XTIA's Technology

A unique concept

 

Pushing the limits of measurement

Optical frequency combs are the most accurate rulers to measure both frequency and time. It is a special type of laser made of sharp and equally spaced spectral lines resembling the teeth of a comb. Leveraging the unique properties of optical combs, Dr Kourogi thought that if it could measure time with high accuracy, it could be applied to highly accurate distance measurement. Using a simple structure in which the laser input and output lines are coaxial, the original concept was transformed into a highly accurate rangefinder. Adding a scanner head, it then became a highly accurate 3D profiling system.

High accuracy in a coaxial configuration

XTIA's optical comb laser can measure with micron accuracy in a coaxial configuration. Although the principle and structure of the laser are complex, its simple use and its coaxial configuration allows for a whole new range of measurements and great benefits. Here are some of the unmatched advantages XTIA's sensors.

+Enables complex 3D shape profiling
+Long working distance
+Unaffected by ambient light
+High-speed measurement
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XTIA is very proud of offering a very simple and user-friendly 3D profiler based on its optical comb laser. By using this unique optical concept, XTIA has created unmatched advantages but the principles of our technology are not straightforward. In the next chapter we will explain the principle as simply as possible.

The principle of optical frequency combs


In a nutshell, the optical frequency comb technology is a special type of light that has the properties of both a monochromatic laser and a white light containing multiple wavelengths. Its main features are as follows:
- It includes the light of multiple frequencies/wavelengths.
- The laser of each frequency is a laser presenting a narrow linewidth.
- The interval between each laser frequency is constant.
- All laser frequencies are in phase.
This type of light is dubbed an optical frequency comb because in the frequency domain each laser line resembles the tooth of a comb. Standard profile measurement by normal lasers rely on the so-called time-of-flight method. It determines distances by measuring the time it takes for a laser pulse to travel to the target object and travel back to its origin after reflection. In order to accurately measure a difference in distances ranging between 1 and 10 micrometers with a normal laser, one would need to measure the time-of-flight difference at the femtosecond scale. Detectors with such time precision levels however do not exist and instruments using the timeof-fl ight method with normal lasers are thus very inaccurate.

By contrast, intruments based on optical combs can rely on the multiple lasing frequencies to drastically improve this accuracy. Using two optical combs serving respectively as a reference and a probe, and knowing the phase difference between all teeth of the combs, it is possible to expand the time-scale needed to measure the time of flight difference. As a result the time needed to measure micrometer distances is not at the femtosecond level any more but orders of magnitude longer, at the nanosecond level. Such a time-scale is compatible with existing detectors and the intrinsic features of our optical comb lasers thus allow for high-accuracy measurement down to the micrometer level.