Laser-induced bubble dynamics inside and near a gap between a rigid boundary and an elastic membrane

Aspects of laser-induced bubble dynamics in sample geometry closely resembling intraocular environment were studied. Laser pulses with a few millijoules of energy were focused into the sample, producing optical breakdown followed by formation of single bubbles. The sample consisted of a piece of polymethyl methacrylate (PMMA) material and a thin polyethylene (PE) elastic membrane which was carefully positioned parallel to the flat PMMA surface, creating a small and adjustable gap between them. The arrangement was placed in distilled water. Such geometry is frequently encountered in ophthalmology, specifically in posterior capsulotomy where there is a gap present between the intraocular lens and the posterior capsule. The formation and evolution of the laser-induced bubble was recorded with a high speed camera for different positions of the laser focus, i.e. inside the gap as well as outside the gap, in the water. The bubble dynamics was compared to the dynamics of the bubbles created near a rigid boundary alone and near an elastic membrane alone. The comparison showed that the evolution of the bubble created inside the gap can be described as a combination of the features which are characteristic for the rigid boundary and the elastic membrane cases, depending on relative dimensions of the gap and the bubble and on their relative positions. Possible influence on related medical procedures is discussed.