Patent ID: 7519502

Claim:
A method for obtaining liquid surface profile information, the method comprising: recording plural calibration images of a liquid surface, said recording of calibration images including recording at least two said calibration images at different elevations relative to said liquid surface, each said calibration image including plural calibration laser spots projected onto said liquid surface by a stationary device for recording said calibration images; performing calibration with respect to said calibration images, each said calibration laser spot being characterized by two apparent coordinates (x a , y a ) and three physical coordinates (x p , y p , z p ), said performing of calibration including performing surface displacement calibration and performing X-Y mapping calibration, said surface displacement calibration being for determining a relationship between said physical coordinate z p and said apparent coordinates (x a , y a ), said X-Y mapping calibration being for determining a relationship between said physical coordinates (x p , y p ) and said apparent coordinates (x a , y a ), said performing of X-Y mapping calibration including effecting intensity-based centroid estimation to determine the centroid of each said calibration laser spot, said performing of calibration including obtaining three calibration curves for each said calibration laser spot, each said calibration curve representing a second-order polynomial least-squares fit for one of the three said physical coordinates (x p , y p , z p ) of a said calibration laser spot; recording plural measurement images of said liquid surface, said recording of measurement images being performed in a time-resolved manner whereby said measurement images are time-sequentially recorded of said liquid surface in a dynamically changing condition, each said measurement image including plural measurement laser spots projected onto said liquid surface by a stationary device for recording said measurement images; performing data processing with respect to said measurement images, each said measurement laser spot being characterized by said two apparent coordinates (x a , y a ) and said three physical coordinates (x p , y p , z p ), said performing of data processing including effecting intensity-based centroid estimation to determine the centroid of each said measurement laser spot, said performing of data processing further including performing coordinate mapping of said measurement images, said performing of coordinate mapping including applying the corresponding said three calibration curves to each said measurement laser spot so as to transform said apparent coordinates (x a , y a ) of said measurement laser spot to said physical coordinates (x p , y p , z p ) of said measurement laser spot.