ID: 
2172
Maker's Name: 
unknown
Dimensions: 
32 × 1.1 × 1.1 cm

Fused silica tube as used to stabilise the length of the resonator of a submm laser in the 1980s (leftover scrap). The narrow gain linewidth of such lasers, and the long wavelength, requires that the resonator length be adjusted accurately to an integer number of half-wavelengths and maintained there in spite of any temperature variations.