Components · Lighting
Lighting decides what the camera can see. The right geometry, wavelength and drive mode turn subtle features into high-contrast, repeatable images — before a single line of software runs.
Chiếu sáng quyết định camera nhìn thấy gì. Chọn đúng hình học, bước sóng và chế độ điều khiển đèn giúp đặc điểm khó thấy trở nên rõ nét và ổn định.
How it works
Light reflects from a smooth surface at the same angle it arrives. If that mirror reflection travels into the lens, flat areas look bright — this is bright-field illumination. If the light arrives at a low angle, the mirror reflection misses the lens and flat areas look dark; only scratches, edges and raised features scatter light into the camera — this is dark-field illumination.
Diffuse light (dome, flat dome) arrives from many directions at once, hiding texture and glare on shiny or curved parts. Backlight places the part between light and camera to create a sharp silhouette for outlines and holes.
Wavelength is the second lever. A colored feature looks bright under light of its own color and dark under the complementary color. Short wavelengths (blue, UV) reveal fine surface detail; infrared reduces color variation and can see through some inks and plastics.
Types
Open each type for how it works, where it fits, its limitations and the specifications to check.
How it works. Direct light from a ring mounted around the lens. Narrow-angle rings act as bright field; wider angles soften reflections.
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How it works. LEDs point almost parallel to the surface. Flat areas reflect light away from the lens and stay dark; scratches, dents, embossing and edges scatter light upward.
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How it works. One or more bars aimed at the part from chosen angles. Two or four bars create symmetric illumination; a single low bar gives directional dark field.
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How it works. LEDs illuminate the inside of a white dome which reflects light onto the part from every direction. The camera looks through a hole at the top.
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How it works. A flat diffuse panel combines the softness of a dome with an on-axis component, removing the dark spot that a dome creates on reflective parts.
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How it works. A half-mirror reflects light straight down onto the part. Flat reflective areas send light straight back into the lens (bright); engraved, embossed or textured features scatter it away (dark).
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How it works. A uniform panel behind the part produces a high-contrast black-on-white outline. Collimated (telecentric) backlights send parallel light for the most accurate edges.
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How it works. High-power LEDs focused into a thin line that matches the single sensor line of a line-scan camera, enabling very short exposures at high web speeds.
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How it works. A concentrated beam, often with a focusing lens, illuminates one small area at a high intensity — useful with small fields of view or as a fiber-coupled source.
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How it works. Images taken with light from different directions are combined in software to calculate surface slope. Shallow dents, embossed text and texture defects stand out while color and print are suppressed.
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How it works. Constant-current controllers keep brightness stable. Strobe controllers pulse the light only during exposure; overdrive pulses at higher current for very short, very bright flashes that freeze motion.
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Specifications
| Specification | What it means | How to choose |
|---|---|---|
| Wavelength / color | Peak emission of the LEDs (e.g. 470 nm blue, 625 nm red, 850 nm IR) or white. | Pick the color that maximizes contrast between feature and background; use the Color Contrast tool below. |
| Intensity | How much light reaches the part at the working distance. | Higher intensity allows shorter exposure to freeze motion and smaller apertures for depth of field. |
| Uniformity | Variation of brightness across the illuminated area. | Critical for measurement and for thresholds that must work across the whole image. |
| Geometry & angle | Direction from which light reaches the part. | Decides bright field, dark field, diffuse or silhouette — see the principle above. |
| Working distance | Distance from the light to the part for the intended effect. | Domes and low-angle rings must be close; bars and spots can be farther away. |
| Drive mode | Constant, strobe or overdrive operation. | Strobe or overdrive for moving parts; constant for slow or static scenes. |
| Supply & connection | Typically 24 V DC with a connector to the controller. | Match connector and current to the controller; check cable length. |
| Thermal & lifetime | LED life depends strongly on temperature and drive current. | Use strobing, heat sinks or cooling for high-power lights to keep output stable. |
| Accessories | Diffusers, polarizers, filters, protective windows. | Polarizer pairs cut glare; bandpass filters on the lens block ambient light. |
Interactive Lighting Lab
Pick a lighting technique to see how light reaches the part — and what the camera sees.
Light geometry
Camera view
Bright, direct light from around the lens axis. Compact and versatile.
Engineering tools
Quick estimates based on standard formulas. Always confirm with a test on real parts.
Choose the colors of the feature and background and the light color. The tool shows how a monochrome camera would see them and estimates the contrast.
Selection guide
| Requirement | Recommended | Why / note |
|---|---|---|
| Scratches or dents on flat metal | Low-angle ring or bar (dark field) | Defects glow on a dark background. |
| Print on curved, shiny surfaces | Dome light | Removes glare and hotspots. |
| Laser marks on mirror-like metal | Coaxial or flat dome | Flat areas bright, marks dark. |
| Outer dimensions, holes | Backlight (collimated for precision) | Sharp silhouette for edge measurement. |
| Fast webs or long parts | Line light + line-scan camera | Very high intensity for short exposure. |
| Shallow 3D defects on textured parts | Multi-angle lighting | Separates shape from color and print. |
| Remove color variation, read through film | Infrared (850–940 nm) | Many dyes and films become transparent. |
| Fluorescent glue, marks or coatings | UV (365–405 nm) + long-pass filter | Only the fluorescing material appears bright. |
| Color checks and sorting | White light + color camera | Or mono camera with several colored lights. |
Examples
Illustrative setups showing how the components are combined in practice.
Application example
Application example
Application example
Application example
FAQ
A single wavelength lets you control contrast precisely: features of the same color look bright, complementary colors look dark. A monochrome sensor also uses every pixel, giving higher effective resolution than a color sensor.
Strobe switches the light on only during the camera exposure, reducing heat and extending life. Overdrive briefly drives the LEDs above their continuous rating for very bright, very short flashes that freeze fast motion — with strict limits on pulse length and duty cycle.
Lifetime depends mainly on temperature and drive current. Strobing, good heat sinking and moderate current keep output stable for a long time; constant high-current operation in a hot enclosure shortens it.
A bandpass filter matched to your light blocks ambient light and other stations' lights, making results more stable. Polarizers reduce glare on glossy parts.
Yes. Custom lengths, diameters, angles and wavelengths are common when a standard light does not fit the station or the part.
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