Knowledge Bank

Three of the factors which affect energy limited resolving power of recording plane grating spectrometers employing parabolic mirrors are: 1. Off-axis aberrations at ends of slits 2. Curvature of spectral images 3. Finite width of grating We are constructing a spectrometer in this laboratory which will avoid these limitations. The optical system described by $Ebert,1$ employing a large spherical mirror will form almost perfect images of very long slits of the slits are properly curved. The required slit curvature happens to be just correct to remove wavelength error caused by spectral curvature. Multiple use of the grating, as described by $Walsh2$ is planned for later incorporation to remove the limitation imposed by the finite width of the grating. Experimental results so far obtained and an analysis of the image forming properties of the Ebert system will be presented.