| 摘要 |
PROBLEM TO BE SOLVED: To provide an inner diameter measuring apparatus which emits a laser beam in a whole circumferential direction by a cone mirror, thereby forming a light ring on the inner surface of a cylindrical body, and measures the inner diameter of the cylindrical body on the basis of the light ring while suppressing the influence of the laser beam reflected on the inner surface on the inner diameter measurement.SOLUTION: An inner diameter measuring apparatus comprises: a cone mirror 29 having a conical reflecting surface at a tip thereof; a laser beam emitting part 3 which makes a laser beam 17 incident on the tip of the cone mirror 29; a light transmitting window part 6 for transmitting the laser beam 17 reflected on the cone mirror 29 in a whole circumferential direction; an imaging part 2 which images a light ring formed on an inner surface of a cylindrical body by the laser beam 17 emitted through the light transmitting window part 6; and a laser beam blocking member 34 which is attached in such a manner that it is rotatable around the light transmitting window part 6 and covers a predetermined range of the light transmitting window part 6. |
