The industry-oriented research at CAPPA aims at providing photonics-based solutions to companies in a wide range of sectors. The activities span from collaborations with photonics companies looking for assistance in designing or understanding the physics of a new product, to companies in sectors such as pharmaceutical or food manufacturing where photonics can offer relatively straightforward yet powerful methods for quality analysis and process monitoring. (See the Case Studies pages for some examples of how companies have worked with CAPPA in the past). Many of these solutions are based around the extensive spectroscopy, imaging and design capabilities available to CAPPA; this section gives a brief description of these, together with some basic examples.
Spectroscopy in a broad sense is the study of the interaction between radiation and matter as a function of wavelength. CAPPA’s spectroscopic platform is primarily based on Fourier Transform Infrared (FTIR) and Raman spectroscopy techniques and its capabilities cover the spectral range from the ultraviolet, through the visible, near IR and mid IR and beyond to the Terahertz region. FT-IR measurements at all wavelengths can also be carried out with an evacuated optics bench that can eliminate atmospheric moisture absorptions for ultimate sensitivity and stability. In addition to traditional spectroscopy CAPPA also engages in both Photo-reflectance and Photoluminescence Dynamics Spectroscopy as well as Two-colour Pump-Probe Spectroscopy (see the Advanced Research section).
CAPPA’s Terahertz capabilities can provide unique spectroscopic signatures not found at other wavelengths and can resolve many of the questions left unanswered by complementary techniques, such as optical imaging, Raman and Infrared. Many common materials and living tissues are semi-transparent to Terahertz light which as a result presents exciting opportunities not available in traditional near-IR spectroscopy.
In addition to the FTIR and Raman spectroscopy, CAPPA also carries out energy dispersive spectroscopy (EDS) which measures the number of x-rays produced by a solid sample when irradiated by electrons versus the energy of these x-rays. The EDS technique identifies and quantifies the elemental constituents of the sample under test.
This broad platform allows CAPPA to engage in wide range of fundamental, applied and process related activities including:
- Gas analytics, atmospheric research
- Solid state spectroscopy
- Surface analytics
- Life science applications
- Microscopy including FT-IR and Raman imaging
An example of the atmospheric absorption spectrum spanning the infra-red and THz regions measured using CAPPA’s Bruker Vertex 80v FT-IR Spectrometer.
Imaging is a key application of optics and photonics and CAPPA is engaged in a number of advanced imaging activities. The goal is to gain insight into the structure, form, shape and constituents of the sample under investigation in a non-destructive manner. The three key techniques that CAPPA employs are:
- Environmental Scanning Electron Microscopy (ESEM)
- Hyperspectral Imaging
- Interferometric & Phase Shift Techniques
Through the use of variable pressure Scanning Electron Microscopy (SEM), non-conducting and water containing samples can be imaged to nanometer resolution. The SEM imaging can be combined with energy dispersive spectroscopy (EDS) to identify and quantify the element constituents of the sample under test. Traditionally, nonconductive samples had to be coated prior to SEM imaging and it was not possible to image wet samples at all. The ability to image nonconductive samples without coating gives CAPPA a great advantage over traditional SEM imaging. Samples can now be imaged in a nondestructive manner and microanalysis can be performed without the influence of carbon or metal coating. The chamber size available can also accommodate large and irregularly-shaped specimens. All this flexibility lends itself to imaging samples in their native state. This is ideal for gaining insight into product performance under varying environmental conditions as well as understanding the effect of various process steps and parameters.
By extending the spectroscopic capabilities CAPPA can also carry out FT-IR and Raman imaging. This technique is often termed Hyperspectral Imaging, Spectroscopic Imaging or Chemical Imaging. This is a powerful combination of FT-IR and Raman Spectroscopy and Microscopy which yields information on the spatial distribution of the spectral properties within a sample. CAPPA can employ this to investigate the homogeneity of a sample and the distribution of its constituents can be observed. CAPPA can also investigate the form of a surface through interferometric or phase-shifting techniques which can be design and tailored depending on the sample under test.
All the above techniques have various applications and deployment depending on the sample being investigated and the information required.
Chemical Imaging of solid dose pharmaceutical tablet displaying the distribution of the Active Pharmaceutical Ingredient in the tablet.
While optical design and simulation is a complementary feature of much of the projects carried out by CAPPA, the activity can also be standalone. Optical designs can be modelled in both sequential and non-sequential modes allowing CAPPA to work on both traditional lens systems and those requiring stray-light analysis.
Work can involve design from scratch, re-engineering of current designs or simulation to understand current or future performance with regard to layout or operating parameters. To help strengthen this design and simulation work CAPPA is also capable of testing and characterising the performance of existing or prototype systems. Again this activity can be standalone or also be used to make a more complete model for use in the design and simulation work.
This section describes the CAPPA research which is typically of most interest to industry, as it is usually of most relevance to process analysis and prototype development. However, some companies and academics may also be interested in the more fundamental and experimental research of CAPPA, described in the Advanced Research section. This includes techniques such as Time-Resolved Photoluminescence, Pump-Probe Spectroscopy, FREAG and Mode-Locked Lasers, as well as activities such as Femtosecond Physics, Non-Linear Dynamics of Semiconductor Lasers and Photoluminescence Dynamics.