After analysis of the possible causes for the measurement error of contacting contour measurement instruments

based on the least square method

a mathematical model was established to correct the errors caused by the inclination in

X

Y

direction

eccentricity in

X

Y

Z

direction that exists in the positioning of aspheric lens

inaccuracy of curvature radius

and the random micro-excursion between the circumrotating center and the detecting header of contour measurement instrument. By mathematical simulation

it is proved that this model could achieve high precision in correcting those errors stated above. To eccentricity less than 1 cm and inclination less than 0.1 degree

this model could completely correct these errors

it is also very effective in correcting the errors of curvature radius. The results of practical engineer implementation indicate that this model is very reliable and effective and can provide a loose lens positioning condition and function of automatic fit of optimal curvature radius for the measurement of contacting aspheric lens contour. Especially this model offers the function of automatic correction of measurement errors originated from the random micro-excursion between the circumrotating center and the detecting header of contour measurement instrument

and it will improve the measurement accuracy and measurement result repeatability of the contour measurement instrument.