The micropolarizing equipment of the present invention consists in a pair of capillary tubes of black glass or glass with a black outer coating which fit into sockets in three prisms, the first being a 45.degree. prism over the central aperture of the microscope stage which reflects the plane polarized beam at right angles through one of the capillary tubes; a second prism, which is double, reflects light emerging from the first capillary tube at right angles up to a second 45.degree. prism into which the second capillary tube is mounted in a socket and is parallel to the first capillary tube. The third prism receives the other end of the second capillary tube in a socket and reflects the light up into the objective of the microscope. While split field, null point determination may be used, a much more efficient device is one or more small anisotropic crystals mounted, for example in a drop of liquid or in a thin film, on the top of the third prism and located to be in the path of the light reflected up into the objective of the microscope. The crystal, or one of the crystals, when viewed with polarizer and analyzer crossed is bright, usually in color depending on the wavelength of the light source used, and the particular crystal on which the microscope objective is focused disappears when the stage has been turned to compensate for the optical rotation of the sample in the two capillaries. The extinction of the crystal is very sharp and is preferred over split field devices.
An apparatus, particularly a microscope, for the examination of a plurality of gemstones, pearls or similar small objects, comprises means to create dark-field illumination and a slide-type displaceable specimen holder of plastics material which has an elongate recess in its upper surface with a cross-section which narrows towards the bottom of the recess for example. The means to create the dark-field illumination comprises a cold light source, a glass-fiber bundle and polarization filter means, and the specimen holder consists of translucent material, especially Plexiglass. Additionally there is provided a device for aiding the examination of uncut gemstones and similar small objects, comprising means to create dark-field illumination and means for immersion inspection which comprises a vessel containing an immersion liquid. This vessel is equipped with a damping float of transparent material having a flat base and an open upper end, which in the operational position of the apparatus is inserted into the immersion liquid and floats therein, with the base of the damping float having a surface which is at least as large as the object to be examined.
There is provided a three-dimensional object observing microscope which can easily observe a three-dimensional object in a three-dimensional manner. A three-dimensional object observing microscope comprising a table on which a three-dimensional object is placed, an imaging part which consists of an imaging lens and an imaging camera for imaging this three-dimensional object from an inclined upper position, and a casing which supports the imaging part rotatably in a horizontal direction and also integrally supports the table and the imaging part.
A polarizing accessory system for use with a microscope. The microscope comprises an optical tube having a eye-piece lens and an objective lens, a stage having an aperture therein, and a light conveying rod arranged to covey light through the aperture to the objective lens and the eye-piece lens. The accessory system comprises a first, tray-like polarizing unit arranged to be disposed on the microscope stage over the aperture, and a second, cup-shaped polarizing unit arranged to be releasably mounted over the eye-piece lens. Each polarizing unit includes a planar polarizing filter or film mounted therein. The tray-like unit comprises a peripheral planar frame defining a central window in which a first polarizing filter element is located. The central window forms a support surface for two, conventional specimen-holding slides disposed in a side-by-side array. The width of the window is equal to the width of the slides to hold them securely in place thereon. The tray enables the slides to be positioned at any place on the surface of the microscope's stage. The cup-shaped polarizing unit is rotatable with respect to the optical tube (and the tray-like polarizing unit disposed on the stage) so that one can readily adjust the amount of light polarization desired.
