Canon EF 50mm f/1.8 STM Lens - 50 millimeter lens
thorlabs half wave plate400-800
Thorlabs half wave platepdf
The LCC1111-D from Thorlabs Inc is a Waveplate with Wavelength Range 1650 to 3000 nm, Waveplate Thickness 8.0 mm (0.32"), Waveplate Diameter(Inch) 1 Inch, Waveplate Diameter(mm) 25.4 mm. More details for LCC1111-D can be seen below.