Design and fabrication of diffractive optical elements

Invited Review Article: Imaging techniques for harmonic and multiphoton absorption fluorescence microscopy

“…[89][90][91] Used in combination with two galvanometric scanners, they obtained TPEF images with a field of view of 100ϫ 100 m and a resolution of 512 ϫ 512 pixels in approximately 100 ms. 92 Their DOE generates a 4 ϫ 4 foci array with 25 m separation between foci ͑using a 60ϫ, 1.4 NA objective͒ with 75% diffraction efficiency. The use of a DOE permits a very uniform ͑ϳ1%͒ intensity distribution at the focal plane, this is in sharp contrast with microlens arrays that might have intensity fluctuations as high as 50% from their central part to their edges.…”

Multi-step electron beam technology for the fabrication of high performance diffractive optical elements

“…To maintain g P 90%, an overlay tolerance of approximately 1% is required. This entails an accuracy of less than 100 nm for NA P 0.06 (k = 630 nm), which is beyond the capabilities of most photolithographic equipment available today (±150 to ±300 nm) [3,4].…”

“…From the fabrication viewpoint, large NA and high diffraction efficiency will result in a pattern with sub-wavelength resolution and multi-level phase profile that has to be controlled with nanometer accuracy. In spite of the rapid development of DOEs fabrication techniques observed during last years, only a few methods demonstrate the potential to fulfill such high requirements [3,4]. The most advanced of these methods are based on the semiconductor processing technology and can be broadly divided into two major groups:…”

Computer-Generated Phase-Only Holograms for Real-Time Image Display

“…Fault tolerance of the optical system, which is achieved since the hologram pattern is decoupled from the desired image by a Fourier relationship, is also an attractive property in some applications where display integrity is required and "dead pixels" are unacceptable. Although there have been plenty of examples of using fixed holograms for 2D image formation by Heggarty & Chevalier (1998); Kirk et al (1992); Lesem & Hirsch (1969); Taghizadeh (1998;2000); Takaki & Hojo (1999), previous attempts at real-time image projection and display using CGHs have been mainly limited to the 3D case and the demonstrations by Ito et al (2005); Ito & Okano (2004); Ito & Shimobaba (2004); Sando et al (2004) have required significant computational resources. The few attempts at an implementation of real-time 2D holographic projection by, for example, Mok et al (1986); Papazoglou et al (2002); Poon et al (1993) have been affected by critical limitations imposed both by the computational complexity of the hologram generation algorithms required, and by the poor quality of images produced by the binary holograms they generate.…”