| 摘要 |
The Fresnel structure of the invention is variable with regard to both angular pitch and curvature. A stretchable membrane (51) forms a surface which describes a Fresnel zone. Altering angular pitch is achieved by actuating a first side (49) relative to a second side (55). Such actuation causes the membrane (51) connected to both (49) and (55) to lengthen. Said lengthening causes a first fluid (47) on a first side of the membrane and a second fluid on a second side of the membrane to be reshaped with regard to angular pitch. Altering curvature is achieved by altering the pressure of the first fluid (47) relative to the pressure of the second fluid (53). The unit reliable produces variable Fresnel structures which can be altered with regard to angle and curvature. Transmissive and reflective structures are described. Refraction, diffraction, deflection, and reflection can all utilize these variable Fresnel structures. |
