| 摘要 |
PURPOSE:To enable the contrast of an electron microscope image to be held mederately, by installing a mechanism for travelling a sample position along the optical axis direction of the objective lens and a mechanism for travelling the diaphragm position of the objective lens along the optical axis direction. CONSTITUTION:An objective lens 2 is composed of a lens coil 3 wound around the optical axis Z of the lens, a yoke which contains said coil 3, and magnetic pole pieces 5 and 6; when said coil 3 is excited by electric source 7 of the objective lens, a strong lens magnetic field is formed between the magnetic pole pieces 5 and 6. In this magnetic field, a sample holder 8 and a diaphragm holder 9 are inserted through the body-tube 1 and yoke 4 along a direction which internsects orthogonally with the optical axis Z, and a position control is carried out by means of a sample-travelling mechanism 10 and a diaphragem-travelling mechanism 11 including the travel toward the optical axis Z direction. A position signal implying said axis Z direction of the sample detected by said mechanism 10 is monitored by a CPU 12 , the position of the objective lens along the axis Z direction which is optimum to the new sample position is calculated, and thus it is allowed to control said mechanism 11 through a position control circuit 13. Consequently, the optimum control can be achieved. |
