The focal spot is the tiny area on the anode where the electron beam strikes and produces X-rays. In conventional industrial tubes, that spot can be relatively large, spreading the X-ray emission over a wider area. A small focal spot X-ray tube maintains a much smaller, well-defined focal spot typically in the tens of micrometers range. This tighter spot:
What Is a Small Focal Spot X-Ray Tube?
The focal spot is the tiny area on the anode where the electron beam strikes and produces X-rays. In conventional industrial tubes, that spot can be relatively large, spreading the X-ray emission over a wider area.
A small focal spot X-ray tube maintains a much smaller, well-defined focal spot typically in the tens of micrometers range. This tighter spot:
- Reduces geometric unsharpness
- Improves spatial resolution
- Helps capture fine details, edges, and interfaces
Because of that, small focal spot or mini focus X-ray tubes are widely used in:
- Electronics and PCB inspection
- X-ray thickness gauging of coatings and films
- Battery and additive manufacturing inspection
- High-precision NDT of small components
The Micro X Tube is Micro X-Ray’s dedicated microfocus / mini-focus tube family, designed to make these performance gains accessible in compact, OEM-ready packages.
Why Focal Spot Size Matters for Image Quality
For any X-ray imaging system, image sharpness is driven by two main elements:
- Detector performance (pixel size, noise, dynamic range)
- Source geometry, especially focal spot size and distance to the object
Even with a state-of-the-art detector, a large focal spot will blur fine details. A smaller focal spot reduces this blur, improving:
- Spatial resolution – the ability to separate features that are close together
- Edge definition – sharper boundaries around defects, voids, or layer interfaces
- Measurement accuracy – more precise thickness, porosity, and dimensional measurements
For X-ray thickness gauging or micro-CT applications, these improvements directly translate to better process control and fewer false rejects.
The Engineering Challenge: Small Spot, High Stability
Shrinking the focal spot size isn’t only a matter of focusing the electron beam more tightly. It also introduces engineering challenges:
- Higher power density – the same power is concentrated into a smaller area, increasing thermal load on the target.
- Target stability – overheating can cause target damage or focal spot drift, degrading resolution over time.
- Mechanical robustness – the tube must handle thermal expansion and cycling without misalignment.
Micro X-Ray addresses these challenges in the Micro X Tube with:
- Optimized anode and heat-sink design to remove heat efficiently from the focal spot region
- Carefully controlled electron optics for stable, repeatable focal spot positioning
- Rugged mechanical construction for long service life under demanding duty cycle
The result is a small focal spot X-ray tube that delivers both the resolution and uptime industrial users require.
Small Focal Spot vs. Conventional Industrial X-Ray Tubes
When should you choose a small focal spot or mini focus tube instead of a standard industrial X-ray tube?
Choose a small focal spot / mini focus X-ray tube when:
- You need to resolve fine structures such as bond wires, vias, micro-cracks, or thin coatings
- You are measuring very small thickness changes or density variations
- You are limited in source-to-object distance and can’t simply “zoom in” the geometry
- You are developing compact, high-magnification micro-CT or laminography systems
A conventional tube may still be sufficient when:
- Features of interest are relatively large
- Penetration power and field size are more critical than resolution
- Your application is low-magnification radiography of heavy or thick parts
Because many OEMs run a mix of applications, the Micro X Tube is designed to provide microfocus performance while remaining straightforward to integrate alongside or as an upgrade to existing inspection platforms.
Key Applications for Small Focal Spot X-Ray Tubes
Electronics & Semiconductor Inspection
For PCBs, BGAs, and semiconductor packages, a small focal spot helps reveal:
- Voids in solder joints
- Misaligned or broken bond wires
- Delaminations in multilayer structures
Mini focus X-ray tubes like Micro X Tube allow inline inspection systems to detect these issues earlier and more reliably.
X-Ray Thickness Gauging
In continuous production lines, small focal spot X-ray tubes improve thickness measurements of:
- Metallic or non-metallic coatings
- Films and foils
- Multilayer composites
Sharper beam geometry means more accurate edge detection and more confident control of target thickness.
Battery, Additive Manufacturing & Advanced Materials
For lithium-ion cells, 3D-printed parts, and advanced composites, micro-scale defects can have macro-scale consequences. Microfocus tubes provide the resolution needed to see:
- Micro-voids and inclusions
- Layer-by-layer structural anomalies
- Early signs of fatigue or cracking
What to Look for When Selecting a Small Focal Spot X-Ray Tube
When evaluating mini focus X-ray tubes manufacturers, engineers typically compare more than just focal spot size. Key parameters include:
Spot size and stability
- Nominal focal spot dimension (e.g. < X µm)
- How stable the spot remains over time and operating conditions
Power and kV range
- Tube voltage and current ratings
- Whether the tube can reach the penetration required for your material and thickness range
Thermal management and duty cycle
- Maximum continuous and pulsed power ratings
- Cooling requirements and recommended operating duty cycles
Beam quality and filtration
- Target material options
- Filtration and window materials suitable for your energy range
Integration & lifetime
- Mounting interfaces and envelope dimensions
- Expected tube life at typical operating conditions
- Service and support from the manufacturer
The Micro X Tube family is engineered with these factors in mind, giving OEMs a balanced combination of resolution, power, and long-term stability.
Spotlight on Micro X Tube: A Small Focal Spot Tube for Demanding OEMs
The Micro X Tube is Micro X-Ray’s purpose-built small focal spot X-ray tube series, designed to integrate easily into compact industrial, scientific, and medical OEM systems.
Key advantages include:
- High-resolution microfocus / mini-focus performance
Small, stable focal spots deliver crisp images and precise thickness measurements in demanding inspection and gauging applications. - Optimized thermal design
Carefully engineered anode and heat-sink structures support higher power densities while protecting target integrity, extending tube life. - OEM-friendly integration
Compact geometry, standardized interfaces, and compatibility with common high-voltage generators simplify design and integration into new or existing systems. - Customizable configurations
Options for different target materials, focal spot sizes, and operating ranges help tailor Micro X Tube performance to specific application requirements.
Whether you are upgrading an existing inspection station or designing a new high-magnification system from scratch, Micro X Tube provides a reliable small focal spot source that keeps your imaging performance competitive.
Micro X Tube – Small Focal Spot X-Ray Tube for High-Resolution Imaging
Engineered for OEMs who need maximum detail from compact X-ray systems, the Micro X Tube combines a small, stable focal spot with robust thermal management and long service life. It’s ideal for electronics inspection, X-ray thickness gauging, battery R&D, and other applications where every micron counts.
- Delivers high-resolution microfocus / mini focus performance in a compact tube design
- Supports demanding duty cycles with optimized heat removal and target protection
- Offers flexible configurations to match your kV, power, and application requirements
2020 Micro X-Ray 
