Thorn Halogen Infrared Cooker with Side Reflector
Following the development of the original infrared quartz lamp by GE of America in the mid 1950s, its design was improved slightly by adding a halogen gas filling following that company's subsequent invention of the halogen quartz lamps in 1958. During the next few decades they found many applications, but almost always confined to industrial heating and drying. The next major development arrived in the 1980s when Thorn EMI of the UK developed two new applications - infrared spaceheating, and infrared cooking.

Thorn owned not only a lighting division, but also several applicance businesses including Tricity, a manufacturer of electric cookers. A joint project was started in the early 1980s under the leadership of Alex Halberstadt of the Enfield labs, to develop quartz halogen lamps for cooking hobs. Halogen lamps feature much lower thermal inertia than conventional electric heaters, and introduced the novel feature of near instant heat and much quicker regulation of temperature. This allowed electric cookers to compete for the first time with the speed and controllability of gas.

In the original design an array of four short linear lamps were placed behind an infrared-transmitting heat resistant glass-ceramic plate invented by Corning of USA, which served as a tough surface for the cooking hob. This particular lamp is a later model invented by Alex Halberstadt and Roger Hume which features a side reflector of alumina powder flamesprayed onto the quartz tube. Alumina is an excellent reflector of shortwave infrared radiation, and eliminated of the much larger external metallic reflectors. This allowed the lamps to be spaced closer together for better heating uniformity, and increased power density.
Manufacturer: Thorn EMI
Lamp Power: 450 Watts
Lamp Voltage: 240 Volts
Lamp Current: 1.88 Amperes
Cap Type: NPS Wires Vidaflex sleeved
Bulb Type: T-10.5 T-3 in eighths/inch
Bulb Finish: Side Alumina Reflector Quartz
Filament Type: CC-8 Coiled Coil Axial
Lighted Length 137 mm 53/8 inches
Atmosphere: Argon 0.05% Methylene Bromide
Luminous Flux: 2250 lumens
Luminous Efficacy: 5.0 lm/W
Luminous Intensity: N/A
Beam Distribution: N/A
Colour Temperature & CRI: CCT: 2400K Ra 100
Chromaticity Co-ordinates: CCx: 0.485 CCy: 0.413
Lifetime: 5000 hours
Burning Position: Horizontal
Overall Length: 216 mm 81/2 Inches
Factory: Enfield, London United Kingdom
Date of Manufacture: Approx. 1985
Original Value:
References: 1) Thorn Lighting Product Data Sheet 16-5146, Enfield Factory, 11-IV-1989.
2) GB Patent 2,132,060 - Heating Apparatus - Thorn EMI Appliances Ltd - Filed 1983.