New imaging secret to trigger the revolution in optical microscopy
(Opto-Electron. Adv., No.1, Vol.1, 2018)

Solution to the 300 years’ old optical challenge| Optical imaging has a long and rich history. Early in the 17th century, the wish of visualizing our micro-world was granted by the invention of optical microscope. Bio-medical, chemistry, material science, electronics and other various application fields were pushed to a new level of advancement. This is the gift of light, and the contribution of optical microscopy. Since then, the optical imaging techniques have witnessed the advances in the scientific society. However, with further research over the centuries, a technical bottleneck was found in the optical diffraction limit being imposed by the illumination wavelength. Detours were taken by applying electron beam or near-field optical probe as mapping tools to sketch the surface textures of tiny samples. Also, special treatments to the bio-samples by activating fluorescence were invented so as to image the small features down to dozens of nanometers, which was awarded The Nobel Prize in Chemistry 2014. However, unavoidable damage is inflicted on the samples by these approaches. 
To solve these problems, Prof Hong’s team proposed the new design for the optics in the microscope, which provides a solution to break the theoretical limitation for optical imaging. The latest progress is published in the Opto-Electronic Advances. Their design utilizes the focusing effect of the particle lens in nano-scale. It visualizes comparable feature sizes by pure optical means, without disturbing the samples, and at the same time, to keep the design simple and cost effective. Affordable optical nanoscope would come in handy from daily use at homes, education at school, product inspection at industry and early diagnose at hospital, to the most leading research in laboratories. It serves as a general tool which possesses the ability to observe and detect nano-scale features. Such a breakthrough would lead to impact by enabling us to examine nature from micro-world down to nano-world at a fast speed and in ambient natural conditions. 

Reaching the impossible goal| Enlightened by the sharp focusing of transparent microsphere in laser illuminated lithography and the idea of the reversible nature of light, Prof Hong’s team proposed the microsphere magnification design. Theoretical, the interaction between the microsphere and sample structure enriches the information carried in the propagating electromagnetic wave, which was then captured by an optical detector. Such elegant and effective design only requires small changes to conventional white light microscope and achieves a super-resolution, which presents a cost-efficient and universal approach to upgrade the normal microscope to provide up to 10 times better resolution. This imaging capability can bring revolutionaries to many fields related to microscopy. This new design does not require any extra training for the user and the operation procedure is as friendly as the conventional setups in the schools, hospitals, medial labs and micro-fabrication factories. Due to the careful choice of the materials and design strategy, it does not add cost to the exiting setups. Instead, the equipment cost to provide nano-scale resolution can goes down by at least 50%, which makes the nano-vision affordable for the more students, doctors and engineers. 

Impact achievement & world reputation| Due to its simplicity in design, current optical microscopes can be easily upgraded and preserve all its advantages. This innovative design can be installed in all the primary schools and even kindergartens, students at early age would be able to see our nano-world and more creations can be inspired. Moreover, this optical microsphere nanoscope finds wide application in bio-medical research labs where the most advanced life science is studied. Most of the viruses are at the size of tens of nanometers, and current methodologies require complicated preparation procedures which modify the bio-molecules before one can unveil their details. With this nanoscope, virus, bacteria or other cells can be maintained alive in their aqueous environments and images/videos can be captured in vivo. Hence, this design received many recognitions in worldwide. It is granted the Prestigious Engineering Achievement Award from Institution of Engineers Singapore. This design also represented Singapore to win the Outstanding Engineering Achievement Award from the Association of Southeast Asian Nations. Attracted by these impactful applications, Prof Hong’s team have initiated a spin-off for the technical commercialization of this novel optical microsphere nanoscope. 
“Science serves as the fundamental force to increase the happiness for the human beings. My dream is to invent the useful optical technology and make it ready to benefit every one. Let’s expect more light to be in our lives!” says Prof Hong when talking about this new technique. 

(a) Schematics of the setupfor the remote microsphere system; (b) Mechanism to illustrate the enlarged virtual image by the microsphere system; (c) Optical image captured in this system (Sample: Blue-ray disc; scale bar: 2 µm);
 Inset: SEM image of the nano-grooves (scale bar: 150 nm)

Chen L W, Zhou Y, Wu M X, Hong M H. Remote-mode microsphere nano-imaging: new boundaries for optical microscopes. Opto- Electronic Advances 1, 170001 (2018).