A proposal of depth of focus equation for an optical system combined a digital image sensor

Abstract

When an optical system and a digital image sensor are combined, it is known that pixel size of the sensor affects digital images. In particular, the DOF was not represented in a simple formula due to the influence of pixel size. To consider the effect of pixel size on digital images, we set the ratio, fC/fN, between the cut-off frequency of the optical system, fC, and the Nyquist frequency of the imaging device, fN, as the parameter expressing the effect of the pixel size. By using the parameter, we derived that the DOF can be expressed as a simple formula. For confirming the DOF formula, we measured the DOF of a microscope combined a digital image sensor. The values calculated from the DOF formula that we derived were consistent with the experimentally measured results.We propose our formula expressing the DOF when an optical system and a digital image sensor are combined

Keywords

• Depth of focus
• Digital image sensor
• Microscope