title: Dual channel light pulse exposure timer.
abstract: An instrument has been developed for routine measurement of pulse durations of lasers and pulsed light sources. A four digit light emitting diode (LED) count display is used with a range of selectable clock rates in five decades from 1 MHz to 100 Hz with a longest time duration corresponding to 99.99 s. The performance of the system was verified using a Schmidt trigger test circuit to drive an LED where the time of the drive pulse was compared to that indicated by the timer unit and where also silicon photodiodes of different detector areas were used to verify device measurement accuracy.A buffered output channel allows inspection by an oscilloscope to verify output pulse characteristics. This can be especially relevant to verify performance characteristics of a given laser/pulsed light system and to establish definitive assessments for eye safety based on relevant standards.
authors.affiliation: Department of Clinical Physics and Bioengineering, Radiotherapy Centre, University Hospitals Coventry and Warwickshire NHS Trust, Walsgrave Hospital, Coventry, CV2 2DX, UK. douglaas.clarkson@uhcw.nhs.uk
authors.forename: D M
authors.initials: DM
authors.lastname: Clarkson
mesh_terms: D004581:Electronics / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007834:Lasers; D055095:Optics and Photonics / Q000295:instrumentation; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers