In optics, a Littrow prism or Littrow spectrometer or Littrow mirror is a reverse-reflecting dispersion prism arranged in such a way that the deviation of the incident beam entering at Brewster Angle is minimized, so the most dispersive Littrow prism is usually a 30°/60°/90° prism with a reflective film coated on the opposite surface of the 60° Angle. A typical Littrow prism is used at the end of a laser optical cavity to adjust the output frequency of the laser by changing the Angle of incidence.
As shown in the figure, half a 60° dispersion prism is plated with a reflection film layer on the long side of the right Angle. Through reflection, half a prism acts as a 60° dispersion prism. The compact structure of the Littrow dispersion prism system. For some expensive prism materials such as quartz, using this prism can save material.
Both coated and uncoated Littrow prisms by ECOPTIK have an Angle tolerance of greater than 1 arcsecond, a 10/5 surface mass, a λ/20 surface accuracy, and a dimensional tolerance of +.001 in.
N-BK7, UV Fused Silica, other optical glass
±3 arc min
±30 arc sec
>85% of dimension
Reflection coating, AR coating etc. upon requirement