Estimation of Electron Dose Rate using CCD Camera

We report a useful method to estimate the electron dose rate which may be a decisive factor to characterize sample properties. Even though most mircoscopes have their own expo- sure meters, there are several practical concerns when such expo- sure meters are used to measure the electron dose rate: 1) Speci- men should be avoided within the entire area of exposure meter; 2) beam current has to be always recorded whenever the operation mode is changed; 3) the electron dose rate can not be calculated for the beam current beyond the detectable range. To overcome these limitations, we suggest a useful method which utilize a CCD (charge coupled device) camera which is now a popular detector to obtain the final electron micrographs. We have evaluated the CCD sensitivity using the linear relationship between electron current on the exposure meter and counter ratio on the CCD cam- era which are built in KBSI-HVEM (high voltage electron micro- scope). Applying the new method, we obtained the CCD sensitivi- ty which are approximately 0.039 counts/e - and 1.37 counts/e - for the Top-TV and the HV-GIF CCD cameras, respectively. (김진규, 김영민, 김윤중, 이상희, 홍기민, 오상호 : CCD 카메라를 이용한 전자빔 조사량의 예측)