Mtf cameraexplained

Cameras are classic examples of concatenated imaging systems, comprising a lens focusing a real image onto a pixelated image sensor for recording. When specifying a camera system for your application, a reasonable question to ask is “Am I going to be able to resolve a feature of size X?”

MTFOptics

More detailed analysis of lenses accounting for effects like other aberrations, variation of performance across the field of view, chromatic errors, and other pupil shapes quickly gets into the arena of optical engineering. For that, Optikos relies on sophisticated raytracing software with Fourier analysis tools to evaluate and optimize image quality. Optikos is also a world leader in the measurement of MTF so that the effects of manufacturing tolerances can also be understood and mitigated.

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Modulation transfer function

Any device that relays, records, displays, or otherwise operates on an image has its own MTF curve describing the fidelity of that process. When concatenating incoherent imaging systems together, the product of their MTF curves describes the image quality of the entire system. Beware that there are scenarios where this multiplication is not valid—read more about MTF multiplication here.

MTFimage quality

The calculator above can help answer that question. It calculates Camera MTF while taking advantage of a couple of idealizations:

For more information on MTF, see our page How to Measure MTF. And as always, if you need help designing a camera system for your business, reach out to our teams on our site here or at sales@optikos.com.

MTFlens

When switching into Defocus Mode, you will notice the diffraction-limited lens MTF change into the form of a straight line, as is expected for a square aperture lens. For focusing errors that lead to large departures from the diffraction limit, this Lens MTF is a reasonable approximation for a circular aperture lens.

To relate with feature sizes in object space, multiply the image space frequencies by the magnification of the lens to transform into object space frequencies.

…a microscope is called the numerical aperture (NA) and is equal to the sine of half the angle subtended by the aperture at an object point times the index of refraction of the medium between the object and the objective lens. For binoculars, telescopes, and photographic lenses in which the…

MTF cameratest

He designated the term numerical aperture (N.A.) as the measure of the objective’s ability to collect diffracted light and thus also of its power to resolve detail. On this basis it is obvious that the greater the magnification of the objective, the greater the required N.A. of the objective.…

These idealizations allow a closed form solution that can be described with simple equations, as described in Joseph W. Goodman’s book Fourier Optics, particularly in sections 2.4 Two-Dimensional Sampling Theory, and 6.3.3 The OTF of an Aberration-Free System.

…microscope are determined by the numerical aperture (N.A.) of the objective. The N.A. is defined as the sine of half the angle of the cone of light from each point of the object that can be accepted by the objective multiplied by the refractive index (R.I.) of the medium in…

The Modulation Transfer Function (MTF) is commonly employed as an objective characterization of image quality. It is typically analyzed as a one-dimensional function of image contrast (resolution) versus spatial frequency (feature size).