| 摘要 |
<p>A phase grating which has a trapezoidal waveform cross section on its grating face side, has a trapezoid factor (B/A) of the trapezoidal waveform, is 0.006 ≤B/A<1 (where A is the difference in area between 'a perfect trapezoid' circumscribing the trapezoidal waveform and 'a sinusoidal curve' inscribing 'the perfect trapezoid' and B is the difference in area between 'the perfect trapezoid' and 'the trapezoidal waveform'). The higher order diffracted light components of a conventional phase grating having a trapezoidal cross section are reduced and the decline of the MTF in a low space frequency region is reduced.</p> |
