OPTICAL BLOCK AND OPTICAL AXIS ADJUSTING METHOD

PROBLEM TO BE SOLVED: To provide an optical block and an optical axis adjusting method easily adjusting an optical axis.SOLUTION: The optical block 10 is equipped with: a first surface M1; a second surface M2 inclined to the first surface M1 by 30°, reflecting a part of incident light LA2 toward the first surface M1, and transmitting the other part of the incident light LA2; and a third surface M3 inclined to the first surface M1 by 60° and inclined to the second surface M2 by 30°, and reflecting transmitted light from the second surface M2 toward the first surface M1.