Collimation evaluation device and collimation evaluation method

A collimation evaluation device comprising:

• a first reflection member having a first reflection surface for reflecting a part of incident light and a second reflection surface for reflecting light transmitted through the first reflection surface in the incident light;
• a second reflection member having a first reflection surface for reflecting a part of light emitted from the first reflection member and a second reflection surface for reflecting light transmitted through the first reflection surface in the light;
• and
• an observation unit configured to observe light L11 reflected on the first reflection surface of the first reflection member and the first reflection surface of the second reflection member, light L12 reflected on the first reflection surface of the first reflection member and the second reflection surface of the second reflection member, light L21 reflected on the second reflection surface of the first reflection member and the first reflection surface of the second reflection member, and light L22 reflected on the second reflection surface of the first reflection member and the second reflection surface of the second reflection member, and configured to enable interference fringes formed by the light L12 and the light L21 to be observed, wherein
• the first reflection surface of the first reflection member and the first reflection surface of the second reflection member face each other and are parallel to each other,
• an incidence plane is defined as a plane parallel to both the incident light and the reflected light, and the first reflection surface and the second reflection surface are non-parallel to each other in a direction parallel to both the incidence plane and the first reflection surface, in both or one of the first reflection member and the second reflection member,
• the observation unit is configured such that incident regions of the light L12 and the light L21 overlap each other and do not coincide with each other on the observation unit, the interference fringes are formed on an overlapped region, and the light L11 and the light L22 are not incident on the overlapped region being an interference fringe formation region, and
• the collimation evaluation device is configured to evaluate collimation of the incident light on the basis of a direction of the interference fringes formed by the light L12 and the light L21 on the observation unit.