# US 8,569,701 B2 · Absolute cavity pyrgeometer > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,569,701 B2 - Document ID: US8569701B2 - Status: Granted - Kind: B2 - Application number: 13/049,275 - Filed: 2011-03-16 - Published: 2012-09-20 - Granted: 2013-10-29 - Earliest claimed: 2011-03-16 - Assignees: Alliance for Sustainable Energy, LLC - Applicants: Ibrahim Reda - Inventors: Ibrahim Reda - Web page: https://patentgrep.com/patent/US8569701B2 ## CPC - G01J 5/061: by controlling the temperature of the apparatus or parts thereof, e.g. using cooling means or thermostats - G01J 1/0252: {Constructional arrangements for compensating for fluctuations caused by, e.g. temperature, or using cooling or temperature stabilization of parts of the device; Controlling the atmosphere inside a photometer; Purge systems, cleaning devices (protection against electromagnetic interferences G01J2001/0276)} - G01J 1/0422: {using light concentrators, collectors or condensers} - G01J 1/42: using electric radiation detectors (optical or mechanical part G01J1/04; by comparison with a reference light or electric value G01J1/10) - G01J 5/007: {for earth observation} - G01J 5/064: {Ambient temperature sensor; Housing temperature sensor; Constructional details thereof} - G01J 5/0815: {Light concentrators, collectors or condensers} - G01J 5/12: using thermoelectric elements, e.g. thermocouples - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) ## Abstract Implementations of the present disclosure involve an apparatus and method to measure the long-wave irradiance of the atmosphere or long-wave source. The apparatus may involve a thermopile, a concentrator and temperature controller. The incoming long-wave irradiance may be reflected from the concentrator to a thermopile receiver located at the bottom of the concentrator to receive the reflected long-wave irradiance. In addition, the thermopile may be thermally connected to a temperature controller to control the device temperature. Through use of the apparatus, the long-wave irradiance of the atmosphere may be calculated from several measurements provided by the apparatus. In addition, the apparatus may provide an international standard of pyrgeometers' calibration that is traceable back to the International System of Units (SI) rather than to a blackbody atmospheric simulator. ## Claims ### Claim 1 An apparatus for measuring atmospheric long-wave irradiance comprising: a concentrator comprising: a first irradiance receiving aperture at a first region of the concentrator; a second aperture at a second region of the concentrator; and a compound parabolic-shaped chamber with a reflective surface, the first aperture configured to allow atmospheric long-wave irradiance to enter the chamber such that the reflective surface of the chamber reflects long-wave irradiance toward the second aperture of the concentrator; a thermopile positioned at the second aperture of the concentrator such that at least some of the reflected atmospheric long-wave irradiance strikes the thermopile; a thermal mass in thermal communication with the thermopile; and an insulator located between the thermal mass and the concentrator, the insulator configured to reduce thermal communication between the thermal mass and the concentrator. ### Claim 2 (depends on 1) The apparatus of claim 1 further comprising: a temperature controller in thermal communication with the thermal mass, the temperature controller configured to regulate the temperature of the thermal mass. ### Claim 3 (depends on 2) The apparatus of claim 2 wherein the temperature controller comprises: a conducting plate in thermal communication with the thermal mass, the conducing plate comprising one or more tubes positioned within the conducting plate; one or more connecting hoses in fluid communication with the one or more tubes within the conducting plate; and a temperature controlled fluid flowing through the one or more connecting hoses and the one or more tubes, wherein the temperature controlled fluid varies the temperature of the conducting plate. ### Claim 4 (depends on 1) The apparatus of claim 1 further comprising: one or more concentrator temperature sensors associated with the concentrator to provide a temperature of the concentrator. ### Claim 5 (depends on 1) The apparatus of claim 1 further comprising: at least one thermopile temperature sensor in thermal communication with the thermopile to provide the temperature of a reference junction of the thermopile. ### Claim 6 (depends on 1) The apparatus of claim 1 wherein the thermopile comprises a receiving surface, the receiving surface at least partially colored. ### Claim 7 (depends on 1) The apparatus of claim 1 wherein the concentrator further comprises a cylindrical-shaped outer surface, and wherein the chamber and the outer surface of the concentrator are gold plated. ### Claim 8 (depends on 6) The apparatus of claim 6 wherein the thermopile is configured to convert atmospheric long-wave irradiance striking the receiving surface into a reference voltage from which the atmospheric long-wave irradiance is determined. ### Claim 9 A method for measuring the absolute atmospheric long-wave irradiance comprising: orienting an absolute cavity pyrgeometer to receive and measure atmospheric long-wave irradiance, the absolute cavity pyrgeometer comprising at least a concentrator, a thermopile and a temperature controller in thermal communication with the thermopile; cooling the thermopile by lowering a temperature of the temperature controller; obtaining one or more measurements from the absolute cavity pyrgeometer; calculating the sensitivity of the thermopile from the one or more measurements from the absolute cavity pyrgeometer; and calculating the atmospheric long-wave irradiance from the one or more measurements from the absolute cavity pyrgeometer and the calculated sensitivity of the thermopile. ### Claim 10 (depends on 9) The method of claim 9 further comprising: monitoring one or more long-wave irradiance detectors to determine the stability of the atmospheric long-wave irradiance. ### Claim 11 (depends on 9) The method of claim 9 further comprising: transmitting the one or more measurements to a computing device; and storing the one or more measurements in a computer-readable medium. ### Claim 12 (depends on 9) The method of claim 9 wherein the cooling operation comprises: cooling a fluid associated with the temperature controller; and circulating the fluid through a conductor plate in thermal communication with the thermopile. ### Claim 13 (depends on 9) The method of claim 9 wherein the one or more measurements from the absolute cavity pyrgeometer have traceability to the International System of Units (SI). ### Claim 14 (depends on 9) The method of claim 9 wherein the one or more measurements comprise: a temperature of the concentrator; a temperature of the thermopile; and a voltage output of the thermopile. ### Claim 15 (depends on 9) The method of claim 9 further comprising: calibrating one or more pyrgeometer devices to the absolute cavity pyrgeometer to create an international standard for pyrgeometer calibration based on the absolute cavity pyrgeometer. ### Claim 16 A system for measuring absolute atmospheric long-wave irradiance comprising: a computing device comprising: a processor in communication with a computer-readable medium; and an absolute cavity pyrgeometer comprising: a thermopile configured to detect atmospheric long-wave irradiance and to output a voltage related to the detected atmospheric long- wave irradiance to the computer-readable medium of the computing device; a concentrator configured to reflect atmospheric long-wave irradiance to the surface of the thermopile; a temperature controller in thermal communication with the thermopile configured to control the temperature of at least one surface of the thermopile; one or more thermistors associated with the concentrator configured to provide temperature information of the concentrator to the computer-readable medium of the computing device; and one or more temperature sensors associated with the thermopile configured to provide temperature information of the thermopile to the computer-readable medium of the computing device. ### Claim 17 (depends on 16) The system of claim 16 wherein the absolute cavity pyrgeometer further comprises: one or more long-wave irradiance detectors configured to determine the stability of the atmospheric long-wave irradiance and provide stability information to the computer-readable medium of the computing device. ### Claim 18 (depends on 17) The system of claim 17 wherein the processor of the computing device is configured to: obtain the thermopile output voltage, the temperature information of the concentrator, the temperature information of the thermopile and the stability information from the computer-readable medium; calculate the sensitivity of the thermopile; and calculate the atmospheric long-wave irradiance detected by the absolute cavity pyrgeometer.