Fast focal plane array detector and readout for pulsed opto-thermal radiometry

Mid-infrared focal plane array spectroscopic or spatial imaging of opto-the rmal transient emission is reported. Pulsed near-surface optical heating of arbitrary unprepared room temperature surfaces produce depth-resolved tran sient thermal emissions in the mid-infrared chemical fingerprint spectral r egion. Two optical configurations, both offering a significant advance in p ulsed photothermal radiometry, may be realised: (1) an opto-thermal spectro graph capturing entire time-resolved emission spectra with each laser excit ation shot; and (2) an opto-thermal camera producing thermal emission trans ient spatial line images, again, with each optical stimulus. A high-speed t ime-gated focal plane array detector forms the centrepiece of this new inst rumentation; its adaptation, in relation to the measurement of sequenced tr ansient phenomena, is the subject of this paper.