of an epidermis;
optically forming an image of light reflected from the measurement target portion onto a photodetector using a first lens disposed between the measurement target portion and the photodetector, the first lens being optically conjugated to focus the reflected light from the measurement target portion onto a light receiving surface of the photodetector such that reflected light from a skin surface of the living body is defocused at the light receiving surface or guided outside an area of the light receiving surface on the photodetector; and
receiving the reflected light with the photodetector and detecting intensity of the reflected light.
19 . The substance-in-blood concentration measurement method of claim 18 , further comprising condensing the laser beam onto the measurement target portion by using a second lens disposed between the laser and the measurement target portion.
20 . The substance-in-blood concentration measurement method of claim 19 , wherein, on the optical path from the measurement target portion to the photodetector, in a section from a target placement surface to the photodetector, the reflected light propagates through space, except where transmitted through the first lens, and
on the optical path from the laser to the measurement target portion, in a section from the laser to the target placement surface, the laser beam propagates through space, except where transmitted through the second lens.
21 . The substance-in-blood concentration measurement method of claim 20 , wherein irradiating the measurement target portion is from a back surface side opposite a body placement side of the target placement surface, and receives the reflected light component of the laser beam reflected from the measurement target portion from the back surface side of the target placement surface.
22 . The substance-in-blood concentration measurement method of claim 18 , further comprising, prior to forming the image, adjusting an optical path length from the measurement target portion to the photodetector so that the light reflected from the measurement target portion forms a focused image on the photodetector.
23 . The substance-in-blood concentration measurement method of claim 22 , wherein adjusting includes causing a two-dimensional imaging means disposed in a position relative to the measurement target portion that is equivalent to the position relative to the measurement target portion of the photodetector to receive the reflected light reflected from the measurement target portion, and detecting whether or not the focused image is formed based on the reflected light.
24 . The substance-in-blood concentration measurement method of claim 18 , wherein signal strength detected by the photodetector from reflected light from a skin surface is lower than that from the reflected light from the measurement target portion inward of the epidermis.