The Ophir SWIR & NIR 25-250mm continuous zoom lens provides long-range detection and integration within small airborne systems, ensuring clear and precise imaging in various weather conditions.
This advancement reflects the relationship between cutting-edge technology and strategic operations, with each influencing the other. The dynamic integration of short-wave infrared (SWIR) sensors into aerial electro-optical systems (EOS) highlights this interaction.
Aerial EOS require versatile optics that operate across a wide range of wavelengths. Recent battlefield experiences have driven these systems to become more comprehensive while minimizing payload size to extend mission durations.
From high-speed and surveillance aircraft to various-sized unmanned aerial vehicles (UAVs), these systems must operate in challenging environments, including poor visibility and laser pointer detection.
SWIR sensors, typically operating in the 0.9-1.7mm wavelength range, complement thermal (MWIR/LWIR) systems by performing well in both low light and daylight conditions. Additionally, SWIR technology has emerged as a powerful tool for laser applications and has introduced new capabilities in advanced aerial EOS products.
Limitations of Visible & Thermal Imaging
Historically, Aerial EO systems included two imaging channels: visible and thermal. The introduction of smaller, lighter optics has made it easier to use medium-wave infrared (MWIR) or long-wave infrared (LWIR) thermal sensors with smaller pixel sizes and larger arrays.
The visible channel often incorporates a near-infrared (NIR) capability inherent in the silicon arrays used. However, users have identified limitations with these two channels, which SWIR technology addresses.
Despite advances in sensor technology, optics integration remains a challenge. Ophir has developed the 25 – 250mm continuous zoom lens to meet the needs of small pixel detectors, enhancing EOS accuracy, precision, and efficiency, especially in low-visibility conditions.
Advantages of SWIR & NIR
Atmospheric Obscurants Penetration
SWIR is crucial for aerial imaging due to its ability to penetrate haze, smoke, and maritime fog. The Ophir SWIR & NIR 25 – 250mm continuous zoom lens enhances image clarity through such obscurants, improving visibility in challenging conditions.
Thermal Interference Resilience
Thermal imagers often struggle when the temperature of the background and the target are similar, a situation known as thermal crossover. SWIR technology, which relies on reflected energy, provides improved contrast in dynamic thermal environments. The Ophir SWIR & NIR 25 – 250mm continuous zoom lens leverages this technology to enhance imaging performance in such scenarios.
Natural Ambient Light Utilization
SWIR sensors utilize natural light sources like sunlight, moonlight, and artificial lighting, enabling effective imaging during daylight and low-light conditions. This capability is crucial for accurate identification in various operational scenarios. The Ophir SWIR & NIR 25 – 250mm continuous zoom lens ensures reliable performance across diverse lighting conditions.
Long-Range Daytime Observation
SWIR wavelengths are valuable for long-range daytime observation, as they scatter similarly to visible light. SWIR also penetrates fog and water vapor, offering advantages over visible light imagery in poor weather conditions.
Glass Transmission
SWIR wavelengths can pass through glass, which is beneficial for certain surveillance applications. The Ophir SWIR 25 – 250mm continuous zoom lens is designed to take advantage of this capability, enhancing its effectiveness for specific use cases.
See-Spot Solutions for Laser Designators
SWIR imagers that cover wavelengths from NIR to SWIR (0.7 – 1.7μm) can capture lasers commonly used in military operations (e.g., 850, 905, 1064, and 1550nm). The Ophir SWIR & NIR 25 – 250mm continuous zoom lens is well-suited to provide clear and accurate imaging of these lasers.
The Ophir SWIR & NIR Zoom Lens
The Ophir SWIR & NIR lens 25–250mm f/5.5 (NOFV) f/4 (WFOV) represents a significant advancement in continuous zoom lens technology, designed to integrate with various SWIR sensors featuring pixel pitches of 5μm, 10μm, and 15μm, and array sizes up to 1280 x 1024 (5μm and 10μm).
Optical Flexibility
This apochromatic lens offers exceptional optical flexibility in a compact design, making it ideal for compact gimbal systems and diverse operational scenarios. Advanced algorithms enable seamless integration of images into multispectral content.
Optical Performance
MTF testing shows near diffraction-limited performance in narrow FOV across all field positions, especially with SXGA 5μm detectors, and minimal distortion at all zoom levels. Ophir has rigorously tested this lens to ensure it meets all design criteria.
Figure 1 (top to bottom): theoretical (black) and measured (green – sag., red – tang.) MTF at NFoV (250mm EFL) vs. spatial frequency (cycles / mm) for light at 1.52μm and on-axis. Figures at the top right corners represents theoretical (top) and measured (bottom) wavefront distortion.
Broad Spectral Band Coverage
Spanning wavelengths from 700 to 1700 nm, this lens covers a wide NIR to SWIR range, supporting various subbands and applications, including “see-spot” solutions for laser designators.
Low SWaP Design
At just 860 grams and 224 mm in length, this lens sets new standards for lightweight, compact design, enhancing operational endurance and mission effectiveness, and making it suitable for compact system designs.
Chromatic Correction
Correcting chromatic aberration across a broad spectrum is challenging due to the limited optical glass types available for the SWIR region. Extensive glass selection and strategic placement of doublets have resulted in well-corrected apochromatic performance across the entire zoom range.
The Ophir SWIR & NIR 25-250mm continuous zoom lens is suited to high-performance SWIR imaging systems due to its apochromatic design, continuous zoom capability, and compatibility with various pixel pitches. Designed with low SWaP characteristics, it aligns with the needs of compact gimbal systems in UAVs, aircraft, or other low SWaP applications.
