Different wavelengths of light are absorbed differently by each component of tissue. The main chromophores (light absorbing constituents) within tissue which are relevant to most medical laser wavelengths are; water, hemoglobin and melanin (the primary pigment in skin). Hemoglobin (the oxygen carrying component that gives blood its red color) can be further categorized into oxygenated hemoglobin and deoxygenated hemoglobin.
The goal of laser manufacturers is to develop lasers that generate light at a wavelength that offers doctors the optimum combination of absorption characteristics for a particular application. For example, in dermatology applications where doctors are trying to remove colored skin lesions, lasers that are more highly absorbed by blood or melanin may be desirable. Likewise in retinal surgery on the eye it might be desirable to use a wavelength that is very highly absorbed by blood but not by water. For superficial skin resurfacing, the opposite may be true; a doctor may want a wavelength that is highly absorbed by water but not by blood or melanin. For prostate surgery the goal is to efficiently vaporize tissue, immediately removing it while still having good control of bleeding (hemostasis).
In addition to wavelength, lasers are sometimes designed to achieve certain tissue interactions through the pulsing of the lasers energy output. In some cases, the laser energy is delivered at extremely high powers for extremely short periods of time. Sometimes this can be useful…sometimes it can be detrimental. In prostate surgery, a smooth continuous-wave laser provides the best result.
The laser of choice in prostate surgery is one can deliver a high-power continuous-wave of energy at a wavelength that is highly absorbed by water while still generating enough heat to provide bleeding control (hemostasis). This criteria is ideally met by the Cyber TM thulium laser.