{"id":3857,"date":"2026-11-05T14:47:03","date_gmt":"2026-11-05T06:47:03","guid":{"rendered":"https:\/\/www.ihylight.com\/?p=3857"},"modified":"2026-11-05T14:47:03","modified_gmt":"2026-11-05T06:47:03","slug":"machine-vision-lighting-techniques-for-oem-inspection-systems","status":"publish","type":"post","link":"https:\/\/www.ihylight.com\/ko\/machine-vision-lighting-techniques-for-oem-inspection-systems\/","title":{"rendered":"Machine Vision Lighting Techniques for OEM Inspection Systems"},"content":{"rendered":"

\"Infrared<\/p>\n

In machine vision, lighting is not an accessory, it’s part of the measurement. The correct geometry determines whether a camera sees an edge, a readable mark, a surface defect or only glare. Ring, backlight, bar, and coaxial illumination each solve a specific imaging problem. Selecting among them starts with the feature to be inspected the surface finish, the camera axis, the working distance and the motion of the production line.<\/p>\n

This guide covers how each technique works, where it usually fits, and what to check before you commit a custom light to an inspection station. Shenzhen IHY Lighting develops\u00a0\/ customs\u00a0COB LED, LED module and application oriented lighting solutions; its published product range covers COB LED and LED modules for OEM integration\u00a0but the final geometry, wavelength, and interface always come down to the inspection job.<\/p>\n

Start With the Image Task, Not the Fixture Shape<\/b><\/strong><\/h2>\n

Start by defining what the camera actually needs to see. A gauging task usually needs a high contrast silhouette or a repeatable edge. A print or code reading task needs even contrast across the field of view. Scratch, burr, dent and raised text inspection often needs controlled scattering. Reflective metal, glass and polished plastic require a geometry that keeps the reflection away from the lens or spreads it into a predictable field.<\/p>\n

Before we choose\u00a0a light, record the part material and finish, the feature size and color, and the optical and mechanical constraints. Ambient light, enclosure space, and heat limits also matter. A light that produces a good bench image can fail on a moving line if it cannot be strobed, synchronized, or mounted at the required distance. Put these conditions into the lighting spec from the start. Don’t leave them to be fixed after you’ve bought the light.<\/p>\n

Ring Lighting for General Front Illumination<\/b><\/strong><\/h2>\n

A ring light places LEDs around the camera lens and sends light toward the part from a near\u00a0axis, front\u00a0facing direction. Its circular arrangement gives broad coverage and is often a practical starting point for flat or gently curved parts, assembly presence checks, label reading, and general surface inspection. Different working distances and diffusion treatments change how much shadow, texture, or specular reflection reaches the sensor.<\/p>\n

Ring illumination is useful when the part must be lit from several azimuths at once, but it is not automatically shadow\u00a0free. Recesses, tall edges, and glossy surfaces can still create uneven highlights. A low\u00a0angle ring or segmented control can emphasize edge texture, while a diffused ring can reduce harsh point reflections. For an OEM station, specify the inner diameter, outer envelope, working distance, beam angle, color or wavelength, diffuser, trigger interface, and access for the lens and cable routing.<\/p>\n

Backlighting for Silhouettes and Dimensional Edges<\/b><\/strong><\/h2>\n

Backlighting places the source behind the part, opposite the camera. The camera sees the object as a dark silhouette against a bright field. This separation is valuable for outline measurement, hole and slot detection, presence or absence, position checks, and dimensional gauging. Because the image depends mainly on the boundary, small changes in surface color or texture often matter less than they do with reflected\u00a0light inspection.<\/p>\n

The trade\u00a0off is deliberate: surface markings, scratches, and color information largely disappear. Use a backlight when the edge is the measurement target, not when the inspection depends on top\u00a0surface appearance. Mechanical alignment is critical. The source must fill the intended field without exposing gaps around the part, and the camera, part plane, and light plane must remain stable as the line runs. Verify edge sharpness at the actual lens aperture and exposure settings rather than judging only by brightness.<\/p>\n

Bar Lighting for Directional and Long<\/b><\/strong>\u00a0<\/b><\/strong>Format Coverage<\/b><\/strong><\/h2>\n

Bar lights use one or more linear LED assemblies positioned beside, above, below, or at an angle to the part. They are flexible when the camera cannot be surrounded by a ring or when the target is long, wide, recessed, or moving through a constrained inspection window. Multiple bars can be arranged as a two\u00a0sided, four\u00a0sided, or opposed\u00a0angle system, with each channel tuned for a different feature.<\/p>\n

The main design variable is direction. A shallow angle can make scratches, raised edges, knurling, or embossed text scatter light into the camera. A higher angle can provide broad bright\u00a0field coverage for flat faces. Bar spacing and overlap determine uniformity, while the bar length and diffusion determine whether the ends of the image are darker than the center. For OEM equipment, confirm mounting rigidity, adjustment range, cable exit, heat path, strobe response, and whether independent channels are needed for alternate recipes.<\/p>\n

Coaxial Illumination for Flat Reflective Surfaces<\/b><\/strong><\/h2>\n

Coaxial illumination sends light along the camera’s optical axis, typically through a beam\u00a0splitting arrangement. The result is a controlled, nearly on\u00a0axis field that can reveal contrast on flat, mirror\u00a0like, or highly reflective surfaces where an angled source would produce a bright spot or a reflection of the fixture. It is commonly considered for glass, polished metal, wafers, films, and flat code or mark inspection when surface geometry is controlled.<\/p>\n

Coaxial designs are sensitive to working distance, optical path, and the exact flatness and finish of the target. Curved parts can still produce gradients or reflections outside the useful field. Check the beam\u00a0splitter envelope against the lens, camera mount, and enclosure, and test the complete optical stack with the production material. If a mark is low contrast, wavelength and polarization may matter as much as the housing geometry; those choices should be validated with images from representative parts.<\/p>\n

How to Choose Between the Four Techniques<\/b><\/strong><\/h2>\n

Use this decision sequence for an OEM inspection system:<\/p>\n