Engineering Systems

We are interested in the development of new techniques which could end up in medical instruments or devices. Some of our research projects result in the implementation of proof-of-principle instruments, while in other projects we need to build measurement systems in the lab to carry out experiments. As a result most of the work we do involves a significant amount of engineering design effort in the areas of electronics, optics, mechanics and software, and we have a well developed set of expertise in these areas.

Optical design and fabrication

We frequently build systems in both bulk optics (free space) and fibre-optics. We have a good inventory of optical equipment for creating systems for lab experiments on optical tables and for portable instruments. We use software such as ZEMAX and Optica to model and design the optical systems.

Figure 1. Zemax modelling: We model the performance of various optical systems, including optical delay lines, high resolution imaging setups and micro-optical assemblies.

We also build fibre-optic circuits which usually involves optical connectors and/or splicing with various types of optical fibre, standard single-mode communications fibre, polarization-maintaining fibre, short-wavelength (small core) fibre, and photonic crystal fibre.

A specialized area of expertise developed in OBEL is in the area of fabrication of micro-optics assemblies. The in-house capability was developed because there are very few companies which offer prototyping services of this kind, and also because a large amount of control of the construction process is often required.

Figure 2. Optical design: We build fibre-optic circuits, free-space optics setups, and fabricate micro-optics.

Electronics

We often design and fabricate electronic circuits for optical detectors, signal processing and for electronic control. Low-noise design techniques are often necessary to ensure that the electronic circuit does not adversely impact the system signal-to-noise ratio. An example of a signal processing circuit we have built is a logarithmic demodulator circuit which has a buffered input and output, and interchangeable bandpass and lowpass filter boards. Electronic control applications involved embedded systems utilizing microprocessors which read sensors, control actuators and use a two-way communication channel with a personal computer running the high-level software application. An example of this is an Atmel ATtiny2313 based control system for calibrated control of rotation and translation of an endoscopic fibre-optic probe under computer control.

Figure 3. Signal processing electronics: Most signal processing systems for optical coherence tomography require high bandwidths and good noise performance.

Mechanical design

Most aspects of our prototype instruments development involve mechanical design considerations. Examples are the creation of fibre-optic endoscopic probes and drive systems, the design of an ergonomic hand-held optical coherence tomography sample head, and the construction of miniature needle probes. We typically use 3D CAD software to model our designs before constructing them in-house or sending them to an outside party. OBEL has links with mechanical engineering at UWA and we have had several mechatronics student projects working on aspects of OBEL systems.

Software

Most of our instruments and experimental systems have software custom-written to control the instrument and to perform data acquisition, processing and display. Most of this software has been created using Labview (National Instruments) and C++.

Figure 4. Custom software: A schematic of a multi-threaded C++ application, and a rapid-prototyped control and acquisition program in Labview

Building systems

OBEL typically builds systems into portable instruments which can be taken to hospitals, clinics and other labs to carry out experiments.

Figure 5. Portable instrumentation developed at OBEL: A diffuse reflectance spectrometry system, and a portable anatomical optical coherence tomography system.