Energy absorption and heat transfer are important factors for regulating the effects of ablation of biological
tissues. Heat transfer to surrounding material may be desirable when ablating hard tissue, such as teeth or bone,
since melting can produce helpful material modifications. However, when ablating soft tissue it is important to
minimize heat transfer to avoid damage to healthy tissue - for example, in eye refractive surgery (e.g., Lasik),
nanosecond pulses produce gross absorption and heating in tissue, leading to shockwaves, which kill and thin the
non-replicating epithelial cells on the inside of the cornea; ultrafast pulses are recognized to reduce this effect.
Using a laser system that delivers 1ps pulses in 10μs pulsetrains at 133MHz we have studied a range of heat- and
energy-transfer effects on hard and soft tissue. We describe the ablation of tooth dentin and enamel under
various conditions to determine the ablation rate and chemical changes that occur. Furthermore, we characterize
the impact of pulsetrain-burst treatment of collagen-based tissue to determine more efficient methods of energy
transfer to soft tissues. By studying the optical science of laser tissue interaction we hope to be able to make
qualitative improvements to medical treatments using lasers.