||Crown Mirror lamps became popular during the early 1970s, when Philips introduced the combination of a new lamp and a specially engineered luminaire for spotlighting applications. By mounting the lamp at the focus of a parabolic reflector, it was possible to achieve beams of narrower angle and much higher intensity than with earlier reflector lamps.
With traditional optical systems where a reflector is mounted behind the light source, much light is radiated into the beam in an uncontrolled fashion without striking the reflector. However with crown mirror lamps, the forward light is efficiently collimated and sent back to the reflector of the luminaire, resulting in a beam of higher intensity. Another advantage is that the crown mirror masks the filament from view and presents a very low glare form of spotlight.
The first lamp was rated 60W and employed a normal 60mm pear-shaped bulb. The range was soon extended to other powers, but a problem emerged in the miniature 40W lamp. Due to its small bulb, a greater proportion of the light reflected by the crown fell in the area of the cap, leading to poor efficiency and high cap temperatures. The problem was alleviated with the narrow E14 cap, and solved completely in 1978 with the introduction of a specially engineered Ogive shape bulb. This allowed increases of up to 4x in luminous intensity, as well as a more homogeneous beam.
Further miniaturisation was achieved around 1982/83 with this 30W lamp in a tiny 35mm bulb. Beam uniformity was maximised by adding a third filament support, that principle being applied later to the larger lamps. However the 30W model never proved popular, and was discontinued in 1987.