Effects Of Nonlinear Resonant Absorption On Sodium Laser Guide Stars

Byron M. Welsh; Chester S. Gardner; Laird A. Thompson

doi:10.1117/12.960825

20 September 1989 Effects Of Nonlinear Resonant Absorption On Sodium Laser Guide Stars

Byron M. Welsh, Chester S. Gardner, Laird A. Thompson

Proceedings Volume 1114, Active Telescope Systems; (1989) https://doi.org/10.1117/12.960825
Event: SPIE 1989 Technical Symposium on Aerospace Sensing, 1989, Orlando, FL, United States

Abstract

Saturation effects may severely limit the brightness of guide stars created in the mesospheric sodium (Na) layer. Saturation arises when the laser energy density is large enough to significantly alter the population densities of the atomic states within the layer. These altered state populations lead to nonlinear absorption of the laser energy thereby producing in a reduced rate of fluorescence and an increased rate of stimulated emission. The level of saturation is determined by the laser's pulse length, pulse energy, beamwidth and linewidth. We have quantified the saturation effects in terms of these laser parameters and have formulated design equations which will allow us to design a laser capable of achieving a specified guide star brightness while at the same time minimizing the power and pulse length requirements. Our calculations show that a Na laser having a pulse energy and pulse length on the order of 106 mJ and 69 μs respectively and an linewidth of 600 MHz will produce a guide star at zenith which is bright enough to drive an adaptive optics system with a seeing cell size of r_o = 18.5 cm. This energy corresponds to a laser power of 21 watts at 200 pulses per second.

Citation Download Citation

Byron M. Welsh, Chester S. Gardner, and Laird A. Thompson "Effects Of Nonlinear Resonant Absorption On Sodium Laser Guide Stars", Proc. SPIE 1114, Active Telescope Systems, (20 September 1989); https://doi.org/10.1117/12.960825

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available