A theoretical analysis and implementation of a high sensitivity infrared thermometry system for a precise real-time temperature control in domestic induction cooktops is presented. The temperature in the cookware constitutes the control variable of the closed-loop power control system implemented in a commercial induction cooktop. The system includes an InGaAs PIN photodiode and a differential preamplifier which detects the infrared radiation (IR) emitted from the bottom of the cookware and the glass-ceramic top. The analysis includes an algorithm to discount the contribution of the glassceramic material from the total signal. In an infrared thermography application where an IR sensor is used, measuring the object’s surface emissivity is crucial because it significantly impacts the temperature measurement result. For a precise temperature control with a maximum temperature error of 5°C in all range of cooking temperatures (60°C to 250°C) a cookware emissivity measurement system is included. The accuracy and the validity of our model have been tested and confirmed with measurements performed with the proposed system. The experimental arrangement built to test the proposed system has validated the usefulness of the IR thermometry system applied to the cookware within the range of cooking temperatures from 60°C to 250°C, making it suitable for this application. It has been proved that the IR sensor and the associated electronic works properly in a high-temperature environment such as a real induction heating cooktop.
In this work we present a characterization of the chirp parameters of a commercially available ILM by means of
measurements made with a high-resolution optical spectrum analyzer. Particularly, we will use the FM/AM method for
the characterization of the transient chirp parameter and will compare results with the standard Fibre Transfer Function
method. The FM/AM method will be applied to frequencies down to 100 MHz due to the capabilities of the high-resolution
optical spectrum analyzer. We will see that, for the studied ILM, the transient chirp parameter varies in such a
way that it changes from positive to negative values when the bias voltage applied to the device changes from 0 to -1,5
volts. Moreover, we will also characterize the adiabatic chirp of the device, which is a parameter difficult to measure due
to the small value it has compared with directly modulated lasers. In this case, the possibility of measuring optical
frequencies with extremely high resolution will simplify the measurement and will provide accurate values for this
parameter.
We present a methodology for the characterization of the main parameters of VCSELs for its use in direct modulation.
Power response, chirp parameter alpha, linewidth, side-mode suppression ratio, relaxation oscillations peak frequency,
damping rate and relative intensity noise (RIN) are obtained from measurements of the emitted optical spectrum in
continuous wave (CW) operation by means of a high resolution (10 MHz) and high dynamic range (80 dB) optical
spectrum analyzer. Many of the main static and dynamic parameters of VCSEL lasers can be obtained from the analysis
of the optical spectrum when emitting in CW operation, but traditional spectrum analysis techniques do not achieve
enough high resolution and dynamic range and high signal to noise ratio to perform it. Recent developments in high
resolution optical spectrum analyzer (OSA) technology allow a deeper characterization of the main properties of
VCSELs for its applications in optical communication systems by analyzing their CW emitted spectrum.
We present results on the characterization of the main parameters of DFB lasers for its use in direct modulation: chirp parameter, linewidth, relaxation frequency and RIN, obtained from measurements of the emitted optical spectrum in continuous operation mode using a high resolution (10 MHz) and high dynamic range (80 dB) optical spectrum analyzer. Results obtained from the characterization of commercial grade available DFB lasers with this method, present
typical parameter values, but are also checked with well-know, but more resource demanding, methods involving modulation and optical to electrical conversion.
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