Sylvania Super Tru-Flector Dichroic DLS
On 6th March 1961 Sylvania made history with the launch of this lamp, the world's first to feature a cool-beam dichroic reflector. Cold light coatings were pioneered several years earlier by Bausch & Lomb, to reduce the heat from carbon arcs in 35mm cinema film projectors. B&L offered its new technology to GE, which ridiculed the idea of a dichroic lamp due to the high costs. It therefore approached Sylvania, which immediately saw the potential and developed a manufacturing technique to minimise the cost impact. This was based on the sagging process, in which a thin glass sheet is heated and allowed to slump into a mould to produce an ellipsoidal reflector with excellent surface quality.

The first lamp is believed to be this ANSI-coded DLS model, based on the earlier DLG of similar design with aluminium reflector. A multilayer dichroic coating of magnesium fluoride and zinc sulphide reflects visible light forward while infrared is transmitted backwards, reducing heat in the beam by 50%. This allowed the brightness of projected movies to be greatly increased, without risk of overheating the film. Image sharpness was also improved by limiting expansion as the film passed through the heat at the projection gate. Another advantage was a small spectral shift, achieving a whiter light with the appearance of being brighter.

The dichroic lamp triggered a new era in 8mm projectors, and was quickly followed by the 250W DLR for 16mm film. It proved so popular that GE was forced to copy the design, introducing its 'Dikor' DEF in 1962. Sylvania maintained its lead by adapting the dichroic reflector into the bulb envelope for its Tru-Beam DNF and Halogen Super Tru-Beam, whose invention led to the ubiquitous MR16 dichroic lamps.
Manufacturer: Sylvania Electric Products Inc.
Lamp Power: 150 Watts
Lamp Voltage: 21.5 Volts
Lamp Current: 7 Amperes
Cap Type: GX17q Aluminium Bronze
Bulb Type: T-44.5 T-14 in eighths/inch
Bulb Finish: Clear soda-lime glass Internal Dichroic Mirror
Filament Type: CC-8 Coiled-Coil Axial
Atmosphere: 95:5 Argon:Nitrogen High pressure fill
Luminous Flux: 60 screen lumens 1" to f1.2 projection lens
Luminous Efficacy: 0.4 screen lumens per Watt
Peak Intensity: N/A
Focal Distance: 44.5mm from centre of lamp 1.75 inches
Colour Temperature & CRI: CCT: 3450K CRI: Ra99
Chromaticity Co-ordinates: CCx: 0.408 CCy: 0.391
Rated Lifetime: 10 hours @ 21.5V 15 hours @ 21.0V
Burning Position: Horizontal
Overall Length: 85.7 mm 33/8 inches
Light Centre Length: 39.7 mm 19/16 inches
Factory: Boston Street, Salem U.S.A.
Date of Manufacture: 1962 October Date Code:2223
Original Value: Unknown Unknown
References: 1) Movie Projector Lamp Cuts Heat, Ann Arbor News, 4th March 1961
2) Projector Lamp, US Patent 3,162,785, R.F. Scoledge & R.M. Shimer, Sylvania Electric Products, Filed 22nd April 1960
3) Sylvania Projection Lamps Brochure WC-171, 1963 May, p.5
4) Sylvania Photolamp Technical Manual Volume 1, Page DLS 1st December 1964