ANALYSIS AND REPRESENTATION OF THE SIZE SHAPE AND ORIENTATION CHARACTERISTICS OF THE COMPONENTS OF A SYSTEM

摘要

1356467 Diffraction systems J H TALBOT 27 May 1971 [29 May 1970 23 Nov 1970] 17662/71 Heading G2J [Also in Division G1] In analyzing the goemetrical characteristics of components of a system 17, such as in tissue matching or controlling the quality of a mill product having particles suspended in a liquid, the system 17 is illuminated with coherent light 12, to form the far-field diffraction pattern 25 which is variably attenuated outwards from the centre according to a rational power of the distance from the centre. The attenuation may be performed by a filter 24 and the output produced on a viewing screen Fig. 2, (not shown) graduated to give a read-out of the desired parameter. Different filters are so designed as to provide information concerning the number of components of the system, their linear dimensions, their specific surface area or their mean volume. The information may be detected photo-electrically. In one embodiment a system in a flow cell 50 Fig. 4 is illuminated with coherent light 12. The diffraction pattern is split by beam splitter 56 to form on two photo-cells 57, 58, each having a filter 65, 66. The outputs are amplified at 67, 74, rectified and integrated at 68, 73 and the signal from integrator 73 converted to digital form at 72. Integrated signal 68 is compared at 69 to reference signal 70; and when it equals this it gives the command to digital printer 71 to print the integral registered by integrator 73. Since the integral registered on integrator 68 is a constant set by the reference voltage 70 this integral is used in effect as a constant denominator and thus the information printed out represents the ratio of the two outputs. The output may be detected by a photocell through an annular mask movable along the optic axis of the system or by a series of annular photo-cells Fig.5 (not shown) located along the optic axis, the filtering function being effected by adjusting the gain of the output. Alternatively, Fig. 6, (not shown), it may be measured by a spring mounted photo-cell located on an arm rotated in the plane of the diffraction pattern and caused to follow a spiral scan across the pattern. Suitable optical filters are concentric dark and transparent rings having either a linear or parabolic gradient; a filter having annular sectors with circumferentially distributed dark and transparent rows with a radial parabolic gradient; a stemless four-leaf clover pattern, or a transparent cross on a dark background.