Optical ophthalmic apparatus and method of focusing image of retina

A method of focusing an image of a retina of an eye on an image sensor of the image detector of optical ophthalmic apparatus, the method comprising providing, by an image source of the optical ophthalmic apparatus, a picture;

• directing, by the image source, light of the picture toward an imaging arrangement of the optical ophthalmic apparatus, the method comprising
• forming, by the imaging arrangement together with refraction of an eye, an image of the picture on a first image plane;
• locating, by the imaging arrangement, the first image plane at a known location with respect to a typical eye of a human being in a situation where the optical ophthalmic apparatus is in an examination position with respect to the typical eye;
• directing, by the imaging arrangement, light from the retina to an image detector of the optical ophthalmic apparatus;
• forming, by the imaging arrangement together with refraction of the eye, an image of the retina on a second image plane;
• focusing, by the imaging arrangement the first image plane and the second image plane of which are optical conjugates to each other, the image of the retina accurately on an image sensor of the image detector if the image of the picture is simultaneously accurately focused on the retina of the eye by the eye, or stimulating the eye to accommodate in order to focus the image of the picture accurately on the retina if the image of the picture is out-of-focus on the retina;
• and
• receiving, by a focus adjustment unit of the optical ophthalmic apparatus, control from a person the eye of whom is examined and altering at least one of the following:
• a focal length of the imaging arrangement and a distance between the imaging arrangement and the first image plane or the second image plane for accurately focusing the image of the picture on the retina of the eye based on the control, if the image of the picture is out-of-focus on the retina based on the accommodation of the eye,
• wherein the imaging arrangement comprises a common optical component that is common to light of the picture and light received from the retina, and
• wherein the focus adjustment unit is configured to modify at least the common optical component.

A method of focusing an image of a retina of an eye on an image sensor of the image detector of optical ophthalmic apparatus, the method comprising providing, by an image source of the optical ophthalmic apparatus, a picture;

• directing, by the image source, light of the picture toward an imaging arrangement of the optical ophthalmic apparatus, the method comprising
• forming, by the imaging arrangement together with refraction of an eye, an image of the picture on a first image plane;
• locating, by the imaging arrangement, the first image plane at a known location with respect to a typical eye of a human being in a situation where the optical ophthalmic apparatus is in an examination position with respect to the typical eye;
• directing, by the imaging arrangement, light from the retina to an image detector of the optical ophthalmic apparatus;
• forming, by the imaging arrangement together with refraction of the eye, an image of the retina on a second image plane;
• focusing, by the imaging arrangement the first image plane and the second image plane of which are optical conjugates to each other, the image of the retina accurately on an image sensor of the image detector if the image of the picture is simultaneously accurately focused on the retina of the eye by the eye, or stimulating the eye to accommodate in order to focus the image of the picture accurately on the retina if the image of the picture is out-of-focus on the retina;
• and
• receiving, by a focus adjustment unit of the optical ophthalmic apparatus, control from a person the eye of whom is examined and altering at least one of the following:
• a focal length of the imaging arrangement and a distance between the imaging arrangement and the first image plane or the second image plane for accurately focusing the image of the picture on the retina of the eye based on the control, if the image of the picture is out-of-focus on the retina based on the accommodation of the eye,
• wherein the imaging arrangement comprises a common optical component that is common to light of the picture and light received from the retina, and
• wherein the focus adjustment unit is configured to modify at least the common optical component to alter the focal length of the imaging arrangement and/or the distance between the imaging arrangement and the first image plane or the second image plane.