Thermal And Night Vision Revealed

The most obvious differences between Gen 2 and Gen 3 night vision units are the addition of a chemical, gallium arsenide, to the photocathode and an ion barrier flm to the input side of the micro-channel plate—resulting in brighter imaging, reduced noise and extended tube life.

More and more shooters and hunters are using thermal or night vision optics these days. So what “Gen” are we on now anyway? Here’s a primer on “see in the dark” scopes— along with an inside look at how they differ and how they work.

BY KEVIN REESE

onning night vision goggles for the frst time can be a life-changing experience. That’s how I remember it from my days as a young Marine in the early 1990s. I frst strapped on AN/PVS-7B Gen III goggles because, well, moonbeams were scarcely adequate for fnding my way to the head. Also, the use of fashlights and cigarettes in blackout conditions were cause for a beating—you’d be surprised at just how far away they can be seen.

The night-vision devices (NVD) of that period were staple gear only for a select few, such as HMMMV (Humvee) drivers, because jumping behind the wheel during a blackout, with little or no light, was a recipe for disaster. Still, driving with PVS-7B Gen IIIs was tricky at best. More than once, shaded ground turned out to be eroded holes and ditches.

Few things come easy in the Marine Corps, including driving with NVDs, but the goggles were a necessity and quite a welcome tool considering the thought of running an archaic PVS-5 Gen I … or nothing at all. Of course, thermal was also in use, but it was essentially folklore for most of us. Honestly, even the military’s current PVS-14 Gen III night vision monocular is far from ideal, especially for driving or high-speed movements; however, the PVS-14 continues to hold its own on a frearm.

And, while I consider how mind-blowing night vision was for us decades ago, the PVS-7B’s technology, even by today’s consumer standards, seems a bit archaic, especially considering the digital-night-vision and thermalimaging optics currently available and in use by law enforcement, security personnel, shooters and hunters. That said, understanding the origins of night vision and thermal helps paints a clearer picture of today’s exciting and affordable technology. A SNAPSHOT HISTORY OF NIGHT VISION

Believe it or not, night vision is rooted in World War II-era innovation. During the war, Germany, followed quickly by allied forces, employed near-infrared (NIR) rifescopes. In a nutshell, these devices featured a large NIR light mounted above a rifescope. The top-mounted light cast signifcant NIR illumination. Essentially, the light refected off the target, bouncing back into the rifescope where an image tube multiplied it. Roughly 10 years later, in the mid-50s, just after the Korean War, technology fnally made its way into generational night vision with an improved tube and a more effcient NIR illuminator. Today, three generations of night vision are available for military, law enforcement and consumers alike.

KNOW YOUR NIGHT VISION

Woody Harrelson’s character in the movie “Doc Hollywood” said it best, “I could have been a doctor. It was the science I had a problem with.” Understanding night vision can be diffcult as it’s all high-tech. But in the simplest terms I can muster, night vision is considered to be either active or passive.

Active night vision requires the use of infrared (IR) illumination or, in the case of the World War II iteration, NIR and other Gen 0 devices. Passive night vision is exceptionally effcient at gathering all available light for processing, including from stars, the moon and industrial light sources. While passive night vision effectively harnesses light particles, it still does not do as well as one might hope on moonless nights—you know the kind; you can’t see the ground beneath your feet. Fortunately, passive devices also include IR illuminators designed to create the light you need to expose the feld of view, at least as far as the light’s throw.

The light gathered by Gen 1 to Gen 3 devices comes from every imaginable source in the form of particles known as photons. They pass through the objective lens and into the image-intensifer tube where three elements are housed—the photocathode, microchannel plate and phosphor screen. Once the photons enter the image intensifer tube, they pass through the photocathode and are converted into electrons. The electrons then move through a multi-channel plate covered in microchannel tubes. As the electrons pass through the microchannel tubes they are converted into exponentially more electrons before continuing to the phosphor screen where they are converted back into photons, this time, to create the image you are viewing in a green hue.

As night vision technology has progressed, image quality has improved, even as the price and size of the devices that make it possible have, relatively speaking, decreased.

WHAT’S THE DEAL WITH GENERATIONS?

Today’s traditional night vision devices, excluding digital night vision (DNV), consist of three generations commonly referred to as Gen 1 (I), Gen 2 (II) and Gen 3 (III). A few companies offer “Gen 4 (IV)” products; however, no military branch currently recognizes Gen 4, including, most importantly, the U.S. Army Night Vision and Electronic Sensors Directorate. Tasked with ascribing and defning generation-level requirements, this offce has yet to accept Gen 4 night vision technology. If you’re in the market for night vision, read through the following descriptions of the various generations so that you can determine which level best fts your needs.

GEN 1: While the earliest version of night vision, Gen 0, was active, Gen 1 units are typically passive. Even so, due to limitations, these devices still beneft from IR illumination in most environments. Originally available in the 1960s and used in Vietnam (AN/PVS-5), Gen 1 optics deliver the greenscreen goods up to roughly 75 yds. away, perhaps even 100 on a clear, moonlit night. As the most affordable night vision currently available, display resolution takes a hit; it’s often grainy. In Gen 1 optics, “blooming” is also an issue—the feld of view becoming completely obscured by a bright light.

GEN 2: Continued development gave rise to Gen 2 devices in the 1970s. Original Gen 2 devices were smaller and much better-suited for both handheld and helmet-mounted use. Gen 2 devices incorporate improved, more compact tubes and better gain. Resolution was dramatically increased, and blooming was largely resolved. The Gen 2 detection range was also substantially increased; most Gen 2 optics are capable of reaching out to 200, even 250 yds. Of course, more compact Gen 1 and Gen 2 models are available to consumers today and are well-suited for handheld, helmetmounted and frearm-mounted tasks.

GEN 3: Considered the crème de la crème of night vision, at least for regular Joes like me, Gen 3 arrived in the late 1970s/early ’80s and boasts a rich, high-resolution image.

The most dramatic improvements over Gen 2 include an extended range, upwards of 400-plus yds., and auto-gating for reduced blooming and effective use in a wide range of lighting conditions. Gen 3 also improves on passive use—the ability to run a Gen 3 night-vision device without IR—however, most optics do include an onboard IR, and numerous manufacturers offer incredibly powerful, opticmountable IR illuminators to take your detection range even farther, some as far as 500 yds. As a side note, while auto-gating certainly increases the ability to operate units in changing light conditions, I would be careful about running traditional night vision during daytime. Daytime use of a night-vision optic is a job best-suited for today’s digital night vision.

Depending on the generation, night vision can be expensive. Gen 1 devices usually cost between $200 and $600, while Gen 2 averages $1,000 to $3,000 and Gen 3 is a bank-breaker for many folks at $3,000 to $6,000. As a side note, Gen 1+ and Gen 2+ optics also are available and generally rest at price points on the high end of those just mentioned. That’s a lot of dough for an optic you can’t run 24/7; so, what’s the solution? Enter digital night vision. PUTTING THE DIGITAL IN NIGHT VISION

Today, digital night vision optics with improved sensors— most often a charged coupling device (CCD)—are designed to deliver fawless performance day or night without the need for a special lens cover. Sure, digital night vision scopes are, in fact, night vision scopes through and through; however, they process differently … digitally speaking. Digital night vision incorporates an electric signal. Remember, traditional night vision follows this process: Photons become electrons, which become exponentially more electrons before converting back into photons again to create an image on a green display. Digital night vision, on the other hand, works in the following manner: Light particles enter the objective lens and are converted to an electric signal in a high-tech CCD sensor. The electric signal is sent to a display, often a liquidcrystal display (LCD) or active-matrix organic light-emitting diode (AMOLED). Digital night vision displays are often black and white; although several color flters also are available.

Digital night vision performance has averaged between Gen 1+ to Gen 2+ generations without paying an arm and a leg for top-end imaging at either level. Current prices average $500 to $2,500—not bad for an optic you can use day or night.

A cutaway of a Pulsar Digisight N960 digital night vision rifescope (above) reveals a high-tech mix of lenses and circuitry delivering Gen 2+ performance day or night. The German Zielgerat 1229 Vampir night vision rifescope mounted on an StG 44 (r.) had an oversize infrared illuminator and backpack battery.

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