New 3D printing system produces higher quality micro-optics

l Additive manufacturing offers greater levels of design freedom and precision

l ‘We are only at the beginning.’ Optics industry yet to fully tap into 3D printing

Nanoscribe has developed a one-step 3D printing system capable of producing a range of micro-optical components with smoother surfaces, higher shape accuracy and significantly smaller geometrical constraints than those achievable using standard 3D printing technologies. The new Photonic Professional GT

system combines two writing modes in one device: an ultra-precise piezo mode for arbitrary 3D trajectories (FBMS) and the high-speed galvo mode (MBFS) for fastest structuring in a layer-by-layer fashion. The instrument will allow optical designers to take advantage of the fast and flexible design iterations offered by additive manufacturing, enabling designs to be turned into functional prototypes within a matter of days. An example of this has been carried out by researchers collaborating with Nanoscribe at the University of Stuttgart, who were able to print a doublet lens system directly onto CMOS image sensors, creating a high-performance and compact imaging system. It took the researchers less than a day to implement new designs from the idea to the final part. The main advantage of additive

manufacturing is that it offers greater levels of design freedom and precision compared with traditional manufacturing. ‘3D printing… provides the benefit of producing very high quality polymer micro- optics directly,’ said Dr Fabian Niesler,

Nanoscribe’s Photonic Professional GT 3D printer can produce micro-optics in one manufacturing step

head of applications and processes at Nanoscribe, in a recent article for Electro Optics. ‘With 3D printing, we have almost no restrictions on the shape of optics.’ Standard refractive micro-optics, freeform optics, diffractive optical elements and multiplet lens systems can all be printed with the new Nanoscribe system. Using polymer materials to produce

lenses in a single-step 3D printing process will also reduce manufacturing costs dramatically compared to producing glass lenses through multiple steps. According to Niesler, the optics industry

is yet to tap into the full potential of 3D printing. ‘I would say that first of all we are only at the beginning,’ he explained. ‘The challenge for people is to understand the possibilities with access to a tool such as 3D printing; you have to re-think your design ideas, how you fabricate these

Photonic lanterns used in spectroscopy breakthrough

Physicists at Heriot-Watt University and the Universities of Bath and Edinburgh in the UK have broadened the potential applications of time-stretch spectroscopy by increasing its detection capabilities by more than two orders of magnitude. The news was reported in Nature Communications in January. Time stretch spectroscopy

has previously been used to measure the colours of light that form optical pulses instead of using bulky and expensive instruments. Until now, however,

the technique has had limited applications outside the lab. ‘Conventionally, time-stretch

spectroscopy has used single- mode optical fibres, where the light is guided in a single high refractive index core region in the middle of the fibre,’ said Heriot-Watt’s Professor Robert Thomson. ‘Unfortunately, the use of these fibres severely limited the real-world applications of this technique.’ Professor Thomson and his

team have created a new way to analyse these colours, using

multicore optical fibres, photonic lanterns and single-photon- sensitive detector arrays. ‘Time-stretch spectroscopy

relies on the fact the different colours of light that form an optical pulse travel at different velocities in an optical fibre,’ explained Thomson. ‘By measuring the arrival times of individual photons at the opposite end of the fibre, we can infer the colours of the individual arriving photons, and construct the spectrum of the input pulse.’ Researchers showed multicore

fibres and advanced single- photon sensitive detector arrays can be used in multiplexed time- stretch spectroscopy, where 100 individual single-mode channels can be detected and processed simultaneously. ‘We have also demonstrated

advanced photonic devices, known as photonic lanterns, can be used to efficiently couple light from the real world to these multicore fibres,’ continued Thomson. ‘This is a key step that holds great promise for real- world applications.’

ideas.’ In the short term, the materials, in particular the photopolymers, have to improve. ‘Not only do there need to be more materials compatible with 3D printing, but also materials that provide the optical properties necessary for optical applications,’ he continued. Hemispherical micro lenses with a shape accuracy better than 1µm, a height of 150µm and a surface roughness better than 10nm Ra have been demonstrated with the system. The company also claims that, by means of Nanoscribe’s Photonic Professional GT system, functional multi-layered diffractive optical elements (DOEs) can be directly patterned onto glass substrates. DOEs can be designed for functionalities that are difficult to achieve using standard refractive optics, such as the generation of almost arbitrary light distributions in the far-field.

8 Electro Optics March 2017

@electrooptics |


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