Researchers at the University of Basel have found a way to cut much deeper and faster with a surgical laser than with previous laser systems.
The team, led by Dr Ferda Canbaz from the University of Basel’s Biomedical Engineering Department, achieved a breakthrough by using a different laser beam profile, enabling them to remove bone material more efficiently and faster to a depth of 4-4.5cm.
Ferda Canbaz said: ‘Increasing the energy of the laser beam would not be a good solution. This could char the bone and negatively impact the healing process. That’s why we changed the shape of the laser, or rather its profile.’
The typical beam profile is strongest at the centre, weakening towards the edges, like a flashlight’s beam with a Gaussian intensity curve. The new ‘top hat’ profile caps the tip, distributing energy evenly across the surface before sharply dropping at the edge. This uniform energy transmission improves cutting efficiency and speed.
The team tested both laser profiles on bovine bones. The bone was cleaned and cooled with compressed air and water to prevent heat damage and keep the cut clear.
The trials showed that, while the laser with the usual Gaussian distribution cut only about 2.6cm deep, the one with the new top hat profile reached 4.4cm.
A key factor in cutting efficiency is that, with the conventional laser profile, the cut walls absorb some of the energy. At a certain depth, the energy at the bottom of the cut becomes insufficient to continue cutting. The top-hat profile overcomes this issue because the beam’s energy is distributed differently and isn’t consumed by the cut’s walls.
The researchers are now working on further optimising the depth and speed of their laser. The laser blade is still significantly slower than a metal one: in one second, it can remove around 0. 4 cubic millimetres, while a mechanical saw can remove 11 cubic millimetres, more than 20 times as much. This means the laser is still too slow, but it is approaching the required depth for the first time.
Canbaz said: ‘As part of the next steps, we will also need to investigate how we can adapt the system to the more complex situation in the body. There, it is also about protecting the surrounding tissue.’
