Herschel wedge
![Diagram of a Herschel Wedge and other solar viewing methods.](/Images/godic/202501/18/SolarEyepieces0641.png")
A Herschel wedge or Herschel prism is an optical prism used in solar observation to refract most of the light out of the optical path, allowing safe visual observation. It was first proposed and used by astronomer John Herschel in the 1830s.