The Complete Guide to IR Lenses - Avantier Inc.

Infrared Lenses (IR Lenses)

Avantier designs and manufactures custom infrared (IR) lenses for advanced applications in

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• Manufacturing
• Defense and security
• Scientific research
• Medical diagnostics

IR lenses operate beyond the visible light spectrum, capturing and focusing infrared radiation to enable high-precision thermal imaging and detection.

Key IR Lens Types

We offer optical systems across the full infrared spectrum, including:

• Near-Infrared (NIR)
• Short-Wave Infrared (SWIR)
• Mid-Wave Infrared (MWIR)
• Long-Wave Infrared (LWIR)

Each lens type is optimized for its target wavelength range and application.

IR Lens MWIR Lens Germanium MWIR Lens SWIR Lens LWIR Lens Germanium LWIR Lenses NIR Lens Motorized MWIR Lens

Factory Standard (Manufacturing Capability)

SWIR lens MWIR lens LWIR lens NIR lens Wavelength 0.9 um-2.5 um 3 um-5 um 8 um-12 um 0.9 um-1.5 um Focal length 25 mm 50 mm 6 mm 25 mm F/# 2.5 0.94 1 2 Sensor 2/3″ 2/3″ 1″ 2/3″ FOV 25° 13° 128° 25°

Custom IR Lens Options

Material Selection

Our IR lenses are fabricated using infrared-transparent materials, such as:

• Germanium (Ge)
• Zinc Selenide (ZnSe)
• Chalcogenide glass
• Zinc Sulfide (ZnS)
• Silicon (Si)
• Sapphire (Al₂O₃)
• Calcium Fluoride (CaF₂)
• Cadmium Telluride (CdTe) – as needed for specialized applications

These materials offer high refractive indices and are selected for optimal spectral performance and aberration correction. The optical parameters are as follows: Refractive index Transmission spectrum CaF2 1.414@3.5 μm 0.23-9.7 μm Ge 4.033@3.5 μm 2-15 μm Chalcogenide 2.0~3.0@10μm 0.6-20 μm CdTe 2.677@8.0 μm 6-22 μm Sapphire 1.695@3.5 μm 0.2-5.5 μm Si 3.428@3.5 μm 1.36-11 μm ZnSe 2.417@8 μm 0.55-18 μm ZnS 2.223@8 μm 0.42-18 μm

Technical Resources

How Does an Infrared Lens Work?

Unlike visible light, infrared light—also known as infrared radiation (IR)— is undetectable to the human eye and standard optical systems such as conventional cameras or the retina. Infrared lenses are engineered to overcome this limitation by:

• Capturing infrared radiation emitted or reflected by objects in the environment
• Focusing this radiation onto a specialized IR sensor within the camera system

This enables the generation of thermal or infrared images, which visualize temperature differences and energy signatures.

Key Functional Aspects:

• Material transparency: IR lenses are made from materials like germanium or zinc selenide, which are transparent to IR wavelengths but opaque to visible light.
• Wavelength range: Typical operating ranges begin at 700 nm (near-infrared) and extend into the long-wave IR (up to ~14 µm), depending on application.
• Design differences: Unlike standard optical lenses, IR lenses are optimized for minimized chromatic aberration, thermal stability, and high transmission in specific IR bands.

By combining the lens with IR filters, sensors, and camera electronics, the system becomes capable of capturing detailed thermal or IR imagery, critical for applications like surveillance, diagnostics, and industrial monitoring.

Structure of Lens

An infrared imaging lens, often referred to as an objective lens or machine vision lens, is composed of several functional parts:

• Focus Adjustment Ring: Changes the focal distance (working distance) between the lens and the object.
• Iris/Aperture Ring: Adjusts the F-number (f/#) to control light intake and image quality.
• Thumbscrews: Lock settings in place to prevent accidental shifts.
• Lens Information: Printed on the barrel—includes focal length, minimum f/#, and model number.
• Working Distance Range: Indicates the focusing range of the lens.
• f/# Tick Marks: Help set the aperture precisely.
• Filter Thread: Mounting point for filters; adapters may be needed for wide-angle lenses.
• Camera Mount: Connects the lens to a camera (e.g., C-Mount, F-Mount, TFL-Mount).
• Rear Protrusion: Portion that extends into the camera—must avoid sensor or filter interference.
• First and Last Optical Surfaces: Define working distance and optical path.
• Lens Shoulder & Flange Distance: Ensure proper mounting alignment and sensor positioning.
• Image Plane: Where the lens focuses light—typically the camera sensor.

Cooled vs. Uncooled Infrared Detectors

Cooled IR Detectors

• Used in: MWIR and LWIR imaging
• Cooling Required: Yes (often liquid nitrogen)
• Advantages:
  • High sensitivity and image resolution
  • Long detection range
• Applications: Aerospace, defense, high-end scientific imaging

Cooled lenses must align with a cold stop, which increases lens complexity and size but ensures better thermal noise suppression.

Uncooled IR Detectors

• Used in: Mostly LWIR imaging
• Cooling Required: No
• Advantages:
  • Compact, cost-effective
  • Operates at room temperature
• Disadvantages: Lower sensitivity and slower response
• Applications: Civilian use, building inspection, automotive systems

Uncooled IR lenses typically have low F-numbers (f/1–f/2) to maximize thermal signal capture and are optimized for wide fields of view.

Types of Infrared Lenses (IR Lenses)

Infrared lenses are typically categorized by the wavelength range they are designed to capture. Each type is suited for different applications and detector technologies.

Short-Wave Infrared (SWIR) Lenses

• Wavelength: 800– nm
• Key Features:
  • Works with reflected IR light
  • High-resolution imaging
  • Performs well in low-visibility environments (e.g., smoke)
• Applications:
  • Semiconductor inspection
  • Anti-counterfeiting
  • Medical diagnostics
  • Quality control and machine vision

SWIR lenses reveal material properties invisible to visible light systems, such as water absorption and silicon transparency.

Medium-Wave Infrared (MWIR) Lenses

• Wavelength: – nm (3–5 μm)
• Key Features:
  • Captures emitted thermal radiation from hot objects
  • Requires cooled detectors
  • Higher resolution than LWIR
• Applications:
  • Fire detection
  • Engine diagnostics
  • Military target acquisition
  • Long-distance surveillance

MWIR is ideal for scenarios with higher object temperatures and offers superior performance in humid environments.

Applications of Infrared Lenses

Infrared lenses are critical components in modern imaging systems, supporting diverse applications across multiple industries. From medical diagnostics to national defense, their ability to detect invisible infrared radiation makes them indispensable for thermal and spectral imaging.

Medical Instrumentation

Infrared lenses are widely used in thermal imaging and non-invasive diagnostics. Equipped with MWIR or LWIR lenses, infrared thermal cameras can detect subtle surface temperature variations on the skin—useful in identifying:

• Inflammation
• Circulatory issues
• Cancerous growths
• Endoscopic systems

Life Sciences

In life sciences and pharmaceutical research, infrared lenses enable precise NIR light focusing for:

• Near-infrared (NIR) spectroscopy
• Chemical composition analysis
• Food quality inspection

Surveillance & Security

Infrared lenses play a pivotal role in night vision and thermal imaging surveillance.

• SWIR lenses enhance visibility in low-light or obscured environments (smoke, fog, darkness).
• LWIR lenses are widely used in thermal cameras to detect intruders and monitor infrastructure in all weather conditions.
• Border security
• Critical infrastructure monitoring
• Law enforcement and crowd control

Aerospace & Defense

Defense systems rely heavily on MWIR and LWIR lenses for:

• Long-range surveillance
• Target acquisition and tracking
• Navigation in low-visibility conditions
• SWIR imaging also supports target recognition and identification, especially in harsh or camouflaged environments.

Industry Use Cases at a Glance

Application Area

Typical Infrared Lens Types

Use Cases

Life Sciences

NIR, SWIR

Spectroscopy, chemical imaging

Security & Surveillance

SWIR, LWIR

Night vision, perimeter monitoring

Medical

MWIR, LWIR

Thermography, diagnostics, endoscopy

Aerospace & Defense

MWIR, LWIR, SWIR

Reconnaissance, threat detection

Future Trends and Technologies

As demand for infrared imaging continues to grow, several key trends are shaping the future of IR lens development:

Enhanced Performance

Advances in optical materials and coatings will lead to:

• Higher IR transmission efficiency
• Lower aberrations and distortion
• Improved resolution and clarity

Miniaturization

With increasing demand for compact devices, IR lenses are being designed for:

• Wearable medical monitors
• Lightweight UAV and drone systems
• Portable inspection tools

Multi-Spectral Imaging

Next-gen IR lenses may combine multiple wavelength bands (e.g., SWIR + MWIR), enabling:

• Simultaneous data capture across the IR spectrum
• Advanced imaging for agriculture, environment, and security

AI & Machine Learning Integration

When paired with AI-powered imaging systems, IR lenses can support:

• Real-time threat recognition
• Automated quality control
• Predictive maintenance in industrial settings

Emerging Applications

As infrared imaging becomes more accessible, new use cases are emerging in:

• Smart agriculture
• Energy efficiency and HVAC diagnostics
• Waste sorting and recycling

In Summary

Infrared lenses are advancing rapidly—enabling smarter, faster, and more accurate imaging across critical sectors. Whether it’s improving patient care, enhancing national security, or enabling better environmental analysis, IR lenses will remain at the forefront of innovation.

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In the realm of thermal imaging, Mid-Wave Infrared (MWIR) and Long-Wave Infrared (LWIR) technologies play crucial roles. Recent market developments, particularly in lens materials, have significantly impacted the cost-benefit analysis of these technologies.

Spectral Ranges:

• MWIR: Typically 3-5 μm
• LWIR: Typically 8-14 μm

Lens Material and Cost Considerations:

The most critical recent development in the thermal imaging industry is the dramatic increase in germanium prices. Germanium, a key material in infrared optics, has seen its price double in the past year, with an even more pronounced effect on long-focus lenses.

LWIR Lens Costs:

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• Heavily reliant on germanium, especially for long-range applications.
• Typically require large aperture lenses (often F/1.0) for adequate performance.
• The combination of large lenses and expensive materials has led to a substantial increase in LWIR optics costs.
• Long-focus LWIR lenses have seen price increases even beyond the doubling of raw material costs.

MWIR Lens Advantages:

• Can utilize smaller aperture lenses (e.g., F/4 or F/5).
• Reduced germanium requirements lead to significantly lower material costs.
• Less affected by the recent germanium price inflation.
• Alternative materials can sometimes be used, further reducing costs.

This cost factor is now a major consideration in system design and technology choice, especially for long-range applications.

Other Key Differences:

Image Quality and Performance:

• MWIR: Generally superior in image quality and contrast, especially in high-humidity conditions.
• LWIR: Effective in dusty or smoky environments.

Detection Range:

• MWIR: Excels in long-range detection due to better atmospheric transmission.
• LWIR: Suitable for shorter ranges and larger temperature differences.

Sensor Technology:

• MWIR: Often uses cooled sensors (e.g., Mercury Cadmium Telluride - MCT).
• LWIR: Employs both cooled (mainly in military and scientific research) and uncooled sensors (e.g., microbolometers).

Environmental Factors:

• MWIR: Less affected by atmospheric moisture, ideal for maritime use.
• LWIR: Better performance through smoke and dust.

Sensitivity and Cooling:

• MWIR: Cooled sensors offer higher sensitivity and faster frame rates.
• LWIR: Uncooled sensors provide lower cost and maintenance requirements.

Cost-Benefit Analysis:

While cooled MWIR systems have higher initial costs due to cooling mechanisms, the significantly lower lens costs - especially for long-range applications - can make them more economically viable in the long term. This is particularly true given the current trends in germanium pricing.

LWIR systems, despite generally lower sensor costs, are facing increasing challenges in long-range applications due to the escalating prices of large germanium lenses.

For more information, please visit MWIR Lens for Cooled Camera.