LSU was one of the largest manufacturers of paper and glass stereoviews with images from the First World War. Surprisingly, there’s not much known about the company. It was founded by Paul Rolland and located at 51, boulevard Saint-Martin in Paris. In 1925 he started a partnership with Albert Dollberg from Anglet. This partnership is documented and stored in the archives of the French Chamber of Commerce. It describes the following business activities:
The manufacturing, acquisition and sale of devices, stereoviews, projections, film and all related items. Also: publishing, buying and selling of artistic paintings.
Paul Rolland was the technical director and responsible for financial management. Albert Dollberg was the commercial director.

It makes sense that they also produced the devices to view their stereoviews. I’ve seen an image on the web of a simple LSU stereoscope. An invoice on the website The Great War in 3D proves that they were still in business in 1938.
LSU produced glass stereoviews in both 45x107 and 6x13 formats. Many slides (not all) contain the abbreviation 'LSU' and are numbered by using different numbering schemes.


La Stéréoscopie Universelle probably also operated the seller service of the Union Nationale des Combattants (UNC). This was a French veterans organisation, founded on 11 November 1918 (Armistice Day). Its goal was improving the pensions and living conditions of veterans. The seller service Service des Ventes de l'U.N.C. (SDV) offered stereoviews with images from the war and LSU produced most of the slides.
SDV stereoviews were sold in series of 10. Some series were available in both 45x107 and 6x13 formats, others only in 45x107 format. They were numbered using a unique numbering scheme. Some of the slides are just 're-used' LSU views with a new number added.

Related posts:
References:
- Archives Commerciales de la France, March 1925 (via: Gallica)
- The Great War in 3D - La Stéréoscopie Universelle (LSU), Bob Boyd & Doug Jordan