Optical measurement instrument for living body semiconductor laser installation for living body light measuring device

• US 20080234560A1
• Filed: 11/15/2007
• Published: 09/25/2008
• Est. Priority Date: 03/23/2007
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ohtoshi, Tsukuru, Kiguchi, Masashi, Nomoto, Etsuko
• Granted Patent: US 8,369,913 B2
• Time in Patent Office: Days
• US Class Current: 600/310
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/043 in a linear array
• CPC Class Codes: A61B 2562/046 in a matrix array
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01N 2021/3144 for oxymetry
• CPC Class Codes: G01N 2021/3148 using three or more wavelengths
• CPC Class Codes: G01N 21/3151 using two sources of radiation of different wavelengths G01N21/33 - G01N21/39 take precedence
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01S 5/02257 using windows, e.g. specially adapted for back-reflecting light to a detector inside the housing
• CPC Class Codes: H01S 5/0234 Up-side down mountings, e.g. Flip-chip, epi-side down mountings or junction down mountings
• CPC Class Codes: H01S 5/0287 Facet reflectivity
• CPC Class Codes: H01S 5/0683 by monitoring the optical output parameters
• CPC Class Codes: H01S 5/22 having a ridge or stripe structure
• CPC Class Codes: H01S 5/32333 based on InGaAsP
• CPC Class Codes: H01S 5/3403 having a strained layer structure in which the strain performs a special function, e.g. general strain effects, strain versus polarisation
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence
• CPC Class Codes: H01S 5/4056 emitting light in more than one direction
• CPC Class Codes: H01S 5/4087 emitting more than one wavelength

Abstract

A living body measuring instrument having a sub-mount on which plural light-emitting devices oscillating at different wavelengths are mounted in proximity, one optical output monitoring device that detects the optical outputs of these light-emitting devices and a light source mounted on the same heat sink which are housed in one can-package, a light-receiving device that detects a signal from a living body, and a circuit that separates the optical output signals from the light-emitting devices, wherein at least one light-emitting device has a light-emitting layer including a In_1-xGa_xAs_yP_1-y quantum well layer and a barrier layer on a GaAs substrate, the strain E satisfies 0.4%≦ε≦1.4%, wherein y in the composition satisfies 0.10≦y≦0.45, and the wavelength of the emitted light is from 700 nm to 760 nm.

Claims

1. An optical measurement instrument for a living body, the instrument comprising:

a light source that emits a plurality of optical signals to the surface of a living body, a light-receiving device that detects the plurality of optical signals emitted from the surface of the living body after they have passed through the interior of the living body, and a signal separation circuit that separates the plurality of optical signals for each wavelength,

wherein the light source includes a plurality of semiconductor light-emitting devices having mutually different wavelengths from the visible to the infrared mounted on a sub-mount, a driving circuit that controls the optical signal output connected to the plurality of semiconductor light-emitting devices, and one optical output power monitoring device that detects the optical signal outputs emitted from the plurality of semiconductor light-emitting devices, these elements being housed in one package,

a monitored signal circuit that separates the plurality of optical signals detected by the optical output power monitoring device for each wavelength, and

the optical signal output of the plurality of semiconductor light-emitting devices is controlled by feeding the optical signals having different wavelengths separated via the monitored signal separation circuit back to the driving circuit connected to the semiconductor light-emitting devices that emit the wavelengths.

2. The optical measurement instrument for a living body according to claim 1, wherein the optical signals emitted from the plurality of semiconductor light-emitting devices contain two wavelengths selected so that the difference between the absorption coefficient for each wavelength of the optical signals emitted from the plurality of semiconductor light-emitting devices to a plurality of biological materials forming the living body is greater than a predetermined value, and at least one wavelength intermediate between these two wavelengths.

3. The optical measurement instrument for a living body according to claim 1, wherein the shortest wavelength among the wavelengths of the plurality of optical signals is 705±

5 nm.

4. The optical measurement instrument for a living body according to claim 1, wherein the plurality of optical signals have wavelengths including 755±

5 nm.

5. The optical measurement instrument for a living body according to claim 1, wherein the light source and light-receiving device are disposed at a distance at which the temperature of the living body can be detected.

6. The optical measurement instrument for a living body according to claim 5, having a device to cause the light emitted from the semiconductor light-emitting devices to diverge.

7. The optical measurement instrument for a living body according to claim 5, wherein the wavelength fluctuation of the semiconductor light-emitting devices in the usage environment is within ±

5 nm for each semiconductor light-emitting device.

8. The optical measurement instrument for a living body according to claim 5, wherein the reflectance of a light-emitting facet at the wavelength of the light emitted from the light-emitting facet, is 50% or more.

9. The optical measurement instrument for a living body according to claim 5, wherein the semiconductor light-emitting devices perform self-pulsation.

10. The optical measurement instrument for a living body according to claim 1, wherein at least one of the semiconductor light-emitting devices has an emission layer including an In_1-xGa_xAs_yP_1-y quantum well layer having a lattice constant a_w in the surface and a barrier layer provided on a GaAs substrate having a lattice constant a,

wherein the emission layer is such that the strain ε

defined by ε

(%)=(a_w−

a)/a×

100 satisfies 0.4%≦

ε

≦

1.4%, wherein y in the composition satisfies 0.10≦

y≦

0.45, and the wavelength of the emitted light is from 700 nm to 760 nm.

11. The optical measurement instrument for a living body according to claim 1, wherein at least one of the semiconductor light-emitting devices has an emission layer including an In_1-xGa_xAs_yP_1-y quantum well layer having a lattice constant a_w in the surface and a barrier layer provided on a GaAs substrate having a lattice constant a,

wherein the emission layer is such that the strain ε

defined by ε

(%)=(a_w−

a)/a×

100 satisfies 0.4%≦

ε

≦

1.2%, wherein y in the composition satisfies 0.10≦

y≦

0.25, and the wavelength of the emitted light is from 700 nm to 730 nm.

12. The optical measurement instrument for a living body according to claim 1, wherein at least one of the semiconductor light-emitting devices has an emission layer including an In_1-xGa_xAs_yP_1-y quantum well layer having a lattice constant a_w in the surface and a barrier layer provided on a GaAs substrate having a lattice constant a, wherein:

the emission layer is such that the strain ε

defined by ε

(%)=(a_w−

a)/a×

100 satisfies 0.4%≦

ε

≦

0.9%, wherein y in the composition satisfies 0.10≦

y≦

0.20, and the wavelength of the emitted light is from 700 nm to 720 nm.

13. The optical measurement instrument for a living body according to claim 1, wherein at least one of the semiconductor light-emitting devices has an emission layer including an In_1-xGa_xAs_yP_1-y quantum well layer having a lattice constant a_w in the surface and a barrier layer provided on a GaAs substrate having a lattice constant a,

wherein the emission layer is such that the strain ε

defined by ε

(%)=(a_w−

a)/a×

100 satisfies 0.6%≦

ε

≦

1.4%, wherein y in the composition satisfies 0.20≦

y≦

50.35, and the wavelength of the emitted light is from 725 nm to 760 nm.

14. A semiconductor laser installation, wherein a plurality of laser devices respectively emitting two wavelengths such that the difference between the absorption coefficient for each wavelength of the measurement light of a plurality of biological materials forming the living body to be measured is greater than a predetermined value, and at least one wavelength intermediate between these two wavelengths, are mounted in one package.

15. The semiconductor laser installation according to claim 14, wherein the shortest wavelength among the plurality of wavelengths of the laser installation is 705±

5 nm.

16. The semiconductor laser installation according to claim 14, wherein the plurality of wavelengths includes the wavelength of 755±

5 nm.

17. The semiconductor laser installation according to claim 14, having a device that causes a laser beam emitted from the laser devices to diverge.

18. The semiconductor laser installation according to claim 14, wherein the wavelength fluctuation according to the usage environment of each device forming the laser installation is within ±

5 nm.

19. The semiconductor laser installation according to claim 14, wherein at least one of the devices forming the laser installation has an emission layer including an In_1-xGa_xAs_yP_1-y quantum well layer having a lattice constant a_win the surface and a barrier layer provided on a GaAs substrate having a lattice constant a,

wherein the emission layer is such that the strain ε

defined by ε

(%)=(a<sub>w−

a)/a×</sub>

100 satisfies 0.4%≦

ε

≦

1.4%, wherein y in the composition satisfies 0.10≦

y≦

0.45, and the wavelength of the emitted light is from 700 nm to 760 nm.