Thermal-infrared-spectrum atmospheric extinction measurement method and device

Abstract

The invention discloses a thermal-infrared-spectrum atmospheric extinction measurement method and device. The device comprises a normal-temperature surface source black body. A plane mirror is disposed right ahead the normal-temperature surface source black body in a light transmission direction; and a Fourier spectrometer is disposed at the right side of the plane mirror in a light transmission direction. An aperture diaphragm is arranged between the normal-temperature surface source black body and the plane mirror in the light transmission direction and is arranged at an optical chopper. A chopper plate of the optical chopper is arranged in front of the normal-temperature surface source black body; and the center of the chopper plate is located at the right side of the normal-temperaturesurface source black body. A neutral infrared attenuation sheet is also arranged on the chopper plate. According to the invention, the atmospheric extinction is inverted by measuring atmospheric radiation spectra at different zenith angles, so that the dependence on standard satellites is eliminated and the infrared atmospheric extinction spectral distribution can be obtained simply, convenientlyand efficiently. The high-precision measurement of spectral atmospheric extinction can be realized; and a problem that the calibration black body and atmospheric radiance exceed the linear dynamic range of a measuring instrument is solved.

Description

technical field [0001] The invention belongs to the field of optical technology, and in particular relates to a thermal infrared spectrum atmospheric extinction measurement method and device. Background technique [0002] Thermal infrared (wavelength 3-14um) observations on the ground inevitably suffer from the attenuation of infrared radiation by the earth's atmosphere, that is, atmospheric extinction. Atmospheric extinction leads to a decrease in the signal-to-noise ratio, causing large measurement errors, and a corresponding decrease in the target detection distance. Therefore, the measurement of atmospheric extinction is very important in the fields of scientific research and military defense. The traditional method of measuring atmospheric extinction uses an extra-atmospheric standard star to measure the remaining intensity after passing through the atmosphere by observing a standard star with known radiation intensity. The atmospheric magnitude difference per unit mass...

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Problems solved by technology

[0010] The method used in this paper has certain shortcomings. The equipment used cannot measure spectral atmospheric extinction. Only a band with good optical transmittance is selected, and the formula (3) is approximated, so that α≈1, and no radiation calibration is performed in the measurement , the radiance from the instrument cannot be distinguished from the spectral line radiance from the atmosphere that does not change with the zenith angle, which increases the error

[0011] Accurate measurement of atmospheric extinction requires radiation calibration. The equivalent blackbody temperature of the atmosphere is usually at the level of -10°C to -50°C. Calibration requires a low-temperature surface source blackbody, but the low-temperature surface source blackbody is complex and inefficient when observed in the field, and is prone to condensation , but the radiance of surface source blackbody at room temperature is much higher than that of atmospheric radiation, and the linear dynamic range of infrared instruments is insufficient, resulting in large calibration errors

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