There are a number of ways of measuring a component or assembly: there’s the trusty micrometer and vernier; point-based systems like coordinate measuring machines and laser trackers and line-based systems such as laser scanners. Each has its own pros and cons, strengths and weaknesses but for Loughborough-based Phase Vision and its range of Quartz non-contact 3D scanners, full field white light is the technology of choice as Dave Tudor discovered.

Located in the Charnwood building at Holywell Park in Loughborough, there’s an immediate ambience of technological expertise when entering Phase Vision’s premises for the first time. The technology behind the company’s Quartz scanners is clearly high tech, yet the scanners themselves have been designed for the real world and real world environments. They may not actually be bullet proof but they certainly look like they could be!

Formed in 2008, Phase Vision is a relatively new company and still very much in the embryonic stages of its development but its systems – which offer a marriage of accuracy and repeatability coupled with ease of use and robust operation are proving to very popular in a number of market sectors – most notably aerospace and motorsport.

Although Phase Vision as a company is comparatively new, the white light technology used in its systems most certainly isn’t. CEO Ralph Weir takes up the story: “Back in the late 1990s, two very bright academics from Loughborough University were involved in some consultancy work for Airbus. At the time, Airbus used lasers to measure aircraft panels but this was far from ideal. Although it sounds non-intuitive, the laser systems being used were actually too accurate. They would measure in nanometres when microns would be perfectly good enough. Also, the laser method was extremely slow – it could take hours to produce the data and on top of all that, the results could be unreliable if the part or assembly being measured moved at all during measurement.”

In fact, the earlier statement that Phase Vision was formed in 2008 isn’t entirely accurate. The company was actually born in 2002 but acted as a consultancy rather than the fully fledged solution provider it is today. Back then, the company did indeed pioneer white light 3D scanning systems but the computational power needed to drive these systems efficiently and rapidly simply wasn’t around. Then, later in the decade as computers got faster, Phase Vision’s Quartz systems evolved and following extensive testing in real world manufacturing environments, the first products were unleashed in 2010.

Fringe benefits

Phase Vision’s Quartz scanners all employ SmartFringe technology which is a third generation structured light system said to offer excellent resilience to ambient light, allowing measurement of challenging surfaces and materials. According to Mr Weir, SmartFringe technology has a number of advantages over older white light systems – the principle one being the capacity to operate with reduced contrast between the black and white stripes of the structured light pattern.

In practical terms this means that the Quartz range of 3D scanners can be used on surfaces with high levels of light absorption like carbon fibre and composites and bright surfaces such as machined metal parts in conditions with bright ambient lighting conditions such as workshops, hangars or factories. Significantly, because the light can be spread over a large area, the scanners are suitable for larger components.

Currently, there are two models in the Quartz range: the 800 which is optimised for the measurement of smaller parts ranging from 50mm to 1,000mm in length; and the 1200 which is designed to handle component lengths from 440mm in length up to 2,200mm.

With any measurement system, accuracy and repeatability are of paramount importance. In this regard the Quartz scanners tick all the boxes – the 800 scanner for example is capable of accuracies better than 50µm across a 500mm x 500mm x 500mm volume. Both systems can be dynamically adjusted to offer lower accuracy and higher acquisition speed and vice versa. Similarly, both systems are available in one, four or eight megapixel variants and can be mounted on a tripod, gantry or robotic arm depending on the application in hand.

Making sense of it all

Of course no measurement system worth its salt would be without an accompanying software package to process all that useful data. Quartz systems can take millions of measurements in seconds so capturing the data itself is only part of the story.

On the software front, Phase Vision offers GEM Studio, a powerful suite of configuration tools to complement the scanner itself. The suite comprises: GEM Scan which has an intuitive interface with configurable levels of user access for typical shopfloor environments, providing a simple interface for operators, while offering advanced users all the power of the scanner. It includes cross checks to ensure that the data is accurate and that the scanner is within calibration.

Next up is GEM Align which can combine multiple scans taken from different angles or of different aspects of a component. This is either based on an enhanced photogrammetric approach or on the texture of the object itself. Completing the line up is GEM Calibrate which provides an easy to use system for calibration of a scanner, allowing users to recalibrate whenever required. Importantly, GEM Studio is compatible with all the industry leading analysis and CAD/CAM tools, supporting major file formats as standard.

“The GEM Studio software suite is designed specifically for use with Quartz scanners so we tend to supply the two as a complete package,” Mr Weir advises. “In fact we strongly advise it. We see ourselves as a complete measurement solutions provider and not simply a shifter of metrology equipment. We like to engage with the customer early on in a project, understand the task in hand and make recommendations towards solving a particular measurement challenge. That’s why we offer a total package: you get the Quartz scanner itself, the GEM Studio software package, a PC or laptop, an optional tripod and rotary table as well as comprehensive training and product support. There’s also a maintenance contract if required – which most customers take advantage of. The final icing on the cake is the fact that we’re approved agents for PolyWorks and Geomagic CAD systems which integrate seamlessly with our products. Our customers really like this aspect because it means they have a single point of contact for all the constituent elements of the total system.”

In practice, with PolyWorks for example, this would be integrated with a CAD software system such as CATIA or SolidWorks. PolyWorks effectively takes the data from SolidWorks (or similar system) and compares it to the data coming out of the scanner itself.

Get real

White light scanning is traditionally the domain of a laboratory environment so one of the biggest challenges for Phase Vision was making the Quartz products robust enough for industrial use. “You’d be surprised at some of the real life scenarios we’ve encountered with our products,” Mr Weir recalls. “In an aircraft hangar we’ve seen forklift trucks driven into the scanner, a spanner dropped onto the unit from 20 feet above and people using angle grinders in close proximity to where the scanner is operating. We’ve had forklift trucks with orange flashing lights interfering with the measurements being taken and we’ve had to deal with massive fluctuations in temperature as factory doors are opened and closed on a regular basis.”

He continues: “Whilst our scanners aren’t totally resilient to the effects of these conditions, they do provide good indicators towards how robust our products need to be to operate in the real world. These experiences have directly influenced the design of our Quartz scanners and we’ve made them as solid and robust as possible. In my opinion, in terms of their build quality and rock solid construction, there’s nothing to touch them in the marketplace. One particular application we’re working on at the moment is with a casting foundry. It really doesn’t get much more extreme than that.”

Quick comparison

It’s maybe worth reflecting on the merits of white light 3D scanning compared to other technologies. Briefly, aside from manual instruments such as verniers and micrometers, we’re talking three main groups here: point-based, which encompasses CMMs and laser trackers; line-based systems which include laser scanners and; area-based which is where the Quartz scanners make an entrance.

All technologies have their respective advantages and disadvantages: CMMs are supremely accurate but can be slow in operation. The probe can’t physically reach into certain crooks and crannies and they’re not great for measuring curves and profiles. Also, they’re most effective on relatively small items. Laser trackers are essentially long range CMMs. They can measure over long distances but are quite slow in operation and provide relatively few inspection points. Laser scanners are ideal for reverse engineering, but being a manual process, scanning is a slow and unsuitable for certain surfaces. Also the scanners ideally need to be mounted on an arm or CMM to provide accurate scan alignment.

The Quartz scanners are different again, offering accurate, precise high speed measurement which can be scaled for large structures such as car bodies, aircraft wing structures and marine applications. They can’t compete with CMMs for out and out accuracy but they are portable and extremely robust making them ideal for shopfloor use. In addition Quartz scanners can be used effectively for reverse engineering – constructing a 3D model from a finished part. The truth is that all methods have their pros and cons – what’s right for one application may not be the best option for another and vice versa. In reality, the best results are often achieved through the use of multiple systems.

Sine of the times

In terms of its customer base, Phase Vision’s customers tend to be in industries where there is a requirement to 100% measure large complex profiles such as aerospace, (wings, spars, wing skins, panels) motorsport (carbon fibre body panels, chassis, wings, gearbox casings) and marine (boat hulls). However, the company is currently in talks with a major automotive manufacturer and that could be the start of something new for the company. “Quartz scanners would be absolutely ideal for inspection and verification processes on an automotive production line,” Mr Weir enthuses. “We’re not quite there yet – approvals for automotive production lines take an age – but it’s definitely work in progress and future business in this sector looks very promising.”

In conclusion, Mr Weir is upbeat and positive about the future. “Essentially we’re still a start up company and didn’t unveil the Quartz product range until MACH 2010 so we’re still very much the new kid on the block,” he affirms. “Things are really starting to take off though. We exhibited successfully at the recent Aero Engineering show and will be at Southern Manufacturing and MACH in 2012.

“Whilst there are a number of competitors manufacturing white light scanners, there’s no one else using sine wave technology in white light metrology,” he concludes. “Our philosophy is simple – 3D scanning should be easy to use. If you can’t get a 3D scan from our systems in five minutes from turning it on for the first time, we simply haven’t done our job right.”

Phase Vision
www.phasevision.com