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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

Comparison of digital microscope and OCT images of faulty and normal LED. (a) Abnormal (no wire) and normal LEDs digital microscope image; (b) Abnormal (no wire) and normal OCT image.
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f7-sensors-12-10395: Comparison of digital microscope and OCT images of faulty and normal LED. (a) Abnormal (no wire) and normal LEDs digital microscope image; (b) Abnormal (no wire) and normal OCT image.

Mentions: We compared an abnormal LED with a normal one using digital microscope and OCT as shown in Figure 7. The images, shown in Figure 7(a), represent the digital microscope views of the abnormal and normal samples. The left black LED is the abnormal sample without wire connections. The inner structures are also observed with OCT as shown in the Figure 7(b). We could confirm the wire-connection status of abnormal and normal LEDs with OCT imaging. Through this experiment, OCT imaging can detect the status of LEDs by observing the wire-connection status.


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

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

Comparison of digital microscope and OCT images of faulty and normal LED. (a) Abnormal (no wire) and normal LEDs digital microscope image; (b) Abnormal (no wire) and normal OCT image.
© Copyright Policy
Related In: Results  -  Collection

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

f7-sensors-12-10395: Comparison of digital microscope and OCT images of faulty and normal LED. (a) Abnormal (no wire) and normal LEDs digital microscope image; (b) Abnormal (no wire) and normal OCT image.
Mentions: We compared an abnormal LED with a normal one using digital microscope and OCT as shown in Figure 7. The images, shown in Figure 7(a), represent the digital microscope views of the abnormal and normal samples. The left black LED is the abnormal sample without wire connections. The inner structures are also observed with OCT as shown in the Figure 7(b). We could confirm the wire-connection status of abnormal and normal LEDs with OCT imaging. Through this experiment, OCT imaging can detect the status of LEDs by observing the wire-connection status.

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