ZEISS Newsletter
Glossary old book

Glossary

  • Coaxial Light

    Coaxial Light

    Lightpath pico side view

    The light coming from the light guide on the rear side of the microscope is reflected by an internal mirror through the lens onto the treatment area. The coaxial light provides shadow free illumination and illuminates cavities and root canals.





    The coaxial light of S7 / OPMI PROergo, S100 / OPMI pico and S100 / OPMI pico in combination with MORA interface provides a shadow free light for homogenous illumination even in cavities or root canals. With coaxial light fine details are visible (1). Diffuse light (2) or oblique light (3) produce shadows. Root canals or fractures in shadowy areas might be missed.

    Coaxial Light

    (1) Coaxial Light

    Room Light

    (2) Room Light

    Oblique Light

    (3) Oblique Light

  • Lightpath

    Lightpath

    The lens collects the image information from the object. The left and right light path in the surgical microscope view different angles of the object and thus create the impression of a three-dimensional image.

    The magnification changer minifies or magnifies the image depending on the selected position. The tube lens creates an intermediate image of the object, which is projected into the eye magnified with the eyepiece.

    The prisms in the tube rotate the image the right way and allow for adjusting the pupil distance, so that the pupils of the viewer match the surgical microscope's exit pupils.

    Stereoscopic lightpath

    The Stereoscopic Lightpath of a surgical microscope provides a
    Three Dimensional Image Impression.

  • Magnification

    Magnification

    The magnification with which we can see a structure in the eyepiece is the end magnification. It is the end result of the various optical components of a surgical microscope. It can be calculated easily with the following formula:

    magnification

    The magnification was calculated for an OPMI pico with 12,5 x eyepieces, focal length of the tube of 170 mm and a 250 mm fixed focal length lens. The lower the magnification the bigger is the field of view. Therefore, a small magnification provides a good overview and easy orientation in the treatment area.

    Example:

    Focal distance tube: f = 170mm
    Focal distance of lens: f = 250 mm
    Magnification changer factor: 2.5 x
    Eyepiece factor: 12.5x

    The formula for the calculation of the end magnification applies to surgical microscopes with fixed focal length
    (like OPMI pico).

  • Varioscope

    Varioscope

    Unlike an objective lens, the varioscope of S7 / OPMI PROergo can be set to different focusing ranges. That accommodates a working distance of between 200 and 415mm. OPMI PROergo can then be positioned at varying distances within this range from the treatment area. Unlike a surgical microscope with a fixed focal distance lens (like S100 / OPMI pico and S100 / OPMI pico in combination with MORA interface), it is not necessary to raise or lower OPMI PROergo to focus it.

    How is that possible? The lens system of a varioscope is composed of two lens groups. To focus at a selected working distance, the upper lens group is repositioned along the optical axis. The motorized varioscope of OPMI PROergo can be controlled by pressing a button on the multifunctional handgrip.

    varioscope

    The working distance can be changed according to the internal displacement of the varioscope's second lens system.

  • Working Distance

    Working Distance

    When working with a surgical microscope on a patient, a certain distance is required between the object and the front lens of the surgical microscope. That is what is referred to as the working distance. The working distance is the distance between the front lens of the surgical microscope and the object.

    The closer the working distance, the higher the end magnification. The longer the working distance, the lower the end magnification.

    For S100 / OPMI pico and S100 / OPMI pico in combination with MORA interface lenses with 200, 250 or 300 mm working distance are available. These are lenses with a fixed focal length. The varioscope of the OPMI PROergo accommodates a working distance of between 200 and 415mm. This allows the dentist to adjust the surgical microscope to suit his or her individual ergonomic needs.

    working distance

    The working distance of a microscope is the distance between the opbject level and the front lens of the microscope.

  • Apochromatic Optic

    Chromatic Aberration

    Chromatic Aberration
    Chromatic Aberration

    A typical optical aberration leading to reduced image quality is chromatic aberration. This results in color fringes that blur the image. This aberration is caused by the prismatic effect of a lens. White light emerging from an object and passing through the lens is dispersed into its spectral colors when it exits the lens. The lens bundles the exiting light rays at one focal point, but because blue light is refracted more strongly than the other colors, it is focused closer to the lens. Red light is focused at the greatest distance from the lens. This means that the focus is "smeared," leading to color fringes and an impression of blurring.

    Apochromatic Correction

    Apochromatic Correction
    Apochromatic Correction

    Chromatic aberration can be largely corrected by implementing the appropriate lens design and by using glass materials with special refractive indices. Apochromatic correction is the term used to describe the highest level of correction utilized to remedy this aberration by imaging red, green and blue light at a common focal point, therefore generating excellent image quality and outstanding color rendition right into the periphery of the lens.