Monocular and Related Topics

Telescopic sight

Optical sighting device based on a refracting telescope.

Leupold and Stevens Mark 6 scope with variable magnification X3-X18, mounted on an M24 SWS

German military sniper rifle with a mounted telescopic sight and dismounted NSV80 clip on optoelectronic image intensifier

Telescopic sight (German made ZF Ajack 4×90 (4×38 in modern terminology) for the World War II pattern Swedish sniper rifle m/1941.

Russian Model 1891/30 sniper rifle with PU 3.5×21 sight

The Zielgerät ZG 1229 Vampir displayed by a British soldier (ca 1945)

A Swift model 687M variable power rifle telescopic sight with parallax compensation (the ring around the objective lens is used for making parallax adjustments).

The adjustment controls of a telescopic sight with an elevation adjustment knob featuring a zero-stop and second revolution indicator.

TA31RCO-M150CPO 4×32 ACOG sight using a combination of fiber optics (visible on top) and self-luminous tritium for reticle illumination

Simple animation demonstrating the extent of noticeable parallax shift with eye movements in telescopic sights with and without parallax compensation.

Austrian military issued Steyr SSG 69 sniper rifle with Kahles ZF 69 6×42 mm telescopic sight adjusted to be parallax free at 300 m

Scrome LTE J10 F1 with a lens hood mounted at the ocular and a flip-open cover at the objective mounted on a PGM Hécate II

Two Diarange telescopic sights with integrated laser rangefinders

Colt Python Silhouette, with 8-inch barrel, factory scope, and case – 500 made in 1981 by the Colt Custom Gun Shop.

A mount with three scope rings for telescopic sight interface and Picatinny rail for receiver interface.

Drawing of Zeiss rail compatible telescopic sight and mount (left) and a traditional ring mount (right). Both feature a picatinny rail receiver interface.

Telescopic sight fitted with scope rings on a Picatinny/MIL-STD-1913 rail mounted above the receiver of a sniper rifle.

Design difference in grabber interfaces between the Picatinny rail and the new NATO Accessory Rail.

The scope mount itself can be used as the interface for attaching other accessories.

A telescopic sight mounting set featuring three rings on a heavy-recoiling .338 Lapua Magnum chambered TRG-42 sniper rifle

Looking through a USMC sniper rifle's scope

PSO-1 reticle, the bottom-left corner can be used to determine the distance from a 170-cm-tall target (expected average height of an enemy combatant).

Swedish Ak4OR (H&K G3 variant) with Hensoldt 4×24 M1 telescopic sight.

Dual combat sighting system: ZF 3×4° optical sight topped with red dot sight as used on German G36A1 assault/sniper rifles.

Picatinny rail on a rifle receiver for mounting sights.

A dovetail rail on a rifle receiver for mounting sights with a drilling on top for an additional shape connection.

Side mounting rail on a PKP Pecheneg machine gun.

"STANAG" claw mount (receiver interface) on an FN FAL. This type of mount has also been used on several previous models by Heckler & Koch, such as for example MP5 and G3.

A relatively new type of telescopic sight, called prismatic sight or "prism scope", replaces the image-erecting relay lenses of a traditional telescope with a roof prism design commonly found in compact binoculars, monoculars and spotting scopes.

Binoculars

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 (binocular vision) when viewing distant objects.

Cross-section of a relay lens aprismatic binocular design

Roof prism binoculars with the eyepieces in line with the objectives

Parameters listed on the prism cover plate describing 7 power magnification binoculars with a 50 mm objective diameter and a 372 foot field of view at 1000 yards

The small exit pupil of a 25×30 telescope and large exit pupils of 9×63 binoculars suitable for use in low light

Central-focusing binoculars with adjustable interpupillary distance

Binoculars with red-colored multicoatings

Special reflective coatings on large naval ship 20×120 binoculars

Vector series laser rangefinder 7×42 binoculars can measure distance and angles and also features a 360° digital compass and class 1 eye safe filters

German U.D.F. 7×50 blc U-boat binoculars (1939–1945)

7×50 marine binoculars with dampened compass

US Naval ship 'Big eyes' 20×120 binoculars in fixed mounting

25 × 150 binoculars adapted for astronomical use

A simulated view of how the Andromeda Galaxy (Messier 31) would appear in a pair of binoculars

Beam path at the roof edge (cross-section); the P-coating layer is on both roof surfaces

Unlike a (monocular) telescope, binoculars give users a three-dimensional image: each eyepiece presents a slightly different image to each of the viewer's eyes and the parallax allows the visual cortex to generate an impression of depth.

Laser rangefinder

Rangefinder that uses a laser beam to determine the distance to an object.

Time-of-flight principles applied to laser range-finding.

An OLS-27 IRST with laser rangefinder on the Sukhoi Su-27

An American soldier with a GVS-5 laser rangefinder

A Dutch ISAF sniper team displaying their Accuracy International AWSM .338 Lapua Magnum rifle and VECTOR IV Leica/Vectronix laser rangefinder binoculars

This LIDAR scanner may be used to scan buildings, rock formations, etc., to produce a 3D model. The LIDAR can aim its laser beam in a wide range: its head rotates horizontally, a mirror flips vertically. The laser beam is used to measure the distance to the first object on its path.

Laser rangefinder TruPulse used for forest inventories (in combination with Field-Map technology)

Handheld military rangefinders operate at ranges of 2 km up to 25 km and are combined with binoculars or monoculars.

Sextant

Doubly reflecting navigation instrument that measures the angular distance between two visible objects.

U.S. Navy Quartermaster 3rd Class, practices using a sextant as part of a navigation training aboard the amphibious assault ship USS Bonhomme Richard (LHD 6), 2018

Sextants can also be used by navigators to measure horizontal angles between objects

Most sextants mount a 1 or 3-power monocular for viewing.

Total internal reflection

Optical phenomenon in which waves arriving at the interface (boundary) from one medium to another (e.g., from water to air) are not refracted into the second ("external") medium, but completely reflected back into the first ("internal") medium.

Fig.2:Repeated total internal reflection of a 405nm laser beam between the front and back surfaces of a glass pane. The color of the laser light itself is deep violet; but its wavelength is short enough to cause fluorescence in the glass, which re-radiates greenish light in all directions, rendering the zigzag beam visible.

Fig.3:Total internal reflection of light in a semicircular acrylic block.

Fig.7:Total internal reflection by the water's surface at the shallow end of a swimming pool. The broad bubble-like apparition between the swimmer and her reflection is merely a disturbance of the reflecting surface. Some of the space above the water level can be seen through "Snell's window" at the top of the frame.

Fig.9:Depiction of an incident sinusoidal plane wave (bottom) and the associated evanescent wave (top), under conditions of total internal reflection. The reflected wave is not shown.

Fig.10:Disembodied fingerprints visible from the inside of a glass of water, due to frustrated total internal reflection. The observed fingerprints are surrounded by white areas where total internal reflection occurs.

Fig.14:Porro prisms (labeled 2 & 3) in a pair of binoculars.

An Indian triggerfish and its total reflection in the water's surface.

Total reflection of a paintbrush by the water-air surface in a glass.

Total internal reflection of a green laser in the stem of a wine glass.

The efficiency of the total internal reflection is exploited by optical fibers (used in telecommunications cables and in image-forming fiberscopes), and by reflective prisms, such as image-erecting Porro/roof prisms for monoculars and binoculars.

Shark

Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head.

Fossil shark tooth (size over 9 cm) with crown, shoulder, root and root lobe

Megalodon (top two, estimated maximum and conservative sizes) with the whale shark, great white shark, and a human for scale

Identification of the 8 extant shark orders

Shark fossil, Lebachacanthus senckenbergianus, at Permian period

The teeth of tiger sharks are oblique and serrated to saw through flesh

The dermal denticles of a lemon shark, viewed through a scanning electron microscope

The shape of the hammerhead shark's head may enhance olfaction by spacing the nostrils further apart.

Eye of a bigeyed sixgill shark (Hexanchus nakamurai)

Electromagnetic field receptors (ampullae of Lorenzini) and motion detecting canals in the head of a shark

Unlike many other sharks, the great white shark is not actually an apex predator in all of its natural environments, as it is sometimes hunted by orcas

A sign warning about the presence of sharks in Salt Rock, South Africa

Snorkeler swims near a blacktip reef shark. In rare circumstances involving poor visibility, blacktips may bite a human, mistaking it for prey. Under normal conditions they are harmless and shy.

Shark-themed nose art, made popular by the Flying Tigers (pictured), is commonly seen on military aircraft.

The annual shark catch has increased rapidly over the last 60 years.

The value of shark fins for shark fin soup has led to an increase in shark catches where usually only the fins are taken, while the rest of the shark is discarded, typically into the sea; health concerns about BMAA in the fins now exists regarding consumption of the soup

A 14 ft, 1200 lb tiger shark caught in Kāne'ohe Bay, Oahu in 1966

The shark's field of vision can swap between monocular and stereoscopic at any time.

SIG Sauer

Several brother companies that design and manufacture firearms use the brand name SIG Sauer.

A SIG Sauer P226 semi-automatic pistol, with magazine removed

Magnifiers

Joseph LeConte

Physician, geologist, professor at the University of California, Berkeley and early California conservationist.

He published a series of papers on monocular and binocular vision, and also on psychology.

Reinke's edema

Swelling of the vocal cords due to fluid collected within the Reinke's space.

The movement of the vocal folds during speech

Vocal stripping was often performed without magnification and with a monocular laryngoscope, instead of a binocular scope.

Early depiction of a "Dutch telescope" from 1624.

History of the telescope

Submitted by Hans Lippershey, an eyeglass maker.

$Optical diagram showing light being refracted by a spherical glass container full of water, from Roger Bacon, De multiplicatione specierum$

Notes on Hans Lippershey's unsuccessful telescope patent in 1608

Reproduction of one of the four optical devices that Zacharias Snijder in 1841 claimed were early telescopes built by Zacharias Janssen. Its actual function and creator has been disputed over the years.

19th-century painting depicting Galileo Galilei displaying his telescope to Leonardo Donato in 1609.

$Engraved illustration of a 45 m focal length Keplerian astronomical refracting telescope built by Johannes Hevelius. From his book, "Machina coelestis" (first part), published in 1673.$

A replica of Newton's second reflecting telescope which was presented to the Royal Society in 1672.

William Herschel's 49 in "40-foot" telescope of 1789. Illustration from Encyclopædia Britannica Third Edition published in 1797.

The 200 in Hale telescope at Mount Palomar

ESO's VLT boasts advanced adaptive optics systems, which counteract the blurring effects of the Earth's atmosphere.

The 250 ft Lovell radio telescope at Jodrell Bank Observatory.

The Italian polymath Galileo Galilei was in Venice in June 1609 and there heard of the "Dutch perspective glass", a military spyglass, by means of which distant objects appeared nearer and larger.