Intense pulsed light systems are currently in widespread use in clinical applications. Verification of spectral content and associated pulse waveforms is, however, not featured in product support and calibration. A measurement system was developed to determine the spectral output of such sources within a series of discrete wavelength intervals. Such a system utilised a series of 11 broadband optical filters with centre wavelengths within the range 450-950 nm in circuit with silicon photodiodes as optical detectors. Signals were captured using a low cost 8-channel 16-bit universal serial bus data capture module interfaced to a laptop computer. This allowed the pulse profile of selected filter components to be separately captured and analysed. Calibration of individual filter channels was undertaken using a Bentham dmc150 spectroradiometer and reference tungsten light source. Initial measurements undertaken of the intense pulsed light output of a Lumenis One system using the system are described.

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Porokeratosis, a disorder of keratinisation, is clinically characterized by the presence of annular plaques with a surrounding keratotic ridge. Clinical variants include linear, disseminated superficial actinic, verrucous/hypertrophic, disseminated eruptive, palmoplantar and porokeratosis of Mibelli (one or two typical plaques with atrophic centre and guttered keratotic rim). All of these subtypes share the histological feature of a cornoid lamella, characterized by a column of 'stacked' parakeratosis with focal absence of the granular layer, and dysmaturation (prematurely keratinised cells in the upper spinous layer). In recent years, a proposed new subtype, follicular porokeratosis (FP_, has been described, in which the cornoid lamella are exclusively located in the follicular ostia. We present four new cases that showed typical histological features of FP.