High-speed thermoreflectance microscopy using charge-coupled device-based Fourier-domain filtering

Abstract

We present a Fourier-domain filtering method for charge-coupled device (CCD)-based thermoreflectance microscopy to improve the thermal imaging speed while maintaining high thermal sensitivity. The time-varying reflected light distribution from the surface of bias-modulated microresistor was recorded by a CCD camera in free-run mode and converted to the frequency domain using the fast Fourier transform (FFT) for all pixels of the CCD. After frequency peak filtering followed by inverse FFT, a thermoreflectance image was obtained. The imaging results of the proposed method were quantitatively compared with those of the conventional four-bucket method, showing that the Fourier-domain filtering method can provide thermal imaging 24-42 times faster than the four-bucket method, depending on the required thermal sensitivity.

Simultaneous multicolor imaging of wide-field epi-fluorescence microscopy with four-bucket detection

“…Unlike other lock-in techniques (e.g., fast Fourier transform (FFT)), because only four images are required for reconstructing the intensity and phase images, the four-bucket technique provides not only a small data load to the computer but also short image acquisition times for achieving the final separated image, which is less than 1 s in our experiment. Of course, the capability to selectively detect signals of interest might decrease compared with the use of FFT because reconstruction of the signal is conducted using few images [20]. However, based on the results of our experiments on the discrimination of multi-fluorescence emissions, the four-bucket method had sufficient capability to discriminate each multifluorescence emission.…”

Laser Scanning Confocal Thermoreflectance Microscope for the Backside Thermal Imaging of Microelectronic Devices

“…The scheme of thermoreflectance imaging in TRM is based on detecting the reflectivity variation Δ R with respect to the temperature modulation of the DUT. In our previous study, a Fourier-domain filtering method for CCD-based TRM was introduced as a thermoreflectance image acquisition strategy and offered high-sensitivity thermoreflectance imaging at a faster imaging speed than the conventional four-bucket method [ 15 ]. Here, the Fourier-domain filtering method was conceptually applied to laser scanning confocal TRM but was implemented in different ways as follows.…”