Clip-on target designation sensor to night vision goggles

A target engagement system includes a night vision goggle system operating within a predetermined wavelength band, and a laser module projecting light onto a target, where the light operates at a wavelength that is outside of the predetermined wavelength band. Also included is a receive system for receiving the light reflected from the target and converting the light into a wavelength within the predetermined wavelength band. In this manner, the receive system provides the converted light to the night vision goggle system, and the night vision goggle system amplifies the converted light for viewing by a user. The receive system includes a clip-on device for removably attaching the receive system between the target and the night vision goggle system. The receive system includes an up-converting phosphor layer for up-converting the received light into a wavelength detectable by the night vision goggle system.

FIELD OF THE INVENTION

The present invention, in general, relates to night vision goggles and, more particularly, the present invention relates to laser target designators for night vision goggles.

BACKGROUND OF THE INVENTION

Detecting human targets is a primary task of an infantry soldier. Completing this task at night poses peculiar difficulties to the soldier. First, the soldier must be able to see the target and then aim his weapon at the target to ensure hitting the target. Soldiers are outfitted with night vision goggles (NVGs) that permit target detection at night. In order to engage the target, the soldier has a laser aiming light mounted on, and boresighted to his weapon. The aiming light provides energy at a particular wavelength that the image intensifier (I2) tube in the NVG can detect. Thus, the soldier sees the target with the NVG. He also sees the aiming light through his night vision goggle and, thus, can move the aiming light onto the target. Since the aiming light is boresighted with his weapon, he can pull the trigger when viewing the aiming light on the target.

The aiming light, which is sensed by the night vision goggle is not visible to the human eye. In the past, this combination enabled the advantage of covert operation; e.g. the solder can see the enemy, but the enemy cannot see the soldier. Today, as a countermeasure, the enemy is capable of fielding a night vision goggle that can detect the aiming light. Consequently, covert operation is no longer possible. Presently, when a soldier turns on his aiming light, the enemy can see him and can engage to target him.

SUMMARY OF THE INVENTION

To meet this and other needs, and in view of its purposes, the present invention provides a laser projecting light. The laser projecting light includes: a laser module for projecting light onto a target. The light operates at a wavelength outside of a wavelength band detectable by a night vision goggle system. The laser module is removably attached to a weapon system, and is boresighted to the weapon system. The light may operate at a wavelength longer than 950 nanometers. The light may operate at a short wave infrared (SWIR) wavelength. The light may also operate at a wavelength shorter than 400 nanometers.

Another embodiment of the present invention is a target engagement system including a night vision goggle system operating within a wavelength band, a laser module for projecting light onto a target, the light operating at a wavelength and outside of the wavelength band. Also included is a receive system for receiving the light reflected from the target and converting the light into a wavelength within the wavelength band. The receive system provides the converted light to the night vision goggle system, and the night vision goggle system amplifies the converted light for viewing by a user.

The receive system includes a clip-on device for removably attaching the receive system between the target and the night vision goggle system. The receive system is configured to up-convert the received light into a wavelength detectable by the night vision goggle system.

The receive system may include a relay objective, a fold mirror and an insertion beam combiner for relaying the received light to the night vision goggle system.

The receive system may include a fiber optic bundle for relaying the converted light directly into the night vision goggle system.

In the target engagement system, the light reflected from the target is invisible to the user, and the converted light is visible to the user.

Yet another embodiment of the present invention is a target engagement system including a night vision goggle system operating within a wavelength band; a laser module, boresighted to a weapon system, for projecting light onto a target, the light operating at a wavelength outside of the wavelength band detectable by the night vision goggle system; a receive system for receiving light reflected from the target and converting the light into a wavelength within the wavelength band; and a clip-on device for removably disposing the receive system between the target and the night vision goggle system. The receive system sends the converted light to the night vision goggle system, and the night vision goggle system amplifies the converted light for viewing by a user.

It is understood that the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring first toFIG. 1, there is shown an embodiment of the present invention, referred to herein as a covert target designation system10. The system includes two components: an aiming light module12that transmits light which is not detectable by Gen II or Gen III night vision goggles and a clip-on detection device14that attaches to a night vision goggle system16.

A typical light module12may include a short wave infrared (SWIR) targeting laser which is boresighted to a soldier's weapon. The aiming light module12may includes a battery, a laser and a collimating lens, packaged as a unit and mounted to the weapon, with the aid of a mechanical device to permit attachment and removal from the weapon. The wavelength of the aiming light may be any wavelength longer than 950 nm. It is preferred that a laser be the source of the aiming light, as a laser has a collimated beam, which projects a small spot onto the target at a long range.

The typical laser sight is mounted on the top of a weapon, or on the bottom of the weapon. The laser sight, when properly aligned, places a red dot of light on the target, where the bullet will also strike when the gun is fired. Using this type of sight, enables the soldier to rapidly position the weapon and verify the desired target. Using a laser sight enables accurate shots to be fired at distances of more than 50 feet.

The SWIR receive system14may be a clip-on device which includes a light collection lens, an up-converting phosphor, and either an optical system or a fiber-optic bundle to relay and invert the image for presentation to an input of the I2system16in the night vision goggle system.

Referring next toFIG. 2, the SWIR receive system14and the I2system16are shown in greater detail. As shown, the receive system14includes relay objective20, fiber inverter21, up-converting phosphor surface22, mirror23, relay eyepiece24, and beam combiner25. The objective lens20focuses the received image onto the up-converting phosphor surface22. The up-converting phosphor detects light from the SWIR targeting laser12and up-converts the light to a shorter wavelength. That is, by example, if the laser wavelength is 1.55 nm, then the phosphor surface detects this energy and outputs light at 810 nm wavelength. The 1.55 nm wavelength cannot be detected by the I2system16, but the 810 nm is spectrally positioned near the peak sensitivity of the I2system.

The image formed by the phosphor surface needs to be inverted, translated and collimated, in order to be observed properly by the night vision device. The image inversion is accomplished by depositing an up-converting phosphor layer onto a fiber optic module. The translation and/or the inversion may be accomplished by two fold mirrors23and25, and the collimation is accomplished by a relay eyepiece24, as shown inFIG. 2. Thus, the image is presented to the NVG I2system16, which can amplify and output the out-of band laser wavelength to the soldier as part of his night vision scene.

In order to permit the night vision goggle to view a normal night vision scene, one of the fold mirrors, namely insertion beam combiner25, is coated as a beam splitter. The coating is designed to be highly reflective at the emission wavelength of the phosphor surface (for example, 95% reflective at 810 nm) and highly transmissive at all other wavelengths.

The night vision goggle (NVG) I2system16is positioned to receive the light reflected from beam combiner25, including the up-converted returned SWIR energy reflected from the target. Of course, the NVG I2system16also receives light from the target that is transmitted through beam combiner25. Thus, if the SWIR receive system14is disabled, the NVG system16remains operational in order to view a target in the normal night vision scene.

In operation, the soldier clips the SWIR receive system14onto the front of his night vision goggle. For navigation and detection of targets, he sees only the normal night vision scene. When the out-of-band laser is turned ON, the soldier sees a round dot, wherever the laser reflects off a target. He also sees other objects in the scene by way of the insertion beam combiner25.

Another embodiment of the present invention is shown inFIG. 3, which provides increased efficiency when compared to the embodiment shown inFIG. 2. It will be appreciated that many up-converting phosphors are not very efficient and, thus, the transmitting SWIR laser's power requirement needs to be high, in order to engage the target at normal ranges. In order to reduce power or increase engagement range, an up-converting phosphor, designated as32, may be “pumped” with light from an LED pump30. These pumped phosphors are more efficient than passive, non-pumped phosphors.

The LED pump30may be placed in a position in which the LED light can strike the up-converting phosphor, as illustrated inFIG. 3. It is desirable that the wavelength of the LED pumping light be blue (<500 nm) and, therefore, not be visible to the NVG I2system. The LED pump may be powered by a battery31, such as a small watch battery. The pumping of the LED pump may be, optionally (as shown by a dashed line), synchronized to a laser ON/OFF switch, generally designated as34, which may also control the SWIR transmit system12. As a result, power may be saved by shutting off the SWIR transmit light12and the LED pump30.

Yet another embodiment of the present invention is shown inFIG. 4, which functionally illustrates a clip-on receive system42that is located on top of, or beside an NVG system40. The clip-on receive system42is removably attached to NVG system40by way of clips, or hinges, generally indicated as48.

Also shown, adjacent to a viewer's eye, are the eyepiece lens of the NVG system and the up-converting phosphor layer of the clip-on receive system, respectively, designated by46and54. Disposed remotely from the viewer's eye are the objective lens of the NVG system and the relay objective of the clip-on receive system, respectively, designated by44and52.

Accordingly, the embodiment shown inFIG. 4relocates the relay objective and the phosphor layer, so that they are disposed beside the NVG system instead of being disposed in front of the NVG system, the latter NVG system shown inFIGS. 2 and 3. It will be appreciated that clipping onto the front of the objective lens extends the length of the NVG system. As a result, the NVG system is prone to snagging on environmental hazards, such a vines and branches. Soldiers may tire and have neck pain due to the clip-on device. By adding weight to the front of the NVG, the clip-on device moves the center of gravity further away from the neck, thereby more easily tiring the soldier, when the NVG is used for an extended period of time.

To relocate the lens and phosphor to a location beside the NVG, a fiber optic cable50is used, as shown inFIG. 4, to translate the image toward the front of the NVG system from the back of the phosphor plane, The fiber optic inverter may be eliminated since the optical inversion may be done with the fiber cable that translates the image.