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  2. Precision glass moulding - Wikipedia

    en.wikipedia.org/wiki/Precision_glass_moulding

    Consequently, the glass exhibits a small change in the refractive index which has to be considered in the optical design. A higher cooling rate corresponds to a larger decrease of the refractive index. A lower cooling rate could circumvent the index drop, but would be less cost-efficient. Glass material. Many glasses can be used with PGM.

  3. Fluoride glass - Wikipedia

    en.wikipedia.org/wiki/Fluoride_glass

    Fluoride glass. Fluoride glass is a class of non-oxide optical glasses composed of fluorides of various metals. They can contain heavy metals such as zirconium, or be combined with lighter elements like aluminium and beryllium. These heavier elements cause the glass to have a transparency range extended into the infrared wavelength.

  4. Upside down goggles - Wikipedia

    en.wikipedia.org/wiki/Upside_down_goggles

    Upside down goggles. Upside down goggles, also known as "invertoscopes" by Russian researchers, [1] are optical instruments that invert the image received by the retinas upside down. They are used to study human visual perception, particularly psychological process of building a visual image in the brain. Objects viewed through such a device ...

  5. Deck prism - Wikipedia

    en.wikipedia.org/wiki/Deck_prism

    Deck prism. A deck prism, or bullseye, is a prism inserted into the deck of a ship to provide light down below. [1] [2] [3] For centuries, sailing ships used deck prisms to provide a safe source of natural sunlight to illuminate areas below decks. Before electricity, light below a vessel's deck was provided by candles, oil and kerosene lamps ...

  6. Four prism dioptre reflex test - Wikipedia

    en.wikipedia.org/wiki/Four_prism_dioptre_reflex_test

    4 dioptre prism, either loose or prism bar; Bright lighting conditions; Method of assessment. As it is an objective test, few instructions are required to be given to the patient. The patient is asked to fixate on a target while the examiner places a 4 prism dioptre base-out prism over the patient's eye, observing the response of the fellow eye.

  7. History of glass - Wikipedia

    en.wikipedia.org/wiki/History_of_glass

    Without proper rendering support, you may see question marks, boxes, or other symbols. The history of glass-making dates back to at least 3,600 years ago in Mesopotamia. However, most writers claim that they may have been producing copies of glass objects from Egypt. [1] Other archaeological evidence suggests that the first true glass was made ...