New York (PTI): Scientists have developed an electron microscope which they claim is small enough to fit onto a fingertip and four times more powerful than the best ones already available in the market.

Scanning electron microscopes (SEMs) focus a beam of electrons instead of light and can capture stunning images of tiny structures with a 3D appearance, like the pollen grains pictured (right), according to them.

Lead scientist Derek Eastham said that his SEMs could achieve a resolution around four times better -- as low as 0.01 nanometres -- as compared with the best pieces.

In fact, the new product's design uses a much lower energy beam in a device with just a few millimetres between the electron generator and the object being studied. That distance is more usually a few feet.

Instead of firing electrons from a tungsten filament, it will shoot them from a single atom at the peak of a tiny gold pyramid with a height of around 100 nanometres. The beam will be focused as it passes through a two micrometre hole in a silicon chip before it hits the target below.

"The electrostatic lens used in the new SEM still contains imperfections that will limit the microscope's resolution but the effect should be much smaller," the 'New Scientist' quoted Eastham as saying.

The scientists' approach produces a beam with around 100 times less energy than usual in an SEM. Cutting power consumption addresses one of the greatest costs of SEM technology, according to them.

Using lower power should also make it possible to study delicate structures normally destroyed by electron microscopes -- for example, untreated proteins and DNA.

However, other microscopy experts are more conservative in their expectations of the microscope's performance. "The basic concept is certainly correct," David Joy at the University of Tennessee in Knoxville in the US said.