INTERNAL INSPECTION UNIT FOR HOLLOW PATH

PROBLEM TO BE SOLVED: To obtain an internal inspection unit for hollow path in which a wide image pickup region can be covered, an image being picked up can be enlarged while reducing distortion, and sufficient quantity of light can be ensured by providing a light emission source, a plane mirror, a convex mirror and an image pickup means. SOLUTION: Diffused light from a light source passes through an optical fiber 15 and enters into a plane mirror 12 and a reflected light Lb passes through a hollow path 4a. The light Lb travels through the hollow path 4a while repeating diffuse reflection and reflected on a convex mirror 13 while being magnified. The reflected light passes through a lens 16 and received by a camera 14 on a two-dimensional plane thus picking up the planar inside image of hollow path 4a. Subsequently, a decision is made whether an abnormality is present in the path 4a by identifying the features, e.g. brightness and area, from the image being picked up. Image pickup region as wide as 100-120 deg. can be covered using the convex mirror 13. Furthermore, since a picked up image 17 is enlarged while reducing distortion, features of the image, e.g. brightness and area, can be identified easily and accurately.