... optics.¹

This absorbtion law vas first observed by Pierre Bougier (1989-1758) and in 1729 it was analyzed in detail by Johann Heinrich Lambert. As late as 1852 Beer showed that in solutions the absorbtion coefficient value is proportional to the concentration of molecules [2]

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... aperture²

Aperture is an opening trough which light may pass. And may take any arbitrary shape. To observe diffraction the diameter should be small, that is, comparable with wavelength of light used

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... slit³

Slit is an aperture, typically rectangular in shape, whose length is large compared to its width.

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... image⁴

Two images are produced only by a thin hologram (Sect. 2.2). These images are equivalent and can be seen with the bare eye or can be projected onto a screen. The real image looks visually inverted and a little bit smeared. Thick or volume holograms have only one three dimensional image. The terms real and virtual images are by D. Gabor who used a coaxial recording scheme in which the virtual image could not be seen. [2]

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... aberrations⁵

Aberration is an optical defect resulting from design or fabrication error that prevents the optical system from achieving precise focus and a sharp, non-smeared image with little or no difference among the object and the image.

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