Dynamic space shaping of intense ultrashort laser light with blazed-type gratings

Author(s): I. Marienko, V. Denisenko, V Slusar, and M. Soskin

Abstract:

“A beam shaper for dynamic transversal shaping of broadband laser pulses that utilizes a blazed ruled grating and a blazed-type grating simulated on Spatial Light Modulator was demonstrated. The introduced shaper scheme is an extension of 2f-2f scheme [Mariyenko, et al., Opt. Express 13, 7599 (2005)] where the two thin holograms with matched grating constants performed light shaping. The new scheme utilizes the diffraction gratings with different grating constants. Dispersion-free light shaping is achieved by means of the intermediate transversal light beam magnification. The magnification balances the mismatch in the grating constants resulting in total residual angular dispersion compensation. In turn, the magnified beam covers a greater area on the modulator matrix thus reducing the incident light power density by a value equal to square of the magnification factor. It translates to the safe-operation threshold extension of the modulator allowing shaping pulses that are powerful enough to be used in the applications. With a proper components selection, the throughput efficiency of the shaper can be well above 40%. A proper shaper operation was demonstrated with the 140-fs Ti:Sapphire oscillator. Theoretical calculations support the conclusions.”

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Publication: Optics Express
Issue/Year: Optics Express, Vol. 18, Issue 24, pp. 25143-25150 (2010)
DOI: 10.1364/OE.18.025143

Generation of a high depth of focus with constant transversal spot size using a phase-only pupil filter

Author(s): D. Iwaniuk, E. Hack, P. Rastogi.

Abstract:

“A novel approach is proposed to obtain an extended depth of focus (DoF) in white light with constant transversal spot size within the DoF. It combines a phase-only pupil filter based on multiplexed radial zones with alternating quartic phase functions. The design is first tested via numerical simulations of the point spread function (PSF) based on the scalar diffraction theory. The results for a fourfold gain of the depth of focus are experimentally verified with a phase-only spatial light modulator liquid crystal device combined with a 3D PSF measurement system. A close conformity between the experimental and simulation results proves the effectiveness of the proposed approach.”

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Publication: Journal of Modern Optics
Issue/Year: Journal of Modern Optics, Volume 57, Issue 21, (2010)
DOI: 10.1080/09500340.2010.529516

Isotropic Diffraction-Limited Focusing Using a Single Objective Lens

Author(s): Emeric Mudry, Eric Le Moal, Patrick Ferrand, Patrick C. Chaumet, and Anne Sentenac

Abstract:

“Focusing a light beam through a lens produces an anisotropic spot elongated along the optical axis, because the light comes from only one side of the focal point. Using the time-reversal concept, we show that isotropic focusing can be realized by placing a mirror after the focal point and shaping the incident beam. This idea is applied to confocal microscopy and brings about a dramatic improvement of the axial resolution.”

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Publication: Physical Review Letters
Issue/Year: Phys. Rev. Lett., Volume 105, 203903 (2010)
DOI: 10.1103/PhysRevLett.105.203903