Power meter for measurement of radiation

Claim 2

A power meter for measuring radiant energy which comprises: an annular cooling body having an inner hollow cylindrical core portion constructed of a material of high thermal conductivity, a plurality of circular disc-shaped, outer cooling vanes concentrically fixed on the inner core portion and constructed of a material of high thermal conductivity, an interior axially facing shoulder on the inner core, a retainer ring threaded into the inner core and facing toward said shoulder, a radiation receiver disc, a soft metal seal engaging the periphery of said radiation receiver disc, said radiation receiver disc and said seal clamped between said shoulder and said retaining ring, an end cap threaded into the inner core and having an axially extending guide aperture for directing radiation to the receiver disc, with the diameter of said aperture less than the diameter of said shoulder and said retainer ring, means for measuring the temperature gradient on said radiation receiver radially of said radiation receiver between said aperture and said shoulder.

Claim 3

A power meter comprising a flat surface exposed to radiation formed by edges of a plurality of stacked flat plates, a plurality of first electrical conductors formed of a first metal with each of said conductors having a first end portion and a second end portion, said first electrical conductors being mounted uniformly on said flat plates so that said first end portions lie in a row near said edges forming the surfaCe exposed to radiation and said second end portions lie in a parallel row at a substantial distance from said edges, a plurality of second electrical conductors formed of a second metal different from said first metal with each of said second conductors electrically connected between one of said first end portions of said first conductors and one of said second end portions of a different first conductor such that the first conductors and the second conductors are alternately linked in electrical series, electrical output leads connected to opposite ends of said electrical series; a liquid cooling system formed by at least one chamber in said stacked flat plates on the side of said conductors opposite to said surface and connected to a liquid supply and liquid discharge for maintaining said plates at said rows substantially distant from said edges at a temperature substantially constant and lower than the temperature of said plates at said rows near said edges whereby an electromotive force will be generated between said output leads which is substantially unaffected by the location on said flat surface at which said radiation is incident and which can be measured to indicate the intensity of radiation incident on said flat surface.

Claim 4

A power meter comprising a flat surface exposed to radiation formed by edges of a plurality of stacked flat plates, a plurality of first electrical conductors formed of a first metal with each of said conductors having a first end portion and a second end portion, said first electrical conductors being mounted uniformly on said flat plates so that said first end portions lie in a row near said edges forming the surfaCe exposed to radiation and said second end portions lie in a parallel row at a substantial distance from said edges, a plurality of second electrical conductors formed of a second metal different from said first metal with each of said second conductors electrically connected between one of said first end portions of said first conductors and one of said second end portions of a different first conductor such that the first conductors and the second conductors are alternately linked in electrical series, electrical output leads connected to opposite ends of said electrical series; a liquid cooling system formed by at least one chamber in said stacked flat plates on the side of said conductors opposite to said surface and connected to a liquid supply and liquid discharge for maintaining said plates at said rows substantially distant from said edges at a temperature substantially constant and lower than the temperature of said plates at said rows near said edges whereby an electromotive force will be generated between said output leads which is substantially unaffected by the location on said flat surface at which said radiation is incident and which can be measured to indicate the intensity of radiation incident on said flat surface.

Claim 5

A power meter for sensing incident radiation comprising a circular thermoconductive disc, a plurality of first electrical conductors formed of a first metal with each of said conductors having a first end portion and a second end portion, with said first end portions mounted on said disc and positioned uniformly around the periphery of a first circle which is concentric with said disc and with said second end portions mounted on said disc and positioned uniformly around the periphery of a second circle which is concentric with said disc and substantially larger than said first circle, a plurality of second electrical conductors formed of a second metal different from said first metal with each of said second conductors electrically connected between one of said first end portions of said first conductors and one of said second end portions of different first conductors such that the first conductors and the second conductors are alternately linked in electrical series, electrical output leads connected to opposite ends of said electrical series, an annular cooling body connected to the periphery of said disc at a location outside said second circle for maintaining the temperatures of said disc at said second circle substantially constant and lower than the temperature of said disc at said first circle whereby an electromotive force will be generated between said output leads when said disc is heated by incident radiation, a differential amplifier having first and second inputs and an output for providing an output signal responsive to the signals at said inputs, means for connecting one of said output leads to said first amplifier input, means connected to said amplifier output for indicating the output signal of said amplifier, a resistance-capacitance circuit connected between said indicating means and said remaining output lead for providing the electrical analog of the time lag in said target, voltage divider means connected across said resistance-capacitance circuit, and means for connecting a point on said divider to the second input of said amplifier.

Claim 6

A power meter for sensing incident radiation comprising a circular thermoconductive disc, a plurality of first electrical conductors formed of a first metal with each of said conductors having a first end portion and a second end portion, with said first end portions mounted on said disc and positioned uniformly around the periphery of a first circle which is concentric with said disc and with said second end portions mounted on said disc and positioned uniformly around the periphery of a second circle which is concentric with said disc and substantially larger than said first circle, a plurality of second electrical conductors formed of a second metal different from said first metal with each of said second conductors electrically connected between one of said first end portions of said first conductors and one of said second end portions of different first conductors such that the first conductors and the second conductors are alternately linked in electrical series, electrical output leads connected to opposite ends of said electrical series, an annular cooling body connected to the periphery of said disc at a location outside said second circle for maintaining the temperatures of said disc at said second circle substantially constant and lower than the temperature of said disc at said first circle whereby an electromotive force will be generated between said output leads when said disc is heated by incident radiation, a differential amplifier having first and second inputs and an output for providing an output signal responsive to the signals at said inputs, means for connecting one of said output leads to said first amplifier input, means connected to said amplifier output for indicating the output signal of said amplifier, a resistance-capacitance circuit connected between said indicating means and said remaining output lead for providing the electrical analog of the time lag in said target, voltage divider means connected across said resistance-capacitance circuit, and means for connecting a point on said divider to the second input of said amplifier.

Claim 7

A power meter for measuring the output power of lasers comprising: target means for absorbing the output power of lasers, said target means having a thermal propagation time lag; means for cooling said target means; thermopile means disposed to measure the gradient in said target means and having output terminals for producing an electrical signal which is a parameter of the thermal gradient in said target means; a differential amplifier having first and second inputs and an output for providing an output signal responsive to the signals at said inputs; means for connecting one of said thermopile output terminals to said first input; p1 means connected to said amplifier output for indicating the output signal of said amplifier; a resistance-capacitance circuit connected between said indicating means and a second output terminal of said thermopile for providing the electrical analog of the time lag in said target; voltage divider means connected across said resistance-capacitance circuit; and, means for connecting a point on said divider to the second input of said amplifier.

Claim 8

A power meter for measuring the output power of lasers comprising: target means for absorbing the output power of lasers, said target means having a thermal propagation time lag; means for cooling said target means; thermopile means disposed to measure the gradient in said target means and having output terminals for producing an electrical signal which is a parameter of the thermal gradient in said target means; a differential amplifier having first and second inputs and an output for providing an output signal responsive to the signals at said inputs; means for connecting one of said thermopile output terminals to said first input; p1 means connected to said amplifier output for indicating the output signal of said amplifier; a resistance-capacitance circuit connected between said indicating means and a second output terminal of said thermopile for providing the electrical analog of the time lag in said target; voltage divider means connected across said resistance-capacitance circuit; and, means for connecting a point on said divider to the second input of said amplifier.

Claim 9

A power meter for measuring the output power of lasers comprising: target means for absorbing the output power of a laser, said target means having a thermal propagation time lag, wherein said target means comprises a plurality of stacked flat plates and wherein the target surface is formed by the edges of said flat plates; means for cooling said target means; thermopile means associated with each of said stacked flat plates between said cooling means and said surface for measuring the thermal gradient across each plate; said thermopiles connected together and having output terminals for producing an electrical signal which is a parameter of the thermal gradient in said target means; detecting means including an indicating means connected to said output terminals for providing the electrical analog of the time lag in said target means; said indicating means providing an indication of said laser output power.

Claim 10

A power meter for measuring the output power of lasers comprising: target means for absorbing the output power of a laser, said target means having a thermal propagation time lag, wherein said target means comprises a plurality of stacked flat plates and wherein the target surface is formed by the edges of said flat plates; means for cooling said target means; thermopile means associated with each of said stacked flat plates between said cooling means and said surface for measuring the thermal gradient across each plate; said thermopiles connected together and having output terminals for producing an electrical signal which is a parameter of the thermal gradient in said target means; detecting means including an indicating means connected to said output terminals for providing the electrical analog of the time lag in said target means; said indicating means providing an indication of said laser output power.

Claim 11

The power meter according to claim 5 wherein said detecting means comprises a resistance-capacitance circuit having a time constant substantially equal to the time lag in said target means.