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VCSEL system comprising detectors for controlled heating Disclosure Number: IPCOM000236235D
Publication Date: 2014-Apr-14
Document File: 5 page(s) / 356K

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VCSEL system comprising detectors for controlled heating

    VCSEL systems are powered by an electronic driver system, enabling switching or pulsing and precise control of the infrared power from zero to full power. Closed loop process control can thereby easily be realized.

    Beyond that, individual radiation zones of a VCSEL module can be controlled independently by setting the current levels of each heating zone individually to its desired level (illustration on the right). This enables adjustment, change and control not only of the total heating power, but also of also the spatial heating profile. Even dynamically changing heating profiles during operation are possible, enabling an unprecedented level of control in industrial heat treatment processes.

    High power VCSEL systems are applied for heating in material processing applications. The system consists of a number of similar emitter modules, which can be controlled independently. Combined with the unique emission profile, local and dynamical control of the applied heating profile on a target surface is possible.

    Photo-detectors specifically allocated to emitters in the system enable a closed control loop with the electrical power supply. Thereby a chosen temperature profile can be realised and an especially robust control strategy is defined.

    Industrial heating is today mainly realized by ovens, which are powered by flames, electrical resistance heating or halogen lamps. These solutions do not allow for any localized heating profiles nor a fast dynamical adaptation during the process. An expensive and complicated alternative is the application of a standard laser via an additional optical scanner system; apparently not really easy and slow because of the sequential scanning.

    High power VCSEL systems with many small, LED like lasers enable a new approach, which combines an almost lamp like ease-of-use with full flexibility and control. Modules or "heating zones" can be defined which are independently driven by electrical power supplies and can be set to a specific output power.

    In traditional heating ovens, the required process settings are determined in tedious calibration procedures including test series with varied power settings.

    Temperature measurements for real time process control in laser supported processing can be done with pyrometers (e.g. US4956538) or thermo-cameras. Alternatively the measurement of specific properties of materials contained in the workpiece modified by the laser treatment (e.g. resistivity US2005/0199597, photocurrent) can be used to generate a feedback signal to control the process. Such methods are normally applied at a specific location of the workpiece but can also be scanned across the workpiece or applied on multiple points e.g. via a fiber optical system (US5255286). This patent also describes the use of a "real time multi zone controller" to control the power of several lamp modules. On the

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