The new electron microscope “Tronscope TRS-50” Part II: Method of alignment and inspection
Since the optical system of the Tronscope TRS-50 is fixed, the factors which determine the resolution can be checked. These factors are listed in the first column of Table 1. In the second column the formulas for the calculation of the factors are given. The third column gives the numerical constants in the formulas, and the fourth column, the maximum allowable aberrations at the final tests. The numerical constants have been all obtained from actual measurements. The spherical aberration coefficient, Cö was measured from the distortion of the selected-area diffraction pattern (7). The on-axial and off-axial chromatic aberration coefficients were obtained from the measurement of the movement and blur of the image when a voltage fluctuation of about 1,000 times the actually allowable fluctuation was applied. Since the voltage center is clearly found, the off-axial chromatic aberration due to the voltage fluctuation can be expressed by the distance r between the center of the screen and the voltage center (Fig. la). On the other hand, in the range of high magnification, it is practically impossible to find the current center. Therefore, the off-axial chromatic aberration due to the current fluctuation is given by the maximum movement K i of the final image, when a certain constant current fluctuation is applied (Fig. lb).
Unable to display preview. Download preview PDF.
- 1.Glaser, W.: Handbuch der Physik, Bd. 33, p. 373, 1956.Google Scholar
- 2.Leisegang, S.: Optik 11, 397 (1954).Google Scholar
- 3.Leisegang, S.: Handbuch der Physik, Bd. 33, p. 401, 1956.Google Scholar
- 4.Leisegang, S.: Handbuch der Physik, Bd. 33, p. 473, 1956.Google Scholar
- 5.Leisegang, S.: Handbuch der Physik, Bd. 33, p. 480, 1956.Google Scholar
- 7.Klemperer, O.: Electron Optics. Cambridge 1953, p. 136.Google Scholar