Pewter known as "trifling metal" or "trifle", was used for holloware and is made up of fine metal with approximately 4% lead. The last type of pewter, known as "lay" or "ley" metal, was used for items that were not in contact with food or drink. It consisted of tin with 15% lead. These three alloys were used with little variation until the 20th century. Older pewters with higher lead content are heavier, tarnish faster, and oxidation gives them a darker silver-gray color. Pewters containing lead are no longer used in items that will come in contact with the human body
Photon etc. Photon etc. Photon etc. is a Canadian manufacturer of infrared cameras, hyperspectral imaging and spectroscopic scientific instruments for academic and industrial applications. Its main technology is based on volume Bragg gratings, which are used as filters either for swept lasers or for global imaging. As a spin-off of the California Institute of Technology, the company was founded in 2003 by Sébastien Blais-Ouellette who was working on narrow band imaging tunable filters for the detection of hydroxyl groups in the Earth atmosphere. This is how he developed the main technology of the company, a patented volume Bragg grating for filtering purposes.