Broadband passive optical limiter using a photorefractive crystal, cylindrical lens and filter to protect against substantially all pulsewidths and continuous wave lasers

US5449904A · kind A · utility

Assignee

• The United States of America as represented by the Secretary of the Army · US

Inventors

• Mary Jayne Miller · Kettering, US
• Gregory J. Salamo · Fayetteville, US
• William W. Clark · Wexford, US
• Gary L. Wood · Rural Hall, US
• Edward J. Sharp · Fort Washington, US
• Brian Monson · Farmington, US

Key dates

• Filing date: Nov 30, 1994
• Grant date: Sep 12, 1995
• Expiry date: Nov 30, 2014

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F1/0338
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A passive broadband sensor protection and enhancement system and technique. ncident light is focused with a cylindrical lens on the optical axis into an intense light strip onto the input face of a photorefractive crystal on the optical axis. The crystal includes optional anti-reflection coatings proximate to the input and output face. A broadband high reflection coating is proximate to the input face for reflection of all radiation from approximately 0.68 to at least out to 1.5 micrometers wavelength. Light exiting from the output face of the crystal results from a photorefractive process that includes a transmitted beam and beam fan. The beam fan is fanned out of the optical path in a direction determined by the c-axis, dominant electro-optic coefficient, and charge carriers participating in the photorefractive process. The transmitted beam contains only incoherent radiation as input to a sensitive detector resulting in broadband multiline protection from the visible spectrum for substantially all pulsewidths and cw lasers, with enhanced time response and interaction length.