Since their debut in the 1920s, Poul Henningsen’s three shade lamps have embodied a perfect harmony of form and function. Defined by a distinctive numbering system, these designs reflect Louis Poulsen’s enduring commitment to innovation and craftsmanship.
Each PH lamp is identified by a two-part number that corresponds to the dimensions of its shades. The first digit represents the upper shade’s diameter in decimeters (e.g., “3” for 30 cm), while the second indicates the size of the middle and lower shades. This system ensures a balanced, lightweight aesthetic that maintains visual harmony.
Notably, the two lower shades always remain paired and are derived from the upper shade of a corresponding even-numbered model. For example, the lower shades of a PH 4/3 originate from a PH 3/3, while its upper shade comes from a PH 4/4. To maintain proportionality, size increments rarely exceed two steps—hence, a PH 8/5 would not exist, but a PH 8/6 would, preserving the lamp's elegant coherence.
At the heart of Henningsen’s design lies the logarithmic spiral, a geometric principle that dictates the precise curvature and positioning of the shades.
This ensures an optimal distribution of direct and diffused light while seamlessly adapting to various light sources. The result is a glare-free illumination that has remained relevant for nearly a century.
