Fresnel zone

About: Fresnel zone is a research topic. Over the lifetime, 2337 publications have been published within this topic receiving 37650 citations.

Development of a Unique, High Precision Linear Motor Integrated Air Slide Table, and Its Application to Laser Beam Writers

Abstract: This paper reports on the development of a unique, high precision linear motor integrated air slide table for precise positioning and its application to laser beam writers for photo-mask pattern-making. The air slide table takes advantage of the balance between the air bearing’s levitating and magnetic forces. A brushless linear motor and a high resolution linear encoder are integrated into the table. The unique construction of the device results in a very compact package with excellent accuracy. The basic characteristics of the air slide table are evaluated. The device is applied to a laser beam writer, which must be capable of rendering minute and precise patterns for photo-masking equipment. Examples are given including optical devices such as wave guides and Fresnel zone plates which were fabricated and evaluated. Experimental data is given to show that the Fresnel zone plate fabricated here can be used to focus a laser beam to the theoretical limit, just like a standard refractive lens.

Thin film deposition: an alternative technique for the fabrication of binary optics with high efficiency

Abstract: Binary optics were fabricated by an ion-beam sputter deposition technique on different substrate materials for the wavelengths of 1.52 mu m and 0.63 mu m respectively. The blazed profile of thin film dielectric gratings was approximated by a 2 and 4 phase level profile and the kinoform profile in each zone of the Fresnel zone lenses was approximated by a 2,4,8,16 and a 32 level profile. Such stepped profiles were realized with several masks, written with electron-beam and with photolithographic technology. The microlenses were coated with an anti-reflection coating. The reflection of these lenses was optimized on the basis of an angular spectrum approach. A minimum reflectivity as low as 1*10/sup -4/ was realized using in situ controlled multilayers of TiO/sub 2/ and SiO/sub 2/. The measurements reveal, that the spot-sizes of the fabricated microlenses are close to the diffraction limited values. The highest measured diffraction efficiencies for the 32 level structures are 97%. The effects of fabrication errors, such as level heights, alignment and linewidths errors, on the diffraction efficiency of Fresnel zone lenses were discussed. >

Laser resonator with high aspect ratio gain region and azimuthally symmetric Fresnel number

Abstract: An unstable optical resonator having a gain region that has an elliptic or other non-circular cross section still has the benefits of a total collimated cavity Fresnel number that is azimuthally symmetric by the combination of several cavity regions of azimuthally non-uniform Fresnel number of appropriate size.

Temporal zone plate.

Abstract: This paper extends the investigation of zone plates to the temporal case. By exploiting the space-time duality between the paraxial diffraction of beams in space and the linear dispersion of optical pulses, we present the time-domain analog of a multiple imaging system. The temporal system is created by using a digital chirp signal generator together with two dispersive delay lines. The key motivation is the potential application of the temporal zone plate to multiple compressions of pulses in dispersive lines.