Accurate measurement of Nano-patterned substrates: measuring the spot size of a micron-scale spectrometer



Research areas


Nanophotonics is the interaction of light with structures on the order of, or smaller than the wavelength of light.  At these length scales optical structures can be engineered to manipulate light: to diffract it, scatter it, concentrate it and even to bend it.  Recent advances in large scale fabrication of optical nanostructure arrays, for example nanoimprint lithography and holographic techniques, have meant that nanophotonics has found many new applications: from improving the sensitivity and selectivity of sensors and photodetectors, to increasing the efficiency of light harvesting for photovoltaics.  

For research purposes rapid prototyping of different geometries is highly desirable.  The standard way of fabricating nanophotonic structures in the lab is by electron beam lithography: writing patterns in a special resist with a focused beam of electrons.  Electron beam lithography (EBL) allows the flexibility to design and realise a wide range of nanostructures, but there is a catch: it is very slow.  For the types of patterns used in many optoelectronic applications, we are typically limited to array sizes of a few 10s to 100s microns square.  These size restrictions make it challenging to optically characterise EBL fabricated structures.

The goal of this project is to characterise the spot size of our custom made Micro-Spectrometer. This setup was designed and built by a Masters student at RSEng in 2016 to measure the reflection and transmission of small area, i.e. a few 10s – 100s of microns square, nano-patterened areas.  This set-up is a critical component of the new Nano-photonics Characterisation Lab in room E135 of the Engineering building, being set up by Dr Tom White and Dr Fiona Beck as part of their research on nanostructured optoelectronics.


  1. Familiarise yourself with optical components and systems, and existing techniques to characterise light beams.
  2. Develop a protocol for measuring the spot size on the micro-spectrometer. Evaluate the accuracy of this method compared with standard beam profiling techniques requiring expensive optical devices.
  3. Investigate a range of light sources to identify the limits of spot size that can be achieved on the system.
  4. Produce documentation detailing beam size specifications and procedures for spot size measurements.


This is a ‘hands-on’, practical project, suitable for students with an interest in nanophotonics, optics, optical devices and optoelectronics.  It would be particularly good experience for anyone interested in a research career, or in R&D in the area of optical characterisation.  Some knowledge or experience with optical components would be useful, but is not essential: more importantly, a certain amount of meticulousness (i.e. the ability to pay attention to detail) and persistence will be required.  The ability to think logically and creatively solve problems will be necessary.

Suitable for: 6 unit courses for R&D students: ENGN 2707, 3706, 4706

Prerequisite: ENGN3512 (Optical Physics) would be useful, a basic understanding of optics is essential.


This is the chance to develop protocal to characterise a research grade optical set up, take it through the testing and verification phase, all the way to documentation and hand over.  Over the course of the project you will:

  • Gain a thorough background in optical characterisation, and the operation and limitations of optical systems
  • Get a chance to independently and creatively solve problems
  • Project manage
  • Gain practical experience in technical documentation
  • Undertake independent research and build up your analytical skills
  • Be able to walk away knowing that something you developed is being used by researchers


Optical devices, Optoelectronics

Updated:  8 September 2015/Responsible Officer:  Head of School/Page Contact:  CECS Marketing