fbpx
Wikipedia

Stereo microscope

The stereo, stereoscopic or dissecting microscope is an optical microscope variant designed for low magnification observation of a sample, typically using light reflected from the surface of an object rather than transmitted through it. The instrument uses two separate optical paths with two objectives and eyepieces to provide slightly different viewing angles to the left and right eyes. This arrangement produces a three-dimensional visualization of the sample being examined. Stereomicroscopy overlaps macrophotography for recording and examining solid samples with complex surface topography, where a three-dimensional view is needed for analyzing the detail.

Stereo microscope
Modern stereomicroscope optical design.
A - Objective B - Galilean telescopes (rotating objectives) C - Zoom control D - Internal objective E - Prism F - Relay lens G - Reticle H - Eyepiece

The stereo microscope is often used to study the surfaces of solid specimens or to carry out close work such as dissection, microsurgery, watch-making, circuit board manufacture or inspection, and fracture surfaces as in fractography and forensic engineering. They are thus widely used in manufacturing industry for manufacture, inspection and quality control. Stereo microscopes are essential tools in entomology.

The stereo microscope should not be confused with a compound microscope equipped with double eyepieces and a binoviewer. In such a microscope, both eyes see the same image, with the two eyepieces serving to provide greater viewing comfort. However, the image in such a microscope is no different from that obtained with a single monocular eyepiece.

Contents

The first optically feasible stereomicroscope was invented in 1892 and became commercially available in 1896, produced by Zeiss AG in Jena, Germany.

1896 Greenough Stereo Microscope by Carl Zeiss Jena

American zoologist Horatio Saltonstall Greenough grew up in the elite of Boston, Massachusetts, the son of the famous sculptor Horatio Greenough Sr. Without the pressures of having to make a living, he instead pursued a career in science and relocated to France. At the marine observatory in Concarneau on the Bretton coast, lead by the former director of the Muséum national d'histoire naturelle, Georges Pouchet, he was influenced by the new scientific ideals of the day, namely experimentation. While dissection of dead and prepared specimens had been the main concern for zoologists, anatomists and morphologists, during Greenough’s stay at Concarneau interest was revived in experimenting on live and developing organisms. This way scientists could study embryonic development in action rather than as a series of petrified, two-dimensional specimens. In order to yield images that would do justice to the three-dimensionality and relative size of developing invertebrate marine embryos, a new microscope was needed. While there had been attempts to build stereomicroscopes before, by for example Chérubin d’Orleans and Pieter Harting, none had been optically sophisticated. Furthermore, up until the 1880s no scientist needed a microscope with such low resolution.

Greenough took action and, influenced by his Concarneau colleague Laurent Chabry’s attempts to construct intricate mechanisms to turn and manipulate the live embryo, conceived of his own instrument. Building on the recent discovery of binocularity as the cause of depth perception by Charles Wheatstone, Greenough designed his instrument with the phenomenon of stereopsis in mind.

Unlike a compound light microscope, illumination in a stereo microscope most often uses reflected illumination rather than transmitted (diascopic) illumination, that is, light reflected from the surface of an object rather than light transmitted through an object. Use of reflected light from the object allows examination of specimens that would be too thick or otherwise opaque for compound microscopy. Some stereo microscopes are also capable of transmitted light illumination as well, typically by having a bulb or mirror beneath a transparent stage underneath the object, though unlike a compound microscope, transmitted illumination is not focused through a condenser in most systems. Stereoscopes with specially-equipped illuminators can be used for dark field microscopy, using either reflected or transmitted light.

Scientist using a stereo microscope outfitted with a digital imaging pick-up and fibre-optic illumination

Great working distance and depth of field are important qualities for this type of microscope. Both qualities are inversely correlated with resolution: the higher the resolution (i.e. the greater the distance at which two adjacent points can be distinguished as separate), the smaller the depth of field and working distance. Some stereo microscopes can deliver a useful magnification up to 100×, comparable to a 10× objective and 10× eyepiece in a normal compound microscope, although the magnification is often much lower. This is around one tenth the useful resolution of a normal compound optical microscope.

The large working distance at low magnification is useful in examining large solid objects such as fracture surfaces, especially using fibre-optic illumination as discussed below. Such samples can also be manipulated easily so as to determine the points of interest.

There are two major types of magnification systems in stereo microscopes. One type is fixed magnification in which primary magnification is achieved by a paired set of objective lenses with a set degree of magnification. The other is zoom or pancratic magnification, which are capable of a continuously variable degree of magnification across a set range. Zoom systems can achieve further magnification through the use of auxiliary objectives that increase total magnification by a set factor. Also, total magnification in both fixed and zoom systems can be varied by changing eyepieces.

Intermediate between fixed magnification and zoom magnification systems is a system attributed to Galileo as the "Galilean optical system" ; here an arrangement of fixed-focus convex lenses is used to provide a fixed magnification, but with the crucial distinction that the same optical components in the same spacing will, if physically inverted, result in a different, though still fixed, magnification. This allows one set of lenses to provide two different magnifications ; two sets of lenses to provide four magnifications on one turret ; three sets of lenses provide six magnifications and will still fit into one turret. Practical experience shows that such Galilean optics systems are as useful as a considerably more expensive zoom system, with the advantage of knowing the magnification in use as a set value without having to read analogue scales. (In remote locations, the robustness of the systems is also a non-trivial advantage.)

Stereomicroscope with an illuminated butterfly specimen

Small specimens necessarily require intense illumination, especially at high magnifications, and this is usually provided by a fibre-optic light source. Fiber optics utilize halogen lamps which provide high light output for a given power input. The lamps are small enough to be fitted easily near the microscope, although they often need cooling to ameliorate high temperatures from the bulb. The fibre-optic stalk gives the operator much freedom in choosing appropriate lighting conditions for the sample. The stalk is encased in a sheath that is easy to move and manipulate to any desired position. The stalk is normally unobtrusive when the lit end is near the specimen, so usually does not interfere with the image in the microscope. Examination of fracture surfaces frequently need oblique lighting so as to highlight surface features during fractography, and fibre-optic lights are ideal for this purpose. Several such light stalks can be used for the same specimen, so increasing the illumination yet further.

More recent developments in the lighting for dissecting microscopes include the use of high-power LEDs which are much more energy efficient than halogens and are able to produce a spectrum of colors of light, making them useful for fluorophore analysis of biological samples (impossible with a halogen or mercury vapor light source).

Digital display

Labomed LB-343 5.0 MP digital stereo microscope with 9 inch HD LCD screen, HDMI video output, X/Y digital micrometer and moving stage

Video cameras are integrated into some stereo microscopes, allowing the magnified images to be displayed on a high resolution monitor. The large display helps to reduce the eye fatigue that would result from using a conventional microscope for extended periods.

In some units, a built-in computer converts the images from two cameras (one per eyepiece) to a 3D anaglyph image for viewing with red/cyan glasses, or to thecross converged process[clarify] for clear glasses and improved color accuracy. The results are viewable by a group wearing the glasses. More typically, a 2D image is displayed from a single camera attached to one of the eyepieces.

  1. "Introduction to Stereomicroscopy" by Paul E. Nothnagle, William Chambers, and Michael W. Davidson, Nikon MicroscopyU.
  2. Simon-Stickley, Anna (2019). "Image and Imagination. The Stereomicroscope on the Cusp of Modern Biology". NTM Journal of the History of Science, Technology and Medicine. 27 (2): 109–144. doi:10.1007/s00048-019-00211-0. PMID 31062033. S2CID 146809758.
  3. "Illumination for Stereomicroscopy: Reflected (Episcopic) Light" by Paul E. Nothnagle, William Chambers, Thomas J. Fellers, and Michael W. Davidson , Nikon MicroscopyU.
  4. "Illumination for Stereomicroscopy: Darkfield Illumination" by William Chambers, Thomas J. Fellers, and Michael W. Davidson , Nikon MicroscopyU.
Wikimedia Commons has media related toStereo microscopes.

Stereo microscope
Stereo microscope Language Watch Edit 160 160 Redirected from Stereomicroscope The stereo stereoscopic or dissecting microscope is an optical microscope variant designed for low magnification observation of a sample typically using light reflected from the surface of an object rather than transmitted through it The instrument uses two separate optical paths with two objectives and eyepieces to provide slightly different viewing angles to the left and right eyes This arrangement produces a three dimensional visualization of the sample being examined 1 Stereomicroscopy overlaps macrophotography for recording and examining solid samples with complex surface topography where a three dimensional view is needed for analyzing the detail Stereo microscope Modern stereomicroscope optical design A ObjectiveB Galilean telescopes rotating objectives C Zoom control D Internal objective E Prism F Relay lensG Reticle H Eyepiece The stereo microscope is often used to study the surfaces of solid specimens or to carry out close work such as dissection microsurgery watch making circuit board manufacture or inspection and fracture surfaces as in fractography and forensic engineering They are thus widely used in manufacturing industry for manufacture inspection and quality control Stereo microscopes are essential tools in entomology The stereo microscope should not be confused with a compound microscope equipped with double eyepieces and a binoviewer In such a microscope both eyes see the same image with the two eyepieces serving to provide greater viewing comfort However the image in such a microscope is no different from that obtained with a single monocular eyepiece Contents 1 History 2 Differences to normal optical microscopes 3 Magnification 4 Illumination 4 1 Digital display 5 See also 6 ReferencesHistory EditThe first optically feasible stereomicroscope was invented in 1892 and became commercially available in 1896 produced by Zeiss AG in Jena Germany 2 1896 Greenough Stereo Microscope by Carl Zeiss Jena American zoologist Horatio Saltonstall Greenough grew up in the elite of Boston Massachusetts the son of the famous sculptor Horatio Greenough Sr Without the pressures of having to make a living he instead pursued a career in science and relocated to France At the marine observatory in Concarneau on the Bretton coast lead by the former director of the Museum national d histoire naturelle Georges Pouchet he was influenced by the new scientific ideals of the day namely experimentation While dissection of dead and prepared specimens had been the main concern for zoologists anatomists and morphologists during Greenough s stay at Concarneau interest was revived in experimenting on live and developing organisms This way scientists could study embryonic development in action rather than as a series of petrified two dimensional specimens In order to yield images that would do justice to the three dimensionality and relative size of developing invertebrate marine embryos a new microscope was needed While there had been attempts to build stereomicroscopes before by for example Cherubin d Orleans and Pieter Harting none had been optically sophisticated Furthermore up until the 1880s no scientist needed a microscope with such low resolution Greenough took action and influenced by his Concarneau colleague Laurent Chabry s attempts to construct intricate mechanisms to turn and manipulate the live embryo conceived of his own instrument Building on the recent discovery of binocularity as the cause of depth perception by Charles Wheatstone Greenough designed his instrument with the phenomenon of stereopsis in mind 2 Differences to normal optical microscopes EditUnlike a compound light microscope illumination in a stereo microscope most often uses reflected illumination rather than transmitted diascopic illumination that is light reflected from the surface of an object rather than light transmitted through an object Use of reflected light from the object allows examination of specimens that would be too thick or otherwise opaque for compound microscopy Some stereo microscopes are also capable of transmitted light illumination as well typically by having a bulb or mirror beneath a transparent stage underneath the object though unlike a compound microscope transmitted illumination is not focused through a condenser in most systems 3 Stereoscopes with specially equipped illuminators can be used for dark field microscopy using either reflected or transmitted light 4 Scientist using a stereo microscope outfitted with a digital imaging pick up and fibre optic illumination Great working distance and depth of field are important qualities for this type of microscope Both qualities are inversely correlated with resolution the higher the resolution i e the greater the distance at which two adjacent points can be distinguished as separate the smaller the depth of field and working distance Some stereo microscopes can deliver a useful magnification up to 100 comparable to a 10 objective and 10 eyepiece in a normal compound microscope although the magnification is often much lower This is around one tenth the useful resolution of a normal compound optical microscope The large working distance at low magnification is useful in examining large solid objects such as fracture surfaces especially using fibre optic illumination as discussed below Such samples can also be manipulated easily so as to determine the points of interest Magnification EditThere are two major types of magnification systems in stereo microscopes One type is fixed magnification in which primary magnification is achieved by a paired set of objective lenses with a set degree of magnification The other is zoom or pancratic magnification which are capable of a continuously variable degree of magnification across a set range Zoom systems can achieve further magnification through the use of auxiliary objectives that increase total magnification by a set factor Also total magnification in both fixed and zoom systems can be varied by changing eyepieces 1 Intermediate between fixed magnification and zoom magnification systems is a system attributed to Galileo as the Galilean optical system here an arrangement of fixed focus convex lenses is used to provide a fixed magnification but with the crucial distinction that the same optical components in the same spacing will if physically inverted result in a different though still fixed magnification This allows one set of lenses to provide two different magnifications two sets of lenses to provide four magnifications on one turret three sets of lenses provide six magnifications and will still fit into one turret Practical experience shows that such Galilean optics systems are as useful as a considerably more expensive zoom system with the advantage of knowing the magnification in use as a set value without having to read analogue scales In remote locations the robustness of the systems is also a non trivial advantage Illumination Edit Stereomicroscope with an illuminated butterfly specimen Small specimens necessarily require intense illumination especially at high magnifications and this is usually provided by a fibre optic light source Fiber optics utilize halogen lamps which provide high light output for a given power input The lamps are small enough to be fitted easily near the microscope although they often need cooling to ameliorate high temperatures from the bulb The fibre optic stalk gives the operator much freedom in choosing appropriate lighting conditions for the sample The stalk is encased in a sheath that is easy to move and manipulate to any desired position The stalk is normally unobtrusive when the lit end is near the specimen so usually does not interfere with the image in the microscope Examination of fracture surfaces frequently need oblique lighting so as to highlight surface features during fractography and fibre optic lights are ideal for this purpose Several such light stalks can be used for the same specimen so increasing the illumination yet further More recent developments in the lighting for dissecting microscopes include the use of high power LEDs which are much more energy efficient than halogens and are able to produce a spectrum of colors of light making them useful for fluorophore analysis of biological samples impossible with a halogen or mercury vapor light source Digital display Edit Labomed LB 343 5 0 MP digital stereo microscope with 9 inch HD LCD screen HDMI video output X Y digital micrometer and moving stage Video cameras are integrated into some stereo microscopes allowing the magnified images to be displayed on a high resolution monitor The large display helps to reduce the eye fatigue that would result from using a conventional microscope for extended periods In some units a built in computer converts the images from two cameras one per eyepiece to a 3D anaglyph image for viewing with red cyan glasses or to the cross converged process clarify for clear glasses and improved color accuracy The results are viewable by a group wearing the glasses More typically a 2D image is displayed from a single camera attached to one of the eyepieces See also EditForensic engineering Fractography Scanning electron microscopy Operating microscope MicroscopeReferences Edit a b Introduction to Stereomicroscopy by Paul E Nothnagle William Chambers and Michael W Davidson Nikon MicroscopyU a b Simon Stickley Anna 2019 Image and Imagination The Stereomicroscope on the Cusp of Modern Biology NTM Journal of the History of Science Technology and Medicine 27 2 109 144 doi 10 1007 s00048 019 00211 0 PMID 31062033 S2CID 146809758 Illumination for Stereomicroscopy Reflected Episcopic Light by Paul E Nothnagle William Chambers Thomas J Fellers and Michael W Davidson Nikon MicroscopyU Illumination for Stereomicroscopy Darkfield Illumination by William Chambers Thomas J Fellers and Michael W Davidson Nikon MicroscopyU Wikimedia Commons has media related to Stereo microscopes Retrieved from https en wikipedia org w index php title Stereo microscope amp oldid 1052306052, wikipedia, wiki, book,

books

, library,

article

, read, download, free, free download, mp3, video, mp4, 3gp, jpg, jpeg, gif, png, picture, music, song, movie, book, game, games.