Testing echelle gratings: a simple method

The authors present a simple method for testing echelles, requiring a turntable, a means for mounting the grating, and a He-Ne laser. A translator through which the grating can be moved sideways is desirable but not necessary. For very accurate measurements an instrument for measuring the relative intensities of the diffracted spectral orders of the laser light is needed. Most of this equipment can be found in almost any university physics department.