JPS55136943A - Inspection apparatus for surface condition - Google Patents

Abstract

PURPOSE:To improve the inspection precision of the surface condition of a body by finding in order the difference between an original signal and a plurality of delay signals formed from the original signal in order to obtain a response signal even from a defect of a gentle change. CONSTITUTION:A light-receiving device 32 outputs a signal (a) which has a response part (A) corresponding to a sharp defect 34 and a response part (B) corresponding to a gentle defect 34'. The signal (a) is sent to an amplifier 9 and an envelope circuit 10 to obtain a signal (b), which is provided with delays in delay circuits 111, 112, and 113 to obtain signals (e), (f), and (i) respectively. The difference between the signals (e), (f), and (i) and the original signal (b) is subtracted from the signals (e), (f), and (i) in differential amplifiers 121, 122, and 123 to obtain signals (d), (g), and (j) respectively. The signal (e) having a pulse (C) corresponding to the sharp defect 34 is obtained from the signal (d), a signal (h), from the signal (g), and a signal (k) having a pulse (D) corresponding to the gentle defect 34', from the signal (j). The signals (e), (h), and (k) are transmitted to an OR circuit 16 to obtain a signal l having the pulses (C) and (D) corresponding to the defect part.