Photothermal Deflection Spectroscopy (PDS)

PDS is a highly sensitive optical absorption spectrometry technique that is ideal for characterising weakly absorbing thin films. Our PDS can measure the absolute absorption of a thin film with its substrate down to 10-6. In comparison, common reflection-transmission (R&T) based absorption spectrometers can only reliably measure down to 0.5×10-2.

In addition to the overall higher sensitivity, the PDS technique is most sensitive to the first micrometres of material and less sensitive to the substrate. PDS is the most sensitive and versatile technique for characterising absorption in thin films presently available.

Our first commercial prototype is presently under development. However, our key performance benchmarks to date are given below:
Details on the PDS System
Dimensions of PDS System

including inbuilt light source and computer

width: 1000mm
depth: 610mm
height: 300mm
weight: <50kg

main power: 90~264VAC,  47~63Hz,  500W(max)


Measurement Sample

sample size minimum:   6mm x 12mm x 1mm thick   (special version for smaller samples available on request)
sample size maximum:   10mm x 35mm x 4mm thick   (special version for larger samples available on request)
measured layer thickness:   2nm to 10um
measurement spot size:  5mm x 0.3mm

wavelength range:  250nm to 2,500nm  (special version for up to 12,000nm on request)
sensitivity:  10^-6 in absorption

sample substrate:  the substrate may be comprised of any material with lower optical absorption than the measured thin film, e.g, quartz


Other Characteristics of the System
  • The sample placement is alignment-free
  • The spectral absorption coefficient:
    • is calculated automatically by utilising the full 1D thermodynamic and optical model
    • is reference corrected
    • has spectral uncertainty values
    • output is in .CSV file

Our first operational experimental laboratory version is used on daily basis at the University of New South Wales (UNSW), in Sydney Australia.

Our first miniaturised automated commercial prototype was presented at the Asia Pacific Solar Research Conference (APSRC) at UNSW in December 2018. The response was greatly prositive and characteristics have been seen to fill a capability gap in present research laboratories. We have been encouraged to press forward with the developoment and the final commercial reslease.

PDS prototype presented at the Asia Pacific Solar Research Conference (APSRC) at UNSW in December 2018.

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Soon we will be launching our first prototype