Baku. 8 December. REPORT.AZ/ Pascal Cotte French scientist said he has spent more than 10 years using the technology to analyse the painting. Report informs citing the BBC.
He claims the earlier portrait lies hidden underneath the surface of Leonardo's most celebrated artwork.
A reconstruction shows another image of a sitter looking off to the side.
The Louvre Museum has declined to comment on his claims.
Instead of the famous, direct gaze of the painting which hangs in the Louvre Museum in Paris, the image of the sitter also shows no trace of her enigmatic smile, which has intrigued art lovers for more than 500 years.
But Mr Cotte's claims are controversial and have divided opinion among Leonardo experts.
The scientist, who is the co-founder of Lumiere Technology in Paris, was given access to the painting in 2004 by the Louvre.
He has pioneered a technique called Layer Amplification Method (LAM), which he used to analyse the Mona Lisa.
However, not all scientists are convinced about this. Louvre declined to comment on the statement.