Lens/zone plate combination for chromatic dispersion correction
First Claim
1. An optical apparatus for correcting chromatic dispersion between an infrared light source and a visible light source of substantially differing wavelengths, comprising a lens/zone plate combination, the zone plate having a phase depth on the order of the wavelength of the visible light to transmit substantially all of the infrared light into its zeroth order and to diffract most of the visible light into its first order, thus changing the focal length of the visible light to coincide with the focal length of the infrared light.
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Abstract
Chromatic dispersion between first and second wavelengths of light is corrected by a lens/zone plate combination. The zone plate is adapted both to send most of the first wavelength light into its zeroth order and to send most of the second wavelength light into its first order and to change the focal length of the second wavelength light to coincide with the focal length of the first wavelength light. A preferred embodiment includes a zinc/selinide sulfide lens having a zone plate etched onto one of its surfaces. The zone plate has a multi-step phase profile including four phase levels. The lens/zone plate combination is particularly adapted for use with CO2 and HeNe lasers to bring their focal lengths into coincidence.
54 Citations
19 Claims
- 1. An optical apparatus for correcting chromatic dispersion between an infrared light source and a visible light source of substantially differing wavelengths, comprising a lens/zone plate combination, the zone plate having a phase depth on the order of the wavelength of the visible light to transmit substantially all of the infrared light into its zeroth order and to diffract most of the visible light into its first order, thus changing the focal length of the visible light to coincide with the focal length of the infrared light.
- 15. Optical apparatus for correcting chromatic dispersion between light from a CO2 laser and a HeNe laser comprising a zinc selinide lens having a zone plate etched on one of its surfaces, the zone plate having a phase depth of 0.75 of the wavelength from the HeNe laser and having a four level phase profile.
Specification