question: How do laser sights work? it's either below or above the barrel, so if they're parallel then the trayectory of the laser and the bullet wont intersect, and if it's at an angle then they will but only at a certain distance right? so how does that work?
comment: While the LASER travels in a straight line, the actual bullet travels in an extended arc. There are generally 2 places along that arc where the LASER and the bullet would intersect. You can adjust your LASER to shift the point of aim at a given distance. Any further or closer than that calibrated space and the point of impact would shift either above or below where the LASER shows on target.
passages: BULLET::::- P90 Laserex models:The "P90 LV" (Laser Visible) and "P90 IR" (InfraRed) models, both of which were introduced in late 1995, have an integrated laser sight manufactured by Laserex Technologies in Australia. The "P90 LV" model projects an 8 mW visible laser intended to be used as a low-light shooting aid or for dissuasive effect, while the "P90 IR" model projects a 4.5 mW infrared laser that can only be seen with night vision equipment. Both laser systems are compact, consisting of a small, flat panel integrated into the front end of the weapon's frame.
   BULLET::::- It does not distort the wavefront and will be an optical element with sufficient optical flatness (less than one tenth of a wavelength) and homogeneity
  
  BULLET::::- It can handle the required optical power
  
  For laser beam profiling with CCD sensors, typically two types of attenuators are used: neutral density filters, and wedges or thick optical flats.
  
  Section::::Techniques.:CCD camera technique.:Attenuation techniques.:Neutral density filters.
  
  Neutral density (ND) filters come in two types: absorptive and reflective.
   The laser has in most firearms applications been used as a tool to enhance the targeting of other weapon systems. For example, a "laser sight" is a small, usually visible-light laser placed on a handgun or a rifle and aligned to emit a beam parallel to the barrel. Since a laser beam has low divergence, the laser light appears as a small spot even at long distances; the user places the spot on the desired target and the barrel of the gun is aligned (but not necessarily allowing for bullet drop, windage, distance between the direction of the beam and the axis of the barrel, and the target mobility while the bullet travels).
   Section::::Design details.:Sights.
   BULLET::::- White light halogen incandescent flashlight, 6–8 W, 90–120 lm, 2.5–4 kcd, 100–120 m ANSI/NEMA FL 1-2009 beam distance;
  
  BULLET::::- Non eye-safe laser sight, the visibility depends on the environmental light conditions, suited for quick shots. At dusk the red laser dot is visible just over 150 m;
  
  BULLET::::- Infrared (IR) laser, visible only when LUCIE (part of Germany's IdZ modernization program) or another infrared night vision device is used, unless the enemy has IR night vision equipment the IR laser will not reveal the presence of the LLM01 IR light beam;
   There are two main types of reticles:
  
  BULLET::::- Wire reticles
  
  BULLET::::- Etched reticles
   Using the naked eye to boresight can be difficult due to the tunnel vision and lack of brightness, especially with longer-barreled guns. A more advanced method of boresighting uses a collimator, an optical attachment similar to a scope sight, which fits onto the end of the barrel. Using this method, the normal sight (which is fixed to the receiver) and the collimator (which is fixed to the barrel) can be sighted to match. Most collimators have grid patterns for rechecking the zero after the barrel is sighted.
  
  Section::::Laser boresighting.
   The machine is set up using the built-in spirit level or plumb bob, and the line along the surface is then guaranteed to be accurately horizontal or vertical to within a certain tolerance, specified either in millimetres per metre or fractions of an inch over a specified distance in feet. A more advanced device may be accurate to within 0.3 mm/m; while lower-end models may be closer to 1.5 mm/m.
  
  The illuminated line is necessarily absolutely straight, so that the line level can be used as a straightedge; for example, to see if a shelf is warped, even if not horizontal.
   BULLET::::- 35 mm, a rare tube size which only is seen on some current models from Romanian IOR and U.S.-based Vortex and Leupold
  
  BULLET::::- 36 mm, only used on some newer scope models by Zeiss and Hensoldt
  
  BULLET::::- 40 mm, only used on some scopes made by Romanian IOR and the new Swarovski dS scope
   BULLET::::- Three-dot: On semi-automatic handguns, the most common type of enhancement is a bright white dot painted on the front sight near the top of the blade, and a dot on each side of the rear sight notch. In low lighting conditions the front sight dot is centered horizontally between the rear sight dots, with the target placed above the middle (front) dot. Some sight vendors offer differently colored dots for the front and rear sights.
   Several techniques generate more control data, such as a continuous range of values like those in typical MIDI controllers:
  
  BULLET::::- An infrared or ultrasonic rangefinder attached to the instrument that determines the position of the hand that blocks a beam
  
  BULLET::::- A laser-based rangefinder that determines the distance from the hand to the laser's starting or ending point (and possibly using this laser itself as the string)—or a variation of this that uses the intensity of the sensor signal itself
   BULLET::::- Phase-front technique: The beam is passed through a 2D array of tiny lenses in a Shack–Hartmann wavefront sensor. Each lens will redirect its portion of the beam, and from the position of the deflected beamlet, the phase of the original beam can be reconstructed.
  
  BULLET::::- Historical techniques: These include the use of photographic plates and burn plates. For example, high-power carbon dioxide lasers were profiled by observing slow burns into acrylate blocks.
   BULLET::::- A camera that tracks position and motion of the laser dot on the hand, or length of the exposed beam if visible, then calculates a continuous value based upon a reference
  
  The first of these is relatively inexpensive and straightforward to implement, and can use the same micro-controller that drives the lasers and reads the detectors.
   BULLET::::- Other:
  
   mil and  mil can be found in some short range sights, mostly with capped turrets, but are not very widely used.
  
  Section::::Sight adjustment.:Subtensions at different distances.
   BULLET::::- VCSEL with longitudinally integrated monitor diode: A photodiode is integrated under the back mirror of the VCSEL. VCSEL with transversally integrated monitor diode: With suitable etching of the VCSEL's wafer, a resonant photodiode can be manufactured that may measure the light intensity of a neighboring VCSEL.
   formula_6
  
  In most regular sport and hunting rifles (except for in long range shooting), sights are usually mounted in neutral mounts. This is done because the optical quality of the scope is best in the middle of its adjustment range, and only being able to use half of the adjustment range to compensate for bullet drop is seldom a problem at short and medium range shooting.
   BULLET::::- Fiber optic: A growing trend, started on air rifles and muzzleloaders, is the use of short pieces of optical fiber for the dots, made in such a way that ambient light falling on the length of the fiber is concentrated at the tip, making the dots slightly brighter than the surroundings.This method is most commonly used in front sights, but many makers offer sights that use fiber optics on front and rear sights. Fiber optic sights can now be found on handguns, rifles, and shotguns, both as aftermarket accessories and a growing number of factory guns.
  
  Section::::See also.
   No matter which method of bore sighting is used, the result is to align the cross-hairs of the scope to the spot where the barrel is pointing at a particular distance. Because of variations in the trajectory of ammunition and other factors the bore-sighted rifle will probably not shoot to the exact spot that the cross-hairs indicate, and live ammunition will need to be fired to fine-tune the sighting process.
   Section::::Description.
  
  The basic layout of a collimator sight is a closed tube with a lens at its open end and a luminous reticle mounted near the closed end at the focus of the lens, creating an optical collimator. The reticle is illuminated by an electronic light source (an incandescent light bulb or, more recently, a light-emitting diode) or by ambient light gathered behind the reticle via an opalescent window or fiber optic light pipe.
  
  Section::::Applications.
   BULLET::::- Infrared target illuminator, the IR illuminator has a maximum range of up to 10 m;
  
  BULLET::::- Combinations of white light flashlight and laser red dot and IR laser and IR target illuminator, appropriate for simultaneous lighting and aim point determination.
   This sight is based on the 400 meter concept, so if an operator shot from a distance of 100 meters, the bullet point of impact would be 22–25 centimeters higher than your intended point of impact. The largest chevron is intended for ranges from 0 to 400 meters. Inside the center chevron lies a dot that was implemented to be used against targets that are 500 meters from the operator. The 2nd and 3rd chevrons are for targets that are 600 and 700 meters away. While this scope does not have the range calculating system that the PSO implements it is possible to use the dimensions of the hash marks to calculate range.
   The rest Noblex Sights share the same footprint that became an industry standard and is used also by brands like Meopta, Vortex Optics, Leica Camera and others . They come with either 3.5 MOA red dot (for rifle use) or with 7.0 MOA red dot (for handgun use).
  
  Riflescopes produced by Noblex are divided in the following series: 
  
  BULLET::::- Noblex N6 ED
  
  BULLET::::- Noblex N6 (formerly known as Docter V6)
  
  BULLET::::- Noblex N5
  
  BULLET::::- Noblex N4 (Formerly known as Docter Basic)
   As laser technology has become less expensive, laser boresighters have become popular for sighting in rifles. One type of laser boresighter is shaped like a cartridge, and when inserted into the chamber projects a laser beam through the barrel onto the target. The user then adjusts the rifle scope until the crosshairs are on the projected laser dot. Another type of laser boresighter is more universal and is attached to the muzzle of the barrel, either by inserting into the bore ("arbor" type) or via a magnet. It is held in alignment with the barrel and projects a laser beam onto the target. Again, the user aligns the crosshairs to the laser dot on the target.
   BULLET::::- Knife-edge technique: A spinning blade or slit cuts the laser beam before detection by a power meter. The power meter measures the intensity as a function of time. By taking the integrated intensity profiles in a number of cuts, the original beam profile can be reconstructed using algorithms developed for tomography. This usually does not work for pulsed lasers, and does not provide a true 2D beam profile, but it does have excellent resolution, in some cases 1 µm.
   BULLET::::- P90 USG:The "P90 USG" (United States Government) model is similar to the standard P90, except the reflex sight housing is aluminium, and the sight has a revised reticle. The black reticle consists of a tiny dot inside of a small ring, which is joined by three posts that glow red in low light conditions due to tritium-illumination. The USG reflex sight can be removed and replaced with a special MIL-STD-1913 ("Picatinny") rail mount for attaching a different sight.
  
presuppositions: Bullets travel in straight lines. Bullets travel in straight lines.
corrections: Bullets travel in extended arcs, while a laser travels in a straight line. Bullets travel in extended arcs.
raw_presuppositions: Bullets travel in straight lines. Bullets travel in straight lines. Bullets travel in straight lines.
raw_corrections: Bullets travel in extended arcs, while a laser travels in a straight line. Bullets travel in extended arcs. Bullets travel in extended arcs.