Optical element for photographic radiometer

Claim 2

An optical element for filtering infrared light comprising at least one metal-organic infrared absorbing dye at least partially dissolved homogeneously throughout a molded optical plastic.

Claim 3

The element of claim 1 wherein said infrared absorbing dye comprises a metal complex of the formula: ##STR5## wherein Me is selected from the group consisting of metals of the first, second, and third transition metal series which will provide a complex that is an effective infrared absorber and which is effectively transparent to light in the visible region of the spectrum; and each R is selected from the group consisting of hydrogen, alkyl, aromatic, heterocyclic and nuclearly substituted aromatic and heterocyclic rings.

Claim 4

The element of claim 2 wherein said metal complex is chosen from the group consisting of ##STR6## or mixtures of these.

Claim 5

The element of claim 3 wherein said optical plastic comprises polycarbonate or polystyrene and wherein said infrared absorber consists essentially of a mixture selected from said metal complex groups of claim 3 wherein the concentration of said first mentioned metal complex group is between 0.007 and 0.009 percent by weight of dye to weight of said optical plastic and has a peak absorbance at 920 nm and wherein the concentration of said second mentioned metal complex group is between 0.002 and 0.004 percent by weight of dye to weight of said optical plastic and has a peak absorbance at 820 nm.

Claim 6

The element of claim 4 wherein said optical plastic is preferably polycarbonate and wherein said optical element is molded in the form of a positive lens element of predetermined focal length.

Claim 7

The element of claim 2 wherein said optical plastic comprises polycarbonate or polystyrene.

Claim 8

The element of claim 6 wherein said optical element is molded in the form of a positive lens element of predetermined focal length.

Claim 9

An optical element for use in a radiometer of the type which includes a photoelectric cell that has a predetermined surface and spectral sensitivity and provides an output signal having an electrical characteristic that varies in accordance with the intensity of radiant power incident on its surface, said optical element comprising a positive lens of predetermined focal length molded of an optical plastic comprising polycarbonate or polystyrene for collecting radiant energy to direct said collected radiant energy onto the photoelectric cell surface and including at least one metal-organic infrared absorbing dye at least partially dissolved homogeneously throughout and commonly molded with said optical plastic for selectively attenuating the spectral content of said collected radiation.

Claim 10

An optical element for use in a radiometer of the type which includes a photoelectric cell that has a predetermined surface and spectral sensitivity and provides an output signal having an electrical characteristic that varies in accordance with the intensity of radiant power incident on its surface, said optical element comprising a positive lens of predetermined focal length molded of an optical plastic comprising polycarbonate or polystyrene for collecting radiant energy to direct said collected radiant energy onto the photoelectric cell surface and including at least one metal-organic infrared absorbing dye at least partially dissolved homogeneously throughout and commonly molded with said optical plastic for selectively attenuating the spectral content of said collected radiation.

Claim 11

The element of claim 8 wherein said infrared absorbing dye comprises a metal complex of the formula: ##STR7## wherein Me is selected from the group consisting of metals of the first, second and third transition metal series which will provide a complex that is an effective infrared absorber and which is effectively transparent to light in the visible region of the spectrum; and each R is selected from the group consisting of hydrogen, alkyl, aromatic, heterocyclic and nuclearly substituted aromatic and heterocyclic rings.

Claim 12

The element of claim 9 wherein said metal complex is chosen from the group consisting of ##STR8## or mixtures of these.

Claim 13

The element of claim 10 wherein said optical plastic comprises polycarbonate or polystyrene and wherein said infrared absorber consists essentially of a mixture selected from said metal complex groups of claim 10 wherein the concentration of said first mentioned metal complex group is between 0.007 and 0.009 percent by weight of dye to weight of said optical plastic and has a peak absorbance at 920 nm and wherein the concentration of said second mentioned metal complex group is between 0.002 and 0.004 percent by weight of dye to weight of said optical plastic and has a peak absorbance at 820 nm.

Claim 14

The element of claim 10 wherein said infrared absorbing dye consists of a mixture of said metal complex groups mentioned in claim 10 in concentrations such that the spectral transmission characteristics of said element are within the limits substantially as represented in the following tabular data: ______________________________________ λ T ______________________________________ 350 0 400 12-20 450 47-52 500 56-61 550 57-64 600 60-65 650 62-67 675 50-57 700 59-66 750 25-59 800 4-32 850 8-22 900 7-11 950 5-7 1000 16-19 1050 45-50 1100 67-71 1150 74-77 1200 75-80 ______________________________________ wherein λ is wavelength in nanometers and T is percentage transmission.