To adjust the optical axis of the telescope to be perpendicular to the central axis of the spectrometer, you can put a prism on the stage and adjust the leveling screw under the stage, so that you can see the reflected cross spot in the telescope. Then rotate the stage and adjust the other two surfaces in turn. Then, turn around and adjust the first face, the second face and the third face several times until the three faces of the prism are aligned with the telescope, and the reflected light spot can be seen from the eyepiece. At this time, the telescope optical axis of the spectrometer is perpendicular to the central axis of the spectrometer.

The sign that the optical axis of the telescope is perpendicular to the double-sided telescope: Make the optical axis of the telescope perpendicular to the central axis of the spectrometer, and you can see that the reflected "+"image coincides with the upper cross of the fork wire on the reticle.

Specific method steps of adjustment:

(1) Adjust the telescope with autocollimation method to make it suitable for receiving parallel light;

Turn on the illumination lamp in the side window of the telescope to illuminate the fork wire, and rotate and move the eyepiece so that the fork wire is located on the focal plane of the eyepiece. At this time, you can see the fork wire clearly. Put the flat mirror on the stage (the mirror faces the telescope).

Then slowly rotate the stage, and at the same time adjust the fork wire sleeve (change the distance between the fork wire and the objective lens), and find the fuzzy light spot reflected by the plane mirror from the telescope (if it can't be found, the coarse adjustment does not meet the requirements and should be readjusted).