Optical stereo device and autofocus method therefor

Abstract

The present invention provides an optical stereo device with an autofocus feature as well as a corresponding autofocus method for optical stereo devices. The optical stereo device comprises imaging means configured to provide a stereo image of an object of interest by means of combining a right eye image and a left eye image and a control unit operatively connected to the imaging means and configured to receive the right eye image and the left eye image and to adjust the focus position of the imaging means. The control unit is further configured to: (i) identify a feature in the right eye image and identify the same feature in the left eye image; (ii) determine the direction and / or the magnitude of a displacement vector defined by the displacement of the feature identified in the right eye image relative to the same feature identified in the left eye image; and (iii) to adjust the focus position relative to the identified feature on the basis of the direction and / or the magnitude of the displacement vector. According to preferred embodiments, the imaging means comprise a first and a second imaging unit and the control unit is further configured to adjust the focus position by increasing the focus position in case the displacement of the identified feature is a shift to the right or decreasing the focus position in case the displacement is a shift to the left.

Description

technical field [0001] The invention relates to an optical stereo device and an automatic focusing method thereof. In particular, the invention relates to a stereo camera or stereo microscope and a method of autofocusing such an optical stereo device. Background technique [0002] The use of optical stereo devices, such as stereo cameras, is becoming more and more common in many different fields. For example, in the medical field, more and more stereo cameras and / or stereo microscopes are used to assist medical professionals in performing tasks such as medical operations and examinations. This is because a stereo camera or a microscope can provide a three-dimensional view of the object of interest and thus can provide further information about the object of interest. Typically, optical stereoscopic devices offer the possibility to enlarge the picture by means of special lens systems, such as adjustable lenses. Some sophisticated stereomicroscopes or stereo camera setups i...

AI Technical Summary

Problems solved by technology

The contrast of the image of the object of interest is generally determined by means of image processing software running on the control unit, and the focal length and / or the distance between the camera or microscope and the object of interest are repeatedly changed in the direction of higher contrast until it is no longer discernible Further improvement in image quality until

However, this known autofocus method (i.e. determination of the optimal focus position by means of contrast optimization) has the disadvantage that in most cases there is initially no information about (i) the distance from the current focus position to the optimal or optimal focus position Information about how far away and (ii) in which direction the optimal focus position is relative to the current focus position

As a result of this, it is often difficult to find a range of acceptable focus positions around the best focus position as a first "guess" because the image quality only changes gradually outside such a range of acceptable focus positions

Therefore, autofocus methods based on contrast maximization are computationally quite challenging and usually not very fast due to iterative methods

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