Resolution was assessed using MTFs, calculated from images acquired at 40 kV using the small focal spot
Compared to conventional X-ray tubes, the Variofocus focal spot
is less than half the size and considerably more symmetrical, displaying a value between 250[micro]m at 290W up to 800[micro]m at 1600W.
At the focal spot
diameter 10 urn, the laser power density is about 1h-5x106 W/cm2 for this type of lasers, which is sufficient for melting metal and ceramic powders.
Figure 10 shows the weld width as a function of travel speed at various power levels for PC with the 50-[micro]m focal spot
This is again demonstrated in Figure 2, where the same focal spot
is viewed as a radial graph showing the distribution of energy around the circumference, at the axial focus position.
The greatest possibilities for regulation of temperature conditions for formation of ingots in a mold are ensured by electron beam cold hearth remelting (EBCHR) (Figure 1, d) due to size of the heating spot on surface of a metal being heated, so called focal spot
, and non-inertance of heating by an electron beam.
Distance between the x-ray tube focal spot
and the detector = A
Optical interferometry also has extremely high sensitivity, with surface height accuracy down to subnanometer vertical resolution averaged over the size of the laser focal spot
Even at such high magnifications the latest 1000 x 1000 pixel detectors can easily resolve the resulting x-ray images, so image resolution depends almost entirely on focal spot
size of the x-ray source.
Even if a stone is moving during the procedure, the time-reversed system works so rapidly that the target is still within the focal spot
when the echoed signal returns.