|Fig. 1: Frontal view of XN-1 aboard USS Ponce (Source: Wikimedia Commons)|
In 2014, the United States Navy deployed the AN/SEQ-3 Laser Weapon System, also known as the XN-1 LaWS, aboard the USS Ponce, a Navy ship stationed in the Persian Gulf (see Fig. 1). This event marked the first deployment of a directed-energy weapon as an operational asset in a military theater, with the commander of the USS Ponce being authorized to use the weapon for defensive purposes against non-human targets. The XN-1 is not the first attempt by the US Military to deploy a directed-energy weapon platform, but previous projects have not been able to adequately satisfy the three, often exclusive, constraints of size, weight, and power.
The XN-1 is a solid-state laser that utilizes fiber optic cables as the medium in which it excites particles from a low to high energy state. Though its power is classified, its capabilities, demonstrated in a 2014 test where at a range of less than one mile the XN-1 successfully destroyed an eagle-sized drone, an RPG warhead, and engine components aboard a rubber boat, suggest that the XN-1's power is between 15 and 50 kilowatts.  The XN-1 was assembled using commercially available parts, and given the relatively low performance demands exhibited by the test, there is no indication that the XN-1 is the herald of a breakthrough in beam quality, a longtime bottleneck of properly sized directed-energy weapons. 
Utilizing a directed-energy weapon system creates benefits that extend beyond its postulated combat effectiveness. An energy weapon removes the need for the manufacture, transport, storage, and maintenance of projectiles, a point of extreme concern for military ships. As long as gunpowder based weapons are utilized on ships, the munitions for these weapons must be stored in the ships magazine, an area that if breached often has fatal consequences for the ship and her crew. In addition to these safety and logistical benefits, a directed-energy weapon negates the need for calculating for projectile drop and time to impact, both of which were calculations that gunners had to factor into their targeting equations previously.
As with all lasers, the effectiveness of the XN-1 and its energy beam can be eroded by the presence of humidity, dust, reflective surfaces, and any other atmospheric contaminant that would refract and disrupt particles within the beam. Even at the upper end of the XN-1's theorized range, the weapon will only have an effective range of a few miles, assuming optimal conditions. Additionally, the XN-1 requires power and cooling infrastructure, accommodations that will further cramp a naval ship, where space is already at a premium.
The fact that the XN-1 is the first directed-energy platform to survive military scrutiny and be deployed is a fantastic achievement for directed-energy platforms, especially considering the size and political backing of previous laser programs, such as President Reagan's Star Wars initiative. However, the XN-1 still carries the lingering flaws and constraints of its predecessors, albeit to a much lesser extent. Despite this, the XN-1 could serve to be a spark of hope for the military's continued development of directed-energy weapons, which has a demoralizingly long, expensive, and unsuccessful track record.
© Erik Holmvik. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 V.C. Coffey, "High-Energy Lasers: New Advances in Defense Applications," Optics and Photonics News 25, 28 (2014).
 S. Ghoshroy, "Navy's New Laser Weapon: Hype or Reality?" Bulletin of the Atomic Scientists, 18 May 15.