Measurement method and non-contact displacement detection apparatus thereof

A measurement method, for measuring a position and a tilt angle of a target object, the measurement method comprising a calibration mode and a measurement mode:

• during the calibration mode:
• f) controlling a calibration plate to move within a measurement range, and controlling a first sensor and a second sensor to perform measurement to obtain a position curve;
• and
• g) controlling the calibration plate to rotate within a tilt angle range, and controlling the first sensor and the second sensor to perform measurement to obtain N first tilt angle curves, N second tilt angle curves and a curve of tilt angle versus pixel deviation,
• during the measurement mode:
• a) calculating a pixel deviation between a first pixel and a second pixel of the target object, wherein the first pixel of a first waveform corresponds to a first pixel position, the second pixel of a second waveform corresponds to a second pixel position, and a difference between the first pixel position and the second pixel position is outputted as the pixel deviation;
• b) substituting the pixel deviation into the curve of tilt angle versus pixel deviation to obtain the tilt angle of the target object;
• c) selecting a first target curve from the N first tilt angle curves according to the tilt angle and the first pixel, and selecting a second target curve from the N second tilt angle curves according to the tilt angle and the second pixel;
• d) substituting a zero-tilt angle into the first target curve and the second target curve, respectively, to obtain a pixel at the zero-tilt angle;
• and
• e) substituting the pixel at the zero-tilt angle into the position curve to obtain the position of the target object.