Role of large and small focal spots in X-ray tubes
The size of the focal spot determines the accuracy of the detection image. The smaller the focal spot, the higher the detection accuracy. However, for the inspection of some larger metal components, sufficient X-ray intensity is required, and a larger focal spot can better serve this purpose. A larger tube current results in a better signal-to-noise ratio in the image.
The main role of a small focal spot
- Provide high-resolution imaging
In the field of non-destructive testing, a small focal spot is crucial for observing fine structures. A small focal spot X-ray tube can produce clear and sharp images because it reduces geometric blurring.
- Suitable for high-precision detection
In industrial flaw detection, a small focal spot is indispensable for inspecting small and precise components such as electronic chips. The internal circuits and structures of electronic chips are very fine, with the smallest line width possibly being only a few micrometers or even smaller. A small focal spot X-ray tube can clearly present the internal circuit layout, solder joint conditions, etc. of the chip, and can detect tiny short circuits, open circuits, or false soldering of solder joints. This high-precision imaging capability is one of the key links in ensuring the quality of electronic products.
The main role of a large focal spot is to with stand high power output.
When a higher X-ray intensity is required, a large focal spot can perform better. For instance, when inspecting thick metal materials, such as the critical metal components of large machinery, the thickness of these components may reach several tens of centimeters. To enable the X-rays to penetrate the components, a larger tube current is needed to generate an X-ray beam of sufficient intensity. A large focal spot can tolerate a higher tube current because the area of the electron beam hitting the anode target is larger, allowing the heat to be more evenly distributed over the target surface.