Modulation Transfer Function
The modulation transfer function (MTF) is a measurement of the microscope's ability to transfer contrast from the specimen to the intermediate image plane at a specific resolution. Computation of the modulation transfer function is a mechanism that is often utilized by optical manufacturers to incorporate resolution and contrast data into a single specification. Measurements of the relative modulation is useful for characterizing not only traditional optical systems, but also photonic systems such as analog and digital video cameras, image intensifiers, and film scanners.
Modulation of the output signal, the intensity of light waves forming an image of the specimen, corresponds to the formation of image contrast in microscopy. Therefore, a measurement of the MTF for a particular optical microscope can be obtained from the contrast generated by periodic lines or spacing present in a specimen that result from sinusoidal intensities in the image that vary as a function of spatial frequency. Topics covered in this section also include the optical transfer function, phase transfer function, and the contrast transfer function, all of which play a crucial role in resolution and contrast.
Utilize a periodic line grating as the specimen and simulates images produced with a diffraction-limited optical microscope as a function of spatial frequency in this featured tutorial.
Explore the changes in the point spread function distribution as the spatial frequency cutoff is varied in a typical modulation transfer function plot in the featured tutorial.
Examine the effect of microscope objective and condenser numerical aperture size on the relative modulation as a function of specimen spatial frequency in this interactive tutorial.
The interactive java tutorial demonstrates intensity scans made from images of the periodic lines present on the MBL-NNF test target measured with a plan apochromatic objective.
Examine periodic object produced diffraction images at several focal depths in this featured interactive tutorial. The periodic object featured in this tutorial is a Siemens test star.
Explore the effects of popular contrast modes on image contrast and the modulation transfer function of the modified microscope in this interactive tutorial.
Selected Literature References
The reference materials listed in this section are an excellent source of information on the modulation transfer function, contrast transfer function, and optical transfer function as applied to microscopes and other optical systems, video systems, and photographic film.