抄録
A grating prism is such a prism that the faces of a polygon prism which is used for measurement of angle are substituted by plane gratings, it can be used in the same way as a polygon prism for measurement of angle. With the grating prism, higher order images of the grating act as if the number of faces of the polygon prism are increased, and we have many reference angular positions. For instance, a 90 lines/mm grating hexaprism at λ=589 μy corresponds to a polygon prism of 234 faces.
