Reflective attenuator for high-energy laser measurements

Abstract

A high-energy laser attenuator in the range of 250 mJ (20 ns pulse width, 10 Hz repetition rate, 1064 nm wavelength) is described. The optical elements that constitute the attenuator are mirrors with relatively low reflectance, oriented at a 45 degrees angle of incidence. By combining three pairs of mirrors, the incoming radiation is collinear and has the same polarization orientation as the exit. We present damage testing and polarization-dependent reflectance measurements for 1064 nm laser light at 45 degrees angle of incidence for molybdenum, silicon carbide, and copper mirrors. A six element, 74 times (18 dB) attenuator is presented as an example.

A CW calibrated laser pulse energy meter for the range 1 pJ to 100 mJ

“…As we have demonstrated, the linear range of the meter can be extended by at least a factor of 5 × 10 6 using stable, calibrated, multi-element reflective attenuators described elsewhere [7]. These attenuators can accept beams up to 7 mm diameter (1/e 2 ) and 250 mJ pulse energy.…”

“…More will be said about their use in the relevant sections. The trap tunnel block attenuator, like the trap detector, is based on the strategy of combining reflectors, or partial absorbers, in a 'cube edge' arrangement [7].The beam path within the attenuator forms the edges of a cube. The absorbers in the present case are metal mirrors rather than thin films, chosen so that the attenuation factor remains stable over a wide range of input energy and temperature.…”

Interference effects at a dielectric plate applied as a high-power-laser attenuator

“…The ideal laser attenuator should enable a uniform power reduction over a wide dynamic range, should not significantly affect the beam's geometrical (diameter, divergence, intensity profile, direction) and polarization properties [6], and should have a simple, robust, and inexpensive mechanical and optical design [7]. Among the various attenuation designs [1,2,[4][5][6][7][8][9][10], several principles [1,6,8] can be used for the attenuation of high-peak-power laser beams, where the main obstacles arise from damage and heating instabilities [1].…”

Tilted parallel dielectric slab as a multilevel attenuator for incident p- or s-polarized light

“…Optical attenuators that reduce the intensity of a light beam by a predetermined amount are useful for precise spectrophotometry [1], calibrating filters [2], testing the linearity of photodetectors [3][4][5], and in applications that involve high-power lasers [6][7][8][9][10]. Existing designs include the rotating-sector attenuator [1], a three-polarizer system that consists of two fixed outer polarizers and a rotating middle polarizer [2], variable-gap optical-tunneling (frustrated-total-internal-refection) attenuator [6,7], wedged-plate attenuator [8], and reflective multimirror systems at oblique incidence [10].…”

“…Existing designs include the rotating-sector attenuator [1], a three-polarizer system that consists of two fixed outer polarizers and a rotating middle polarizer [2], variable-gap optical-tunneling (frustrated-total-internal-refection) attenuator [6,7], wedged-plate attenuator [8], and reflective multimirror systems at oblique incidence [10].…”