Optical interference coating and lamps using same
First Claim
1. An optical interference coating for reflecting infrared radiation and transmitting visible light radiation which comprises three spectrally adjacent, multiperiod stacks wherein each stack has at least two periods with one of the stacks being a short wave pass stack and with said second and third stacks spectrally located at wavelengths longer than that of said first stack and different from each other, said periods of said second and third stacks containing seven alternating layers of high and low refractive index materials of the form:
- ##EQU4## wherein ≦
a≦
45≦
b≦
155≦
c≦
151≦
d≦
2.5and wherein L and H are the low and high index of refraction materials, respectively, L and H each being defined as having an optical thickness of a quarterwave of the stack wavelength.
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Abstract
Optical interference coatings useful on lamps for transmitting visible light radiation at about 90% average from 400-770 nm and for reflecting infrared radiation comprise three spectrally adjacent multiperiod stacks of alternating high and low index of refraction layers. Compared to conventional filters, these filters have a greater tolerance to layer thickness variations incurred during manufacture with little or no color shift when viewed at non-normal angles.
67 Citations
29 Claims
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1. An optical interference coating for reflecting infrared radiation and transmitting visible light radiation which comprises three spectrally adjacent, multiperiod stacks wherein each stack has at least two periods with one of the stacks being a short wave pass stack and with said second and third stacks spectrally located at wavelengths longer than that of said first stack and different from each other, said periods of said second and third stacks containing seven alternating layers of high and low refractive index materials of the form:
- ##EQU4## wherein ≦
a≦
45≦
b≦
155≦
c≦
151≦
d≦
2.5and wherein L and H are the low and high index of refraction materials, respectively, L and H each being defined as having an optical thickness of a quarterwave of the stack wavelength. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
- ##EQU4## wherein ≦
-
12. An electric lamp comprising a light transmissive envelope containing an electric light source within wherein at least portion of said envelope is coated with an optical interference coating for reflecting infrared radiation and transmitting visible light radiation said coating having a spectrally broad high transmittance of at least 90% average between about 400 to 770 nm and a spectrally broad high reflectance of at least about 70% average between about 800 to 2900 nm and comprising three spectrally adjacent, multiperiod stacks wherein each stack has at least two periods with one of said stacks being a short wave pass stack and with said second and third stacks spectrally located at wavelengths longer that that of said first stack and different from each other, said periods of said second and third stacks each containing seven alternating layers of high and low refractive index materials of the form:
- ##EQU6## wherein ≦
a≦
45≦
b≦
155≦
c≦
151≦
d≦
2.5,wherein L and H are the low and high index of refraction materials, respectively, L and H each being defined as having an optical thickness of a quarterwave of the stack wavelength, and wherein the layers H/b and L/c have an optical thickness less than one-twentieth of the stack wavelength. - View Dependent Claims (13, 14, 18, 19, 20, 21, 22)
- ##EQU6## wherein ≦
- 15. The lamp of claim 37 wherein said first nd seventh layers in said second and third stacks of said coating have an optical thickness less than that of said lower refractive index layers in said periods of said short wave pass stack.
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23. A tungsten halogen incandescent lamp comprising a vitreous, light transmissive envelope having a filament chamber with a tungsten filament and at least one halogen hermetically enclosed within said chamber, wherein said filament has a longitudinal axis which is radially aligned along the optical center of said chamber with at least a portion of the outer surface of said chamber coated with an optical interference coating for reflecting infrared radiation and transmitting visible light radiation, said coating comprising three spectrally adjacent, multiperiod stacks wherein each stack has at least two periods with one of said stacks being a shortwave pass stack and with said second and third stacks spectrally located at wavelengths longer than that of said first stack and different from each other, said periods of said second and third stacks each containing seven alternating layers of high and low refractive index materials of the form:
- ##EQU8## wherein ≦
a≦
45≦
b≦
155≦
c≦
151≦
d≦
2.5and wherein L and H represent the low and high index of refraction materials, respectively, L and H each being defined as having an optical thickness of a quarterwave of the stack wavelength. - View Dependent Claims (24, 25, 26, 27, 28, 29)
- ##EQU8## wherein ≦
Specification