University of Michigan

Xinbing Liu

Gerard A Mourou

Donald Umstadter

Victor M Elner

Peter P Pronko

Anatoly Maksimchuk

Ron Kurtz

Jeffrey A Squier

Alan Braun

Subrata K Dutta

Detao Du

Paul R Lichter

Jonathan Workman

The invention provides a compact, combined stretcher-compressor assembly which utilizes a single grating element. The single grating element is preferably a holographic transmission grating element. The grating element has first and second surfaces which are opposed major surfaces with a thickness between the surfaces. The grating pattern is patterned in or on the grating element. The grating element is arranged in the assembly to receive a beam for stretching laser pulses in a stretcher beam path, and in the same arrangement, to receive a beam for compressing laser beam pulses in a compressor beam path. The stretcher and compressor beam paths pass through the single grating element. Respective reflecting means are arranged to provide a desired number of passes through the grating element by the stretcher beam path, and through the grating element by the compressor beam path.

Stretcher-compressor assembly having a single grating

In one aspect the invention provides a method for laser induced breakdown of a material with a pulsed laser beam where the material is characterized by a relationship of fluence breakdown threshold (F.sub.th) versus laser beam pulse width (T) that exhibits an abrupt, rapid, and distinct change or at least a clearly detectable and distinct change in slope at a predetermined laser pulse width value. The method comprises generating a beam of laser pulses in which each pulse has a pulse width equal to or less than the predetermined laser pulse width value. The beam is focused to a point at or beneath the surface of a material where laser induced breakdown is desired. The beam may be used in combination with a mask in the beam path. The beam or mask may be moved in the x, y, and Z directions to produce desired features. The technique can produce features smaller than the spot size and Rayleigh range due to enhanced damage threshold accuracy in the short pulse regime.

Method for controlling configuration of laser induced breakdown and

The present invention provides a system and an apparatus to produce x-rays from plasmas by focusing an intense, short duration optical pulse from a laser onto a target. The concentrated energy contained in the focused laser beam ionizes the target material, raising it to a temperature at which ions are produced in a chain reaction ionization, and x-rays are emitted when ions become de-excited (their electrons change energy level) or free electrons recombine with the ions in the plasma. The method comprises controlling pulse time duration of x-rays emitted from a plasma-forming target by generating a beam of one or more laser pulses; adjusting the intensity of the laser pulse to obtain a desired intensity incident at a surface of the plasma-forming target matter; directing the laser pulse onto the surface of the plasma-forming matter to generate the x-rays having a pulse duration which changes in proportion to a change in the incident laser pulse intensity. In one embodiment, the x-rays are then directed onto a sample target.

Method and apparatus for generating laser plasma x-rays

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Ann Arbor, MI, United States of America

Xinbing Liu