Sensors

Claim 2

A sensor for cumulatively monitoring ultra-violet radiation over long periods comprising a metal body, a window in the body through which radiation can enter, an interference filter for removing unwanted non-ultra-violet radiation, a phosphor for converting the ultra-violet radiation into radiation acceptable to a photocell, the phosphor being selected from zinc cadmium sulphide activated by copper and having a hexagonal crystal structure or strontium chlorosilicate activated by divalent europium with the phosphor matrix having an orthorhombic crystal structure, and a photocell for converting the output radiation from the phosphor into an electrical signal.

Claim 3

A sensor as claimed in claim 3, wherein the photocell is a selenium photovoltaic cell.

Claim 4

A sensor as claimed in claim 4, and including a further filter for removing unwanted red light from the output of said phosphor.

Claim 5

A sensor for cumulatively monitoring ultra-violet radiation over long periods comprising a metal body, a quartz dome in said body through which radiation can enter, an interference filter for removing unwanted, non-ultra-violet radiation, a phosphor for converting the ultra-violet radiation transmitted into radiation of a waveband acceptable to a photocell, the phosphor being selected from zinc cadmium sulphide activated by copper and having a hexagonal crystal structure or strontium chlorosilicate activated by divalent europium with the phosphor matrix having an orthorhombic crystal structure, a second filter for removing red light from the output of said phosphor, a selenium photovoltaic cell for converting the output radiation of the phosphor into an electrical signal, and means for maintaining said sensor at a predetermined temperature.

Claim 6

A sensor for cumulatively monitoring ultra-violet radiation over long periods comprising a metal body, a quartz dome in said body through which radiation can enter, an interference filter for removing unwanted non-ultra-violet radiation, a phosphor for converting the ultra-violet radiation transmitted into radiation of a waveband acceptable to a photocell, said phosphor comprising zinc cadmium sulphide activated by copper having a hexagonal crystal structure and wherein the matrix has the composition 92 percent ZnS and 8 percent CdS by weight, a second filter for removing red light from the output of said phosphor, a selenium photovoltaic cell for converting the output radiation of the phosphor into an electrical signal, and means for maintaining said sensor at a predetermined temperature.