Pixel size directly affects: Sampling (sample area per pixel = pixel size / magnification), Sensitivity (photons per pixel ∠pixel area), Full well capacity (∠pixel area), and Data rate (smaller pixels = more pixels = more data). Common scientific camera pixel sizes: 3.7μm (E9/Prime 95B), 4.6μm (qCMOS), 6.5μm (Kinetix, standard sCMOS).
Physical Parameter
Pixel Size
The physical dimension of each sensor element
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Definition
The physical dimensions of each light-sensitive element on the camera sensor, typically measured in micrometers. Smaller pixels enable finer sampling but collect fewer photons per pixel; larger pixels are more sensitive but sample more coarsely.
Technical Details
Simplified
Think of pixels like buckets catching raindrops of light. Smaller buckets (pixels) give you more detail about exactly where the rain is falling, but each bucket catches fewer drops. Larger buckets catch more drops but give a blurrier picture of where exactly the rain landed.
Why It Matters
Pixel size determines the trade-off between spatial sampling and sensitivity. For any given objective, there's an optimal pixel size that captures the optical resolution without sacrificing sensitivity.
Practical Example
E9 (3.7μm pixels) vs Kinetix (6.5μm pixels): At 25×, E9 samples at 148nm (good for 1.1 NA). Kinetix would sample at 260nm (severely undersampling 1.1 NA resolution). Conversely, at 60×, Kinetix samples at 108nm (good for 1.2 NA) while E9 would oversample at 62nm.