- X-Ray cameras with 11 and 16 Mpix
FAQ - Frequently asked questions¶
Q: What does “direct phosphor imaging camera” mean?
This represents a direct way of detecting X-ray photons and converting them into electrical charges and thus digital images.
In this case, the phosphor or Scintillator is applied directly onto the Fiber optic plate which is then optically bonded with optical silicon onto the camera sensor.
The phosphor coating is included and the camera architecture looks the following way:
The Fiber optics plate or FOP is coupled directly to the CCD or CMOS die (sCMOS more recently) on one end and coated with a phosphor scintillator on the other.
Q: What applications are typical for X-ray cameras?
X-ray works in the very short-wave spectrum, 0.01-10 nm wavelengths, and uses Amorphous Si/Se (Silicon with selenium) image detectors.
X-ray cameras can see through any solid surface, including human tissue, and thus are ideal for medical diagnostics or NDT (Non-destructive testing) of various objects.
The latter makes X-ray cameras suitable for a range of manufacturing fields.
For example, multi-layered parts such as printed circuit boards use X-ray to detect defects in the inner layers. Inspection systems of multi-component devices like airbags utilize X-ray when the product is fully assembled.
X-ray detects metal, bone, glass, stone, and some plastic fragments, without damaging packaging for quality assurance.
Q: What is the material and thickness used for the Scintillator?
- Tb = Terbium
CsI = Caesium Iodide
Eu = Europium
GadOx = Gadolinium oxysulfide
Q: What is the Field of View and thickness of the Fiber optic plate?
|MH110XC-KK-FA||36x24 mm||10 mm|
|MH110XC-KK-FA-CSI||36x24 mm||10 mm|
|MH110XC-KK-TP2:1||72x48 mm||35 μm|
|MH160XC-KK-FA||36x24 mm||10 mm|
|MH160XC-KK-TP2:1||72x48 mm||35 μm|
|MJ150XR-GP-FA-GO||21.5x12.6 mm||8 mm|
|MJ150XR-GP-FA-CSI||21.7x12.6 mm||8 mm|
|MX510XR-GP-TP2:1-GO||91.75 mm||92 mm|
Q: What does Rad-hard mean?
The new X-ray camera models from XIMEA use rad-hard type of fiber optic plates.
This stands for Radiation hardened and in connection with the Fiber optic plate, it means a characteristic of the FOP which results in the reduction of so called browning effect that is caused by long exposure to X-ray source.
Q: What is the difference between CsI scintillator and GadOx ?
X-Ray cameras require a radiation source.
Radiation hits the front of the camera, which is coated with s scintillator material.
The scintillator material emits light at different wavelengths if radiation hits, depending on the scintillator material itself.
Here are the differences between GadOx and CsI
As you can see, CsI (Cesium Iodide) is more evenly distributed across the whole spectrum, while GadOx (Gadolinium oxysulfide) has sharp peaks at certain wavelengths.
And CsI has its main peak where most sensors are most sensitive. So, depending on the application, CsI may provide a better result.
Q: What materials are used in the camera and why?
As an example, we will take MJ150XR-GP-FA-GO model:
- The front part of the X-ray camera that provides protection from X-ray is made from a combination of Wolfram (W - Tungsten) and Copper (Cu) with 5.1 mm thickness.
- The entrance window where X-ray should pass is transparent and made from Berylium.
- Next follows the important part of Fiber optic (BYD61-4) with Scintillator on top of it.
- The second protection plate for electronics is also made of Wolfram and Copper being 2.75mm thick.
- The main component of the camera, the sensor, is in this case GSENSE5130, a sCMOS from Gpixel.
- The middle section of the housing is made from Copper for better thermal qualities.
- The last part is providing the cooling which is coming from the Peltier element and the Aluminium fan that is spreading it through the camera.
Q: What kind of customization does XIMEA provide for X-ray cameras?
XIMEA is in general famous for customization skills and in regards to X-ray cameras, they are more extensive and crucial than ever.
The customer, based on the application requirements, can choose different scintillator properties, fiber optic dimensions, extra protection and even sensor models. The customization options include the addition of Taper for a larger Field of view.
Q: What is a Taper?
This is essentially a tapered fiber optic plate that is used to magnify image size and is optically bonded to the sensor instead of the usual FOP.
XIMEA usually offers 2:1 Taper option which magnifies the field of view two times.
An example can we found HERE
It is also possible to magnify 1.85 times for instance.
Q: What temperature conditions or values are important to keep in mind?
With the newest sensors (sCMOS especially) it is not as important to cool down the camera as much as keeping the temperature stable to achieve the same conditions for each case of data acquisition.
The latest sCMOS sensors provide low enough noise and do not benefit considerably from lower temperatures as it was with CCDs.
The Operating temperature is: +5...+50 °C
The threshold temperature value (on camera housing) to start the cooling is 36C.
The environmental temperature should be measured 20 cm from the camera in the horizontal plane.
The main cooling is ensured by the Thermoelectric Peltier element and further enhanced by the fan.
Q: Is the camera vacuum sealed?
The sensor is located in a chamber with inert Xenon gas.
Q: What energy levels can the X-ray camera sustain?
The range of energy is between 5-100 keV.
Using different material thickness in the case of Scintillator or Fiber optics can affect this range, but would also mean having to compromise on image contrast, sensitivity and other parameters.
The front plate of the camera is made from Wolfram which provides certain protection from X-ray.
There is also an option to increase this protection with an extra plate attached to the base.
Q: Does the camera have any TDI type acquisition modes?
These X-ray cameras do not support TDI acquisition modes at the moment.
KAI-11002 sensor has an interline transfer structure, and it is possible to implement some sort of TDI.
Q: If camera Gain is specified as 4e/count to which wavelength/energy of X-rays does it refer to?
Overall Gain range of MH110 and MH160 models is from 0 dB up to 36 dB.
The camera acquisition gain figure is provided from the secondary electrons.
Secondary electrons are generated by CCD from incident photons, which are emitted by the phosphor that is activated by primary electrons or x-ray.
Q: What ADC digitization options do X-RAY cameras provide?
The CCD based X-RAY camera models from XIMEA offer two ADC modes - 12 and 14 bits per pixel.
The maximum Saturation value of the pixel in the case of 14 bits is 16383, the minimum is 512.
The sCMOS based X-RAY camera models can go up to 16 bits.
They are using 2x 12 bit readout with High and low gain.
Q: Do XIMEA cameras support Binning and other partial readout modes?
Yes, both Binning and ROI (region of interest) features are supported.
Assuming readout time is 0.5s for the full frame at Binning 1 (2.1fps) and in case of horizontal ROI the readout time is reduced to 0.1s per frame.
However, there is a constant frame overhead time.
Q: What is the effect when using HS readout mode?
The so-called HS readout, which effectively is the sensor overclocking (50MHz instead of 30Mhz), is used for focusing modes only.
It is expected that HS will increase the noise level in the image.
For these modes, SNR and image quality is not as important as for acquisition modes.
Older CCD based cameras show that noise can be 2-5 times higher with HS and there are other artifacts like gradients, reduced acquisition gain, etc.
Q: Does the camera allow readout of frame n while frame n+1 is being exposed?
Yes, the readout time between frames is important to getting throughput.
XIMEA camera supports overlapped exposure and readout, so you can readout n-1’s frame while n’s frame is being exposed.
Note: Feasible Exposure time ranges from 20 microseconds up to 30 minutes.
Q: What is the specified MTBF?
MTBF - mean time between failures.
The MTBF was estimated at 100 thousand hours.
Q: Are there measurements for the Linearity?
Q: Are there any recommended x-ray sources or any that will not work?
The cameras can withstand energies from around 5 up to 100 kV.
Microfocus x-ray sources (for micro-CT) that could be an option:
Q: What is the position of the scintillator with respect to the input window in all three planes?
Position and how far back from the front of the camera the scintillator is can be seen in the following sketch: It is centered in X-Y plane