A method for EMCCD multiplication gain measurement with comprehensive correction

Li Qiao,Mingfu Wang,Zheng Jin

doi:10.1038/s41598-021-85511-z

Li Qiao, Mingfu Wang + Show 1 more

Open Access

https://doi.org/10.1038/s41598-021-85511-z

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Abstract

In order to improve the image quality, it is imperative to conduct the non-uniformity correction of EMCCD, for which the measurement accuracy of the internal electron multiplication gain of each channel is a prerequisite within multi-channel output EMCCD. It is known that the smaller the image standard deviation of each channel, the better the image uniformity, and the closer the calculated multiplier gain is to the real value. In order to minimize the influence of non-uniformity of background between pixels and light response existing in traditional measurement, a comprehensively modified EMCCD multiplication gain measurement is proposed after the working principle of EMCCD is described. The output images of the camera working in the normal CCD mode and EMCCD mode are corrected comprehensively through this method. The experimental results show that after the comprehensive correction, the standard deviation of the output image of each channel within the camera decreases to about one third of the original when the camera works in the normal CCD mode, while it decreases to about one fifth of the original when the camera works in the EMCCD mode, the signal stability is significantly improved, and the measured multiplier gain of each channel is closer to the true value of the detector, which proves the effectiveness of the proposed method.

Highlights

EMCCD is known as electron multiplying charge coupled device
The multi-tap output structure adopted by EMCCD chip can improve the maximum output frame rate of the detector, which, simultaneously, will introduce the non-uniformity caused by the difference of real multiplication gain between image channels; [2] non-uniformity between pixels within channel
When r = 0, the camera works in normal CCD mode; when r > 0, the camera works in EMCCD mode

Summary

Introduction

EMCCD is known as electron multiplying charge coupled device. Compared with the traditional CCD, EMCCD adds an electron multiplier register (EMR) between the readout register and the readout a mplifier. The EMR can amplify the weak electrical signal exponentially, so as to achieve the purpose of multiplication This process can greatly improve the detection sensitivity of EMCCD, making it one of the most widely used high-end detectors in the field of low-light imaging fields. The multi-tap output structure adopted by EMCCD chip can improve the maximum output frame rate of the detector, which, simultaneously, will introduce the non-uniformity caused by the difference of real multiplication gain between image channels; [2] non-uniformity between pixels within channel. The multiplication of photo-generated charge in EMCCD’s electron multiplier register is a random process, which brings in discrepancies of multiplication gain between pixels and introduces non-uniformity. The real multiplication gain of photogenerated charge in the electron multiplier register is shown in Eq [1]27:. The larger the gain voltage of the multiplier register, the greater r and G and vice versa

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