How automated focusing saves you time in XRF coatings analysis

Setting up a measurement with a coatings XRF (X-ray fluorescence) involves several steps but focusing (correctly setting the geometry between the X-ray tube, part, and detector) is the most critical because it directly affects the accuracy of the results. After the operator finds the measurement location, they need to get the part into focus. 

With traditional instruments this is done by focus laser or video focus. The FT230, our latest XRF coatings analyzer, can use a focus laser, but also offers two automated focusing features to speed up and simplify this step.   

How automated focusing saves you time in XRF coatings analysis

 

Auto approach measures the distance from the X-ray tube to the part and automatically drives the tube to the predefined working distance. Auto focus, sometimes called distance-independent measurement, also measures the distance from the X-ray tube to the part, but instead of moving the tube, it keeps the tube at the same height and uses that distance to correct for the new geometry. Both have their uses, and with either one you can drastically speed up your testing program. So much time could you save?

Auto approach explained

To get consistent results from an XRF coatings analyzer, it’s best to keep the distance between the X-ray tube, part, and detector the same for each measurement. This is because X-ray intensity is a function of distance and because changes to the tube-part-detector geometry affects thickness measurements.  

XRF coatings analyzers typically use one of two ways to retain this critical geometry – a focus laser or video focusing that evaluates image contrast. The benchtop analyzer’s head (containing the X-ray tube and detector) moves up or down until the instrument’s focusing routine is complete, in some cases needing the operator to make mild final adjustments. These routines take time to initialize, move and finalize, and may introduce errors if operators need to make decisions. 

Hitachi’s FT230 can be fitted with a feature called auto approach that requires one click to bring the head to the right position. Sensors inside the instrument measure the distance to the sample. When auto approach is activated, the instrument compares that distance to the working distance (also known as focal distance) selected in the calibration and moves the head to that position. This provides the operator with confidence that the results will be accurate without spending time and possibly making a mistake in focusing the part. 

A simple experiment illustrates the benefits of auto approach. Six parts of heights ranging 4.8 – 6.6” (1.9 – 2.6 cm) are loaded into the chamber.  The operator creates a multipoint program to measure one location on each part. 

This was run by the same, trained operator in two ways: once using a focus laser (the head moves, and the operator determines when the part is in focus) and once using auto approach (the head automatically moves to the correct focal distance without operator intervention). Since the measurement time is identical in either scenario, only the time to set up the program will be considered. The results are shown below. 

Time to create a 6-point program using only the laser focus: 44 seconds 

Time to create a 6-point program using auto approach: 29 seconds 

Time savings: 15 seconds (33% savings) 

 

This might not seem like a lot, but in the common situation where this exercise would be repeated 50 times each day, the operator can save 12 minutes and spend that time performing other tasks. Over the course of 200 days, using auto approach can create nearly 40 hours, or nearly 1 working week, of additional productivity for your XRF operator. Auto approach can be combined with other features such as a wide-view camera to save additional time in getting samples ready for measurements. 

Auto focus explained

After positioning a part for measurement, the last step before pushing the start button is to focus the part. This commonly achieved either with a focus laser or by using a routine that evaluates image contrast. 

Using either method, the analyzer’s head containing the X-ray tube and detector moves up or down until the instrument’s focusing routine is complete, in some cases requiring the operator to make small / minor final adjustments. These routines take time to initialize, move and finalize and may introduce errors if operators need to make decision. 

Hitachi’s FT230 can be fitted with an auto focus feature that doesn’t need operator involvement and doesn’t move the analyzer’s head. While active, the camera is constantly and automatically focusing on the part in the measurement crosshairs. The routine even measures the distance to the part, which allows the operator to measure parts that have different heights or have stepped geometry. This is incredibly fast and allows for higher testing volumes while the operator spends less time setting up the parts. 

A simple experiment illustrates the benefits of using auto focus. Six parts of heights ranging 4.8 – 6.6” (1.9 – 2.6 cm) are loaded into the chamber. The operator creates a multipoint program to measure one location on each part. 

This was run by the same, trained operator in two ways: once using a focus laser (the head moves, and the operator determines when the part is in focus) and once using auto focus (the head doesn’t move, and the operator has no input on the focusing).  Since the measurement time is identical in either scenario, only the time to set up the program will be considered. The results are shown below. 

Time to create a 6-point program using only the laser focus: 44 seconds 

Time to create a 6-point program using auto focus: 17 seconds 

Time savings: 27 seconds (62% savings) 

 

This is nice savings for a single run but consider that it’s common to set up at least 50 runs like this each day. How much time could you save? In one day, that adds up to more than 22 minutes where an operator could be free to perform other tasks.  Over the course of 200 days, auto focus can create over 76 hours, or nearly 2 working weeks, of additional productivity for your XRF operator. Auto focus can be combined with other features such as a wide-view camera to save additional time in getting samples ready for measurements. 

The greater the range of part heights, the more advantageous auto focus becomes because the operator spends less time making adjustments to the head position.  Also, when using the focus laser, the range of part heights is limited by the working range, also known as focal distance.  Using auto focus, the FT230 can measure parts that vary in height by up to 3.1” (80 mm).  

Ultimately, the FT230 benchtop XRF coatings analyzer has been designed to significantly reduce the time taken to make a measurement. Recognizing that the most time is taken with sample setup and measurement recipe selection, automation and innovative software are what makes the FT230 analyzer simply smart.

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Date: 27 June 2022

Author: Matt Kreiner, Product Manager ā€“ Coatings Analysis

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