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To measure the beam profile and power density distribution of a far field target in high energy system performance evaluation,a high energy laser detection method is proposed by combining photoelectric and calorimetric methods.In the method,the total energy of incident laser is measured by an absorber and the spatial and temporal distribution of laser profile measured by a photoelectric detector.The detector is developed,which is consisted of a graphite calorimeter,an InGaAs photoelectric detector array,a temperature and voltage amplifier,an analog to digital converter and a signal processor.The system with an effective sensitive area of 22 cm×22cm can offer a spatial resolution of 1.1cm,a temporal resolution of 20ms,and a low energy measurement uncertainty less than 10%.With the higher temporal resolution and lower energy measurement uncertainty,the system is suitable for high energy and large area near-infrared laser beam measurement.It has been used in field experiments successfully.

A peak value hold circuit is developed for the energy measurement of a high-repetition-rate pulsed laser.The circuit consisting of four modules including a charge integrator,a 2nd-order Butterworth low-pass filter,a time-delay trigger and a peak-value-holder is designed to convert the photocurrent pulses to voltage pulses which are linear to the energies of incident pulse laser.The experimental measurement results indicate that this circuit is suitable for the pulsed laser with a width less than 10 ns and a repetition rate over 2 kHz.The results show that the circuit has a dynamic range about 140 times and works stably.It can be used to achieve a high spatial resolution in photodiode measurement systems.

The transient distortion of a CCD under laser irradiation is explored.A HS-41-02K30 camera with a linear CCD image sensor is irradiated by a 532 nm CW laser,and the experiment shows that a laser spot and three dark spots with the similar size and shape appear in the direction of photosensitive array with an equal space synchronously.These dark spots are a transient distortion phenomenon of the CCD camera under laser irradiation,and are named the shadows of laser spot in this article.The regularity and generation mechanism of the shadow phenomenon are analyzed.It suggests that the inner mechanism of generating shadows is the interaction between four parallel readout circuits of CCD which share the same bias.The expression describing the interaction is deduced,which indicates that reducing the resistance between the bias source and the common node of four readout circuits can weaken the shadow phenomenon,and using four voltage sources to provide bias for four readout circuits respectively can eliminate the shadow phenomenon.Obtained results point out that the expression deduced by this paper not only can explain the shadow phenomenon but also can provide references for the design of CCD in weakening and eliminating the shadow phenomenon.

To measure the mid-infrared deuterium fluoride laser irradiance distribution,a laser beam profile diagnostic system based on uncooled mid-infrared HgCdTe photoconductive detector array is developed.Because the mid-infrared detector is very sensitive to work temperature,it is necessary to quantitatively analyze its temperature characteristics for evaluating the measuring uncertainty of the system and providing the criterion of selecting the satisfactory detector.The responsivity of HgCdTe photoconductive detector related with temperature and wavelength is analyzed.It is deduced that the responsivity can be expressed as a variable-separate function of temperature and wavelength under special conditions.The assumption is validated by the experiment,of which the responsivity of uncooled mid-infrared HgCdTe photoconductive detector in(-40～+30)℃is measured with 3.8μm and 1.31μm lasers.Based on the results,a simple and practical method to measure the temperature characteristic of the responsivity of uncooled MIR HgCdTe detector is presented.