Three Dimensional Color Laser Scanner

Developed over a 17 year period at the National Research Council of Canada (NRC), the Arius3D 3D color imaging system consists of a laser scanner and a motion control system for moving the camera. Scanned data is recorded and processed by software to transform the data into high-quality, 3D color images irrespective of ambient light.

The system employs the principles of high resolution laser triangulation and synchronous scanning to produce high-fidelity digital representations of real-world objects at unprecedented resolution

The laser scanning mechanism characterizes each point on the scanned object according to its color and location in 3-space. It does this by scanning the surface of an object with three different laser wavelengths (red, green and blue) in one focused beam, and recording the reflected light. The X co-ordinate of each point on the object is calculated from an accurate measurement of the position of the scanning mirror in the camera. The Y co-ordinate is calculated from an accurate measurement of the camera’s motion system. The Z, or range co-ordinate, is calculated through laser triangulation within the camera.

At the same time, the color information at each point is gathered by measuring the intensity of the three returning laser beams. Color intensity measurements are an accurate measurement of the surface color of the scanned object.

Each point on the object is described by 6 numeric values; positional values X, Y, and Z, and surface color values R, G, and B.

X-axis:

Scanning in the X direction is accomplished by a galvanometer-driven double-sided mirror. The position of each point on the X-axis is developed from the known angular position of the mirror.

Y-axis:

Scanning in the Y direction is accomplished by motion perpendicular to both the laser axis and the X-axis, usually implemented as a turntable or translation stage. The position of each point on the Y-axis is developed from the known position of the turntable or stage.

Z-Axis:

The position along the Z-axis (the laser axis) is measured by laser triangulation, enhanced by the application of synchronized scanning geometry. This patented method uses one side of the galvanometer-driven mirror to deflect the laser across the scanned object while the opposite side of the same mirror is used to cancel the return beam's angular movement across the CCD sensor. With this geometry, only a change in the position of the light spot along the Z-axis produces net movement across the CCD sensor. A patented sub-pixel interpolation scheme is used to enhance the resolution of the CCD sensor.