Updated 12-III-2023

Alex Leopold Halberstadt

Alex Halberstadt c.1950 (left)2, and receiving a Design Council Award from the Duke of Edinburgh in 1985 (right)1

Born in 1928, the young Alex Halberstadt arrived in Britain in 1939 as a refugee without a word of English. After completing his education, in 1949 he joined the Atlas Lampworks of the famous Austrian emigré Sir Jules Thorn, and became one of the principal scientists at the company which was ultimately known as Thorn Lighting. It is likely that his first employment would have been with their original factory at Edmonton in north London.

At an early stage in his career, the giant General Electric of USA invented the tungsten-halogen lamp, and that technology was swiftly copied by its American competitor Sylvania. Thorn of the UK and Sylvania of the USA had signed a joint technical agreement in 1948 which saw the two companies share all lamp-related patents and know-how, and Halberstadt was at once immersed in the development of the first halogen lamps in Europe. Thorn established its halogen manufacturing at the nearby Tottenham factory, but especially in the later years Alex Halberstadt was based at the company's Enfield facility. That site housed the central development laboratories and fluorescent works, and after the closure of Tottenham in 1981 also the halogen manufacturing.

Halberstadt's contributions to the development of the halogen lamp were numerous, and not limited only to technological breakthroughs. His designs opened up several new commercial avenues, for instance the trend of low voltage halogen lighting which swept across the world during the early 1980s. During the following decades these sparkling and energy-efficient light sources dominated all aspects of retail and display spotlighting, and it was almost impossible to walk along any shopping street of the developed world without passing dozens of installations. He is also recognised as the father of cooking by light, a halogen-heat technology which inspired a new generation of domestic and professional cooker hobs during the later 1980s.

Alex Halberstadt received widespread recognition for his contributions to the lighting world, culminating in a prestigious Design Council Award in 1985 as pictured above. He is believed to have retired from Thorn in the early 1990s, and left a long-lasting legacy of halogen light sources which only in recent years have begun to be replaced by newer technologies in discharge and solid-state lighting.

Halogen Innovations
Halberstadt's initial efforts focussed on the successful manufacturing of standard high power linear lamps, but it was following the 1960 invention of the single ended low voltage capsules by Moore and Jenkins of Osram-GEC that his innovative spirit led to the introduction of a plethora of new types - several of which are illustrated below. The first of these was a tiny light source developed for Eumig of Germany, which resulted in the first tungsten-halogen projector for the booming business of 8mm ciné films. He then went on to devise the first reliable halogen photoflood lamps for portable photographic lighting, achieved by the novel idea of bending a linear halogen lamp into a U-shape - a design which remained in production until as late as 2017.

Certainly it can be said that within Europe, Halberstadt was the leading man behind the development of low voltage multifacetted halogen reflector lamps which dominated accent and display spotlighting applications for many decades. Although not the original inventor of this concept, which is attributed to Emmett Wiley of GE in America who created them film projection applications, Halberstadt was one of the first to recognise that they could be applied with outstanding effects in spotlighting applications. As such, by 1982 Thorn already had a comprehensive range of lamps which had been optimised for long life and high efficacy, several years ahead of its European competitors. Halberstadt did however contribute greatly to the safety of these lamps. The original projector types were intended to be mounted by the moulded glass rim of the reflector, but in display spotlighting designers preferred the hold the lamps only by their base pins, leaving the elegant dichroic reflector unobscured for improved aesthetic appearance. The base pins could not always support the weight of the lamps, especially as the springs in the lampholders aged over time. In the early 1980s there were frequent occurrences of lamps falling from the ceiling, with consequent risk of injury or fire if they fell onto flammable objects. The problem was solved by the simple but effective invention of machining a groove into the side of the glass base, which interlocked with a spring in a modified lampholder to firmly hold the lamps in place. This patented principle was subsequently adopted by all other manufacturers of this style of lamp. Thorn was also first in the world to extend its range to the even smaller MR11 dichroic reflector lamps, whose added sparkle and miniaturised dimensions fuelled the trend of bringing light inside display cabinets such as in jewellery stores.

Having successfully extended the scope of halogen technology from industrial floodlighting to the lighting of retail and commercial indoor spaces, Halberstadt's next major breakthrough targeted the adoption of halogen lamps for domestic lighting. Limitations of tungsten metallurgy meant that the original mains voltage linear halogen lamps could only be made in high wattages which were far too bright for general indoor lighting. Meanwhile his low voltage accent and display lamps, which could be made in smaller lumen packages, required a step-down transformer which made the installations bulky and expensive. It was recognised by all lampmakers around the world that a major breakthrough would be possible if halogen lamps could be engineered into lower powers suitable for use directly on the mains electricity supply.

The original linear halogen lamps were different than all other earlier incandescent lamps in that their long, coiled filaments were supported by the quartz wall - instead of by the usual metallic and glass support structures found in traditional lamps. This design is perfectly satisfactory for high power lamps, but as the wattage is reduced coils of finer wire eventually became so delicate and flimsy that they are unable to support their own weight. For many years it was not feasible to produce mains halogen lamps in ratings below about 300 Watts. Moreover, the original linear lamps could only be operated horizontally - whereas domestic luminaires mainly call for lamps to be operated vertically. Halberstadt solved both problems in 1979 with the elegant solution of what became known as the quartz spine construction. His idea was to include a thin quartz rod within the lamps, bearing multiple auxiliary tungsten wires to support the filament at critical points. The ground-breaking patent at once resulted in the introduction of a smaller 200W halogen lamp, and in the following years the technology was extended down to the market-leading 100W rating. Thorn was first in the world to establish the global standard of 78.3mm linear halogen lamps, whose reduced length fuelled a generation of more compact and attractive luminaires than had been possible with the former 117.6mm standard length.

In an extension of the same filament support technology, Halberstadt's group at Thorn introduced what is believed to be the first halogen retrofit lamp capable of replacing ordinary incandescent household lamps. This comprised one of the new miniaturised mains-voltage lamps on an ordinary E27 screw base, and enclosed in a secondary outer bulb for safety and ease of handling.

Low Wattage Mains Halogen Lamps with Quartz Spine Construction 3

Halberstadt's later career saw a switch from lighting to heating, with the first application of halogen lamps to infrared cooking. Thorn EMI at the time owned not only a lighting business but also the domestic appliance manufacturer Tricity, and a link-up between these divisions resulted in the development of the modern halogen cooker hob. He is also widely recognised as inventor of the first practical ruby halogen infrared lamps and their ruby slim successors, which further extended their applications to the industrial heating of large open spaces without the high levels of glare associated with earlier halogen heat lamps.

Examples of Lamps Developed by Halberstadt
Photoflood P1/19 with U-Tube Construction Theatre Spotlight T/15 with Bulged Envelope Low Voltage Halogen Capsule M/32 Low Power Mains Halogen K/14 Low Power Mains Halogen K/16 Low Power Mains Halogen K/19
Low Power Mains Halogen K/19 FR Low Voltage Metal Reflector M/53 Low Voltage Dichroic Reflector M/50 Low Votlage Dichroic Reflector M/57 Low Votlage Dichroic Reflector M/51 Halogen Cooker Lamp with Reflector
Halogen Spaceheater with Ruby Jacket Halogen Spaceheater with Slim Ruby Bulb

  1. Tungsten Halogen Lamp Development, A. Halberstadt, Thorn Lighting Journal No.3, Autumn 1969, p14-20.

British and European Patents
  1. GB1087448 - 25.05.1965 - Mounting of Tungsten-Halogen Lamps (Blade contact system)
  2. GB1040979 - 09.08.1965 - Improvements in Tungsten-Halogen Lamps (Twin-filament design)
  3. GB1122747 - 04.08.1966 - A Tungsten Halogen Lamp (U-Tube photoflood) - with Reginald Swain
  4. GB1222790 - 17.11.1969 - Tungsten Halogen Lamps (High wattage bulged tubular studio lamps)
  5. GB2064215 - 26.11.1979 - Improvements in Lamp Filament Supports (Backbone construction)
  6. GB2082745 - 27.08.1980 - An Improved Reflector for Electric Projector Lamps (Hybrid with specular and facetted regions) - with John Letchford
  7. GB2129610 - 06.11.1982 - Incandescent Lamps (Single-ended capsule with backbone filament support)
  8. GB2064215 - 11.02.1984 - Improvements in Lamps and Lampholders for Display Lighting (GU5.3 interface) - with David Parlour
  9. GB2153986 - 11.02.1984 - Improvements in Lamps and Lampholders for Display Lighting (GU5.3 interface) - with David Parlour
  10. GB2132060 - 01.08.1983 - Heating Apparatus (Halogen Cooker) - with Peter Crossley, Bernard Fellerman & Graham Goodchild
  11. EP0120639 - 24.03.1983 - Improvements in Quartz Infrared Lamps (Heat-resistant cap) - with John Letchford
  12. EP0131372 - 15.06.1983 - Heating Apparatus (Halogen Cooker) - with Peter Crossley, Kenneth Frost, John Letchford, Robert Smith
  13. EP0133764 - 02.08.1983 - Incandescent Lamp (Halogen Cooker with Side Reflector) - with Roger Hume
  14. GB2154405 - 11.12.1984 - Heating Apparatus (Halogen Cooker) - with John Letchford, Peter Crossley & Graham Goodchild
  15. GB2176587 - 07.06.1985 - Jacketed Linear Lamps (Infrared Spaceheater) - with David Parlour
  16. EP0222553 - 09.11.0985 - Incandescent Lamp (Infrared Cooker with Double Filament and double envelope) - with John Letchford
  17. EP0226343 - 30.11.1985 - Microwave Oven (with halogen browning lamps) - with Geoffrey Bell, Stephen Newton, Peter Crossley & Susan Crocker
  18. EP0429230 - 18.11.1989 - Tungsten Halogen Lamp (Infrared Spaceheater Ruby Slim) - with John Letchford

References & Bibliography
  1. Thorn Lighting - The First Sixty Years, 1988, UK, p.19.
  2. Top 40 Most Influential People in Lighting, Supplement to Lighting Magazine (UK), March 2008 p.19.
  3. Design Council Archive, 1985, Low Wattage Tungsten Halogen Lamps by Thorn EMI Lighting Ltd.
  • Thorn Lighting "Profile" newsletter, 1986 Autumn p3.