On flat polished metal, coaxial light makes the surface bright and a scratch dark, while low-angle darkfield light makes the surface dark and a scratch bright unless aligned with the beam. Compare LXV-3COH, LXV-FPR, and LXV-3DM on the actual part to verify glare suppression and defect contrast.
These photographs show the shop or the catalog comparison. Send the part to match a series.
Open the matching series, then send the part or the images.
**Low-angle darkfield creates high-contrast shadows across shallow directional defects.** Compare low-angle darkfield bar or ring lighting for directional scratches, coaxial lighting for flat reflective surfaces, and diffuse or polarized setups for curved or glossy parts.
**Incident light angle relative to surface topography dictates specular versus scattered reflection.** Record lens and light working distances, field of view, light orientation and mounting clearance for every comparison.
**Surface shape explicitly determines the required illumination angle to avoid localized glare spots.** Shallow scratch, dent, or directional tool mark: Low-angle bar or low-angle ring light creates dark-field shadow contrast across the defect.
**Physical benchmark testing across part variances is mandatory for reliable deployment.** Compare several low-angle darkfield positions against coaxial illumination on the same samples, keeping camera settings fixed for each comparison.
**Physical mechanical clearance and camera sensor specifications constrain available lighting choices.** Part material composition, surface roughness (Ra), plating, coating, and oil state define optical boundaries.
It is a common first test for shallow scratches, but surface finish, curvature, defect orientation, oil films, and line speed may require coaxial, dome, polarization, or strobe illumination.
Send part finish, target defect width and depth, camera lens, field of view, working distance, line speed, trigger mode, and representative sample images.
Discuss representative scratched parts, the test scope and sample shipping arrangements with LuxMV. Compare darkfield and coaxial setups using the actual part, and request available drawings for candidate models.
Ask LuxMV whether evaluation lights or controllers are available for your project. Confirm the selected models, loan terms and test arrangements before planning on-site evaluation.
Reflective metal scratch inspection should be selected from the surface behavior and defect direction, not from a single universal light type. Compare geometry, wavelength, polarization, motion, and sample variation before fixing the final model.
| Lighting method | Best initial fit | Selection risk to test |
|---|---|---|
| Low-angle bar or ring light | Shallow scratches, dents, burrs, and directional tool marks | The defect can disappear if the light is aligned with the scratch direction; compare several incident angles. |
| Coaxial light | Flat reflective surfaces, planar marks, printed features, and mirror-like metal | Curved or uneven surfaces can create unstable glare and require diffuse or polarized comparison. |
| Dome or diffuse light | Curved, glossy, cylindrical, or uneven metal surfaces | Diffuse light can suppress glare but may also reduce contrast for very shallow directional scratches. |
| Polarized lighting | Specular reflection control on glossy surfaces, films, and coated metal | Polarizer angle, lens filter, exposure, and wavelength must be checked together. |
| Line-scan or strobed light | Moving strip, foil, web, and high-speed metal inspection | Line speed, exposure, pulse width, heat, and controller timing define practical limits. |
| Geometry | Model | What the catalog states | What this page does not show |
|---|---|---|---|
| Low-angle | LXV-FPR | 24 V low-angle series. Catalog lists eleven sizes from 50 to 230 mm and reduced reflected flare. | A scratch parallel to the beam can disappear. The public bar-light photo is not an LXV-FPR record. |
| Coaxial | LXV-3COH | Catalog applications include scratches on metal or plastic and short-exposure moving targets. | A sloped or curved face sends the on-axis beam away. No paired coaxial photo of the bar-lit sample is published. |
| Dome | LXV-3DM | Hemispherical diffuse structure for reflective and uneven surfaces. | Diffuse light can lower contrast for a shallow directional scratch. |
