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One of the most important properties of microscope objectives is their magnification.The magnification typically ranges from 4× to 100×. It is combined with the magnification of the eyepiece to determine the overall magnification of the microscope; a 4× objective with a 10× eyepiece produces an image that is 40 times the size of the object.
Cone of light behind an achromatic doublet objective lens (A) without (red) and with (green) a Barlow lens optical element (B). The Barlow lens, named after Peter Barlow, is a diverging lens which, used in series with other optics in an optical system, increases the effective focal length of an optical system as perceived by all components that are after it in the system.
The ratio of the focal length of the objective and the eyepiece, when mounted in a standard tube length, gives an approximate magnification of the system. Due to their design, compound microscopes have improved resolving power and contrast in comparison to simple microscopes, [ 11 ] and can be used to view the structure, shape and motility of a ...
Common eyepiece powers are 8×, 10×, 15×, and 20×. The focal length of the eyepiece (in mm) can thus be determined if required by dividing 250 mm by the eyepiece power. Modern instruments often use objectives optically corrected for an infinite tube length rather than 160 mm, and these require an auxiliary correction lens in the tube.
If you place another lens with focal length f at the distance 2f from that image plane and then put an image sensor at 2f beyond that lens, that lens will relay the first image to the second image with 1:1 magnification (see thin lens formula showing that with object distance = from the lens, the image distance from the lens is calculated to ...
The ability of a lens to resolve detail is usually determined by the quality of the lens, but is ultimately limited by diffraction.Light coming from a point source in the object diffracts through the lens aperture such that it forms a diffraction pattern in the image, which has a central spot and surrounding bright rings, separated by dark nulls; this pattern is known as an Airy pattern, and ...
This Newtonian form of the lens equation can be derived by using a similarity between triangles P 1 P O1 F 1 and L 3 L 2 F 1 and another similarity between triangles L 1 L 2 F 2 and P 2 P 02 F 2 in the right figure. The similarities give the following equations and combining these results gives the Newtonian form of the lens equation.
The optical path length from the light source is used to compute the phase. The derivative of the position of the ray in the focal region on the source position is used to obtain the width of the ray, and from that the amplitude of the plane wave. The result is the point spread function, whose Fourier transform is the optical transfer function.