1991 Coemar Roundlux 750W

Because of their small physical size and the high brightness of their compact filament, tungsten halogen lamps are particularly popular in disco and special lighting purposes. However, there are some applications where a source shape other than point-like is desired, such as in the so-called tunnel projection lighting. In this case, the image of a circular-shaped incandescent filament is projected through artificial fog (i.e., glycerin mist) in order to form a luminous tunnel effect, particularly popular in disco settings. This kind of system presents the advantage of being much simpler and affordable than laser-based projectors.

The 750 W Roundlux presented here is the kind of source used in luminous tunnel projectors. This lamp was made by Philips for Coemar, an Italian manufacturer and supplier of lighting systems for stage, studio, photo, and entertainment applications. The lamp is built from a standard, general-lighting, linear double-ended tungsten-halogen burner shaped into a circle and fitted with a GX9.5 base. In order to form a circle with a small enough radius, the quartz tube was first bent, and then the coiled filament was inserted and the end seals were pressed before the lamp was filled with a mixture of argon and dibromomethane.

Despite the significant decrease in cost and the resulting popularization of economical laser scanning projectors, the halogen-based luminous tunnel projectors still remain widely used because of their high output flux and their very low purchase cost. As a result, these round halogen lamps are still produced to this day, but no longer by Philips, for whom this is now too niche a product.