06 Jul 2005
A newly created Swiss start-up launches a real-time OCT system that has micrometer precision.
Heliotis, the latest spin-out from the Centre Suisse d'Electronique et de Microtechnique (CSEM) in Switzerland, is starting its commercial life with a formidable goal. Using its parallel optical low-coherence tomography (pOCT) technology, the firm hopes to become a leader in the field of real-time 3D imaging with micrometer precision.
pOCT is a non-invasive and non-contact imaging technique which uses interferometry to acquire 3D surface relief (topographic) or internal slices (tomographic) images in real-time. Heliotis' trick is to use a 2D CMOS sensor array where every pixel acquires and processes the optical signal in parallel.
"The CMOS sensor array consists of 144 by 90 smart pixels sensors that also perform signal-preprocessing," Ruedi Frey, the firm's CEO told Optics.org. "The CMOS sensor gives 6000 frames per second, which gives us 10 to 15 3D images per second. The vertical resolution is 10 to 12 microns but we can see that 2 to 3 microns will be possible. We had one setup with a resolution of 5 microns already."
The pOCT system comprises a Twyman-Green interferometer, a superluminescent diode (SLED), the CMOS sensor array and its associated electronics and a linear stage. A single sweep of the interferometer's reference beam scans the complete sample and gives a topographic or tomographic image.
"If the material is penetrable to light, our systems can look into it," said Frey. "Uncolored glass or liquids are easy to penetrate, scattering materials like skin or teeth are more difficult."
According to Frey, the system can look into skin to a depth of between 0.5 to 1 mm. "We can look into teeth to at least 3 mm with good resolution, which will enable us to develop a device for early detection of demineralization by caries," he said. "In a fiber-coupled mode we plan to attach it to the dentist's drill. This way dentists will remove cariotic parts of the teeth very precisely by seeing in real-time what is being removed."
Heliotis will target industrial applications initially and Frey says the system is ideal for a range of applications. "It could be used in die bonding for quality control as well as all applications where volumes of liquid need to be measured such as in lab automation," he added.
The Zurich-based company, which has six employees, has just received its first round of funding. Frey says that he is now in negotiations with investors and hopes to raise a second round next year.