How To Create EDOF (Extended Depth of Focus) Images

Smith, Clinton; Horz, Mike

May 08, 2019

How To Create EDOF (Extended Depth of Focus) Images

Overview of the 3 methods in the LAS X software

Extended Depth of Focus (EDOF) images How_to_create_EDOF_images_intro.jpg

Watch this video to see how you can rapidly record sharp optical microscope images of samples with a large height variation. This is done with the optional Extended Depth of Focus (EDOF) function of the LAS X software from Leica Microsystems. Acquisition of EDOF images of a printed circuit board, recorded from low to high magnification using a Leica microscope, are shown as an example.

What you learn in the tutorial

Key Learnings

The operation of EDOF by acquiring a z-stack of images in 3 modes is demonstrated:

Custom: the top and bottom of the sample feature are brought into focus and used as reference points
Symmetric: the middle of the sample feature is brought into focus and used as a reference point
Start up: the bottom of the sample feature is brought into focus and used as a reference point

How does EDOF work?

EDOF imaging with Leica widefield optics (stereo, compound, or digital microscopes) is based on focus variation. The limited focus depth (depth of field) of the optics is exploited to determine sample height and depth information. Vertical movement of the sample relative to the objective lens enables in-focus information along the optical axis to be determined. For each vertical position of the sample, the LAS X software separates the image region in sharp focus from the out-of-focus one. A “stack” of images is acquired and the areas in-focus are combined to make a sharp composite image of the sample with a large vertical range.