Abstract
The A/D-transformed signal of the integrated speckle intensity detected by a TV camera yields a quantization error, and the 2nd order moment of the signal deviates from that of the integrated intensity. In this paper we have estimated the conditions to minimize the deviation. The deviation depends strongly on the dynamic range L and the quantizing number q of the A/D converter to be used. If the condition 5<L<7 is selected for q=8 bit, it has been found that the 2nd order moment can be determined within an accuracy of 3%. This result admits the image processing of the speckle pattern with enough accuracy, and it has been shown that the surface roughness of an object can be determined from the accurately measured 2nd order moment.
