Smooth operation gives Kaleido optics the edge

24 Aug 2005

Danish firm Kaleido thinks its machining expertise can deliver affordable next-generation optics that slash the cost of optical assembly by a factor of 10. James Tyrrell investigates.

Kaleido Technology's vision is to employ its software-enhanced machining technology to create mouldable, multisurface, monolithic optical components that require no assembly. "Compared with state-of-the-art pick-and-place systems, our technology can reduce costs by a factor of 10 because we can take so much cost out of the assembly procedure," Kaleido's technical director Palle Dinesen explained to OLE. "Any system with two lenses or more has the potential to be replaced by an integrated system."

Kaleido was created in 2001 by four research scientists from Ibsen Microstructures - a Danish manufacturer of fibre Bragg gratings. "Ibsen was founded in 1991; then, in 2000, the company was sold to US firm ADC Telecommunications for about $80 m (€65 m)," said Dinesen. "In the course of the telecoms downturn, ADC decided to shut down the Danish facility one year later, and that is when we started Kaleido." The company attracted additional venture funding in 2003 and now has 10 staff.

Core technology

A custom-machining centre lies at the heart of Kaleido's dual strategy for tackling the optical component market. Specializing in complex geometries, and working with glass, plastics and metal, the firm can make both directly machined components for prototyping and die moulds for volume production.

"We have developed our own machine-control software to directly access hardware features," explained Dinesen. "For demanding applications, such as large free-form mirrors, we had to do quite a bit of customization and stabilize the machining environment."

Dinesen and his team covered the instrument (which began life as an off-the-shelf ultraprecision machining centre from US firm Moore Nanotechnology Systems) in sensors to track its long-term temperature stability. With this information, and thanks to a high-order interpolation scheme, the enhanced apparatus now has an incredibly smooth machining action and can generate surfaces with form errors of better than 0.5 μm.

The high-performance set-up has recently grabbed the attention of US firm Microvision - a developer of MEMS-based head-up displays (HUDs) with clients including major German car-makers. Automotive firms are interested in the display, which features a laser-scanning unit, because it suits high-brightness conditions and can also be dimmed to very low levels for safe night-time driving.

One of the challenges facing Microvision was sourcing a mirror for reflecting the HUD's output up onto the windscreen. "Because the windscreen has a free-form geometry, it is important to use a free-form mirror in the HUD system to give a clear image," commented Dinesen. "If you just took a spherical mirror, the letters and information on the windscreen would be heavily distorted because of the geometry."

Using direct machining, and without polishing, Kaleido was able to deliver large mirrors with a surface roughness of less than 10 nm rms and slope accuracy of better than 70 μrad. Microvision has incorporated the aluminium prototypes into a dashboard-mounted unit and Dinesen is hopeful that HUD manufacturers will look to Kaleido's moulding capability to further reduce cost.

"Typically, moulding becomes [economically] feasible in the few thousands and upwards," said Dinesen, "[and] if we take complex components, then maybe even down to a few hundred in some cases."

Dinesen sees moulding as the way forward for the firm's own range of aspheric cylinder lenses, which are designed for the slow-axis collimation of diode lasers. "You can make a spherical cylinder lens by simply polishing a rod, but if you want an aspheric profile on a cylinder lens then [typically] you have to machine it, which is expensive," he said. "Our moulding technology takes out a lot of the cost." The company's advanced process control allows it to accept challenging designs from clients, such as aspheres with high aspect ratios.

Kaleido's customers include telecoms and construction instrumentation companies, and the firm is establishing a foothold in the European defence market. Being relatively small, Kaleido can avoid competition with major US and Japanese firms.

"The good thing about [Kaleido's] Asian competition is that these are very large companies with a focus on standard components, as opposed to custom products," said Dinesen. "Also, we are seeing that we gain something from being a European supplier."

Dinesen is keen for Kaleido to grow its business, and the company's Farum location has the potential for short-term expansion, with 13,000 ft² of class-10 cleanroom facilities on offer. "We are [already] thinking about buying commercial moulding machines to be able to scale-up production," he added. Looking ahead, Dinesen believes that Kaleido will have to find a larger facility a few years down the road to accommodate additional growth and expansion.