A pseudoscope is a binocular optical instrument that reverses depth perception. It is used to study human stereoscopic perception. Objects viewed through it appear inside out, for example: a box on a floor would appear as a box-shaped hole in the floor.
It typically uses sets of optical prisms, or periscopically arranged mirrors to swap the view of the left eye with that of the right eye.
In the 1800s Charles Wheatstone coined the name from the Greek ψευδίς σκοπειν – 'false view'. The device was used to explore his theory of stereo vision. [1] [2]
Basically, pseudoscopic vision is three-dimensional vision in reverse. For example, in aerial photography, swimming pools appear to look like buildings and buildings appear to look like swimming pools. In red and green plotters like the Kelsh and Multiplex this is achieved by reversing the lenses on the 3D glasses. The images will be reverse order. The right image will be viewed through the left eye, and the left image will be through the right eye.
Switching the two pictures in a standard stereoscope changes all the elevated parts into depressions, and vice versa. The pseudoscope also changes convex into concave, and high-relief into low-relief.
Before the pseudoscope itself was created intentionally, it existed in binocular instruments as an imperfection. The first binocular microscope was invented by the Capuchin friar Cherubin d'Orleans. Because his instrument consisted of two inverting systems, it produced a pseudoscopic impression of depth by accident, although not recognized by microscopists of the time.
The instrument subsequently fell into complete neglect for nearly two centuries. It was revived in 1852 by Charles Wheatstone, who published his ideas in his paper "On Binocular Vision", in the Philosophical Transactions for 1852. Wheatstone's paper stimulated the investigation of binocular vision and many variations of pseudoscopes were created, chief types being the mirror or the prismatic.
In 1853 the American scientist John Leonard Riddell (1807–1865) devised his binocular microscope, which contained the essentials of Wheatstone's pseudoscope. [3]
Binoculars or field glasses are two refracting telescopes mounted side-by-side and aligned to point in the same direction, allowing the viewer to use both eyes when viewing distant objects. Most binoculars are sized to be held using both hands, although sizes vary widely from opera glasses to large pedestal-mounted military models.
A mirror image is a reflected duplication of an object that appears almost identical, but is reversed in the direction perpendicular to the mirror surface. As an optical effect it results from reflection off from substances such as a mirror or water. It is also a concept in geometry and can be used as a conceptualization process for 3-D structures.
In biology, binocular vision is a type of vision in which an animal has two eyes capable of facing the same direction to perceive a single three-dimensional image of its surroundings. Binocular vision does not typically refer to vision where an animal has eyes on opposite sides of its head and shares no field of view between them, like in some animals.
Stereoscopy is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision. The word stereoscopy derives from Greek στερεός (stereos) 'firm, solid', and σκοπέω (skopeō) 'to look, to see'. Any stereoscopic image is called a stereogram. Originally, stereogram referred to a pair of stereo images which could be viewed using a stereoscope.
A monocular is a compact refracting telescope used to magnify images of distant objects, typically using an optical prism to ensure an erect image, instead of using relay lenses like most telescopic sights. The volume and weight of a monocular are typically less than half of a pair of binoculars with similar optical properties, making it more portable and also less expensive. This is because binoculars are essentially a pair of monoculars packed together — one for each eye. As a result, monoculars only produce two-dimensional images, while binoculars can use two parallaxed images to produce binocular vision, which allows stereopsis and depth perception.
Depth perception is the ability to perceive distance to objects in the world using the visual system and visual perception. It is a major factor in perceiving the world in three dimensions. Depth perception happens primarily due to stereopsis and accommodation of the eye.
The field of view (FOV) is the angular extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors, it is a solid angle through which a detector is sensitive to electromagnetic radiation. It is further relevant in photography.
A stereoscope is a device for viewing a stereoscopic pair of separate images, depicting left-eye and right-eye views of the same scene, as a single three-dimensional image.
An autostereogram is a two-dimensional (2D) image that can create the optical illusion of a three-dimensional (3D) scene. Autostereograms use only one image to accomplish the effect while normal stereograms require two. The 3D scene in an autostereogram is often unrecognizable until it is viewed properly, unlike typical stereograms. Viewing any kind of stereogram properly may cause the viewer to experience vergence-accommodation conflict.
A 3D display is a display device capable of conveying depth to the viewer. Many 3D displays are stereoscopic displays, which produce a basic 3D effect by means of stereopsis, but can cause eye strain and visual fatigue. Newer 3D displays such as holographic and light field displays produce a more realistic 3D effect by combining stereopsis and accurate focal length for the displayed content. Newer 3D displays in this manner cause less visual fatigue than classical stereoscopic displays.
Binocular rivalry is a phenomenon of visual perception in which perception alternates between different images presented to each eye.
A random-dot stereogram (RDS) is stereo pair of images of random dots that, when viewed with the aid of a stereoscope, or with the eyes focused on a point in front of or behind the images, produces a sensation of depth due to stereopsis, with objects appearing to be in front of or behind the display level.
Stereopsis is the component of depth perception retrieved by means of binocular disparity through binocular vision. It is not the only contributor to depth perception, but it is a major one. Binocular vision occurs because each eye receives a different image due to their slightly different positions in one's head. These positional differences are referred to as "horizontal disparities" or, more generally, "binocular disparities". Disparities are processed in the visual cortex of the brain to yield depth perception. While binocular disparities are naturally present when viewing a real three-dimensional scene with two eyes, they can also be simulated by artificially presenting two different images separately to each eye using a method called stereoscopy. The perception of depth in such cases is also referred to as "stereoscopic depth".
Pupillary distance (PD), more correctly known as interpupillary distance (IPD) is the distance in millimeters between the centers of each pupil.
A zograscope is an optical device for magnifying flat pictures that also has the property of enhancing the sense of the depth shown in the picture. It consists of a large magnifying lens through which the picture is viewed. Devices containing only the lens are sometimes referred to as graphoscopes. Other models have the lens mounted on a stand in front of an angled mirror. This allows someone to sit at a table and to look through the lens at the picture flat on the table. Pictures viewed in this way need to be left-right reversed; this is obvious in the case of writing. A print made for this purpose, typically with extensive graphical projection perspective, is called a vue d'optique or "perspective view".
Chromostereopsis is a visual illusion whereby the impression of depth is conveyed in two-dimensional color images, usually of red–blue or red–green colors, but can also be perceived with red–grey or blue–grey images. Such illusions have been reported for over a century and have generally been attributed to some form of chromatic aberration.
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 different viewing angles to the left and right eyes. This arrangement produces a three-dimensional visualization of the sample being examined. Stereomicroscopy overlaps macrophotography for recording and examining solid samples with complex surface topography, where a three-dimensional view is needed for analyzing the detail.
A 3D stereo view is the viewing of objects through any stereo pattern.
Instrument myopia is the tendency of a person with normal eyes to focus them too close when looking into an optical instrument at its image. Optical instruments include viewfinders, telescopes, binoculars, and microscopes. For example, through a microscope, a person might focus the eyes to one meter distance although it can present an image at six meters distance.
Upside down goggles, also known as "invertoscopes" by Russian researchers, 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 appear upside down and mirrored. They are constructed using sets of optical right-angle prisms, concave mirrors, or a mirror plus right-angle prisms with unequal cathethus.