| 摘要 |
PURPOSE: To make an interference fringe evaluation apparatus useful for precise and efficient assembly and adjustment of a diffraction interference optical system and carry out quantitative evaluation, e.g. the number of interference fringes, by installing a photo receiving means to detect the alteration of luminous intensity information of interference fringes with the lapse of time and a computing means to quantitatively evaluate the interference fringes. CONSTITUTION: Luminous fluxes from a light source 1 enter a diffraction grating G1 , are divided into zero-order light rays I0 and±1-order diffraction light rays I+1 , I-1 , and come out separately. Then, these light rays enter a diffraction grating G2 and again come out separately as zeroorder light rays and±1-order diffraction light rays. After that, +1-order diffraction light rays I0+1 of the light rays I0 and -1-order diffraction light rays I+1-1 of the I-1 light rays enter almost the same points of a next diffraction grating G3 . Respective light rays come out separately again as zero-order light rays and±-order diffraction light rays. At that time, the -1-order diffraction light rays of I0-1 of I0+1 and the zero-order light rays I+1-10 of the light rays I+1-1 come out in the same direction and mutually interfere. In the case the diffraction gratings are parallel and the grading line directions are also parallel in the optical system, the interference light rays which come out of the grating G3 changes to be bright and dark uniformly by shifting the grating G2 .
|
