US 11,536,560 B2 · Optical apparatus, optical system, and method for measuring an amount of strain of an object

Abstract

An optical apparatus includes a coherent light source; a transmission assembly configured to receive light emitted by the coherent light source, split the light into object light and reference light so that the object light and the reference light travel along different paths receive object light reflected by an object to be measured, and combine the object light reflected by the object to be measured and the reference light; and a photosensitive camera disposed at an output of the transmission assembly, and configured to receive combined light and process the combined light to record light intensity information capable of characterizing a spatial position of a surface of the object to be measured.

An optical system, comprising:

an optical apparatus and a processor,
wherein the optical apparatus comprises:
a coherent light source;
a transmission assembly configured to receive light emitted by the coherent light source, split the light into object light and reference light so that the object light and the reference light travel along different paths, receive object light reflected by an object to be measured, and combine the object light reflected by the object to be measured and the reference light;
and
a photosensitive camera disposed at an output of the transmission assembly and configured to receive combined light and process the combined light to record light intensity information capable of characterizing a spatial position of a surface of the object to be measured;
the processor configured to calculate phase information of the object light reflected by the object to be measured according to light intensity information recorded by the photosensitive camera in the optical apparatus, and calculate an amount of strain of the object to be measured according to a change between phase information before the object to be measured is deformed and phase information after the object to be measured is deformed;
wherein a micro-polarizer array comprises a plurality of micro-polarizers arranged in an array, and the plurality of micro-polarizers are divided into a plurality of repeating units which are same as each other, each repeating unit comprises at least four adjacent micro-polarizers, all micro-polarizers comprised in each repeating unit are arranged in N rows and M columns, and polarization directions of all the micro-polarizers comprised in the repeating unit are different, wherein N is greater than or equal to 2, M is greater than or equal to 2;
and an image sensor comprises a plurality of photosensitive elements disposed in one-to-one correspondence with the plurality of micro-polarizers;
calculating the phase information of the object light reflected by the object to be measured according to the light intensity information recorded by the optical apparatus in the optical system, comprises:
obtaining a relational expression between light intensity information I recorded by each photosensitive element and phase information ω of object light received by a corresponding repeating unit according to a following formula (1):
I
=
1
2
[
I
s
+
I
r
+
2
⁢
I
s
⁢
I
r
⁢
cos
⁡
(
ω
+
2
⁢
α
)
]
,
(
1
)
wherein α represents a polarization angle of a micro-polarizer corresponding to the photosensitive element, Is represents a light intensity of object light received by the photosensitive element, and Ir represents a light intensity of reference light received by the photosensitive element;
and
calculating the phase information ω of the object light received by the corresponding repeating unit according to the relational expression between the light intensity information I recorded by the photosensitive element and the phase information ω of the object light received by the corresponding repeating unit, and the light intensity information I recorded by the photosensitive element, wherein phase information ω of object light received by all repeating units constitutes the phase information of the object light reflected by the object to be measured;
wherein in a case where each repeating unit comprises four micro-polarizers, and polarization angles of the four micro-polarizers are 0°, 45°, 90°, and 135°,
relational expressions between light intensity information I1, I2, I3, and I4 recorded by respective photosensitive elements corresponding to respective micro-polarizers in the repeating unit and the phase information ω of the object light received by the repeating unit are respectively:
I
1
=
1
2
[
I
s
+
I
r
+
2
⁢
I
s
⁢
I
r
⁢
cos
⁡
(
ω
)
]
;
(
2
)
I
2
=
1
2
[
I
s
+
I
r
-
2
⁢
I
s
⁢
I
r
⁢
sin
⁡
(
ω
)
]
;
(
3
)
I
3
=
1
2
[
I
s
+
I
r
-
2
⁢
I
s
⁢
I
r
⁢
cos
⁡
(
ω
)
]
;
(
4
)
I
4
=
1
2
[
I
s
+
I
r
+
2
⁢
I
s
⁢
I
r
⁢
sin
⁡
(
ω
)
]
;
and
(
5
)
according to relational expressions (2) to (5), and the light intensity information I1, I2, I3, and I4 recorded by the respective photosensitive elements corresponding to the respective micro-polarizers in the repeating unit, the phase information of the object light received by the corresponding repeating unit is calculated to be:
ω
=
arctan
⁡
(
I
4
-
I
2
I
1
-
I
3
)
.
(
6
)
wherein calculating the amount of strain of the object to be measured according to a change between the phase information before the object to be measured is deformed and the phase information after the object to be measured is deformed, comprises:
obtaining phase information ω2(i,j) of object light received by respective photosensitive elements corresponding to respective micro-polarizers in a repeating unit that is in an i-th row and in a j-th column before the object to be measured is deformed, and phase information ω1(i,j) of object light received by the respective photosensitive elements corresponding to the respective micro-polarizers in the repeating unit that is in the i-th row and in the j-th column after the object to be measured is deformed;
calculating an amount of strain in an x direction of the surface of the object to be measured that is photographed by the respective photosensitive elements corresponding to the respective micro-polarizers in the repeating unit that is in the i-th row and in the j-th column according to a following formula (7), ω1(i,j) and ω2(i,j):
ε
x
=
ω
1
(
i
,
j
)
-
ω
2
(
i
,
j
)
Δ
⁢
x
;
(
7
)
and
calculating an amount of strain in a y direction of the surface of the object to be measured that is photographed by the respective photosensitive elements corresponding to the respective micro-polarizers in the repeating unit that is in the i-th row and in the j-th column according to a following formula (8), ω1(i,j) and ω2(i,j):
ε
y
=
ω
1
(
i
,
j
)
-
ω
2
(
i
,
j
)
Δ
⁢
y
,
(
8
)
wherein i and j are both positive integers, the x direction and the y direction are perpendicular to each other, and Δx and Δy are respectively actual sizes of a region of the object to be measured corresponding to the photosensitive elements in the x direction and in the y direction.

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Optical apparatus, optical system, and method for measuring an amount of strain of an object

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Optical apparatus, optical system, and method for measuring an amount of strain of an object

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Abstract

Claims14