Photothermal Deflection Spectroscopy (PDS)

PDS is a highly sensitive optical absorption spectrometry technique. It offers unsurpassed sensitivity on weakly absorbing thin films. It is capable of measuring the absolute absorption of thin films down to 10-6. In comparison, common reflection-transmission (R&T) based absorption spectrometers reliably measure down to a mere 5×10-3.

At this time, we are in the development phase of our first commercial prototype. However, below are the key figures of where we are at this moment:

Dimensions of PDS system, without the fibre coupled light source and computer

width: 400mm
depth: 500mm
hight: 300mm

weight: 35kg

main power: 90~264VAC,  47~63Hz,  240W(max)

Dimensions of the fibre coupled light source and computer

width: 650mm
depth: 450mm
hight: 250mm

weight: 25kg

measurement sample

sample size minimum:   9mm x 3mm x 1mm thick
sample size maximum:   20mm x 24mm x 5mm thick   (special version for larger samples is possible)
measured layer thickness:   2nm to 5um
measurement spot size:  50mm x 0.3mm (strip shape)  (in the future, we will also offer a 5mm x 0.2mm)

wavelength range:  350nm to 2,500nm  (special version possible for up to 11,000nm is impossible)
sensitivity:  10^-6 in absorption   (we are testing a new design that might allow even 10^-7)

sample substrate:  any material that has a lower optical absorption constant to the measured thin film. (Quartz glass usually fulfils this requirement.)

Other characteristics of the system

–  Automated sample alignment
–  Automated data analysis

An operational experimental laboratory version is currently used at UNSW, see photo below.
Photos of our first miniaturised and automated commercial prototype will come at the end of the year.

Open Instruments      UNSW