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Simple eye in invertebrates. Head of Polistes with two compound eyes and three ocelli ( circled) A simple eye or ocellus (sometimes called a pigment pit [1] [2]) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish ...
The lens is located towards the front part of the vertebrate eye called the anterior segment which includes the cornea and iris positioned in front of the lens. The lens is held in place by the suspensory ligaments (Zonule of Zinn), [1] attaching the lens at its equator to the rest of the eye [2] [3] through the ciliary body.
Compound eye. A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, [ 1] which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color. The image perceived by this arthropod eye is a ...
In cephalopod eyes, the nerve fibers route behind the retina, and do not block light or disrupt the retina. 1 is the retina and 2 the nerve fibers. 3 is the optic nerve. 4 is the vertebrate blind spot. Cephalopods, as active marine predators, possess sensory organs specialized for use in aquatic conditions. [1]
Cone cells or cones are photoreceptor cells in the retinas of vertebrates' eyes. They respond differently to light of different wavelengths, and the combination of their responses is responsible for color vision. Cones function best in relatively bright light, called the photopic region, as opposed to rod cells, which work better in dim light ...
The numerical aperture with respect to a point P depends on the half-angle, θ1, of the maximum cone of light that can enter or exit the lens and the ambient index of refraction. As a pencil of light goes through a flat plane of glass, its half-angle changes to θ2. Due to Snell's law, the numerical aperture remains the same: NA = n1 sin θ1 ...
A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina that is capable of visual phototransduction. The great biological importance of photoreceptors is that they convert light (visible electromagnetic radiation) into signals that can stimulate biological processes. To be more specific, photoreceptor proteins in ...
Confocal microscopy. Confocal microscopy, most frequently confocal laser scanning microscopy ( CLSM) or laser scanning confocal microscopy ( LSCM ), is an optical imaging technique for increasing optical resolution and contrast of a micrograph by means of using a spatial pinhole to block out-of-focus light in image formation. [ 1 ]