Structured light 3-D measurement module and system for illuminating a subject-under-test in relative linear motion with a fixed-pattern optic
A surface measurement module for 3-D triangulation-based image acquisition of a subject-under-inspection and under observation by at least one camera. The module having: (a) casing housing an optical system comprising a plurality of lens elements positioned between a fixed-pattern optic and a light source; (b) an output of said fixed-pattern optic comprising a multi-frequency pattern comprising a plurality of pixels representing at least a first and second superimposed sinusoid projected simultaneously, each of the sinusoids represented by the pixels having a unique temporal frequency and each of the pixels projected to satisfy I n p = A p + ∑ k = 1 K B k p cos ( 2 π f k y p + 2 π kn N ) Eq . ( 1.1 ) (c) the subject-under-inspection and fixed-pattern optic in relative linear motion during projection onto the subject-under-inspection of the output of the fixed-pattern optic; and (d) plurality of images captured of this output during projection onto the subject-under-inspection are used for the image acquisition.
1. A surface measurement module for 3-D triangulation-based image acquisition of a subject-under-inspection and under observation by at least one camera, the module comprising:
(a) a casing housing an optical system comprising a plurality of lens elements positioned between a fixed-pattern optic and a light source;
(b) an output of said fixed-pattern optic comprising a multi-frequency pattern comprising a plurality of pixels representing at least a first and second superimposed sinusoid projected simultaneously, each of the sinusoids represented by the pixels having a unique temporal frequency and each of the pixels projected to satisfy
I
n
p
=
A
p
+
∑
k
=
1
K
B
k
p
cos
(
2
π
f
k
y
p
+
2
π
kn
N
)
Eq
.
(
1.1
)
where I n p is an intensity of a pixel for an n th projected image in a particular moment in time; K is an integer representing a number of component sinusoids, each component sinusoid having a distinct temporal frequency, where K is less than or equal to (N+1)/2, said output comprising at least N projected patterns; a parameter B k p represents constants that determine an amplitude or signal strength of the component sinusoids; A p is a scalar; f k is a spatial frequency of a k th sinusoid corresponding to temporal frequency k; and y p represents a spatial coordinate in an image projected as a result of said output;
(c) said fixed-pattern optic comprises said multi-frequency pattern fixed into a glass substrate, such that said output thereof results during said projection onto the subject-under-inspection;
(d) the subject-under-inspection and said fixed-pattern optic in motion in relative linear motion during projection onto the subject-under-inspection of said output of said fixed-pattern optic; and
(e) a plurality of images captured of said output of said fixed-pattern optic during projection onto the subject-under-inspection are used for the image acquisition.
2. A system comprising the module of claim 1 positioned for inspection of a pipeline interior wall; the module further comprising a rear annulus and a front annulus for stabilizing the module within said pipeline interior during said relative linear motion.
3. A system comprising the module of claim 1 positioned within a tubing whereby the subject-under-inspection comprises an interior surface of a section of said tubing; the module further comprising a rear annulus and a front annulus for stabilizing the module within said tubing during said relative linear motion.
4. The surface measurement module of claim 1 , wherein said multi-frequency pattern is fixed by etching a reflective material on said glass substrate member.
5. The surface measurement module of claim 1 , wherein said multi-frequency pattern is fixed by depositing a material onto said glass substrate member.
6. A system for implementing 3-D triangulation-based image acquisition of a subject-under-inspection and under observation by at least one camera, the system comprising a surface measurement module comprising:
(a) a casing housing an optical system comprising a plurality of lens elements positioned between a fixed-pattern optic and a light source;
(b) an output of said fixed-pattern optic comprising a multi-frequency pattern comprising a plurality of pixels representing at least a first and second superimposed sinusoid projected simultaneously, each of the sinusoids represented by the pixels having a unique temporal frequency and each of the pixels projected to satisfy
I
n
p
=
A
p
+
∑
k
=
1
K
B
k
p
cos
(
2
π
f
k
y
p
+
2
π
kn
N
)
Eq
.
(
1.1
)
where I n p is an intensity of a pixel for an n th projected image in a particular moment in time; K is an integer representing a number of component sinusoids, each component sinusoid having a distinct temporal frequency, where K is less than or equal to (N+1)/2, said output comprising at least N projected patterns; a parameter B k p represents constants that determine an amplitude or signal strength of the component sinusoids; A p is a scalar; f k is a spatial frequency of a k th sinusoid corresponding to temporal frequency k; and y p represents a spatial coordinate in an image projected as a result of said output;
(c) the subject-under-inspection and said fixed-pattern optic in relative linear motion during projection onto the subject-under-inspection of said output of said fixed-pattern optic; and
(d) a plurality of images captured of said output of said fixed-pattern optic during projection onto the subject-under-inspection are used for the image acquisition.
7. The system of claim 6 , wherein the subject-under-inspection comprises a subject selected from the group consisting of: a pipeline interior wall, an interior surface of a section of tubing, a non-compressible fluid, and a compressible fluid.
8. The system of claim 6 , wherein said fixed-pattern optic comprises said multi-frequency pattern fixed into a glass substrate, such that said output of said fixed-pattern optic results during said projection onto the subject-under-inspection.
9. The system of claim 6 , wherein said fixed-pattern optic comprises said multi-frequency pattern fixed into a glass substrate by etching a reflective material thereon such that said output of said fixed-pattern optic results during said projection onto the subject-under-inspection.
10. The system of claim 6 , wherein said fixed-pattern optic comprises said multi-frequency pattern fixed into a glass substrate by depositing a material thereon such that said output of said fixed-pattern optic results during said projection onto the subject-under-inspection.