Fabrication of nanocrystalline diamond x-ray nano-focusing optics

A collaboration between Diamond Light Source (Synchrotron) and the Bristol Diamond Group aims to produce refractive optics for focusing high-energy x-ray radiation produced at synchrotron facilities. X-ray optics made from diamond are almost transparent, are very strong and are subject to very low thermal expansion. Therefore, they will be able to withstand the powerful beams generated by 3rd and 4th-generation light sources without compromising brilliance. We have proposed and realised a nanocrystalline diamond (NCD) low-absorbing x-ray lens using a moulding technique. With this method, high-quality Si moulds are fabricated using e-beam-written photolithographic etching, and then NCD is deposited using MWCVD at a high growth rate. We recently achieved a focus spot-size of ~140 nm in a 20 keV X-ray beam at a distance of about 20 cm, which is close to the world record for the smallest x-ray spot size ever achieved for a beam as powerful as this. With improvements in seeding and etching, this spot-sized should be reduced even further in the next year or so.

NCD X-ray lens
NCD X-ray lens.		 NCD X-ray lens
NCD X-ray lens.		 NCD X-ray lens
NCD X-ray lens.		 Other X-ray lens structures made from NCD
Other X-ray lens structures
made from NCD

Fabrication of a non-absorbing, high-aperture lens with nano-focusing capabilities will be achieved when the material uniformity, seeding and lens robustness has been improved. We are now targeting the improvement of diamond growth and optimisation of lens structures using modified designs and selective diamond nucleation. This should reduce self-shadowing during deposition and increase depth of fill to allow us to fabricate higher aspect ratio lens structures.

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