Patent ID: 6844925

Claim:
A refracting power measuring apparatus comprising: a measuring optical system for projecting a measuring light toward a soft contact lens wet with liquid to measure optical characteristic values of the soft contact lens in air; a light receiving optical system having a light receiving sensor which receives the measuring light passed through the soft contact lens and outputs a received signal; an arithmetic circuit in which the received signal is inputted and computes the optical characteristic values based on the received signal; a residual quantity arithmetic circuit in which optical characteristic values data corresponding to the optical characteristic values of the arithmetic circuit are inputted every sample time and computes a residual quantity by means of a statistical processing based on the optical characteristic values data to output the residual quantity signal; a delay circuit for delaying the residual quantity signal a time corresponding to the sample time; and a comparing circuit for comparing the residual quantity signal delayed by the delay circuit with the following residual quantity signal and judging whether a difference between the delayed and following residual quantity signals is less than an allowed value, the optical characteristic values in air based on the judged results of the comparing circuit being obtained.