PURPOSE: To measure a local field at a measuring spot without disturbance by utilizing a property that a light transmittance of a plural liquid crystal cell of a thickness is variant according to areas of corresponding parallel electrodes.
CONSTITUTION: A field inductive means 12 is constituted with a plural liquid crystal cell 16A, 16B, ... 16K and a plural pair of light transmissive parallel electrodes 18A and 18'A, 18B and 18'B, 18C and 18'C, ... 18K and 18'K arranged on both sides of each liquid crystal cell. The plural liquid crystal cell 16AW16K has the same thickness and is isolated with an insulating spacer 20. A beam of light 22 incident to the parallel electrode 18 is transmissive through the liquid crystal cell 16 and indicates a light transmittance appearing as a transmitted beam of light 22b from the parallel electrode 18'. Then, an electrostatic voltage between the parallel electrodes 18, 18' is directly proportional to a field strength and inversely proportional to an area. A local field strength can now be measured from exposure of a sensitizing film 24.
KATOU ATSUSHI
SASAKI JIYUNICHI
INOMATA YOUICHI
