High dynamic range laser far-field focal spot measurement device and method

Abstract

The invention relates to a high dynamic range laser far-field focal spot measurement device and method. The high dynamic range laser far-field focal spot measurement device comprises a laser beam shrinkage or expander system, an attenuation wedge plate, a spectroscope, a scientific grade CCD (Charge Coupled Device) detector, a micro lens array, a CCD detector and a control computer; the laser beam shrinkage or expander system, the attenuation wedge plate and the spectroscope are arranged on the same light path in turn; the light incident to the spectroscope is divided into the transmission light and the reflected light through the spectroscope; the scientific grade CCD detector is arranged on a light path of the reflected light after the reflected light passes through the spectroscope; the micro lens array and the CCD detector are arranged on a light path of the refracted light in turn after the refracted light passes through the spectroscope; the scientific grade CCD detector and the CCD detector are connected with the control computer. According to the high dynamic range laser far-field focal spot measurement device and method, the dynamic measurement on high dynamic range laser far-field focal spots can be achieved and the measurement accuracy can be well ensured.

Description

technical field [0001] The invention belongs to the field of optics, and relates to a high dynamic range laser far-field focal spot measurement device and method, in particular to a laser far-field focal spot reconstruction based on Fourier optics theory to realize a high dynamic range laser far-field focal spot Measuring device and its method. Background technique [0002] The laser far-field focal spot is an important index to describe the quality of the output beam of a large laser device, and it is also the main parameter to characterize the ability of the laser beam to enter the hole in the inertial confinement fusion system. Due to the great disparity in the optical energy density aberration between the main lobe and the side lobe of the laser far-field focal spot (above 10000:1), there is no detector with such a high dynamic range. At present, the laser far-field focal spot measurement methods mainly include: long focal length lens imaging method, array camera test m...

AI Technical Summary

Problems solved by technology

The disadvantages are: 1) Since the energy density ratio of the main lobe of the strong laser and the side lobe of the edge can reach several orders of magnitude, which is far beyond the dynamic range of the CCD, the laser focal spot image tested by this method is actually The main lobe distribution of the strong laser focal spot, while the information of the side lobe is covered; 2) The aberration of the focusing lens introduces focal spot distortion, which affects the test accuracy of the far-field focal spot

Its disadvantages are: 1) limited by the linear dynamic range of the recording medium, the array image cannot fully reflect the side lobe information of the laser far-field focal spot; 2) the array camera adopts an off-axis reflective mechanical structure, although the system adjustment has a It is convenient, but the aberration introduced is relatively large; 3) the resolution of the recording medium, namely CCD, is limited, and a certain relative error is introduced when calculating the focal spot diameter of the array image, thereby affecting the test accuracy of the system

The disadvantages are: 1) It is difficult to debug the system, the ratio of the two pairs of split beams is different, and it is difficult to reconstruct the focal spot; 2) Due to the excessive number of focal spots in one row or column, it is difficult to Completely record all information of the focal plane row or column

The disadvantages are: 1) The main lobe and side lobe of the laser far-field focal spot are time-sharing measurements, which are easily affected by the time-domain noise of the detector, ambient airflow disturbance and laser instability; 2) the method The random drift of the laser far-field focal spot is required to be small, which increases the requirements for the beam control system; 3) When measuring the side lobe, the main lobe needs to be blocked by this method, otherwise it will cause damage to the detector, so the performance requirements for the blocked device Relatively high, it must be tightly shielded from light, resistant to laser radiation, and not affect the measurement results

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