Скачать или смотреть Fabry-Perot etalon experiment with a low-pressure sodium lamp

We built a home made Fabry–Pérot interferometer to better examine the spectrum from our low pressure sodium lamp. The mirrors are Thorlabs 90% reflectivity beam splitters (BSX10). They are held in a pair of Thorlabs precision kinematic mirror mounts (KS1). The mounts are attached to a pair of ADM dovetail adapters (VPA ) and these are locked onto a short Williams Optics dovetail (DSD 110). The spacing of the mirrors can be varied from 2mm to 20mm. A gap of 3.0mm is used in the experiment here. The sodium doublet (6 angstrom spacing) is easily resolved. By pushing gently on the mirror mount, the spacing can be slightly varied, making the interference fringes move in and out. The end of the video shows still images that more clearly show the interference rings. Each sodium line appears to be split by a very narrow self-absorption line due to temperature inhomogeneities in the low pressure sodium lamp; this narrow line is visible only in the still photos.