His colleague's interest in the new flash apparatus soon provoked Edgerton to improve upon the design. The mercury lamp's efficiency was limited by the coolest part of the lamp, causing them to perform better when very hot but poorly when cold. Edgerton decided to try a noble gas instead, feeling that it would not be as temperature dependent as mercury, and, in 1930, he employed the General Electric company to construct some lamps using argon instead. The argon tubes were much more efficient, were much smaller, and could be mounted near a reflector, concentrating their output. Slowly, camera designers began to take notice of the new technology and began to accept it. Edgerton received his first major order for the strobes from the Kodak company in 1940. Afterward, he discovered that xenon was the most efficient of the noble gases, producing a spectrum very close to that of daylight, and xenon flashtubes became standard in most large photography sets. It was not until the 1970s that strobe units became portable enough to use in common cameras.