Focusing errors in a collimating lens or mirror: use of a moiré technique.
The Fresnel diffraction pattern of a grating periodically gives an exact reproduction of the grating. By superposing a second grating on such an image, we form a moiré pattern that depends upon the degree of parallelism of the incident beam. We present here the possibility of using this technique for studying the focusing errors in a collimating lens or a mirror.
Fouéré
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JC
Malacara
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