As means for changing the direction of light, there are reflecting mirrors. With a reflecting mirror, by the reflection at its surface of light, the direction changes, but, in the case of a planar reflecting mirror, the width of a light beam projected as incident light thereonto and the width of the reflected light beam are the same, and changing of width is not carried out. In a curved-surface reflecting mirror, although parallel light can be converted into convergent light or divergent light, a parallel light beam cannot be converted into a parallel light beam of different width. In order to convert a parallel light beam into a parallel light beam of different width, heretofore, there has been no way except to use a lens system, but a lens system is expensive, and, moreover, there is a limit in practical use to the width of the light beam which can be processed.
In view of the above facts, this invention has the object of obtaining a device for changing light width and direction which is capable of changing the direction of a light beam as it changes the width with any desired ratio, without any special restriction of the width of the light beam to be processed, and which can be produced by quantity production at a relatively low price.