A research group led by Professor Lars Berglund from Swedish KTH University along with a University of Maryland research group led by Professor Liangbing Hu have developed a method to remove the color and some chemicals from small blocks of wood, followed by adding polymers, such as poly(methyl methacrylate) (PMMA) and epoxy, at the cellular level, thereby rendering them transparent.
As soon as released in between 2015 and 2016, see-through wood had a large press reaction, with articles in ScienceDaily, Wired, The Wall Street Journal, and The New York Times.
Actually those research groups rediscovered a work from Siegfried Fink, a German Researcher, from as early as 1992: with a process very similar to Berglunds and Hus, the German Researcher turned wood transparent to reveal specific cavities of the wood structure for analytical purpose.
In 2021 researchers reported a way to manufacture transparent wood lighter and stronger than glass that requires substantially smaller amounts of chemicals and energy than methods used before. The thin wood produced with "solar-assisted chemical brushing" is claimed to be lighter and about 50 times stronger than wood treated with previous processes.