Leimac Tech Notes

Visualizing Subtle Surface Features with IFCEH Series

For glossy workpieces, surface reflections can make it difficult to detect subtle surface irregularities and differences in shape.

By optimizing the angular distribution and direction of illumination, surface features that are difficult to detect using conventional lighting methods can be made more visible.

Leimac’s IFCEH series features a slim, square dome-style design with a specially engineered light distribution.
The 4-channel model enables independent control of illumination from four directions, supporting surface shape analysis using photometric stereo.

Features of the IFCEH Series

Conventional dome lights provide diffuse illumination from multiple directions by reflecting light off the inner surface of a dome-shaped reflector.
This approach helps minimize localized glare and brightness variations, providing uniform illumination across the workpiece. However, the resulting diffuse illumination may reduce the visibility of subtle surface irregularities.

Imaging Comparison Using Conventional Ring and Dome Lights
Imaging Comparison Using Conventional Ring and Dome Lights

The IFCEH Series combines the benefits of dome-style illumination with an enhanced oblique-light component, making subtle surface irregularities easier to detect.

IFCEH:Light distribution optimized to enhance the visibility of subtle surface irregularities/IFHA:Soft, uniform illumination from multiple directions for consistent surface imaging
Light Distribution Comparison

The IFCEH series incorporates a specially designed light guide plate (LGP) to achieve a light distribution optimized for enhancing the visibility of subtle surface irregularities.

Clear Imaging Through the Light Guide Plate
Clear Imaging Through the Light Guide Plate

Imaging Example: Scratch Inspection on Metal Parts

Scratches on the surface of a metal part were captured and compared using three lighting types with different illumination characteristics.

Scratch Inspection of Metal Parts
Scratch Inspection of Metal Parts
  • IFCEH: Captures scratches with high contrast
    while reducing the influence of surface hairlines.
  • IFHA: In this example, the scratches appear less distinct.
  • IDRA-T (Horizontal Opposed Lighting):
    Scratches are clearly visible, but the surface hairlines
    are also emphasized.

For this workpiece, IFCEH produced clear images of the scratches while maintaining good visibility through the light guide plate.

Photometric Stereo Applications with the 4-Channel Model

The IFCEH series features consistent illumination angles across the field of view, regardless of position.
Leveraging this characteristic, the 4-channel model allows independent control of illumination from four directions, enabling surface shape visualization using photometric stereo.

By processing multiple images captured under different illumination directions using photometric stereo, surface height variations can be extracted, making it easier to detect fine scratches and subtle differences in surface shape.

In this case study, we present an imaging example of a mottled table using the IFCEH series.

アクリルバッチの4方向撮像画像・処理後画像

System Configuration Example

System Configuration Diagram Using the IFCEH Series
Example configuration using a PoE-enabled camera

Equipment Overview

Slim Square Dome Light | IFCEH Series

A slim square dome light featuring illumination characteristics with a strong oblique-light component and a compact, space-saving design.
The 4-channel model supports independent control of illumination from four directions.

Compatible Lighting Controller

Multi-Channel Programmable Controller | IDMU-P Series

A controller used to control illumination for each channel.
It enables the configuration of a lighting control system for photometric stereo applications.