Delivering a battle proven solution
01 July 2021
A global high technology company, headquartered in Rome, Leonardo is well-known for its continuous innovation within aerospace, defence & security. To support today’s military operations, the company developed its hand-held Type 163 laser target designator, with a focus on designing a portable laser that was simple & easy to operate, as well as rugged & reliable.
This case study was originally featured in the July 2021 issue of EPDT magazine [read the digital issue]. And sign up to receive your own copy each month.
Laser specialist & project lead at Pacer, Stuart Sendall explains how the firm got involved and discusses the optoelectronics expertise it brought to the project…
A key requirement in the development of the designator was a laser rangefinder, which would ensure the final design delivered a best-in-class solution, further demonstrating Leonardo’s proven capability in laser designator manufacturing for military applications.
However, limited time and resources meant that the Leonardo team sought support from a flexible and agile partner to further develop the product within a tight timeframe, before the product could ‘go to market’. Recognising its 30+ years’ pedigree in optoelectronics, Leonardo turned to Pacer International and its team of highly skilled engineers to develop the laser rangefinder, aligning with the stringent requirements and technical specifications.
The role of the designator
The Type 163 Laser Target Designator was designed by Leonardo. Its purpose is to meet all of today’s special and conventional force JTACs (Joint Terminal Attack Controllers) and JFOs (Joint Force Operations) mission requirements for marking and terminally controlling semi-active air-to-ground weapons accurately onto the target, at ranges of up to 10km. The laser is designed to support a modular and separable approach to target acquisition and sensor equipment, providing maximum flexibility in mission planning, and, more importantly, helping to minimise individuals’ carrying load.
A challenging approach
Laser specialist and project lead, Stuart Sendall comments: “Designating up to 10km requires a significant amount of energy, via a huge wall of photons, within a short period of time. We needed to be able to consider the huge optical dynamic range required, while managing the atmospheric backscatter in the form of particles, sand, dust and water in the air. Equally, we recognised that we couldn’t design a solution that was too sensitive, whereby false returns from atmospheric conditions were being distributed.
“Fundamentally, we needed to design an electrical circuit that could manage the effects of this wide optical dynamic range and the consequences this could have on amplified saturation and false alarms triggered by atmospheric backscatter.”
The lens design also proved challenging. These designators needed to be able to operate in high ambient light environments, and if sunlight reflects on to the receiver, it can bloom and saturate. Given the size of the designator, there was only an extremely limited space to develop the lens. When considering a long-focused lens, such as a paparazzi lens, some of these can be two feet long. Pacer had only a 30mm space to work with.
Meeting the stringent requirements
Being a military product, the designator needed to meet stringent environmental specifications, particularly in relation to the wide and varied weather conditions these systems would be operating within. They needed to operate optimally without cracking or falling apart.
As such, there was a rigorous design, verification testing and qualification process that needed to be completed to verify that the design did in fact meet the necessary environmental requirements. This involved standard thermal shock tests, as well as an additional salt spray test. The qualification tests also included a calibrated mixture of sand and dust, which was subsequently thrown in front of a fan to blast the product.
“With such small signals, we also had to test the product for electromagnetic immunity, both radiative and susceptibility. In other words, determine what it is radiating – it must not have a signature, but equally, it must not be too sensitive to other devices nearby that are transmitting or radiating signals,” explains Pacer’s Stuart Sendall.
A bespoke mechanical three-lens design was developed to ensure it could withstand all the temperature variations. As lenses get hot or cold, they expand and contract as individual elements, but the distance with respect to one another also changes. Therefore, Pacer undertook a Monte Carlo analysis – a well-known quantitative analysis risk management technique that assesses the system performance impact of a set of variable parameters, by repeatedly calculating possible results, using different set of random values of those parameters. In this instance, the various parameters included dimensional radius, curvatures, X and Y misalignment, and axis variations. This analysis helped us to determine by how much the point of focus altered under the various environmental conditions.
Production of the laser rangefinder took place on a stabilised optical bench, which Pacer invested in specifically for this project. Stuart continues: “We learnt a lot through the production phase, and as such, introduced several bespoke processes to ensure we met the requirements. For example, we assembled the lens stack in a nitrogen purged environment – assembling these lenses in an area with no oxygen ensured that no moisture could invade it. We also had to optically polish our metal work to get it to the flatness required. This level of precision is incredibly rare and reinforces the expert skills of our engineers. We are unaware of any machine process that can achieve that level of precision. Despite the challenges, being able to foresight the designator to 10km range and 2m diameter accuracy, while meeting the rigorous requirements, is a significant technical achievement.”
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