Portable structured light measurement module/apparatus with pattern shifting device incorporating a fixed-pattern optic for illuminating a subject-under-test
A surface measurement module for 3-D image acquisition of a subject-under-inspection. The module having: (a) a casing to house a pattern shifting device having a fixed-pattern optic through which light from a light source is passed, an output of the pattern shifting device being directed at a polarizing beam splitter and the polarized output of the splitter directed through a lens assembly comprising at least one lens element; (b) a reflector to direct the polarized output exiting the lens assembly, to illuminate a surface of the subject-under-inspection; (c) a scattered light illumination off the surface is directed back through the lens assembly for capture by an image sensor; and (d) the casing also housing the polarizing beam splitter, the lens assembly, and the image sensor. The output of the fixed-pattern optic comprises a multi-frequency pattern. The pattern shifting device may be a linear or rotating type.
1. A surface measurement module for 3-D image acquisition of a subject-under-inspection, the module comprising:
(a) a casing to house a pattern shifting device from which an output comprising a multi-frequency pattern comprising a plurality of pixels representing at least a first and second superimposed sinusoid of light from a light source, is directed at a polarizing beam splitter,
(b) each said pixel of said plurality of pixels comprised of said first sinusoid having a first frequency distinct from a second frequency of said second sinusoid;
(c) the polarized output of said splitter directed through a lens assembly comprising at least one lens element;
(d) a reflector to direct said polarized output exiting said lens assembly, to illuminate a surface of the subject-under-inspection;
(e) a scattered light illumination off said surface is directed back to said reflector and then through said lens assembly for capture by an image sensor; and
(f) said casing also housing said polarizing beam splitter, said lens assembly, and said image sensor.
2. The surface measurement module of claim 1 further comprising:
(a) a quarter-wave plate interposed between said surface of the subject-under-inspection and a pathway directed to said lens assembly; and
(b) a plurality of images captured of said scattered light illumination, after passing back through said lens assembly, off said surface being used for the 3-D image acquisition.
3. The surface measurement module of claim 1 positioned for inspection of said surface having been selected from the group consisting of: a surface of mammalian tissue; a surface of an interior of a pipeline; a surface within a cavity of a hydraulic system; a surface of a semiconductor wafer undergoing fabrication; a surface of a printed circuit board (PCB) undergoing testing; and a surface of a product undergoing manufacture.
4. The surface measurement module of claim 3 wherein said surface of mammalian tissue comprises a surface located within a mammalian oral cavity; and said product undergoing manufacture is selected from the group consisting of parts, assemblies, foodstuff, and packaging.
5. The surface measurement module of claim 1 , wherein said pattern shifting device comprises a fixed-pattern optic having said multi-frequency pattern fixed into a substrate support.
6. The surface measurement module of claim 5 , wherein said multi-frequency pattern is fixed into said substrate support such that an output of said fixed-pattern optic has half-tone characteristics during said projection onto said surface of the subject-under-inspection.
7. The surface measurement module of claim 5 , wherein said multi-frequency pattern is fixed by etching said substrate support, said substrate support selected from the group consisting of silicon and metal substrate.
8. The surface measurement module of claim 5 , wherein said multi-frequency pattern is fixed by incorporating a reflective material into said substrate support, said substrate support selected from the group consisting of silicon-based glass and silicon.
9. The surface measurement module of claim 5 , wherein said multi-frequency pattern is fixed by depositing a material onto said substrate support, said substrate support selected from the group consisting of silicon-based glass and silicon.
10. The surface measurement module of claim 5 , wherein said pattern shifting device further comprises a shifting element comprising an element for linear shifting of said multi-frequency pattern.
11. The surface measurement module of claim 10 , wherein said element is conductive and to which, in operation, a voltage is applied.
12. The surface measurement module of claim 1 , wherein:
(a) said pattern shifting device comprises a fixed-pattern wheel; and
(b) said wheel set in motion causes a spatial shift such that said output of said pattern shifting device comprises said multi-frequency pattern.
13. The surface measurement module of claim 1 , wherein said pattern shifting device comprises a fixed-pattern optic having said multi-frequency pattern fixed into a substrate support by incorporating therein a reflective material comprising at least one mirror.
14. The surface measurement module of claim 1 , wherein said pattern shifting device comprises:
(a) a fixed-pattern optic having said multi-frequency pattern fixed into a substrate support; and
(b) a shifting element.
15. The surface measurement module of claim 14 , wherein said shifting element and said fixed-pattern optic are integrated such that a reflective material component comprising at least one mirror is incorporated into said substrate support.
16. A surface measurement module for 3-D image acquisition of a subject-under-inspection, the module comprising:
(a) a casing to house a pattern shifting device from which an output of light from a light source is directed at a polarizing beam splitter;
(b) the polarized output of said splitter directed through a lens assembly comprising at least one lens element;
(c) a reflector to direct said polarized output exiting said lens assembly, to illuminate a surface of the subject-under-inspection;
(d) a scattered light illumination off said surface is directed back through said lens assembly for capture by an image sensor;
(e) said casing also housing said polarizing beam splitter, said lens assembly, and said image sensor; and wherein:
(i) said output of said pattern shifting device comprises a multi-frequency pattern comprising a plurality of pixels representing at least a first and second superimposed sinusoid projected simultaneously; and
(ii) each of the sinusoids represented by the pixels have 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 the intensity of a pixel in the projector for the n th projected image in a particular moment in time; K is an integer representing the number of component sinusoids, each component sinusoid having a distinct temporal frequency, where K is less than or equal to (N+1)/2; the parameter B k p represents constants that determine the amplitude or signal strength of the component sinusoids; A p is a scalar; f k is the spatial frequency of the k th sinusoid corresponding to temporal frequency k; and y p represents a spatial coordinate in the projected image.
17. A surface measurement module for 3-D image acquisition of a subject-under-inspection, the module comprising, the module comprising:
(a) a casing to house a pattern shifting device from which an output comprising a multi-frequency pattern comprising a plurality of pixels representing at least a first and second superimposed sinusoid of light from an incoherent light source is directed at a polarizing beam splitter;
(b) the polarized output of said splitter directed through a lens assembly comprising at least one lens element;
(c) a reflector to direct said polarized output exiting said lens assembly, to illuminate a surface of the subject-under-inspection;
(d) a scattered light illumination off said surface is directed back through said lens assembly for capture by an image sensor; and
(e) wherein said first and second superimposed sinusoid are projected simultaneously, and each of the sinusoids represented by the pixels have 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 said component sinusoids; A p is a scalar; f k is a spatial frequency of a k th sinusoid corresponding to a temporal frequency k; and y p represents a spatial coordinate in an image projected as a result of said output.
18. The surface measurement module of claim 17 , wherein:
(a) said pattern shifting device comprises a fixed-pattern optic having said multi-frequency pattern fixed into a substrate support; and
(b) said casing also housing said polarizing beam splitter, said lens assembly, and said image sensor.
19. The surface measurement module of claim 18 , wherein said pattern shifting device further comprises a shifting element comprising a conductive element for linear shifting of said multi-frequency pattern to which, in operation, a voltage is applied.
20. The surface measurement module of claim 18 , wherein said multi-frequency pattern is fixed by incorporating a reflective material comprising at least one mirror into said substrate support.