| 摘要 |
PROBLEM TO BE SOLVED: To improve the efficiency of flaw detecting work by setting the irradiated surface of visual spot light to a circular or elliptic light distribution of a specified value or more in a prescribed irradiating distance, and raising the illuminance of the irradiated surface. SOLUTION: An elliptic concave reflecting mirror having an opening diameter of 20 mm or less is provided from an ellipse having a long axial diameter of 42-68 mm and a short axial diameter of 20-26 mm, and a spot visual light source is situated between the focus of the elliptic concave reflecting mirror and the long axial diameter-side apex on the line passing this focus and this apex and regulated, whereby a circular or elliptic light distribution in which the 1/2 illuminance range of central illuminance is 100-150 mm or more in an irradiating distance of 300 mm can be provided and a light distribution having a mountain-shaped illuminance can be also provided. Accordingly, the central illuminance can be raised, and the irradiating range can be extended. Since the central illuminance can be suppressed, and the 1/2 illuminance range can be further extended when a ground glass 25 is mounted, this is effective when the central irradiated surface is too bright. |
