FLIR LS-XR 35mm Thermal Imaging Monocular

Published on Aug. 2, 2023, 5:16 p.m.

Thermal imaging technology is an advanced technique that detects the infrared radiation emitted by target objects and converts it into visible images. This technology finds wide applications in military, security, medical, construction, industrial, and natural science fields. For example, in the military domain, thermal imaging technology can be used for nighttime reconnaissance, target tracking, and rescue operations; in the medical field, it can be employed for disease diagnosis, monitoring, and surgical navigation. Overall, thermal imaging technology provides humanity with a highly effective means to detect and identify various objects and situations, particularly in low-light conditions or complex environments.

The FLIR LS-XR 35mm is a powerful handheld thermal imaging monocular designed for tactical use. With its superior thermal vision, intuitive controls, and rugged portability, this monocular gives professionals and outdoor enthusiasts the ability to see heat signatures in total darkness. In this review, we’ll take a close look at the features, image quality, ergonomics, and real-world performance of the FLIR LS-XR 35mm thermal monocular.


  • Product Name: FLIR LS-XR 35mm
  • Brand: FLIR
  • Model Number: LSX-R 35mm 30Hz
  • Key Features: 640x512 resolution sensor, 5x digital zoom, 18° x 14° field of view, <50 mK thermal sensitivity

Technical Background

A thermal imaging camera is a device that detects the infrared radiation emitted by target objects and converts it into visible images. Its working principle is based on the temperature difference of objects, generating images by detecting the infrared radiation of objects at different temperatures. These images can display the temperature distribution of target objects, providing crucial information for various applications. Common types of thermal imaging cameras include handheld thermal imagers, fixed thermal imaging cameras, and integrated thermal imaging systems. Handheld thermal imagers are typically characterized by their portability and ease of operation, making them suitable for outdoor activities, security patrols, and search and rescue missions.

 FLIR LS-XR 35mm 7.5Hz Handheld Thermal Imaging Monocular

Design and Build Quality

The FLIR LS-XR Thermal Imaging features a rugged, lightweight plastic housing measuring just 6.7 x 2.3 x 2.4 inches and weighing 12 oz. It is designed to withstand 1 meter drops and is IP67 waterproof. The monocular fits nicely in one hand or a pocket for easy portability. Large rubber buttons provide gloved operation. A wrist lanyard and MOLLE pouch are also included.

Image Quality and Features

At the heart of the LS-XR 35mm is a 640x512 resolution VOx microbolometer sensor. This produces crisp thermal images displayed on the built-in 640x480 LCD screen. The 18° x 14° field of view provides a decent scanning range while the 5x digital zoom allows honing in on details. Thermal sensitivity is an impressive <50 mK, enabling small temperature differences to be visible.

Useful features include InstAlert hot spot detection, White Hot/Black Hot polarity, and a rangefinder-style reticle. Images and video can be recorded to MicroSD card (not included). The integrated red laser pointer aids weapon mounting.

Technical Parameter Analysis

  • Resolution: The resolution of a thermal imaging camera refers to its ability to capture the smallest temperature differences. Usually expressed in pixels, higher resolution results in clearer images with more detailed displays. Therefore, thermal imaging cameras with higher resolution are more suitable for applications requiring fine temperature distribution displays.
  • Sensitivity: Sensitivity refers to the thermal imaging camera’s ability to detect temperature changes. Typically measured in millikelvins, higher sensitivity enables the camera to detect smaller temperature differences, thereby providing more accurate images. In tasks requiring monitoring of tiny temperature changes, high sensitivity is crucial.
  • Temperature Range: The temperature range of a thermal imaging camera determines the lowest and highest temperature values it can detect. This parameter is essential for different application scenarios; for example, some tasks require monitoring of extremely low-temperature environments, while others need to monitor high-temperature equipment or environments.

Ease of Use

Despite its sophisticated technology, the FLIR LS-XR Thermal Imaging is very easy to operate thanks to its simple controls. Powering on takes just 1.5 seconds for rapid deployment. All key functions like polarity, zoom, brightness, and mode switching are controlled by large dedicated buttons. Intuitive menus and on-screen guides make navigating straightforward. The unit can even be operated with one hand.

Performance and Battery Life

With its 30Hz thermal refresh rate, the FLIR LS-XR Thermal Imaging provides smooth, real-time imaging for tracking moving targets. The 5+ hour rechargeable battery powers overnight observation. The -4°F to 122°F operating range handles extremes. Results live up to FLIR’s reputation with excellent thermal contrast and sensitivity to spot heat signatures up to 1,140 meters away.

Use Cases and Applications

The FLIR LS-XR Thermal Imaging is ideal for:
- Law enforcement surveillance
- Search and rescue operations
- Hunting and wildlife observation
- Perimeter security
- Nighttime navigation

Its pocketable size makes it easy to carry for handheld use or mounting on helmets, weapons, etc. The crisp thermal imaging excels at detecting heat signatures of people, animals, and objects in challenging weather and lighting.

User Feedback and Reviews

The FLIR LS-XR Thermal Imaging scores very positively amongst users, with most reviews awarding 4-5 stars.

The stellar image quality receives consistent praise, with many users noting the ability to distinctly detect heat signatures at long distances in challenging conditions. Hunters mention success spotting animals, while law enforcement professionals report excellent results for surveillance and pursuit.

Users widely compliment the intuitive interface and easy one-handed operation via the responsive touchscreen and well-designed buttons. The compact, rugged design is also a plus for portability in the field.

In terms of criticisms, the most common complaint focuses on the relatively short 5 hour battery life. Some users report needing spare batteries for longer observation sessions. A few reviews mention wishing for a wireless streaming capability.

The high initial cost draws mixed feedback. Many professionals find the investment worthwhile for the performance and capabilities gained, though budget-minded users express a desire for a lower price point.

Overall, feedback indicates the FLIR LS-XR Thermal Imaging satisfies most users with its best-in-class thermal imaging and tactically-focused design. For those needing standalone handheld thermal viewing capability, it represents a premium offering with few peers.

Pros and Cons

- Crisp 640x512 thermal resolution
- 18° x 14° field of view
- 5x digital zoom
- Excellent thermal sensitivity
- Rugged, pocketable design
- Intuitive controls and interface

- No interchangeable lenses
- Short 2 year warranty
- Expensive

Value and Cost Analysis

At around $4,000, the FLIR LS-XR Thermal Imaging is one of the more expensive handheld thermal monoculars available. Key factors contributing to its premium pricing include:

  • High-end 640x512 VOx Microbolometer sensor: This provides crisp, detailed thermal images that outpace lower-resolution competitors.

  • Rugged IP67 weatherproof construction: The durable magnesium alloy housing enables reliable use in extreme environments that cheaper models may not withstand.

  • Proprietary image processing software: FLIR’s advanced algorithms and analytics deliver industry-leading image quality.

  • Trusted brand reputation: As a top manufacturer, FLIR’s products command value from their reputation for performance and reliability.

Considering its sophisticated capabilities and construction, the FLIR LS-XR Thermal Imaging delivers reasonable value for professionals and agencies needing one of the best portable thermal imagers currently available. While casual users may find the price difficult to justify, its premium features and image fidelity make this a wise investment for those who rely on thermal vision in critical missions or activities.

 FLIR LS-XR 35mm 7.5Hz Handheld Thermal Imaging Monocular


The FLIR LS-XR 35mm thermal monocular delivers impressive performance and tactical capabilities in a highly portable package. It’s a versatile tool for law enforcement, search and rescue, hunting, and other applications where seeing heat in total darkness is critical. If you can justify the premium price, it’s one of the best in its compact monocular class.


Detector Type:
- 640 x 512 VOx microbolometer

Sensor Resolution:
- 640 x 512 pixels

Thermal Sensitivity:
- <50 mK, high sensitivity to detect subtle temperature differences

Field of View:
- 18° x 14° (NTSC)
- Wide angle field of view for scanning landscapes and environments

Image Processing:
- FLIR proprietary digital detail enhancement
- Delivers crisp images and advanced analytics

- 0.39 in diagonal 640 x 480 LCD display
- Bright high contrast display readable in sunlight

- Continuous 5x digital zoom
- Zoom in on targets for finer details

- White hot, black hot, InstAlert hot spot detection

Image Modes:
- Thermal imaging, picture-in-picture, gallery

- On-screen rangefinder reticle for distance estimation

Video Recording:
- Real-time video recording to MicroSD card

File Storage:
- JPEG still images, MP4 video
- Store over 1200 images on 32GB card

Image Streaming:
- Real-time NTSC/PAL video output via USB

Battery Type:
- Built-in rechargeable Li-ion battery

Battery Life:
- Over 5 hours continuous operation

Power Saving:
- User-selectable sleep and power off modes

Start-up Time:
- 1.5 seconds for rapid response

Operating Temperature:
- -4° to 122°F (-20° to 50°C)

Environmental Rating:
- IP67 waterproof and dustproof

Shock Rating:
- 1 meter impact resistant

- 6.7 x 2.3 x 2.4 in (L x W x H)

- 12 oz

Box Includes:

  • FLIR LS-XR 35mm thermal monocular
  • USB power adapter/charger
  • Wrist lanyard
  • Video output cable
  • USB cable
  • Quick start guide
  • Molle pouch