Nearly index-matched optics for aspherical, diffractive, and achromatic-phase diffractive elements

Abstract

Nearly index-matched optical elements are described that have application to aspherical, diffractive, and hybrid refractive -diffractive elements. Owing to the small difference in index, tolerances on the interfacial surface profile are much looser than for conventional aspherical and diffractive elements. A condition on both the index and the dispersion is described that results in an achromatic phase, thereby allowing for diffractive elements with high efficiency over broad spectral bands. Properties of the elements are described and compared with those of conventional diffractive elements. Analytical results and experimental measurements with an inexpensive element with 40 waves of asphericity are presented.

Effect of assembling errors on the diffraction efficiency for multilayer diffractive optical elements

“…(11). Equation (15) shows that the diffraction efficiency of MLDOEs is dependent on the working wavelength, and the decenter error Δ, the period T, and the index of refraction of the material and microstructure height are determined.…”

“…However, the diffraction efficiency of single-layer DOEs decreases quickly when the working wavelength deviates far from the design wavelength, which causes the imaging quality of hybrid diffractive refractive optical systems to deteriorate in a wide waveband [11]. To overcome this problem, the idea of multilayer DOEs (MLDOEs) in a wide waveband was discussed [12], and a model to analyze the diffraction efficiency for MLDOEs was proposed [13][14][15]. In 2001, Canon used MLDOEs in a camera telephoto lens [16].…”

Polychromatic imaging with extended depth of field using phase masks exhibiting constant phase over broad wavelength band

“…Opposite etching profiles create the effect of negative and positive phase elements, similar to positive and negative focal length lenses in an achromatic doublet. This method has been investigated in the past [5,6] for limited cases and applications. These known solutions are summarized here, and their limitations are discussed.…”

Characterization of Pseudo-Random-Phase-Plate as a Kolmogorov/non-Kolmogorov turbulence simulator using statistical parameters and the phase structure function

“…Study of propagation of an optical beam through especially fabricated random media like transmissive Pseudo-RandomPhase-Plates (PRPPs) [1][2][3][4] can act as a precursor for understanding the nature of realistic random media, an example being, atmospheric turbulence. Such studies prove to be vital for fields like optical communication, optical imaging and adaptive optics.…”