Lighting Design
With the same camera, a defect can appear or vanish depending on the angle and wavelength of the light. This section collects articles on choosing among coaxial, dome, dark-field and backlight methods, and on handling reflection, wavelength and brightness drift.
Start with these
- Six Machine-Vision Lighting Methods and How to Choose — how each method works and the order for choosing
- For Scratches on Highly Reflective Metal, Choose the Lighting First — a lighting map by surface type
- Why a Black Spot Remains in the Center of a Dome Light — the viewing-hole dark spot and fill light
- When the Light Dims by 5 %, How Many Good Pixels Turn Into Defects? — how brightness change affects decisions
Unfamiliar terms are explained in the Glossary, and a reading order across topics is in the Start Here guide.
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Raising the Camera Leaves the Glint of Its Built-in Light in Place
A camera's built-in light puts a hotspot on a glossy cover at half the LED offset, and raising the camera won't move it. A 12 mm lens must tilt 10.8° to clear it.
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When the Light Dims by 5 %, How Many Good Pixels Turn Into Defects?
With the decision line fixed, a 5 % drop in lamp output turns 19 % of good pixels into defects. This traces how anomaly detection scores slip under lighting change and what a…
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In SWIR, One Stop Down Erases a 3.4 μm Pixel
At 1800 nm a fully open f/2.8 leaves only 15% contrast on a 3.4 μm pixel, and one stop down takes it to zero. Work out the cost of stopping down from wavelength,…
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A Depth Camera’s Error Grows with the Square of Distance
A 50 mm baseline stereo depth camera wobbles by 0.6 mm at 40 cm. Seeing a 0.5 mm lift on a board needs it within 21 cm, and it cannot measure closer than…
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What to Write First in a Spec Sheet Before Buying Machine Vision Equipment
For a 100 μm defect on a 100 mm cover moving at 100 mm/s, filling the request in the order 33.3 μm/px, 244 μs and 122.9 MB/s brings comparable quotes. A 1% miss…
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Reserve Room for Vision Cameras and Lighting at the Mechanical Design Stage
After mechanical design is done, there is no room for the light. A ring light for a 100 mm FOV needs a 106.5 mm opening at 30 mm, and a 40 mm low-angle…
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For Scratches on Highly Reflective Metal, Choose the Lighting First
Scratch lighting on polished or plated metal is chosen by surface shape: coaxial for flat mirrors with a 0.93° tolerance without a diffuser, a dome for curves, 15° low-angle light for hairlines, and…
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Changing the Sensor Means Recalculating the Illumination
A quantum efficiency of 15 % at 940 nm demands 4.9 times the photons and 2.85 times the watts of lighting compared with 550 nm, rising to 14.6 and 8.5 when the exposure…
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On Moving Parts, Photometric Stereo Shrinks the Standstill Condition to 0.5 ms
On a moving part, photometric stereo moves its standstill condition into the gap between two exposures. At 50 μm/px and 100 mm per second the gap is 0.5 ms, and directions split by…
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When an LED Light Dims, Yesterday’s Threshold Misses Today’s Defect
If a white particle clears its threshold by 14.3 %, it passes without any alarm once light output falls 15 %. Warm-up alone can take 7.5 %, so the stop limit sits at…
