Power Measuring The listed power heads are based on thermoelectric principles, which means that the heat generated from the incident radiation is transformed directly into a voltage. The heads of BB – series have a black, broadband absorbing coating, whereas the HP – series is equipped with a ceramic layer allowing higher energy and power densities. The heads need 15 to 20 seconds to reach a thermal equilibrium. To avoid this delay time, we recommend the use of one of our power meters, such as LM 200 or LEM 2020. These devices determine the voltage and their increase and evaluate the laser power from this data. The time constant of the whole system is reduced to 1 second. The head HP 25 S is specially made for service application. The compact dimensions enable easier transport. Due to the smaller heat sink, high powers are only possible for a short time. active diameter max. power permissible power and energy densities vs. wave length for sensors of HP-series permissible power and energy densities vs. pulse width for sensors of BB-series 1 safe operating region zulässiger Arbeitsbereich τ =(T=10ns 10 ns) max. energy density [J/cm²] max. Energiedichte [J/cm²] Safe operating region zulässiger Arbeitsbereich Wellenlänge [nm] wave length [nm] max. power density [W/cm²] [W/cm²] max. Impulsleistungsdichte max. energy density [J/cm²] max. power density [MW/cm²] pulse width [s] Impulsdauer [s] for pulses with widt h τ [ns ] apply : E max [J/cm² ] = 10 − 2 ⋅ (5 + 0 ,03 ⋅ λ [nm ]) ⋅ τ [ns ] Scitec Instruments Ltd · Bartles Industrial Estate · North Street · Redruth · TR15 1HR · United Kingdom Tel: +44 (0)1209 314 608 · Fax: +44 (0)1209 314 609 · www.scitec.uk.com · [email protected]