What is the importance of the Modulation Transfer Function?

Dec 7, 2016 by

As an optical designer, you must’ve heard about the modulation transfer function a couple of times. It is the scientific method that is widely used to describe the performance of the lens. If you are planning to use it, you must ensure that you know how to hire the right MTF testing service here at http://www.image-science.com and of course, you must understand the importance of the modulation transfer function so that you can utilize it properly and wisely.

The name says it all—the modulation transfer function is the measurement of the transfer of the modulation that is extracted from the object onto the image. To put it simply, the modulation transfer function is a tool use for measuring on how the lens’ ability in reproducing the object into the image.

When you are talking about the modulation transfer function of the lens, make sure that you can identify the type of test pattern that you are going to use because there are different types of test patterns out there. One of the most preferred pattern in modulation transfer function is the sine wave pattern in which the density of the optics will vary from white and black in a very smooth manner and of course, the line profile imitates the sine wave perfectly. But, these patterns are quite hard to generate and regarding the image that is produced by this certain type of pattern is hard to measure just by the use of the naked eyes. That is why, as you can notice, in modulation transfer function most of them are using the bar-type pattern. This is because the bar-type patterns can have a higher measurement of the modulation transfer function compared to the sine wave patterns but honestly, the difference is rather small.

You should not only consider the type of the test pattern that you are going to use, but the light that you are going to provide in illuminating as well as the type of detector that you are going to use when it comes to the recording can influence the modulation transfer function a lot. It is because the modulation transfer function will all depend on the wavelengths that are also based on the lights that you are using. For instance, if you opt to use a blue light then you will most likely have a higher modulation transfer function compared to when you use a red light. In most cases, white light is often used, but the results will all depend on the color temperature. On the other hand, tungsten light will have a stronger and longer wavelength component if you will compare it to the daylight so basically, the modulation transfer function that you are measuring using the tungsten light will most likely be lower if you’d compared it to the modulation transfer function that you are going to measure on the daylight. Regarding detector, if the sensor is a bit sensitive to the blue light then you can conclude that the results will have a higher MTF.

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