Dr Alistair Elfick shows Raman Spectroscopy in action at Edinburgh University
Scientists have revealed details of a high-tech breakthrough which could help childless couples.
Edinburgh University researchers have developed a method of testing the sperm quality before it is used for IVF.
They have said the technique could help childless couples in the next five to 10 years.
The new test measures the DNA quality of sperm, but unlike existing tests, it does not kill the sperm, so it can still be used for IVF treatment.
Infertility affects at least one in six couples and currently success rates for IVF treatment are about one in four - but selecting the best quality sperm could increase the chances of a woman becoming pregnant.
Dr Alistair Elfick, lead scientist on the project funded by the Engineering and Physical Sciences Research Council, said: "In natural conception the fittest and healthiest sperm are positively selected by the arduous journey they make to the egg.
"What our technology does is to replace natural selection with a DNA based 'quality score'."
However, he stressed: "This is not about designer babies. We can only tell if the sperm is strong and healthy not if it will produce a baby with blue eyes."
The high-tech test involves capturing an individual sperm between two highly focused beams of laser light.
The DNA properties are then identified by the pattern of vibrations they emit in a process known as Raman spectroscopy.