Stereoscope

A stereoscope is a device that allows the user to see a depth-enabled image by means of stereopsis due to binocular disparity. It does not reproduce all depth cues. The first stereoscopes were made in the 1800s. The instrument shows each eye a separate flat picture of the same scene, drawn or photographed from two slightly different viewpoints, and the viewer's visual system fuses the pair into a single image in relief. Charles Wheatstone described the first stereoscope, which used a pair of mirrors, to the Royal Society in 1838. Lens-based versions by David Brewster and later Oliver Wendell Holmes turned it into a mass-market product in the second half of the 19th century, and the View-Master carried the format into the 20th.

Stereoscopic VR headsets like the Oculus Rift are an evolution of stereoscopes. In his textbook on virtual reality, Steven LaValle describes Wheatstone's 1838 stereoscope as the first experiment to show the 3D effect of stereopsis, and the View-Master as a mass-produced stereoscope. He notes that in a head-mounted display a smartphone-type display can be placed close to the eyes and brought into focus using one magnifying lens for each eye. The Royal Society has written that "the principles behind the stereoscope are also the foundation of 3D films and virtual reality".

Reviewed 27 September 2026. Checked all 23 cited sources, including the Wheatstone 1838, Brewster 1856 and Holmes texts, the Heilig and Howlett patents and LaValle chapters, against the history, optics and VR-lineage claims. About review dates.

How it works

Each eye looks at the world from a slightly different position, so the two retinal images of a solid object differ. Wheatstone's 1838 paper argued that this difference is what gives the sense of depth: "the mind perceives an object of three dimensions by means of the two dissimilar pictures projected by it on the two retinæ". He called the projection of two dissimilar pictures on the two retinae "a new fact in the theory of vision", and noted that the only earlier author he could find who had remarked on the subject was Leonardo da Vinci. A stereoscope reproduces this situation artificially. It holds two pictures of one object made from two viewpoints, and it uses mirrors or lenses so that each eye sees only its own picture and the two appear to occupy the same place. If the pair is drawn or photographed correctly, the viewer sees one picture with depth instead of two flat ones. Oliver Wendell Holmes gave a one-line definition in 1859: "A stereoscope is an instrument which makes surfaces look solid."

The Holmes essay also named the picture pair: "The stereograph, as we have called the double picture designed for the stereoscope". Holmes's own hand-held design held the stereograph card in adjustable holders.

Mirror stereoscope

In Wheatstone's reflecting stereoscope, "A A' are two plane mirrors, about four inches square, inserted in frames, and so adjusted that their backs form an angle of 90° with each other". The two pictures were fixed to panels on either side, with their corresponding horizontal lines at the same level. The observer placed his eyes as close as possible to the mirrors and slid the panels toward or away from himself until the two reflected images coincided. The Royal Society describes the angled mirrors as making the images "appear larger and more distant", which leads the brain to merge them and interpret them in three dimensions.

Lens (lenticular) stereoscope

Brewster's lenticular stereoscope replaced the mirrors with lenses. In his 1856 book on the instrument, Brewster explained that a single lens cut in half, with one half placed in front of each picture, shifts the two images toward each other by refraction so that they unite into one picture "standing out in beautiful relief". Quarter lenses cut into round or square shapes work the same way. With the pictures fixed in the focus of the lenses, the light from them is refracted so that it enters the eyes in parallel directions. Brewster's instrument was a pyramidal box, blackened inside, with a right-eye tube and a left-eye tube. The two halves of the top holding the lenses could slide in grooves "so as to suit different persons whose eyes ... are more or less distant", an adjustment for interpupillary distance, and the eye tubes moved up and down "in order to suit eyes of different focal lengths".

LaValle's textbook notes that the magnifying lens in this kind of viewer forms a virtual image: the display is placed so that it appears magnified and, to the viewer, "infinitely far away". He writes that this "exactly" describes what happens in the View-Master and in smartphone-based VR headsets.

History

Wheatstone and the first stereoscope (1838)

Wheatstone, professor of experimental philosophy at King's College London, published his paper "Contributions to the Physiology of Vision. Part the First. On some remarkable, and hitherto unobserved, Phenomena of Binocular Vision" in volume 128 of the Philosophical Transactions of the Royal Society. The Stereoscopic Society dates the paper to June 1838. In it he wrote, "I therefore propose that it be called a stereoscope, to indicate its property of representing solid figures." The paper illustrated the effect with simple line drawings, a set of outline figures (figs. 10 to 20) meant to be seen in relief in the instrument. Holmes later noted that Daguerre announced his photographic process only a year after Wheatstone's description.

As early as 1840 Wheatstone asked William Henry Fox Talbot to make pairs of stereoscopic photographs. According to the Stereoscopic Society, Talbot made calotype stereo pairs and sent them to Wheatstone that year, and these were the first photographic 3D images; the correspondence between the two men survives, but the images have been lost. Wheatstone's original instruments are preserved in the archives of King's College London.

Brewster, Duboscq and the stereoscope boom (1849-1860s)

David Brewster built the first lens-based stereoscope in 1849. In his own account he had found the reflecting stereoscope "of little service, and ill fitted ... for popular use" while researching binocular vision. The lenticular instrument was exhibited to the British Association in Birmingham in 1849, but Brewster could not persuade opticians in London or Birmingham to manufacture it. In 1850 he took an example made by Mr. Loudon of Dundee to Paris and showed it to the opticians Soleil and his son-in-law Jules Duboscq; Duboscq immediately began making the lenticular stereoscope for sale, along with stereo daguerreotypes to view in it.

Duboscq exhibited a lenticular stereoscope with a set of daguerreotypes at the Great Exhibition of 1851 in London. Brewster wrote that it "attracted the particular attention of the Queen", and he presented a stereoscope made by Duboscq to Queen Victoria before the exhibition closed. Orders from England followed, and demand soon grew so large that opticians of all kinds took up manufacture of the instrument. By 1856 Brewster reported that "it has been estimated that upwards of half a million of these instruments have been sold". The Royal Society notes that the lenticular stereoscope was more compact than Wheatstone's design and gained popularity over it, and that Brewster claimed Wheatstone had no interest in using photographs with the stereoscope and that this was his own innovation. The two men also disagreed about how stereoscopic depth works: Brewster held that perspective was the source of perceived shape, while Wheatstone argued that matching features in the two eyes' images were combined to assign depth.

A commercial trade in stereo pictures grew around the instrument. The London Stereoscopic Company was founded on Oxford Street in 1854; by 1856 it advertised more than 10,000 stereoscopic images, and during the 1862 International Exhibition it took an average of 800 pounds a day selling stereo views. The company closed in 1922.

Holmes stereoscope (1859-1861)

In the United States, the physician and writer Oliver Wendell Holmes wrote about the stereoscope in The Atlantic Monthly in June 1859 and July 1861. Dissatisfied with the box viewers then sold in the country, he designed a simpler "skeleton stereoscope" consisting of lenses shaded by a hood, adjustable holders for the stereograph card, and a handle. He never applied for a patent. A Boston dealer, Joseph L. Bates, saw a future for the design and took it up. In the 1861 essay Holmes wrote that for paper slides "an instrument which may be held in the hand is very convenient", that he had had one constructed which he thought better than any in the shops, and that "Mr. Joseph L. Bates, 129 Washington Street, has one of them". An advertisement from about 1869 in the Boston Medical Library collection promotes "The Holmes stereoscope, with the inventions and improvements added by Joseph L. Bates". According to American Heritage, skeleton stereoscopes were in use everywhere by 1869; lantern slides, postcards, halftone printing and finally moving images later "sent the stereoscope to the attic".

Holmes's 1861 essay also describes the experience of viewing. He attributed part of the effect to isolation from the room: "the shutting out of surrounding objects, and the concentration of the whole attention, which is a consequence of this, produce a dream-like exaltation of the faculties, a kind of clairvoyance, in which we seem to leave the body behind us and sail away into one strange scene after another, like disembodied spirits."

View-Master (1939)

In 1938 Harold Graves, president of Sawyer's Photographic Services, met William Gruber at the Oregon Caves National Monument, where Gruber was taking 3D pictures with two cameras strapped together. Gruber planned to update the stereoscopes common in 19th-century drawing rooms with three-dimensional color slides and a new hand-held viewer, and the two introduced the View-Master at the 1939 New York World's Fair. The Strong National Museum of Play inducted it into the National Toy Hall of Fame in 1999; later manufacturers included Tyco Toys and Fisher-Price. TechCrunch reported in 2015 that more than 1.5 billion View-Master reels and over 100 million viewers had been sold. LaValle's textbook describes the View-Master as "a mass-produced stereoscope that has been available since the 1930s".

Timeline

Year	Event
1838	Charles Wheatstone describes and names the mirror stereoscope in the Philosophical Transactions of the Royal Society
1840	Wheatstone asks Fox Talbot for stereoscopic photographs; Talbot sends calotype pairs
1849	David Brewster's lenticular (lens) stereoscope is exhibited to the British Association in Birmingham
1850	Jules Duboscq begins making the lenticular stereoscope for sale in Paris
1851	Duboscq shows the stereoscope at the Great Exhibition in London; Brewster presents one to Queen Victoria
1854	London Stereoscopic Company founded
1856	Brewster reports an estimated half a million lenticular stereoscopes sold
1859	Oliver Wendell Holmes's essay "The Stereoscope and the Stereograph" appears in The Atlantic Monthly
1861	Holmes describes his hand-held stereoscope; Boston dealer Joseph L. Bates takes up the design
1939	View-Master introduced at the New York World's Fair
1960	Morton Heilig is granted a patent for a "Stereoscopic-television apparatus for individual use"
1960	Bela Julesz of Bell Laboratories publishes his random-dot stereogram experiment
1983	Eric Howlett, inventor of the LEEP optics, is granted a patent on a wide-angle stereo photography and viewing system
1985	NASA Ames researchers build a head-mounted display prototype around LEEP optics
2015	Mattel releases the View-Master Virtual Reality viewer, which works with Google Cardboard

Limitations

A stereoscope supplies binocular disparity, but disparity is only one of many depth cues. LaValle points out that there are many more monocular depth cues than stereo cues, which is why a single photograph can still convey a great deal of depth information. The pictures in a stereoscope are also fixed. LaValle calls it "an unfortunate limitation of these designs" that the viewpoint is fixed with respect to the picture. For VR headsets he notes that head tracking of position, and not only orientation, is needed to preserve depth cues based on motion; a system that tracks orientation alone cannot provide motion parallax when the user moves from side to side.

Stereoscopic displays also have a focus problem. Hoffman, Girshick, Akeley and Banks explain that because computer 3D displays present images on one surface, their focus cues (accommodation and blur in the retinal image) specify the depth of the display rather than the depths in the depicted scene. The resulting uncoupling of vergence and accommodation "frequently reduces one's ability to fuse the binocular stimulus and causes discomfort and fatigue for the viewer". LaValle notes that this vergence-accommodation mismatch occurs in VR headsets as well.

Other uses

Vision research

Wheatstone introduced the stereoscope in a paper on the physiology of binocular vision. More than a century after Wheatstone and Brewster, Bela Julesz at Bell Laboratories generated pairs of random-dot patterns by computer. Viewed through a stereoscope, identical patterns were seen as a single surface; when a central region of one pattern was shifted slightly, that square appeared to move into depth behind its surroundings. His 1960 experiment with what became known as random-dot stereograms showed that stereoscopic depth could be computed "in the absence of any identifiable objects, in the absence of any perspective, in the absence of any cues available to either eye alone".

Aerial photograph interpretation

Stereoscopes are also used to view overlapping aerial photographs in 3D for mapping. Pairs of overlapping aerial photographs, called stereo pairs, are needed for this, and a typical overlap between photographs is 60 percent; the Utah Geological Survey described viewing the stereo pair through a stereoscope to select control points for photogrammetric mapping. A stereoscope in the U.S. Geological Survey museum collection, made by the Q-O-S Corporation of New York for the U.S. Army Corps of Engineers, was originally designed for military reconnaissance work and was used for map reading of aerial photographs up to 8 inches.

Relationship to VR headsets

LaValle traces a direct line from the stereoscope to VR: after Wheatstone's instrument and the View-Master, "pursuing this idea further led to Sensorama", which added motion pictures, sound, vibration and smells. Morton Heilig's patent for a "Stereoscopic-television apparatus for individual use", filed in 1957 and granted on 4 October 1960, describes a hollow casing holding a pair of optical units and a pair of television tube units, with the optics and tubes adjustable relative to the user's eyes, plus earphones and air discharge nozzles. Special lens arrangements bend peripheral rays to create the sensation of peripheral vision filling an arc of more than 140 degrees horizontally and vertically.

Optics developed for wide-angle stereo photography were later used in head-mounted displays. Eric Howlett's patent, filed in 1980 and granted in 1983, covers a camera, a transparency and a magnifying viewer, "all preferably stereoptical", intended to give "very wide field (100 degrees and more) images" on film small enough for two images to be grouped side by side for stereoscopy. Scott Fisher recalls that at NASA Ames in 1985, Michael McGreevy and the contractor Jim Humphries had developed a head-mounted display prototype "based around the LEEP optics" that Howlett invented. The first prototype of the NASA Virtual Environment Workstation was built from a motorcycle helmet, Watchman LCD displays, wide-angle stereoscopic optics and a Polhemus magnetic head-position tracker.

LaValle describes how a smartphone "can be dropped into a case with lenses to provide a VR experience", naming Google Cardboard, which works with a wide variety of phones, and Samsung Gear VR, which is optimized for one particular smartphone (the Samsung S6 in LaValle's example). In the Oculus Rift DK2, whose display is a smartphone screen, the lenses are placed so that the screen appears "infinitely far" away while still filling most of the user's field of view. Mattel and Google announced a virtual reality View-Master in February 2015 that holds an Android phone and uses Google Cardboard technology, priced at US$29.99 with experience reels at US$14.99 for a pack of three. Mattel lists the View-Master Virtual Reality Starter Pack as released in 2015 and discontinued in 2018; it worked with Google Cardboard apps and smartphones with screens between 5 and 6 inches.

See also

• Stereoscopy
• Stereopsis
• Binocular disparity
• View-Master
• Charles Wheatstone
• Head-mounted display
• Stereoscopic rendering
• History of virtual reality