| 摘要 |
PROBLEM TO BE SOLVED: To provide a variable entrance angle illuminator to simultaneously vary entrance angles in up, down, left and right directions while reducing size, thickness and weight of an illumination optical system to efficiently guide a light flux from a light source to the side of a subject by minimizing loss of light quantity. SOLUTION: The variable entrance angle illuminator to irradiate the light flux from a light source means by deflecting it with a prescribed entrance angle via an optical means, is characterized in that the light source means is provided with a tube-like luminous body which is long in one direction, the optical means is provided with a first translucent optical member 4, a second translucent optical member 5 and a third optical member 6, the first and second translucent optical members are oppositely arranged so that relative intervals in both directions becomes variable and inclined surfaces 4e, 4e' of the first translucent optical member are formed to be long in the vertical direction so that a space in a horizontal cross section between the first and second translucent optical members is widened toward an end part of the left and right direction at the end part of an emitting surface of it.
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