A cemented optical element is disposed on a test sample and a laser light which is emitted from a laser light source section is incident into a prismatic plane so as to separate the laser light into a reflected light on the separating plane and a transmitted light on the separating plane on a light path separating plane. The reflected light on the separating plane passes through a prismatic plane so as to be condensed on a light receiving plane. The transmitted light on the separating plane is reflected on a reflecting plane having power so as to be condensed. Spots are formed on the light receiving planes which came through the prismatic plane. Sensitiveness for measuring angles can be changed while changing the length of the light path and the power.