Resolution was assessed using MTFs, calculated from images acquired at 40 kV using the small focal spot
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.
Do you know the matrix size, number of lines on a grid, target material, focal spot
size, software version you are using, who checks the uniformity and how often, who's on first and what's on second?
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
The challenge is that increasing the intensity or density of the beam causes the electrons (within the beam) to repel each other more strongly, which in turn increases 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.
The lens system would be even more effective at longer wavelengths were it not for the spreading of the focal spot
in the vertical direction due to gravity.
decrease the laser focal spot
size to match the target as it is compressed.
The greater the percentage of X-rays brought to focus and the smaller the size of the focal spot
, the sharper the image.