For astronomers missing #SPIE by coming to #Leiden for Exoplanets 5, you can get your #astroninstrumentation fix by visiting the Boerhaave museum and amongst the science exhibits, you can see several lenses hand ground by the Huygens brothers from the 1600’s 🔭🪐 #astrodon #exo5

A signature by Christiaan Huygens scratched in cursive script into the edge of one of his lenses. The handwriting is beautiful cursive script, with the date 1666.
Matthew Kenworthy @kenworthy