optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...

, jitter is used to refer to motion that has high temporal frequency relative to the integration/exposure time. This may result from vibration in an assembly or from the unstable hand of a photographer. Jitter is typically differentiated from smear, which has a lower frequency relative to the integration time. Whereas smear refers to a relatively constant rate during the integration/exposure time, jitter refers to a relatively sinusoidal motion during the integration/exposure time. The equation for the optical

Modulation transfer function The optical transfer function (OTF) of an optical system such as a camera, microscope, human eye, or image projector, projector specifies how different spatial frequencies are captured or transmitted. It is used by optical engineers to describe h ...

associated with jitter is :

MTF_(k) =e^

where k is the

spatial frequency In mathematics, physics, and engineering, spatial frequency is a characteristic of any structure that is periodic across position in space. The spatial frequency is a measure of how often sinusoidal components (as determined by the Fourier tra ...

and

\sigma

is the amplitude of the jitter. Note that this frequency is in radians of phase per cycle. The equivalent expression in Hz is :

MTF_(u) =e^

where u is the spatial frequency and

\sigma

is again the amplitude of the jitter (note that as the jitter approaches infinity, the value of the function tends towards zero). For spacecraft, operation in a vacuum often means low mechanical damping. Meanwhile, spacecraft are compact and rigid, to withstand high launch loads. Jitter, then, is transmitted easily and often a limiting factor for high-resolution optics.

References

{{photography subject Science of photography