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  2. Tired light - Wikipedia

    en.wikipedia.org/wiki/Tired_light

    Tired light was an idea that came about due to the observation made by Edwin Hubble that distant galaxies have redshifts proportional to their distance.Redshift is a shift in the spectrum of the emitted electromagnetic radiation from an object toward lower energies and frequencies, associated with the phenomenon of the Doppler effect.

  3. Bright-field microscopy - Wikipedia

    en.wikipedia.org/wiki/Bright-field_microscopy

    The light path of a bright-field microscope is extremely simple; no additional components are required beyond the normal light-microscope setup. The light path begins at the illuminator or the light source on the base of the microscope. Often a halogen lamp is used. The light travels through the objective lens into the ocular lens, through ...

  4. Tolman surface brightness test - Wikipedia

    en.wikipedia.org/wiki/Tolman_surface_brightness_test

    Tired light hypothesis vs. expanding universe. The Tolman surface brightness test is one out of six cosmological tests that were conceived in the 1930s to check the viability of and compare new cosmological models. Tolman's test compares the surface brightness of galaxies as a function of their redshift (measured as z).

  5. Phase-contrast microscopy - Wikipedia

    en.wikipedia.org/wiki/Phase-contrast_microscopy

    In its positive form, the background light is instead phase-shifted by +90°. The background light will thus be 180° out of phase relative to the scattered light. The scattered light will then be subtracted from the background light to form an image with a darker foreground and a lighter background, as shown in the first figure. [5] [6] [7]

  6. Optical microscope - Wikipedia

    en.wikipedia.org/wiki/Optical_microscope

    The optical microscope, also referred to as a light microscope, is a type of microscope that commonly uses visible light and a system of lenses to generate magnified images of small objects. Optical microscopes are the oldest design of microscope and were possibly invented in their present compound form in the 17th century.

  7. Stereo microscope - Wikipedia

    en.wikipedia.org/wiki/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 ...

  8. Micrograph - Wikipedia

    en.wikipedia.org/wiki/Micrograph

    A light micrograph or photomicrograph is a micrograph prepared using an optical microscope, a process referred to as photomicroscopy. At a basic level, photomicroscopy may be performed simply by connecting a camera to a microscope, thereby enabling the user to take photographs at reasonably high magnification .

  9. Fourier ptychography - Wikipedia

    en.wikipedia.org/wiki/Fourier_ptychography

    The optical configuration for Fourier ptychography. Fourier ptychography is a computational imaging technique based on optical microscopy that consists in the synthesis of a wider numerical aperture from a set of full-field images acquired at various coherent illumination angles, [1] resulting in increased resolution compared to a conventional microscope.