Design And Preliminary Test Of Infrared Integrating Sphere Radiation Source With Wide Dynamic Range

The integrating sphere radiation source is one of the key equipments in the laboratory radiation calibration system.It has excellent radiation characteristics such as high stability and high uniformity.At present,the research and application technology of the integrating sphere radiation source in the solar reflection band is relatively mature,which is widely used in laboratory radiation calibration.However,the development method of the infrared integrating sphere radiati'on source still needs to be explored.It is faced with the key technical problems such as how to achieve high uniformity,wide dynamic range adjustment,high stability and low background radiation output.Aiming at the calibration requirements of infrared remote sensors with large aperture and high temperature sensitivity,a design and preliminary test method of infrared integrating sphere radiation source with high uniformity and wide radiation dynamic range is studied in this paper.In order to select a suitable infrared radiation medium as the light source of the infrared integrating sphere radiation source system in 3-14 ?m band,and produce a highly stable calibration reference light source with adjustable spectral radiance.In this paper,six types of infrared radiation media are investigated and compared,and among them,six kinds of three types are tested for instability and spectral characteristics.Finally,the carbon fiber quartz electric heating tube is selected as the infrared radiation medium of the integrating sphere,and its spectral radiation instability is better than 0.4%within 1 h.Based on the cavity radiation theory of integrating sphere and the blackbody radiation theory,the uniform-light mode of child and parent gold-plated integrating spheres is proposed,which effectively improves the uniformity of the infrared integrating sphere.By changing the current value of the driving power supply,the output radiance of the radiation source can be adjusted with wide dynamic range.Programmable gold-plated apertures are designed,and linear adjustment of radiance at isochromic temperature can be achieved by changing the opening size of the aperture.The temperature of the parent integrating sphere is reduced to 155 K by using the mixed medium cooling module.At this temperature,the background radiation of the parent integrating sphere at 10?m accounts for about 0.5%of the output radiance.The shot peening and vacuum evaporation gold plating process is used to realize the fabrication of the inner wall coating of the children and parent integrating spheres,and the gold-plated apertures are integrated to complete the structural assembly of the infrared integrating sphere radiation source.Characteristics of the infrared integrating sphere radiation source are analyzed and preliminary tested under normal temperature and pressure conditions.Results reveal that the uniformity of the infrared integrating sphere in the area of ?200 mm of the normal at the light exit is 98.87%,the angular uniformity within ±15° in the vertical direction is 99.69%,the dynamic range is nearly linearly adjustable,the background radiation is less than blackbody at the same temperature,and the instability within 30 minutes is 0.16%.These results demonstrate that the infrared integrating sphere possesses excellent performance.The relationship between temperature variation and radiation output stability is established,and the temperature control accuracy of the children and parent integrating spheres is determined.The infrared integrating sphere radiation source is an effective supplement to the traditional blackbody radiation source,and has potential application value in the laboratory spectral radiometric calibration of infrared remote sensors.