| 摘要 |
PURPOSE:To enlarge a luminance contrast of a loss part and its circumference, and to detect easily a loss part by specifying an angle theta of a width A-A' of a non-light emitting part and a surface to be inspected P right below A or A', and an angle theta' of a width B-B' of a light emitting part and a surface to be inspected P' right below B or B'. CONSTITUTION:A titled device is provided with a striped pattern-like light emitting surface on which a non-light emitting part and a light emitting part are formed alternately, and the light emitting surface is made to correspond to a surface to be inspected so that an angle theta (acute angleAPA') made by a width A-A' of the non-light emitting part and a surface to be inspected P right below A or A' becomes <=2.3 deg., and an angle theta' (acute angleBP'B') made by a width B- B of the light emitting part and a surface to be inspected P' right below B or B' becomes 0.14 deg.-0.29 deg.. In case of executing an observation in a state that a loss part 2 is in a virtual image 81 of the non-light emittig part reflected on a surface to be inspected 1, when the observing position is in a range (a) of a direction 41 in which a specular reflecting component S from the loss part 2 becomes maximum and a direction 42 in which said component becomes minimum, reflected lights L1-L2 having a large light quantity, being the specular reflecting component from the loss part 2 are made incident to the observing position, therefore, a luminance contrast of the loss part 2 and its circumference (the virtual image 81 of the non-light emitting part) becomes large, and the loss part looks bright. |
