One of the most misunderstood aspects of X-ray tubes is how the electron beam is shaped internally, and what impact that has on the X-ray spot. As a rule of thumb, for spot sizes above approximately 50 microns, the electron beam can generally be passively focused through a combination of emitter geometry and smart electron gun design. For spot sizes below that 50 micron threshold, or for applications where the flux distribution within the spot is important, more active measures must be taken. In this case, tube designers often use a grid voltage which modifies the electrostatic field around the electron beam, causing the electrons to change their trajectory mid-flight.

Depending on the tube designer, these electron beam shaping devices may be called apertures, grids, or focusing optics (not to be confused with external optics which act on the X-ray beam). Depending on the tube design and spot size requirement, one or more focusing optic element may be required to achieve the customer’s required beam size and shape. It’s important to understand that these focusing optics don’t create new electrons or increase the total flux output of the tube in any way. Rather, they simply re-route the electron beam in flight so it lands in a different spot on the X-ray target than it otherwise would.

In the case of a Minifocus tube such as our Seeray, adding a single grid voltage can concentrate the flux into a smaller spot, which can be beneficial in certain applications. For instance, when coupling a Minifocus tube to an external polycapillary X-ray focusing optic, the addition of a single grid voltage inside the tube can help concentrate the available flux in the center of the spot, enabling more efficient use of the optic.

But What Does a Grid Actually Do?

Let’s take the example of a single grid on a Minifocus X-ray tube.  The cathode of the tube is ground-referenced, and the anode of the tube is at a high voltage. As electrons are emitted from the tube’s filament, they are effectively at a 0V potential. They “see” the high voltage of on the tube’s anode, and race towards it to equalize the potential difference. The stream of electrons flowing from the cathode to the anode forms the electron beam. Because these electrons are at 0V, we have the ability to shape them as they move towards the anode by manipulating the electrostatic field they fly through with a relatively low grid voltage. Using this principal, MXR is able to design the electrostatic field they pass through in order to manipulate their landing pattern on the target, which forms the X-ray spot.

First, let’s look at a visualization of a gridded Minifocus tube’s X-ray spot taken on a production tube at Micro X-Ray, using our pinhole spot photo measurement system with no grid voltage applied. We can distinctly see two lobes in the spot. The total intensity of the spot can be determined by summing the total number of counts in the image, 1.77e7.

As we increase the electrostatic field strength with a grid voltage of -20V, we can see the two lobes are merging into one as a result of the electrostatic fields acting on the electron beam, but the spot’s sides in the X axis are still quite sloped (these slopes are often called the “wings” of the spot). Note the total counts in the spot area remain unchanged.

At -40V, the X-ray spot is now a sharp spike, with very steep sides and an intense center. Note the total count rate still remains unchanged, despite a very different shape than the spot with a 0V grid value. We are not adding X-ray flux, we’re simply focusing it in the center of the spot.

And finally, at -60V, we can see the center intensity fall slightly as the wings of the spot increase – this tells us we’ve applied too much voltage to the grid. Again, the total flux intensity remains unchanged, but over focusing the beam results in a less than optimal distribution of the available flux.

Putting It All Together

In the GIF below, we’ve animated the grid voltage changes from 0V through -65V to show the impact of grid voltage on flux distribution. The ideal grid voltage is slightly different for each X-ray tube, and Micro X-Ray will provide you with the optimal grid voltage for your tube.

So what does it mean for you, and do you need a gridded X-ray tube? As always with X-ray tubes, it depends. A gridded tube isn’t better or worse than a non-gridded Minifocus tube, it just depends what your application requirements are. Many analytical applications don’t care about the spot size at all; as long as the cone angle illuminates a larger area than the largest collimator in the system, that’s good enough for the application. However, when high flux intensity in the center of the spot is important, there’s no substitute for a well designed electron beam focusing optic. If you’re using an external polycapillary optic, this increase in flux, combined with the total power of our Seeray X-ray tube can unlock flux intensity previously reserved for sources in the kW range, allowing ultra-fast micro XRF, and even enabling benchtop XRD from a X-ray source running at under 100W!

For More Information on Gridded Tubes

If you have any questions about our gridded tubes, or any tubes at all, please reach out today!

The post Operational Tips: Do I Need a Gridded Tube? appeared first on Micro X-Ray.

This post serves as a comprehensive guide to help you connect the open-collector outputs on your Micro X-Ray integrated X-ray source to the inputs of your control components, while considering the 20mA maximum sinking current standard across Micro X-Ray integrated sources. By following these guidelines, you can ensure seamless integration and optimal performance of your integrated X-ray source. Additionally, we will explore how to connect and use a relay to drive low impedance and/or high voltage loads, expanding the capabilities of your integrated X-ray source.

Connecting Open-Collector Outputs to Your Control System

Regardless of whether your control system operates at 3.3V, 24V, or somewhere in between, the process of connecting the open-collector outputs from the integrated X-ray source is the same.

Understand Your Input Requirements

Determine the input specifications of your control system components that will receive the signals from the X-ray source module. Pay attention to the input voltage levels, any internal (built-in) pull-up resistors, and maximum current sourcing specification so you can determine if your input can be connected directly to the output, or if intermediary circuitry is required.

Identify Open-Collector Outputs

Review the X-ray source module’s documentation or datasheet to identify the available open-collector outputs and their corresponding pinouts.

Connect the Open-Collector Outputs

For circuits requiring less than 20mA and less than 24V

In the majority of cases, when feeding an open collector output into a digital input, a simple pull-up resistor is all that’s required in order to read the output, as shown in the figure below.

1. Identify the positive voltage supply (up to 24V) and ground of your control system.
2. Connect the open-collector output pin from the X-ray source module to the input pin of your control component.
3. If your control component’s input does not have a built-in pull up resistor, you’ll need to add an external one:
   1. Connect a resistor between the positive voltage supply and the input pin of your control component.
   2. Ensure that the resistor value is appropriately chosen to limit the sinking current to a maximum of 20mA. Ohm’s Law (V=IR) can be used to calculate a suitable value for R with a little rearranging to solve for R=V/I, where V is your positive voltage supply, and I is the current you wish to sink, up to 20mA.

For circuits requiring more than 20mA and/or more than 24VDC

In situations where you need to drive a low impedance load or a load with higher voltage than what can be directly handled by the open-collector outputs, a relay can be employed, as shown in the figure below.

1. Select a Suitable Relay
   1. Choose a relay that meets the specifications of your load requirements, such as the desired switching voltage, current capacity, and contact configuration.
   2. Ensure coil can be operated within the open-collector output specifications of up to 24VDC and less than 20mA sinking current.
2. Connect the Relay Coil
   1. Connect one side of the relay coil to the open-collector output pin.
   2. Connect the other side of the coil to the positive supply voltage, ensuring proper polarity.
3. Connect the Relay Contacts
   1. Connect one side of the load to the common terminal of the relay contacts.
   2. Connect the other side of the load to the appropriate contact terminal based on your desired switching behavior.
4. Power Supply Considerations
   1. Ensure that the power supply for the relay coil and the load is appropriately rated.
   2. Use a separate power supply for the load if its voltage exceeds the rating of the open-collector output.
5. Protection Measures
   1. Implement appropriate protective measures, such as diodes or snubber circuits, across the relay coil to suppress voltage spikes and protect the control circuitry.

Verify the Wiring

For either direct-driven or relay-driven operation, once the connections are made, double-check the wiring to ensure correct polarity and proper grounding. Incorrect connections can lead to malfunctioning or unreliable operation.

Signal Interpretation

In your control system software or firmware, you are now ready to interpret the X-ray source module’s open-collector outputs based on the specifications of your control components and the X-ray source manual. Design your control algorithms or logic accordingly to utilize these signals for the desired system behavior.

Conclusion

By following the steps outlined above, you can effectively connect and utilize the open-collector outputs from your integrated X-ray source module in your control system. Ensure that the sinking current at the output does not exceed the maximum specified limit of 20mA, and the voltage does not exceed 24V. With proper connections and signal processing, you can achieve seamless integration and optimal performance, enabling precise control of your X-ray source in various applications.

As always, if you have any questions about how to select or operate your X-ray source, please reach out today!

Contact Us Today!

The post Operational Tips: Using the Open-Collector Outputs on Your Integrated X-ray Source: A Guide for Low and High Impedance Inputs appeared first on Micro X-Ray.

Picking an X-ray source can be a daunting task – with all the variables and tradeoffs involved in X-ray tubes and the systems that contain them, it’s tough to know where to even begin. In today’s post, we’ll talk through the different packaged tube options available and discuss where each might fit in.

The 50kV, 50 Micron Sweet Spot

Micro X-Ray offers a range of X-ray sources that are designed to meet the diverse needs of a variety of applications. In applications where focus matters, 50kV is often a perfect voltage for our customer’s applications – high enough energy to penetrate a wide variety of common materials in various thicknesses, but low enough to make shielding a relatively straightforward affair with thin sheets of high-Z materials. A spot size around 50-100µm is another sweet spot – well focused enough to enable the high resolution images needed on modern process lines, but not so finely focused that electrostatic focusing voltages (and their complex power supplies) are required.

In the 50kV Minifocus tube category, there are several distinct product families to consider. These product families include the Minifocus Packaged Tube, the Windchill, the Aquachill, the Seeray, and the Seeray with Diamond Target. In this blog post, we’ll compare and contrast these products to help you understand which one is right for your specific application.

Because each product family contains so many options (target material, cone angle, cable lengths, etc), we won’t spend much time drilling down to particular SKUs or specific applications, but instead we’ll discuss general advantages and drawbacks of each of the product families. Once a product family or two has been identified as a good candidate for your application, reach out to Micro X-Ray and we’ll work through the rest together.

Minifocus Packaged X-ray Tube

The Minifocus Packaged X-ray Tube is an industry standard, high volume product offered by MXR. It can generally run up to 50W and has a 1W/µm power loading, with spot sizes ranging from 33µm through 250µm and a wide variety of target material choices. This product is suitable for offline applications where high resolution is important, but where shaving seconds off the measurement or exposure time isn’t the highest priority.

Actively Cooled X-ray Sources

Windchill

The Windchill is a forced air-cooled X-ray source that extends maximum power of a Minifocus Packaged X-ray tube from 50W up to 150W. It uses a small oil pump to move dielectric oil through a heat exchanger to effectively cool down the X-ray tube, enabling higher power and an extended temperature range. The Windchill has a maximum 1W/µm power loading and is suitable for applications that require higher throughput than a Minifocus tube, but where the ambient temperature is still relatively cool, such as a laboratory, or a climate controlled factory floor.

Aquachill

The Aquachill is a water-cooled X-ray source that extends the power range of an X-ray tube from 50W up to 150W. Like the Windchill, it uses an efficient oil pump to move oil through a heat exchanger to cool down the X-ray tube. The main difference between the Aquachill and the Windchill is the cooling method used for the heat exchanger. The Aquachill uses water cooling for more efficient heat removal, making it suitable for applications where the ambient temperature may be too high for forced air cooling.

Direct Anode-Cooled X-ray Sources

Seeray

The Seeray is another water-cooled X-ray source, but unlike the Aquachill which cools the tube indirectly via the oil, the Seeray incorporates direct anode water cooling for the most efficient heat removal possible in an X-ray tube. This product is useful everywhere the Aquachill is and can also provide key performance advantages in applications such as XRD and some imaging applications where focal spot drift is an issue, since the direct water-cooled anode reaches thermal equilibrium within around 5 minutes. The Seeray has a 1W/µm power loading and is suitable for applications with uncontrolled ambient operating environments where X-ray source longevity is critical.

Seeray with Diamond Target

The Seeray with Diamond Target is designed for applications where maximum brightness is required, combined with minimum spot sizes. This product is great for applications like high brightness micro XRF or single crystal XRD where high resolution and high brightness are equally important. With a 1.5W/µm power loading, the Seeray with Diamond Target provides industry-leading brightness of up to 150W in a 100µm spot size. This brightness, combined with the quick spot settling time, make it a perfect choice for coupling with X-ray optics.

Conclusion

MXR offers a range of X-ray sources that can meet the diverse needs of a variety of applications. Ultimately, selecting the right X-ray source will depend on the specific needs of your application, including resolution, throughput, and environmental conditions in your application. The team at Micro X-Ray is standing by to help assist you in selecting the right X-ray source for your application today.

The post Operational Tips: Selecting the Right X-ray Source from Micro X-Ray appeared first on Micro X-Ray.

Important Angles and Distances in X-ray Imaging

Geometry of a typical X-ray application showing the X-ray source, the Object being imaged, and the X-ray detector.

X-ray Coverage Formulas

Calculation of the radius of the X-ray radiation coverage of an object

The coverage area on the detector may be calculated with the same formula, but swapping out the distance variables for Source to Detector distance:

Calculation of the radius of the X-ray radiation coverage of an X-ray detector

Geometric Magnification Formula

Geometric magnification is an easy concept with a (unnecessarily?) confusing name. This is simply the magnification of the object being imaged on the surface of the detector. For example, if you are measuring a 50μm feature, an 8x geometric magnification factor will blow that feature up to 400μm on the detector surface. Understanding your magnification and the size of the features you need to resolve will help you select the correct detector for your application.

Try this: hold your cell phone flashlight a fixed distance away from a flat table, the put a single finger half way between the camera LED and the table. The shadow of your finger on the table will be about 2x its real size. If you hold your phone in one spot and move your finger up and down, you can see the magnification change. As you move your finger closer to the table, the shadow shrinks; as you move your finger closer to your phone, the shadow grows. You can also change the magnification by holding your finger a constant distance from your phone, and moving the phone/finger pair closer and further from the table.

Geometric magnification of X-rays works identically to its counterpart in visible light and shadows. The magnification factor is just a simple ratio comparing the Source to Detector distance to the Source to Object distance:

Calculation of the Geometric Magnification ratio

X-ray Coverage Calculator

Try it yourself! Use the calculator below to check your coverage dimensions and magnification factor for your application or use case.

Practical Limits

It’s important to understand that your can’t increase your magnification infinitely, as there are some real-world constraints to contend with. We’ll cover these more in future articles, but for now keep in mind the following:

• X-ray radiation intensity falls off with distance squared. This means the further away your source is from your detector, the fewer X-rays make it to the detector. At some point, the detector is just too far away to record any meaningful amount of X-ray flux.
• The opposite is also true! If your detector is too close to the source, there may be so much flux that the detector floods and can’t produce a reliable image.
• The resolution of an image is not only controlled by the magnification, but also the X-ray source. As a rule of thumb (and of course there are exceptions – there are always exceptions), the smallest image you’ll be able to resolve is around the same size as your X-ray spot. No matter how much you magnify an image, you’ll never resolve a 10μm feature with a 100μm spot size X-ray tube.

Let’s Talk!

Contact us today to talk about your imaging application, our Microbox source which is purpose-built for X-ray imaging, or anything else X-ray related!

The post Operational Tips: X-ray Coverage and Magnification Formulas and Calculator appeared first on Micro X-Ray.

Why run at low kV?

What’s the problem with low kV operation?

What’s the High Flux, Low Excitation Voltage Solution?

Beam current vs Excitation Voltage for 50W Lightbright, 100W Lightbright, and competitor’s tube

The post Operational Tips: Why is High Beam Current at Low Excitation Voltages So Hard? appeared first on Micro X-Ray.

What to Consider When Purchasing a Microfocus X-ray Source

• Does the Microfocus tube offer the primary features that you require to allow your equipment to function properly?
• What type of housing does the Micro X-ray tube offer? Will it shield against radiation and help regulate the temperature inside of the tube?
• A well-made cooling system is an important factor to consider when purchasing x-ray tubing for the machinery your company uses.
• Do the features of the tube provide the protection required to prevent the device from being damaged and creating hazardous conditions?
• Is the protection to prevent a radiation leak in agreement with the local governing requirements that are in place to prevent people from being exposed to the radiation the tube produces?
• How easy can the source be installed in your system, and how is the source controlled?

Quality Customer Support Provided

When searching for x-ray tubes to install into the equipment your company uses, you want to look for a manufacturer that produces high-quality products. It is also important to find a company that offers exceptional customer support to ensure the component is installed properly and that it will function correctly. With the right organization, they will customize their product and services to meet the specification your company requires to produce reliable equipment for your clientele.

Select a Company Focused on Meeting Their Customers’ Specific Needs

It can be challenging to find the right X-Ray tube that will work efficiently in a machine that requires continuous use. Micro X-Ray Inc. offers each client the personalized services they require in developing high-quality X-ray sources for the equipment they produce. We deliver unique products and services to meet the high demand for x-rays tubes that offer to shield against radiation and a cooling system to help prevent the component from overheating while in use.

The post Operational Tips: How to Find the Right Microfocus X-Ray Tube that Provides Sharp Images appeared first on Micro X-Ray.

Packaged x-ray tubes are the ideal solution for anyone that is looking for an easy plug and play solution! Packaged x-ray tubes are outfitted with shielding and wiring built in so there is nothing else to do but plug them in and use them. They are the ideal solution for a wide range of applications, including high use applications and high voltage applications.

What Are They?

These tubes have a metal housing. The metal housing is a radiation shield and it keeps the tube cool under high temperature conditions. They are a simple solution for a lot of application needs. The housing prevents arcing and allows for cooling. This can be the perfect OEM replacement part.

The Benefits

These tubes offer a range of benefits including:

1. Great thermal properties
2. Easy installation
3. Fully Radiation shielded
4. High voltage isolation
5. And more!

Thermal Properties

Many of the potted tubes cannot stand up to high temperatures as well as this type of packaged tubing. The outer housing allows for a great deal of thermal conductivity allowing high temperature operation without compromise to the tube. This can be a very important attribute for many machines and should be a consideration.

Easy Installation

Since the tube is already packaged the only thing left to do is to plug it up to a power supply. This can be a big reason to consider this type of tube. If you need a solution that is ready to install on the day it is delivered, without much stress, this is the perfect option.

100% Radiation Shielded

You do not have to take any extra precautions because the shielding is already built in.

It is the Right Option?

Of course, all the benefits and all the advantages may still not make it the best choice for your application. Turning to the experts to get information can help you to make the right choice. Getting customized support can help you to be able to take advantage of the packaged x-ray tube option. Micro X-ray offers the type of customized solutions that can help you to get the function that you need. Micro X-Ray will help you to make an informed decision whether you are choosing a packaged tube or another type of tube!

The post Operational Tips: Choosing Packaged X-Ray Tubes appeared first on Micro X-Ray.