13mm f.l. diverging lens for Bath Interferometer (mounted)

Description

Focal length 13mm. Good for testing telescope mirrors down to F/4.7 (cheaper laser with 1.7mm beam I sell) or down to F/3.7 (glass laser with 2.6mm diameter beam that I sell)

This part is from surplus shed part number L8344 (or equivalent) but I usually end up throwing at least half of them away due to defects.  Each lens is cleaned and tested to be sure it is defect free.

Mount for lens is included. Lens will arrive mounted as shown in photo.