6. Rotation Center Alignment This procedure may be performed with the OBJECTIVE APERTURE in place to protect the specimen and add contrast to the image. Focus and center a feature of the specimen at 100,000x. Press ALGN to open the ALIGNMENT SELECTION page. On the upper right-hand side of the page, press ROT CENTER so that it becomes highlighted. (i) If the chosen feature shifts off center laterally, the beam is not aligned along the optical axis of the microscope and must be corrected. (ii) Use the MULTIFUNCTION X/Y knobs to stabilize the feature at the center of the screen, eliminating all lateral movement. The feature should appear to be pulsating. (iii) Press the ALGN button to return to the TEM BRIGHTFIELD page. 7. Centering the Objective Lens Aperture For this procedure a specimen must be in place. Choose an area for which it is acceptable to sustain beam da mage. With the OBJECTIVE APERTURE out, set the magnification to about 3000x and overfocus the beam by turning the INTENSITY knob clockwise from crossover till it’s the size of the large viewing screen. Press the button to put the 'scope in diffraction mode. “D” If necessary, adjust the CAMERA LENGTH to 470 mm using the MAG knob. Center the diffraction spot using the MULTIFUNCTION X/Y knobs. Using the INTENSITY knob, refocus the bea m to the smallest, brightest spot. Insert the OBJECTIVE APERTURE by rotating the aperture displacement lever below it to the left. Apertures may be selected by rotating the largest knurled knob on the objective aperture assembly to any one of four numbered positions. (The APERTURE MEMO lists the dia meters and positions of the apertures currently installed in the 'scope. It may be accessed from the TEM BRIGHTFIELD page by clicking MODES and then CONFIGURATION.) Focus the shadow of the aperture with the FOCUS knob. Once the aperture has been selected, center it using both the middle knurled knob in the series on the aperture assembly and the small knurled knob to the right side. Remember not to manipulate the smallest, inner most knob, which will unscrew the aperture rod. Press to exit diffraction mode. “D” 8. Objective Lens Astigmatism Correction Select an area that may be ima ged at high magnification without harming any desirable portions of the specimen. Increase the magnification to about 100,000x or higher and adjust the
6. Rotation Center Alignment This procedure may be performed with the OBJECTIVE APERTURE in place to protect the specimen and add contrast to the image. Focus and center a feature of the specimen at 100,000x. Press ALGN to open the ALIGNMENT SELECTION page. On the upper right-hand side of the page, press ROT CENTER so that it becomes highlighted. (i) If the chosen feature shifts off center laterally, the beam is not aligned along the optical axis of the microscope and must be corrected. (ii) Use the MULTIFUNCTION X/Y knobs to stabilize the feature at the center of the screen, eliminating all lateral movement. The feature should appear to be pulsating. (iii) Press the ALGN button to return to the TEM BRIGHTFIELD page. 7. Centering the Objective Lens Aperture For this procedure a specimen must be in place. Choose an area for which it is acceptable to sustain beam da mage. With the OBJECTIVE APERTURE out, set the magnification to about 3000x and overfocus the beam by turning the INTENSITY knob clockwise from crossover till it’s the size of the large viewing screen. Press the “D” button to put the 'scope in diffraction mode. If necessary, adjust the CAMERA LENGTH to 470 mm using the MAG knob. Center the diffraction spot using the MULTIFUNCTION X/Y knobs. Using the INTENSITY knob, refocus the bea m to the smallest, brightest spot. Insert the OBJECTIVE APERTURE by rotating the aperture displacement lever below it to the left. Apertures may be selected by rotating the largest knurled knob on the objective aperture assembly to any one of four numbered positions. (The APERTURE MEMO lists the dia meters and positions of the apertures currently installed in the 'scope. It may be accessed from the TEM BRIGHTFIELD page by clicking MODES and then CONFIGURATION.) Focus the shadow of the aperture with the FOCUS knob. Once the aperture has been selected, center it using both the middle knurled knob in the series on the aperture assembly and the small knurled knob to the right side. Remember not to manipulate the smallest, inner most knob, which will unscrew the aperture rod. Press “D” to exit diffraction mode. 8. Objective Lens Astigmatism Correction Select an area that may be ima ged at high magnification without harming any desirable portions of the specimen. Increase the magnification to about 100,000x or higher and adjust the