High-accuracy error-reduction method for 3D complex shape measurement with local-maximum-power-based technique of FMCW

To expand the measurement target from that containing simple cylindrical-shaped components to complexshaped components that have several directional tilted surfaces, we determined an issue in measuring the rough surfaces with laser distance measurement. The issue is that laser speckle causes measurement error, which amount, we found, can be determined by the diameter and irradiation angle of the measurement laser beam. We then developed two error-reduction techniques that are based on the optical properties of a detected waveform and power. We conducted a basic experiment and a feasibility study with actual samples, to evaluate the distance measurement performance of targets with various surface roughness and irradiation angles. The roughness and angle range of the evaluation was determined considering actual measurement needs in parts manufacturing. We confirmed that the measurement error, whose maximum value was nearly 80 mu m, decreased to less than 20 mu m using our proposed local-maximum-power-based technique.

Automated summary

The study expanded the measurement target from simple cylindrical components to complex shapes with rough surfaces, addressing the issue of measurement error caused by laser speckle. Through experiments and technical development, error-reduction techniques based on waveform and power optical properties were proposed, effectively reducing the measurement error to less than 20 micrometers.