This invention relates to a weapon-aiming device, and more particularly to a weapon-mountable red dot sight.
In close quarter combat, typically in the ranges of 2-800 meters, soldiers are required to rapidly acquire, identify, and accurately fire on enemy targets. Soldiers may use weapon-mounted sights with visible and infrared light sources to assist in the aiming process during daytime and nighttime missions. These sights may be mounted on handheld weapons such as the M4A1 carbine and other small arms and are used to provide better target observation, illumination, and marking.
Traditional weapon-mounted sights utilize red dot sights that incorporate a light emitting diode (LED) as a source of illumination in conjunction with a pinhole aperture. Light emitted from the LED and passing through the pinhole is reflected by an optical element and forms an aim point that can be seen by a shooter looking through the close quarter combat sight. Because the LED has a relatively large emitting area and practical transmission and machining capability limitations limit how small a pinhole can be used, the resulting aim point is relatively large in size. Such a large aim point is undesirable and impairs accuracy especially when aiming at a relatively small target or a target at a relatively long distance.
Red dot sights may be used both during the day without assistance or at night with the assistance of a night vision device such as a monocular or goggle. Red dot sights utilizing tritium (a radioactive isotope) exist, but suffer because the brightness can not be increased during the day and decreased during the night to be compatible with night vision devices.
A dichroic coating is commonly used on a lens surface of a red dot sight to partially reflect or transmit light and to provide a simultaneous view of the red dot and the target scene. Because a visible LED has a relatively weak, apertured light intensity, the optical element typically needs to have a highly reflective coating if a significant amount of the light energy is to be reflected toward the shooter. This highly reflective coating effectively blocks light from the target scene in transmission at wavelengths similar to those being reflected from the LED. Therefore if the a red dot sight employs a red LED, the optical element commonly has a coating that reflects a relatively high percentage of the red light energy from the LED to increase the brightness of the LED visible to the eye, and thus also blocks a high percentage of red light from the target scene. The result is the target scene has an undesirable blue tint. Not only does this blue tint cause the scene to look unnatural, it also impairs one's ability to use the sight with two eyes open because one eye sees the target scene in normal color while the eye seeing the target scene through the sight sees a bluish scene. The blue tint also makes target acquisition difficult in low light conditions such as dusk or dawn because a lack of light transmission. Depending on the nature of the reflective coating, the coating impairs the transmission of light in a portion of the electromagnetic spectrum that the night vision device is sensitive thereby reducing the performance capabilities of the night vision device, in turn affecting the ability of the operator to detect and direct fire on the target. This can be quite distracting. The large aim point and the distorted color of the target scene are two major limitations of existing red dot sights.
Traditional red dot sights have optical elements having spherical optical elements or in some cases holographic elements. With such elements, parallax is present to a significant degree. That is, as the observer looking through the red dot sight moves his eye relative to the sight optical aperture, the point of aim moves with respect to the target. This results in a loss of aiming accuracy. Also, since different shooters hold their eye differently relative to the sight, no single boresight or zero setting of the sight is suitable for all users. This means that each shooter may need to boresight or zero the red dot sight for himself.
A weapon mountable sight has a housing configured to be coupleable to a weapon, where the housing houses a laser diode for a light source and a reflective element to reflect light emitted from the laser diode towards a user looking through the housing.
A close quarter combat sight has a housing, where the housing houses a source of light and a parabolic element. The parabolic element having a reflective coating capable of reflecting light in a narrow band within the visible passband, with a transmission of 10%-40% relative intensity.
A weapon aiming system has a weapon with rails along at least a portion of a longitudinal axis between a butt and a muzzle, a magnifier, and a close quarter combat sight. The close quarter combat sight being disposed along the rail in a position between the magnifier and the muzzle.
For a better understanding of the present invention, together with other objects, features and advantages, reference should be made to the following detailed description which should be read in conjunction with the following figures wherein like numerals represent like parts:
By using a laser diode as the light source in a close quarter combat optic, the emitting area is reduced to a fraction of the size of an LED. As can be seen in
In addition, by using a laser diode, the light energy is intense, concentrated, and is essentially monochromatic. This means the reflective coating on the optical element can be a relatively low reflectance coating and still allow for an easily observable dot in the brightest environments. Such narrow band reflective coating reflects a small portion of the light emitted by the laser diode, but because of the low reflectance, blocks only a small percentage of light from the target scene. This results in the target scene retaining its natural color. This in turn results in a brighter and more natural looking scene. This also facilitates using the close quarter combat optic with two eyes open since both eyes see the same scene in terms of brightness, color, and all other scene attributes.
(where: r=radial position on lens surface
The material may be glass or plastic, for example optical grade Xeonex E48R. The optical element 504 may be retained in a housing 502. The housing 502 houses a laser diode 526 that is mounted off-axis from the optical axis OA of the housing 502. The housing 502 may incorporate a mechanism 520 for mounting the red dot sight 500 to a weapon 530, for example a handgun or long gun. The mechanism 520 may have a moveable actuator 522 that travels in an opening 524 for connection to and disconnection from the weapon 530. The red dot sight 500 may be mounted to a weapon using a variety of mounting mechanism, including those disclosed in more detail in U.S. Pat. No. 5,430,967, titled, Aiming Assistance Device for a Weapon, issued on Jul. 11, 1995; U.S. Pat. No. 6,574,901, titled, Auxiliary Device for a Weapon and Attachment Thereof, issued Jun. 10, 2003; and U.S. Pat. No. 6,705,038, titled, Mounting Assembly for a Weapon, issued on Mar. 16, 2004, all of which are incorporated herein by reference in their entirety. Additionally, the auxiliary device may utilize a mounting mechanism compatible with a mounting rail disclosed in military specifications (e.g., MIL-STD-1913), a “rail grabber” mounting mechanism, screws, bolts, and/or the like. In a closed sight configuration, the optical element 504 may be disposed within the housing 502 between an objective window 508 and an eyepiece window 506. The objective window 508 and the eyepiece window 506 may protect the optical element 504 from the environment, for example water and sand. In an open sight configuration, one or more of the objective window 508 and the eyepiece window 506 may not be included. In this configuration the optical element 504 may be exposed to the environment and the laser diode 526 may be protected by a cover 510. A power setting actuator 540 coupled to a power control circuit allows a user to control the brightness of the red dot.
The coating disclosed above is for use with a red light source, which has a wavelength of about 650 nm. If a different color light source were used, for example a green light source, which has a wavelength of about 510 nm, the coating requirement would shift to about 510 nm.
The transmission and reflectance sums to 100% in a non-absorbing coating. The coating described in
Placement of the magnifier 704 between the close quarter combat sight 702 and the target 706 has drawbacks due to magnification and manufacturing tolerances. Magnifiers have one or more lenses that make the target appear larger. These lenses are typically machined and often have undesired imperfections that may cause the aim point to shift when a magnifier is placed in front of the close quarter combat sight. This shift in aimpoint requires a soldier to either boresight the weapon once without the magnifier and once again with the magnifier or to mentally compensate for the difference in the heat of battle. In addition, if the soldier uses a different magnifier, he will have to reboresight the weapon because of different anomalies in the second magnifier or different rotational alignment of the magnifier to the red dot sight. Another problem with placing the magnifier 704 between the close quarter combat sight 702 and the target 706 is that the magnifier 704 needs to be larger and longer as the required size scales with increasing distance from the eye piece.
Although reference is made to a soldier, the present invention has applications outside of military applications.
Although several preferred embodiments of the present invention have been described in detail herein, the invention is not limited hereto. It will be appreciated by those having ordinary skill in the art that various modifications can be made without materially departing from the novel and advantageous teachings of the invention. Accordingly, the embodiments disclosed herein are by way of example. It is to be understood that the scope of the invention is not to, be limited thereby.
The present application claims the benefit of U.S. provisional patent application Ser. No. 60/568,528, filed May 6, 2004, the disclosure of which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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60568528 | May 2004 | US |