Imaging system for shape measurement of partially-specular object and method thereof

• US 20080279458A1
• Filed: 02/08/2008
• Published: 11/13/2008
• Est. Priority Date: 05/09/2007
• Status: Abandoned Application

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Jeong, Joong-Ki, Hong, Deok-Hwa, Cho, Hyung-Suck
• Application Number:
  US12/068,645
• Publication Number:
  US 20080279458A1
• Time in Patent Office: Days
• US Class Current: 382/211
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light
• CPC Class Codes: H01L 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/148 Charge coupled imagers individual charge coupled devices H01L29/765

Abstract

The present invention can perform the optical measurement in the partially-specular object by preventing a generation of light saturation and blooming for an object with partially-specular characteristics by lowering the transmittance of specular lobe through the spatial light modulator. Therefore, the present invention can widen the measurement range up to the partially-specular object in the state where the advantages of the active optical measurement method of contactless, rapid measurement, and high precision are maintained.

Claims

1. An imaging system for shape measurement of a partially-specular object comprising:

a luminous means irradiating light on a surface of a partially-specular object;

a light receiving means having a spatial light modulator measuring the shape information of the partially-specular object through light reflected from the surface of the partially-specular object and controlling the attenuation rate of the points light-saturated in a camera and the corresponding pixels; and

a light receiving means having a spatial light modulator measuring the shape information of the partially-specular object through light reflected from the surface of the partially-specular object and controlling the attenuation rate of pixels corresponding the points light-saturated in a camera; and

a controlling means obtaining final image information wherein the light saturation and blooming phenomena do not occur, by identifying pixels wherein the light saturation occurs and controlling the attenuation rate of pixels in the spatial light modulator corresponding thereto.

2. The imaging system for shape measurement of a partially-specular object as claimed in claim 1, wherein the spatial light modulator is positioned on an imaging surface that is first imaged in order to control, per pixel, light quantity formed on a charge coupled device (CCD) plane for a camera that is a second imaging surface.

3. The imaging system for shape measurement of a partially-specular object as claimed in claim 1, wherein the spatial light modulator is positioned on a position slightly deviating from the imaging surface that is first imaged so that the pixel itself in the spatial light modulator is not imaged on the camera.

4. The imaging system for shape measurement of a partially-specular object as claimed in any one of claims 1, wherein the spatial light modulator controls the light quantity by the specular lobe which is reflected from the surface of the partially-specular object and incidented on camera.

5. The imaging system for shape measurement of a partially-specular object as claimed in any one of claims 2, wherein the spatial light modulator controls the light quantity by the specular lobe which is reflected from the surface of the partially-specular object and incidented on camera.

6. The imaging system for shape measurement of a partially-specular object as claimed in any one of claims 3, wherein the spatial light modulator controls the light quantity by the specular lobe which is reflected from the surface of the partially-specular object and incidented on camera.

7. A method for shape measurement of a partially-specular object using the imaging system as claimed in claim 1, comprising the steps of:

irradiating light from a luminous means on a surface of a partially-specular object;

identifying a light saturated position using a controlling means after all light reflected from the surface of the partially-specular object is transmitted through a spatial light modulator and an image at that time is obtained from the controlling means through the camera; and

obtaining final image information wherein the light saturation and the blooming do not occur and measuring the shape using this information, by controlling the attenuation rate of pixels in the spatial light modulator corresponding to CCD pixels where the light saturation occurs.

8. The method as claimed in claim 7, wherein the shape information is obtained using an active optical measurement method interpreting the final image information wherein the light saturation and the blooming do not occur.

9. The method as claimed in claim 8, wherein as the active optical measurement method, a phase measuring profilometry is used for obtaining the three-dimensional shape information of the object by interpreting a change in a fringe pattern projected on the surface of the object.