German researchers can 3D-print miniscule lenses onto the tip of a needle.

The tiny lenses could pave the way for next-generation sensors, endoscopes (body cameras) and miniaturised robots.

The high-performance lenses can be printed directly onto tiny structures - such as the tip of optical fibres thinner than a needle – as they are only a fraction of a millimetre in size.

Multi-lens optical elements with non-spherical shapes are needed for high-end performance and to correct for aberrations.

Research engineer Timo Gissibl and colleagues at the University of Stuttgart used a femtosecond laser writing system to 3D print multi-lens systems about 0.1 mm in size.

The multi-lens systems feature multiple singlet (simple) lenses that are combined into a compound lens within a supporting shell, all printed at a rate of centimetres per second.

In their latest experiments, the team printed a triplet lens system directly onto the end of an optical fibre that can fit inside a typical syringe needle.

They tested the final device, and showed that objects 3 mm from the lens could be successfully imaged at the other end of the 1.7-m-long optic fibre.

They also built an array of lens systems with four refractive interfaces can be printed onto 5-megapixel CMOS image sensors (used in digital cameras).

“Endoscopic applications will allow for non-invasive and non-destructive examination of small objects in the medical as well as the industrial sector,” the team wrote.

Dr Gissibl added; “The unprecedented flexibility of our method paves the way towards printed optical miniature instruments such as endoscopes, fibre-imaging systems for cell biology, new illumination systems, miniature optical fibre traps, integrated quantum emitters and detectors, and miniature drones and robots with autonomous vision.”

The new paper is accessible here.