Patent ID: 8884187

Claim:
A welding observation apparatus comprising: an arc welding unit; an objective optical system for concentrating light from the arc welding unit; a telecentric optical system for guiding the light concentrated by the objective optical system; a plurality of photochromic filters for illuminating with the light guided by the telecentric optical system, the photochromic filters being superimposed along a light axis; and a solid state imaging device for receiving the light passing through the photochromic filters, the solid state imaging device being disposed adjacent the photochromic filters, wherein a light ray flux of an ultra-violet light and a visible light adjacent the solid state imaging device is substantially parallel each other, the telecentric optical system guides the light so that an ultra-violet image is not made to form an image on any one of the photochromic filters, and that the light ray flux of the ultra-violet light and the visible light does not spread in a whole area of each of the photochromic filters, but is passed through said each of the photochromic filters on a small scale partially, and the light from the arc welding unit is partial-darkened by the photochromic filters.