Limits...
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

850 nm SD-OCT system. (a) Schematic diagram of the SD-OCT system; (b) Photograph of 850 nm SD-OCT system and sample arm optic setup.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3472834&req=5

f2-sensors-12-10395: 850 nm SD-OCT system. (a) Schematic diagram of the SD-OCT system; (b) Photograph of 850 nm SD-OCT system and sample arm optic setup.

Mentions: The schematic diagram of the developed SD-OCT system is shown in Figure 2(a). A 12-bit Complementary Metal-Oxide Semiconductor (CMOS) line-scan camera (Sprint spL2048-140k, Basler AG, Ahrensburg, Germany) with a 70,000 line/s effective line rate in the 2048 pixel mode was used as a detector in the SD-OCT system. With the junction of a EXS8510-2411 Super Luminescence Diode (SLED; λo = 850 nm, Δλ = 55 nm, Exalos Ltd., Schlieren, Switzerland) as a light source, a fiber-based interferometer was implemented. The light source was split into sample and reference arms with the latter terminated by a stationary mirror. A probe at the end of the sample arm delivered light to, and collected back-scattered light from, different depths in the sample. B-mode scanning was performed using a galvanometer scanning mirror (GVS002, Thorlabs, Newton, NJ, USA) at the back focal plane of the objective lens on the sample arm. The output of the line camera was connected to a personnel computer (PC) through a PCIe-1433 frame grabber (NI, Austin, TX, USA) which has a maximum 850 MB/s bandwidth over two camera link cables. The galvanometer scanning mirror was driven by the PC with a PCIe-6321data acquisition board (DAQ, NI) which can provide two analog outputs.


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

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

850 nm SD-OCT system. (a) Schematic diagram of the SD-OCT system; (b) Photograph of 850 nm SD-OCT system and sample arm optic setup.
© Copyright Policy
Related In: Results  -  Collection

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

f2-sensors-12-10395: 850 nm SD-OCT system. (a) Schematic diagram of the SD-OCT system; (b) Photograph of 850 nm SD-OCT system and sample arm optic setup.
Mentions: The schematic diagram of the developed SD-OCT system is shown in Figure 2(a). A 12-bit Complementary Metal-Oxide Semiconductor (CMOS) line-scan camera (Sprint spL2048-140k, Basler AG, Ahrensburg, Germany) with a 70,000 line/s effective line rate in the 2048 pixel mode was used as a detector in the SD-OCT system. With the junction of a EXS8510-2411 Super Luminescence Diode (SLED; λo = 850 nm, Δλ = 55 nm, Exalos Ltd., Schlieren, Switzerland) as a light source, a fiber-based interferometer was implemented. The light source was split into sample and reference arms with the latter terminated by a stationary mirror. A probe at the end of the sample arm delivered light to, and collected back-scattered light from, different depths in the sample. B-mode scanning was performed using a galvanometer scanning mirror (GVS002, Thorlabs, Newton, NJ, USA) at the back focal plane of the objective lens on the sample arm. The output of the line camera was connected to a personnel computer (PC) through a PCIe-1433 frame grabber (NI, Austin, TX, USA) which has a maximum 850 MB/s bandwidth over two camera link cables. The galvanometer scanning mirror was driven by the PC with a PCIe-6321data acquisition board (DAQ, NI) which can provide two analog outputs.

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