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Non-destructive inspection methods for LEDs using real-time displaying Optical Coherence Tomography.

Cho NH, Jung U, Kim S, Kim J - Sensors (Basel) (2012)

Bottom Line: The SD-OCT and SS-OCT images were compared with each other in the same sample to study their advantages.In addition, the volume of the fluorophore space was calculated from the OCT images.We expect this method can improve the inspection efficacy over traditional inspection methods such as Charged Coupled Device (CCD) camera or X-ray instruments.

View Article: PubMed Central - PubMed

Affiliation: School of Electrical Engineering and Computer Science, Kyungpook National University, 1370, Sankyuk-dong, Buk-gu, Daegu 702-701, Korea. nhcho@knu.ac.kr

ABSTRACT
In this study, we report the applicability of two different Optical Coherence Tomography (OCT) technologies for inspecting Light Emitting Diode (LED) structures. Sectional images of a LED were captured using a Spectral Domain OCT (SD-OCT) system and a Swept Source OCT (SS-OCT) system. Their center wavelengths are 850 and 1,310 nm, respectively. We acquired cross-sectional two dimensional (2D) images of a normal LED and extracted sectional profiles to inspect possible wire disconnection that may be present in the LED manufacturing process. The SD-OCT and SS-OCT images were compared with each other in the same sample to study their advantages. The distribution of fluorescence material was observed more clearly with the SD-OCT of 850 nm wavelength, whereas the status of wire connection was clearer in the SS-OCT images with 1,310 nm wavelength. In addition, the volume of the fluorophore space was calculated from the OCT images. This is the first report that a nondestructive optical imaging modality such as OCT can be applied to finding screen defects in LED. We expect this method can improve the inspection efficacy over traditional inspection methods such as Charged Coupled Device (CCD) camera or X-ray instruments.

No MeSH data available.


Related in: MedlinePlus

Circle chip LED. (a) Microscope top view image; (b) 850 nm SD-OCT top view 3D image; (c) 1,310 nm SS-OCT top view 3D image.
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f6-sensors-12-10395: Circle chip LED. (a) Microscope top view image; (b) 850 nm SD-OCT top view 3D image; (c) 1,310 nm SS-OCT top view 3D image.

Mentions: Figure 6 shows the image of the circle chip LED. Figure 6(a) is the 20X magnified image of the circle chip LED using a digital microscope (Dino-lite AM3013, New Taipei City, Taiwan). Figure 6(b,c) are OCT images taken with SD-OCT (850 nm center-wavelength) and with SS-OCT (1,310 nm center-wavelength), respectively. We reconstructed the 3D image from 512 2D images. The 3D image displays the entire internal structure of the LED including the morphological shape of the fluorophore. Also, the status of wire connection appeared in the upper part of the image. The fluorophore is more clearly observable in the SD-OCT image compared to the SS-OCT as shown in Figure 6(b,c).


Non-destructive inspection methods for LEDs using real-time displaying Optical Coherence Tomography.

Cho NH, Jung U, Kim S, Kim J - Sensors (Basel) (2012)

Circle chip LED. (a) Microscope top view image; (b) 850 nm SD-OCT top view 3D image; (c) 1,310 nm SS-OCT top view 3D image.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472834&req=5

f6-sensors-12-10395: Circle chip LED. (a) Microscope top view image; (b) 850 nm SD-OCT top view 3D image; (c) 1,310 nm SS-OCT top view 3D image.
Mentions: Figure 6 shows the image of the circle chip LED. Figure 6(a) is the 20X magnified image of the circle chip LED using a digital microscope (Dino-lite AM3013, New Taipei City, Taiwan). Figure 6(b,c) are OCT images taken with SD-OCT (850 nm center-wavelength) and with SS-OCT (1,310 nm center-wavelength), respectively. We reconstructed the 3D image from 512 2D images. The 3D image displays the entire internal structure of the LED including the morphological shape of the fluorophore. Also, the status of wire connection appeared in the upper part of the image. The fluorophore is more clearly observable in the SD-OCT image compared to the SS-OCT as shown in Figure 6(b,c).

Bottom Line: The SD-OCT and SS-OCT images were compared with each other in the same sample to study their advantages.In addition, the volume of the fluorophore space was calculated from the OCT images.We expect this method can improve the inspection efficacy over traditional inspection methods such as Charged Coupled Device (CCD) camera or X-ray instruments.

View Article: PubMed Central - PubMed

Affiliation: School of Electrical Engineering and Computer Science, Kyungpook National University, 1370, Sankyuk-dong, Buk-gu, Daegu 702-701, Korea. nhcho@knu.ac.kr

ABSTRACT
In this study, we report the applicability of two different Optical Coherence Tomography (OCT) technologies for inspecting Light Emitting Diode (LED) structures. Sectional images of a LED were captured using a Spectral Domain OCT (SD-OCT) system and a Swept Source OCT (SS-OCT) system. Their center wavelengths are 850 and 1,310 nm, respectively. We acquired cross-sectional two dimensional (2D) images of a normal LED and extracted sectional profiles to inspect possible wire disconnection that may be present in the LED manufacturing process. The SD-OCT and SS-OCT images were compared with each other in the same sample to study their advantages. The distribution of fluorescence material was observed more clearly with the SD-OCT of 850 nm wavelength, whereas the status of wire connection was clearer in the SS-OCT images with 1,310 nm wavelength. In addition, the volume of the fluorophore space was calculated from the OCT images. This is the first report that a nondestructive optical imaging modality such as OCT can be applied to finding screen defects in LED. We expect this method can improve the inspection efficacy over traditional inspection methods such as Charged Coupled Device (CCD) camera or X-ray instruments.

No MeSH data available.


Related in: MedlinePlus