Application Notes
Surface profile of the light guide plate for LCDs / Non-contact 3D shape measurement using a laser microscope
Application
Special purpose films are laminated together in an optical system to help liquid crystal displays (LCDs) maintain uniform brightness. Small displays use a light guide plate to help direct light through the panel. Light from a source, such as LEDs installed along the edge of a panel display, is scattered by the plate and repeatedly reflected to illuminate the front of the panel. The density of surface irregularities on the light guide plate is designed in such a way that the scatter is increased as the light travels away from the source. The light irradiated from the plate is made uniform by a diffuser plate. The light is then collected by the prism sheet, intensified, and directed through the TFT panel. Evaluating the surface profile, or roughness, of the light guide plate is important for ensuring uniform brightness in LCD displays.
Olympus' solution
By using Olympus' LEXT 3D scanning laser microscope, the light guide plate’s angle of taper and the peak-to-valley pitch or height can be measured with high resolution and high definition. Thanks to dedicated objective lenses with high numerical apertures and the advanced optical system designed for optimal performance with a 405 nm laser, the LEXT can capture the profile of irregular slopes that were previously impossible to detect, enabling you to acquire more reliable three-dimensional data and ensure the quality of light guide plates.
Three-dimensional surface profile of a light guide plate
100X objective lens; 1x zoom
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Hybrid 3D Optical Profilometer
- Traceable surface measurements from the nanometer to micrometer scale
- Laser scanning microscopy (LSM), white light interferometry (WLI), and focus variation microscopy (FVM) in one award-winning platform
- First 3D optical profilometer to offer guaranteed accuracy and repeatability* for both LSM and WLI measurements
- WLI mode delivers up to 40x faster measurement throughput than conventional LSM
- Exceptional precision across surfaces with in-house engineered optics
- Intuitive interface and smart automation streamline operation for users of all levels
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*Based on Evident’s internal research as of October 2025. The guaranteed accuracy and repeatability apply only if the device has been calibrated according to the manufacturer’s specifications and is in defect free condition. Calibration must be performed by an Evident technician or an Evident-authorized specialist.
LEXT OLS5100
The LEXT™ OLS5100 laser scanning microscope combines exceptional accuracy and optical performance with smart tools that make the system easy to use. The tasks of precisely measuring shape and surface roughness at the submicron level are fast and efficient, simplifying your workflow and delivering high-quality data you can trust.