Optical sensor, optical inspection device, and optical property detection method for detecting light propagated inside a test object

• US 10,067,056 B2
• Filed: 12/29/2015
• Issued: 09/04/2018
• Est. Priority Date: 01/06/2015
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Fujiwara, Masayuki, Ishii, Toshihiro, Takahashi, Yoichiro, Sasaki, Toshihide
• Primary Examiner(s): Le, Que T
• Application Number:
  US14/982,659
• Publication Number:
  US 20160195473A1
• Time in Patent Office: 980 Days
• Field of Search: 250221, 250216, 2505594
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/146 for optical coupling
• CPC Class Codes: A61B 5/0042 for the brain
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: G01J 1/0411 using focussing or collimating elements, i.e. lenses or mirrors; Aberration correction
• CPC Class Codes: G01N 21/359 using near infrared light
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B
• CPC Class Codes: G01N 21/49 within a body or fluid
• CPC Class Codes: G01N 2201/0612 Laser diodes
• CPC Class Codes: G01N 2201/068 Optics, miscellaneous

Abstract

An optical sensor including an irradiation system including at least one light irradiator, the at least one irradiator including a surface emitting laser array having a plurality of light-emitting units, and a lens disposed in an optical path of the plurality of rays of light emitted from the plurality of light-emitting units to cause light exit directions of at least two of the plurality of light-emitting units to be not parallel to each other, such that the at least one irradiator irradiates a same point of a test object with a plurality of rays of light that are not parallel to each other. The optical sensor also including a detection system configured to detect the plurality of rays of light that are emitted from the irradiation system and propagated inside the test object.

Claims

1. An optical sensor comprising:

an irradiation system including at least one light irradiator, the at least one irradiator including

a surface emitting laser array having a plurality of light-emitting units, and

a lens disposed in an optical path of the plurality of rays of light emitted from the plurality of light-emitting units to cause light exit directions of at least two of the plurality of light-emitting units to be not parallel to each other, such that the at least one irradiator irradiates a same point of a test object with a plurality of rays of light that are not parallel to each other; and

a detection system configured to detect the plurality of rays of light that are emitted from the irradiation system and propagated inside the test object, wherein

the plurality of light-emitting units of the surface emitting laser array include a first light-emitting unit furthest from an optical axis of the lens and a second light-emitting unit second furthest from the optical axis of the lens,

the first light-emitting unit and the second light-emitting unit are not parallel with each other,

a light exit direction of the first light-emitting unit has a larger tilt angle with respect to an optical axis of the lens than a light exit direction of the second light-emitting unit,

each one of the plurality of light-emitting units includes an approximately ring-shaped dielectric at a light exit area, and

a center point of the dielectric of at least one of the at least two of the plurality of light-emitting units is displaced from the center point of the light exit area.

2. The optical sensor according to claim 1, wherein the light exit direction of the at least one of the at least two of the plurality of light-emitting units is oblique with reference to an optical axis of the lens.

3. The optical sensor according to claim 1, wherein among at least two of the light-emitting units, relative positions of a center point of the dielectric and a center point of the light exit area are different from each other.

4. The optical sensor according to claim 1, wherein the light irradiator further includes a member, the member being disposed on an optical path of a plurality of rays of light emitted from the at least two of the light-emitting units and passes through the lens, the member having a reflection plane that reflects the plurality of rays of light.

5. The optical sensor according to claim 1, wherein the lens and the surface emitting laser array have a space therebetween filled with a transparent resin whose refractive index is equivalent to that of the lens.

6. The optical sensor according to claim 1, wherein the detection system includes at least one photodetector including a plurality of photoreceptors configured to detect the plurality of rays of light that are emitted from the light irradiator and propagated inside the test object.

7. The optical sensor according to claim 6, wherein the photodetector is disposed between the test object and the plurality of photoreceptors, and has a member provided with a transmissive portion configured to transmit a part of each of the plurality of rays of light propagated inside the test object.

8. The optical sensor according to claim 7, wherein the photodetector includes a light-receptive lens configured to guide the part of each of the plurality of rays of light to the plurality of photoreceptors.

9. The optical sensor according to claim 6, wherein

the light irradiator of the irradiation system includes a plurality of light irradiators,

the photodetector of the detection system includes a plurality of photodetectors,

the plurality of light irradiators and the plurality of photodetectors are disposed for the test object such that the light irradiator and the photodetector are arranged so as to be next to each other in any of two directions that are orthogonal to each other,

light exit directions of the plurality of rays of light emitted from the plurality of light irradiators are inclined with reference to the two directions, and

incident directions of the plurality of rays of light propagated inside the test object and entering the photodetector are inclined with reference to the two directions.

10. The optical sensor according to claim 6, wherein

the light irradiator of the irradiation system includes a plurality of light irradiators,

the photodetector of the detection system includes a plurality of photodetectors,

the plurality of light irradiators and the plurality of photodetectors are disposed for the test object such that two of either one of the light irradiator and the photodetector are at two vertices of a regular triangle separately, and

one of the other one of the light irradiator and the photodetector is at a remaining vertex of the regular triangle.

11. The optical sensor according to claim 1, wherein the light irradiator includes a member that contacts the test object and is composed of a material whose refractive index is greater than that of the test object.

12. The optical sensor according to claim 1, wherein the lens has a convex shape towards the surface emitting laser array.

13. An optical inspection device comprising:

the optical sensor according to claim 1; and

an optical property calculator configured to calculate an optical property of the test object based on a detection result of the optical sensor.

14. A method of detecting an optical property with an optical sensor, the optical sensor including an irradiation system including at least one light irradiator, the at least one irradiator including a surface emitting laser array having a plurality of light-emitting units, and a lens disposed in an optical path of the plurality of rays of light emitted from the plurality of light-emitting units to cause light exit directions of at least two of the plurality of light-emitting units to be not parallel to each other, such that the at least one irradiator irradiates a same point of a test object with a plurality of rays of light that are not parallel to each other, and a detection system configured to detect the plurality of rays of light that are emitted from the irradiation system and propagated inside the test object, the method comprising:

detecting an optical property of the test object using the optical sensor;

calculating a sensitivity distribution of light on the test object; and

calculating an optical property of the test object through solving an inverse problem based on the sensitivity distribution,

the plurality of light-emitting units of the surface emitting laser array including a first light-emitting unit furthest from an optical axis of the lens and a second light-emitting unit second furthest from the optical axis of the lens,

the first light-emitting unit and the second light-emitting unit not being parallel with each other,

a light exit direction of the first light-emitting unit having a larger tilt angle with respect to an optical axis of the lens than a light exit direction of the second light-emitting unit,

each one of the plurality of light-emitting units including an approximately ring-shaped dielectric at a light exit area, and

a center point of the dielectric of at least one of the at least two of the plurality of light-emitting units being displaced from the center point of the light exit area.