| 摘要 |
PURPOSE:To ensure the focus detection with extremely high sharpness for an optical image having various Fourier conversion components, by giving the weighting to the high frequency part of the Fourier conversion component of an object image. CONSTITUTION:The image of an object 6 is formed on a photoelectric transducer 8 through a lens 7. The sawtooth wave given from an oscillator 9 is fed to a differentiating circuit 9', a gain controller 14 and a (v-f) converter 10 respectively. The output of the converter 10 oscillates the element 8 to generate a surface acoustic wave, and a Fourier conversion component is delivered from the element 8 and fed to an amplifier 13. The controller 14 controls the gain of the amplifier 13 in proportion to the output generated from the element 8. The output of amplification is supplied to an integration circuit 15 and then converted into the integral value output of the Fourier conversion component which is obtained in a single scanning mode from the low band to the high band of a sawtooth wave signal. The integral value of each scanning period is applied to a meter 19 via a smoothing circuit, and the maximum value of indication is obtained by shifting the lens 7. Thus, a high-contrast image can be formed. |
