Kinoform

A kinoform is a diffractive optical element (DOE) that approximates a desired wavefront by encoding only the phase information. Unlike holograms, which record both amplitude and phase, kinoforms discard the amplitude information of the wavefront. This simplification allows for higher diffraction efficiency, as all of the incident light is theoretically redirected into the desired image, save for losses due to fabrication imperfections or material absorption.

The term "kinoform" was coined by Lesem, Hirsch, and Jordan at IBM in the late 1960s. The method involves calculating the required phase distribution to create a desired image in a particular plane. This phase distribution is then etched or fabricated onto a transparent substrate, such as glass or plastic, creating a surface relief structure. The depth of the surface relief corresponds to the desired phase delay.

Kinoforms can be implemented using various fabrication techniques, including electron beam lithography, laser direct writing, and photolithography. The resulting structure acts as a phase plate, modifying the phase of the incident light as it passes through. The modified wavefront then propagates and forms the desired image through diffraction and interference.

Applications of kinoforms include beam shaping, optical interconnects, holographic displays, and diffractive lenses. They are particularly useful in applications where high diffraction efficiency and compact size are important considerations.