Optics
This section covers the values that are settled by calculation first: the size of one pixel on the object, working distance (WD) and depth of field. How many pixels a defect occupies on screen is decided by these numbers before any algorithm runs.
Start with these
- How to Calculate Machine-Vision Lens Focal Length — the basic formula from FOV, WD and sensor size
- Machine Vision Lens Calculator — where the shortcut formula breaks at higher magnification, plus depth of field and diffraction
- Vision Types Split First by Wavelength and Pixel Size — several vision methods compared in one table
- In SWIR, One Stop Down Erases a 3.4 µm Pixel — how diffraction covers a pixel as wavelength grows
Unfamiliar terms are explained in the Glossary, and a reading order across topics is in the Start Here guide.
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A Light Field Camera Trades Pixels for Depth
A light field camera bundles the pixels behind each microlens into one point. At 2x on a 25 μm gold wire, no bundle size keeps both the wire and the loop.
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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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How Much Closer Does a CIS Sit Than a Line Scan Camera?
For the same 300 mm field, area scan needs a 555.7 mm WD and line scan 416.2 mm, but a CIS reads from 10 to 20 mm. One 900 dpi line then passes…
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A Board at 0.5 m/s Leans 15 mm Under a Rolling Shutter
On the same 100 mm board, a rolling shutter shifts the top and bottom rows 15 mm, and a global shutter at a 100 μs exposure still smears 50 μm. In color, a…
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Vision Types Split First by Wavelength and Pixel Size
On the same 100 mm PCB, only area and line scan give a 50 μm defect two pixels or more. LWIR blurs it at 48.8 μm, and 3D heights split into 4.9 μm…
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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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Why Do Shiny Parts Look Cold to a Thermal Camera?
A 70 °C aluminum capacitor reads 30.6 °C on a thermal camera and a 90 °C chip reads 75 °C. One reflects the room; the other shares a pixel with the board.
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A Machine Vision Lens Calculator That Catches the FOV Error a Shortcut Formula Misses
At magnification 0.141 the shortcut reports a 4,096 px setup's FOV 14% too wide. A 25 mm lens reaches 100 mm only at 202 mm, and the 3.15 mm depth opened at F8…
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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…
