The Sensor Lens is used to craft the Sensor Glasses.
Galacticraft 2 & Galacticraft 3:
Galacticraft 1 + Basic Components:
Please note that Galacticraft interim versions 18.104.22.1681 through to 22.214.171.1248 had a recipe bug where this item could not be crafted. This was fixed as of version 126.96.36.1999.