# US 10,768,095 B2 · Optical sensor

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- Number: US 10,768,095 B2
- Document ID: US10768095B2
- Status: Granted
- Kind: B2
- Application number: 16/506,160
- Filed: 2019-07-09
- Published: 2020-02-27
- Granted: 2020-09-08
- Earliest claimed: 2018-08-23
- Assignees: Ricoh Company, Ltd.; Advanced Telecommunications Research Institute International
- Applicants: Yoichiro Takahashi; Takeaki Shimokawa; Toshihiro Ishii
- Inventors: Yoichiro Takahashi; Takeaki Shimokawa; Toshihiro Ishii
- Web page: https://patentgrep.com/patent/US10768095B2

## CPC

- G01N 21/01: Arrangements or apparatus for facilitating the optical investigation
- G01N 21/31: Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry {(G01N21/72 takes precedence)}
- A61B 5/0059: {using light, e.g. diagnosis by transillumination, diascopy, fluorescence (photoacoustic A61B5/0093; optical measurement of heart rate A61B5/02416; optical measurement of blood flow A61B5/0261; optical measurement of analytes A61B5/1455)}
- A61B 5/14553: {specially adapted for cerebral tissue}
- G01N 21/17: Systems in which incident light is modified in accordance with the properties of the material investigated (where the material investigated is optically excited causing a change in wavelength of the incident light G01N21/63)
- G01N 21/474: {Details of optical heads therefor, e.g. using optical fibres}
- G01N 21/49: within a body or fluid
- A61B 5/14552: {Details of sensors specially adapted therefor}
- A61B 2562/0233: Special features of optical sensors or probes classified in A61B5/00
- G01N 2201/06: Illumination; Optics
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

An optical sensor includes a light emitter configured to irradiate a surface of an object with a plurality of non-parallel light beams, a light detector configured to detect a plurality of light beams that have been reflected within the object and have returned to the surface from a plurality of directions, a recording unit configured to store pre-calculated results of a plurality of models having different optical properties and physical structures, and a calculating unit configured to calculate a light amount ratio of the plurality of reflected light beams, and estimate an optical property of the object based on the calculated light amount ratio and the pre-calculated results.

## Claims

### Claim 1

An optical sensor comprising:
a light emitter configured to irradiate a surface of an object with a plurality of non-parallel light beams;
a light detector configured to detect a plurality of light beams that have been reflected within the object and have returned to the surface from a plurality of directions;
a recording unit configured to store pre-calculated results of a plurality of models having different optical properties and physical structures; and
a calculating unit configured to calculate a light amount ratio of the plurality of reflected light beams, and estimate an optical property of the object based on the calculated light amount ratio and the pre-calculated results.

### Claim 2 (depends on 1)

The optical sensor according to claim 1, wherein the light detector includes a plurality of divided light receiving areas, and the calculating unit calculates the light amount ratio of the plurality of reflected light beams, the plurality of reflected light beams being detected in the plurality of divided light receiving areas.

### Claim 3 (depends on 1)

The optical sensor according to claim 1, wherein the light detector includes a plurality of light detectors disposed at respective positions whose distances from the light emitter are different from each other.

### Claim 4 (depends on 3)

The optical sensor according to claim 3, wherein the calculating unit calculates a ratio of amounts of light obtained at the respective positions, and estimates the optical property based on a following formula:
ln
⁢
⁢
ϕ
⁡
(
l
1
)
ϕ
⁡
(
l
2
)
=
⁢
ln
⁢
⁢
exp
⁡
(
-
l
1
⁢
3
⁢
μ
s
′
⁢
μ
a
)
/
l
1
exp
⁡
(
-
l
2
⁢
3
⁢
μ
s
′
⁢
μ
a
)
/
l
2
=
⁢
3
⁢
μ
s
′
⁢
μ
a
⁢
(
l
2
-
l
1
)
+
ln
⁢
⁢
l
2
l
1
wherein l1 represents a first distance from the light emitter to one of the plurality of light detectors, l2 represents a second distance from the light emitter to another one of the plurality of light detectors, ϕ(l1) represents a first amount of light detected at the first distance, ϕ(l2) represents a second amount of light detected at the second distance, and μs′ represents a reduced scattering coefficient, and μa represents an absorption coefficient.

### Claim 5 (depends on 1)

The optical sensor according to claim 1, wherein the light emitter includes a light emitting element array having a plurality of light emitting elements, and uses at least some of the plurality of light emitting elements to emit the plurality of non-parallel light beams.

### Claim 6 (depends on 5)

The optical sensor according to claim 5, wherein light emission from each of the plurality of light emitting elements is individually controlled.

### Claim 7 (depends on 5)

The optical sensor according to claim 5, wherein the light emitter uses the at least some of the plurality of light emitting elements to emit the plurality of non-parallel light beams, and uses other light emitting elements of the light emitting element array to monitor emission amounts of the plurality of non-parallel light beams.

### Claim 8 (depends on 5)

The optical sensor according to claim 5, wherein the light emitter is a surface emitting laser array.

### Claim 9 (depends on 1)

The optical sensor according to claim 1, wherein the light emitter irradiates the object with a plurality of polarized light beams whose polarization directions are different from each other.

### Claim 10 (depends on 1)

The optical sensor according to claim 1, further comprising a control unit configured to control the light emitter and the light detector,
wherein the control unit is connected to the light emitter and the light detector by I2C wiring.