Apparatus and method for reconstructing a three-dimensional profile of a target surface

1. An apparatus for reconstructing a three-dimensional profile of a target surface of an object, the apparatus comprising:

a lighting apparatus having at least a first mode of illumination to illuminate the target surface and at least a second mode of illumination to illuminate the target surface independent of the first mode of illumination, the lighting apparatus having a first lighting device to produce the first mode of illumination, which is a pattern onto the target surface and a second lighting device to produce the second mode of illumination, which illuminates every part of the target surface without a corresponding pattern, wherein light from the first and second modes of illumination are arranged to illuminate the target surface along a same angle of incidence and a ratio (R) of a difference of intensity between the first and second modes of illumination (I 1 -I 2 ) against an intensity of the second mode of illumination (I 2 , such that R=(I 1 -I 2 /I 2 ) is constant across the profile of the target surface;

a lighting control apparatus operative to sequentially activate only one of the at least two modes of illumination at a time;

an imaging device operative to sequentially capture a first image of the target surface when the target surface is illuminated by the first mode of illumination and a second image of the target surface when the target surface is illuminated by the second mode of illumination respectively; and

a processor for reconstructing the three-dimensional profile of the target surface based on a combination of image characteristics obtained from only the first and second images of the target surface as captured by the imaging device.

2. The apparatus of claim 1 , wherein the lighting apparatus comprises:

a grating;

a first lighting device arranged relative to the grating, so that the first lighting device is operable to project light onto the grating to thereby produce the pattern onto the target surface; and

a second lighting device is operable to project light to illuminate every part of the target surface.

3. The apparatus of claim 2 , further comprising an optical device,

wherein the grating is arranged between the optical device and the first lighting device so that light from the first lighting device that is projected onto the grating is reflected by the optical device to produce the pattern onto the target surface, and

the second lighting device is arranged relative to the optical device, so that light from the second lighting device is projected through the optical device onto the target surface to illuminate every part of the target surface.

4. The apparatus of claim 3 , wherein the optical device is a beam-splitter.

5. The apparatus of claim 3 , wherein the optical device is a prism.

6. A method of reconstructing a three-dimensional profile of a target surface of an object, the method comprising the steps of:

sequentially activating at least two modes of illumination of a lighting apparatus having a first lighting device to produce a first mode of illumination to illuminate the target surface and a second lighting device to produce a second mode of illumination to illuminate the target surface, wherein the first mode of illumination is a pattern onto the target surface and the second mode of illumination illuminates every part of the target surface without a corresponding pattern, light from the first and second modes of illumination being arranged to illuminate the target surface along a same angle of incidence and a ratio (R) of a difference of intensity between the first and second modes of illumination (I 1 -I 2 ) against an intensity of the second mode of illumination (I 2 , such that R=(I 1 -I 2 )/I 2 ) is constant across he profile of the target surface;

wherein the step of sequentially activating at least two modes of illumination of a lighting apparatus to illuminate the target surface comprises the step of using a lighting control apparatus to control the lighting apparatus to sequentially activate only one of the at least two modes of illumination at a time;

using an imaging device to sequentially capture a first image of the target surface when the target surface is illuminated by the first mode of illumination and a second image of the target surface when the target surface is illuminated by the second mode of illumination respectively; and

using a processor to reconstruct the three-dimensional profile of the target surface based on a combination of image characteristics obtained from only the first and second images of the target surface as captured.

7. The method of claim 6 , wherein the lighting apparatus comprises a grating and first and second lighting devices, the method comprising the steps of:

the first lighting device projecting light onto the grating to thereby produce the pattern onto the target surface; and

the second lighting device projecting light to illuminate every part of the target surface.

8. The method of claim 7 , wherein the grating is arranged between a further optical device and the first lighting device, the method further comprising the steps of:

using the optical device to reflect light that is projected from the first lighting device and onto the grating, so as to produce the pattern onto the target surface; and

projecting light from the second lighting device through the optical device, so as to illuminate every part of the target surface.