A very low-density flow field schlieren measurement system and method based on a programmable spatial light modulator

Abstract

The invention belongs to the technical field of schlieren measurement and imaging, and discloses an extremely low-density flow field schlieren measurement system and method based on a programmable spatial light modulator, in order to solve the problem that the prior art cannot clearly capture low-density flow field shock waves . When the optical signal of the present invention is focused on the programmable spatial light modulator through the first focusing mirror, the programmable spatial light modulator is programmed and controlled by the image fed back by the first CCD image sensor, so that the programmable spatial light modulation The device deflects the brighter low-frequency part of the focused spot, leaving the darker high-frequency part and reflecting it to the second focusing mirror, and then focusing on the second CCD image sensor through the second focusing mirror to achieve low-density flow Imaging observation of field shock images. The invention can detect the signal of several nanometers by filtering out the relatively bright low-frequency part in the light spot, and realizes the detection of the schlieren shock wave in the extremely low-density flow field.

Description

technical field [0001] The invention belongs to the technical field of schlieren measurement and imaging, and in particular relates to a very low density flow field schlieren measurement system and method based on a programmable spatial light modulator. Background technique [0002] The schlieren imaging technology uses the disturbance of the airflow to the light wave to convert the airflow change into an image, that is to say, the principle of the schlieren to capture the flow field is to display its refractive index according to the angular deflection of the light passing through the airflow of different densities. It is a device for measuring the slight deflection angle of light, which converts the change of density gradient in the flow field into the change of relative light intensity on the recording plane, so that the areas with severe density changes such as shock waves and compression waves in the compressible flow field become compressible. Observe, distinguishable ...

AI Technical Summary

Problems solved by technology

[0013] In order to solve the problem that the existing schlieren method cannot clearly capture the low-density flow field shock wave, a very low-density flow field schlieren measurement system and method based on a programmable spatial light modulator are provided, which can measure the air density below The flow field shock wave under the condition of 10Pa is measured

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