Poul Henningsen was a Danish author, critic, architect, designer and also made a film.
His most well known design is a lamp named after his intials, PH lamps.
Henningsen believes that lighting should cover large areas of glare emitted directly from the light source in order to create a beautiful, soft shadow effect.
The design characteristics of PH luminaires are:
(1) all light is reflected at least once before reaching the surface to obtain soft and even illumination
(2) the light source is not visible from any angle so as not to irritate the eyes with glare
(3) Compensate the incandescent light spectrum to obtain a suitable light colour
(4) Diminish the brightness at the edges of the lampshade and allow some light to spill over to avoid excessive contrast in the interior lighting.