Abstract: Methods and apparatus are disclosed for applying acoustic energy to the skin. Acoustic waveguides with elements of varying thickness or shape are disclosed which deliver energy to more than one depth below a surface of the skin substantially simultaneously. The invention is especially useful with devices that focus ultrasound energy by condensing a propagating wavefront. The invention compensates for the mismatch in acoustic properties of the device's waveguide and the biological tissue that typically cause portions of the collapsing wavefront to lag behind other portions and, thereby, limit the focusing capabilities of acoustic treatment devices.

Abstract: Methods and apparatus are disclosed for applying acoustic energy to the skin whereby the wavefront can be controlled to confine the focused energy to a desired subsurface region. Acoustic waveguides are disclosed which compensate for distortions that otherwise occur when a focused acoustic beam crosses a boundary, such as the transition from a treatment device to a target region of skin. The invention is especially useful with devices that focus ultrasound energy by condensing a propagating wavefront. The invention compensates for the mismatch in acoustic properties of the device's waveguide and the biological tissue that typically cause portions of the collapsing wavefront to lag behind other portions and, thereby, limit the focusing capabilities of acoustic treatment devices.

Abstract: The invention features improvements in PRK procedures that relate to preventing non-uniform removal of material from the corneal surface. It has been realized that photoablation by-products resulting during the PRK procedure can affect the accuracy and the predictability of the procedure. Under certain conditions, the plume of photoablation by-products that have left the corneal surface can non-uniformly redeposit onto the ablation area and thus affect the uniformity of subsequent material removal. The plume of photoablation by-products, in the space above the corneal surface, can also non-uniformly affect the escape of further photoablation products from the surface. In addition to the plume effects, it has been realized that the hydration level of the corneal tissue during the PRK procedure can vary over the ablation area and likewise non-uniformly affect the PRK procedure.

Abstract: A circuit for the preionization and main discharge of a pulsed gas laser provides that the sparks intended for the preionization of the working gas have an independent switch function. Capacitive energy storage means 7, 8, 9, 10 are connected low-inductively to the spark electrodes 3, 4, 5, 6. The current flowing in the spark discharge is used selectively for the preionization by means of the spark or for generating a compressed high-voltage pulse. The compressed high-voltage pulse is applied as prepulse to the main electrodes to momentarily greatly increase the voltage obtaining between the main electrodes and thus initiate and supply a homogeneous main discharge.