Which detector design factor most directly contributes to higher spatial resolution?

• A. Fill factor
• B. Pixel pitch
• C. Sensor temperature
• D. Frame rate

Answer: (A)

Spatial resolution in detectors is all about how effectively the image is sampled by the detector’s active area. The fraction of each pixel that is photosensitive, known as the fill factor, directly controls how much of the incoming light from a small detail actually contributes to the pixel’s signal. A higher fill factor means more of the pixel area is collecting photons, so a tiny feature produces a stronger, more faithful signal in the same pixel. This reduces information loss at the gaps between light-sensitive regions, reduces blurring from interpixel gaps, and improves the modulation of the high-frequency content of the image, all of which sharpen the image and reveal finer details.

While smaller pixel pitch can in principle improve resolution by sampling the image more finely, that benefit depends on having enough active area to capture the light. If the fill factor is low, the advantage of smaller pixels is undermined by lost light and increased noise, so the practical gain in resolution is limited. The other factors—sensor temperature and frame rate—primarily affect noise performance and temporal sampling, not the intrinsic ability to distinguish fine spatial details.