Spectroscope, astronomical telescope and method for manufacturing spectroscope

A method for manufacturing a spectroscope which comprises

• a first base member comprising a first surface having a diffraction grating and a second surface which is a rear surface of the first surface,
• a second base member comprising a third surface having a diffraction grating and a fourth surface which is a rear surface of the third surface,
• a holder comprising a lid having first holes and second holes opposed to the fourth surface, and arranging and fixing the first base member and the second base member, and
• a fixing member disposed in the second hole, and connecting and fixing the fourth surface and the lid,
• the method comprising:
• a step of fixing the first base member to the holder,
• a step of disposing the second base member to the holder,
• a step of connecting a posture adjusting member, which is a part of a posture adjusting mechanism, to the fourth surface through the first hole,
• a step of adjusting a location of the second base member according to a location of the first base member by using the posture adjusting mechanism,
• a step of disposing the fixing member in the second hole,
• a step of fixing the fourth surface and the lid via the fixing member, and
• a step of removing at least a part of the posture adjusting member.