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21 Jun 2007
Bossa Nova Technologies, US, is an expert in non-destructive testing equipment. Nadya Anscombe talks to its marketing and sales director Philippe Clemenceau to find out how the steel and cosmetic industries are making the most of the company's technology.
At first glance, the mechanical properties of steel and the glossiness of a lipstick do not have much in common. But measuring these characteristics is the main business of US-based Bossa Nova Technologies.
The company's SAMBA vision system, for example, is used by the cosmetics industry to measure the visual appearance of hair, lipstick and skin. This patented polarization imaging technique acquires colour and gloss images strongly related to visual assessment. "It basically quantifies what the human eye sees," Philippe Clemenceau, Bossa Nova's director for marketing and sales told OLE. "It quantifies the visual appearance of planar and complex 3D surfaces using a polarization analysis of the light scattered by the sample."
He claims that it is the first colour-imaging gloss meter and that Bossa Nova is benefiting from the huge growth in the cosmetics industry. "SAMBA sales make up about half of our business and it is the fastest-growing sector for us," said Clemenceau.
SAMBA is used to substantiate claims – such as "using this shampoo will make your hair glossier" – and also by chemists during formulation of new products. "The use of optical techniques in the cosmetics industry is growing," explained Clemenceau. "Every cosmetics conference I attend has a session on optical techniques."
Seeing the gloss
Conventional gloss meters measure gloss from a flat surface and collect light reflected in an arbitrary direction using a detector. Like conventional meters, SAMBA sends light to an object. The difference is that SAMBA images the reflected light.
"This makes the system much more powerful than a simple gloss meter because the object can have different shapes," explained Clemenceau. "Acquiring the reflected light image is equivalent to knowing how the object reflects light at many angles at the same time. The measurement is also close to how a person perceives an object and allows us to output data correlated to human visual perception."
With a conventional gloss meter, lipstick is applied to a flat card and the meter takes a measurement at various inclinations. With SAMBA, the lipstick is applied directly to the lips, and SAMBA takes images of reflected light. The results show many areas of strong reflections on the lips and image analysis can work out the distribution of gloss on the lips and how that gloss fades spatially. "SAMBA is used by many well-known cosmetic manufacturers such as L'Oreal, for formulation or claim substantiation," added Clemenceau.
But the cosmetics industry is not the only potential user of this technology. It could be used anywhere where gloss and texture is important, such as in the automotive and textile industries.
SAMBA is based on active polarization imaging and can be used to look at specular (mirror-like) reflection; surface scattering and volume scattering. While using polarization imaging is not new, the bit that makes SAMBA unique is the fact that it can switch from one polarization to another at video rate. "This means that the system can be used to take a polarization video – it is fast and responds quickly to the user," said Clemenceau. The fact that the system can take polarization videos means that it has other uses outside of the cosmetics industry, such as detecting bodies of water.
Switching to ultrasonics
The idea of switching quickly between polarization states is a simple yet technically challenging idea. Another part of the business – laser ultrasound – has also been built on a relatively simple, but equally challenging idea. Conventional laser ultrasound systems use a simple interferometer architecture to detect ultrasound waves from a surface that has been hit by laser light. While these systems are very sensitive, they are affected by surface roughness and vibrations from a factory environment.
"We realized that we needed several interferometers working in parallel," explained Clemenceau. "Our system is the equivalent of up to 100 interferometers. Summing the signal of each individual system improves the sensitivity of the overall interferometer and compensates for the roughness of the material while adapting to the object 3D motion."
The company's QUARTET system is so sensitive that it can pick up 1 nm displacements under factory conditions. To generate the ultrasound, a 10 ns pulse from a YAG laser is fired at the material causing it to heat up, expand and release an ultrasonic wave. The ultrasound wave propagates through the material and if it meets a crack for example, it reflects. When the pulse comes back to the original generation site, the surface vibrates. This tiny displacement is on the order of 1 nm.
QUARTET can visualize the propagation of an ultrasound wave through a material and make a movie of this propagation. "This is another reason why our system is unique," said Clemenceau. "Thanks to its ability to record images of wave propagation and the sensitivity of our receivers (up to 1 GHz), material research laboratories can perform high-frequency tests with an affordable, user-friendly compact laser system."
The Aerospace Engineering Laboratory of Georgia Tech, Atlanta, US, recently acquired a laser-scanning system to record the 2D propagation of ultrasonic waves on various composite parts up to 20 MHz. Thanks to this new tool, scientists will improve their understanding of the mechanical properties of new materials and will be able to detect smaller and smaller defects in them.
One of the main users of laser ultrasound for remote sensing is the steel industry. Non-contact ultrasonic inspection can be performed on moving hot steel (1000 °C) with an expensive laser ultrasonic system using high-power lasers. However, Clemenceau claims that by using his company's receiver, it is possible to significantly decrease the amount of laser power needed for the inspection, and as a result significantly decrease the overall system cost and complexity.
The steel industry uses ultrasound for a variety of tests. Because ultrasound is a mechanical wave, it can be used to measure mechanical properties of material. These include thickness, porosity, stiffness, elasticity and the detection of defects. In the steel industry, the advantage of laser ultrasound is the non-contact nature of the test and this means that hot metal can be tested without the need to halt production.
This also has advantages for other applications. "One of our customers, an automobile manufacturer, currently cuts some of its manufactured automobile parts in order to inspect their core visually and evaluate how efficient the steel preparation process is," explained Clemenceau. "After a few tests on some parts, we proved that it was possible to look at the integrity of the material non-destructively and without contact using a low-cost laser ultrasonic system based on our receiver."
The company's system is now at a validation stage at the customer's facility and the goal is to perform inspection without stopping the manufacturing line.
Bossa Nova has also recently completed a research programme funded by the National Science Foundation to improve the sensitivity of its receiver.
• This article originally appeared in the June 2007 issue of Optics & Laser Europe magazine.
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