Choosing the Right Underwater Laser for Inspection and Survey
Not all underwater lasers are created equal. Parallel dot lasers—like SubC’s MantaRay—are best for scale and measurement in imagery. Line and grid lasers, offered through the Skate Mk2, are used for surface profiling, 3D modeling, and photogrammetry. Choosing the right laser depends on your inspection goals, deployment platform, and environmental conditions.
Why Underwater Lasers Matter in Subsea Imaging
When collecting underwater imagery, visual context matters, but scale and accuracy matter too. Lasers are a vital tool for turning raw video or stills into usable, measurable data.
Subsea lasers are commonly integrated with underwater cameras in offshore inspections, marine science, and subsea engineering. They enhance both real-time operations and post-mission analysis.
Lasers help to:
Establishing scale: Known spacing between laser points or lines allows for size estimation and measurement from images.
Improving surface detail: Lasers highlight irregularities like cracks, pitting, or marine growth that aren’t visible under uniform lighting.
Supporting repeatability: Fixed laser positions ensure consistency across surveys and monitoring intervals.
Enhancing pilot visibility: For ROVs or drop cameras, lasers serve as spatial guides to help position and frame the target accurately.
Whether you’re assessing corrosion on a jacket leg or measuring benthic species, lasers help bridge the gap between imagery and insight.
Types of Underwater Lasers for Inspection and Imaging
Parallel Dot Lasers
Parallel dot lasers project two green dots a fixed distance apart—typically 100mm. These serve as visible reference points in images or video, enabling quick size estimation and consistent scale across footage.
They’re especially effective when the laser plane is perpendicular to the camera sensor, such as when imaging the seafloor vertically. Measurements can be made using simple photo editing tools or more advanced software when paired with a calibrated camera.
Common uses:
Measuring marine growth on risers or structures
Estimating size of species during benthic surveys
Providing scale in photo transects
Supporting pilot positioning in drop or diver systems
Line Lasers
Line lasers project a continuous green beam across the scene. When the beam interacts with a surface, it visually reveals contours and structural deformation, making it useful for inspection and surface mapping.
Line lasers are also used in 3D reconstruction workflows and point cloud generation, particularly when combined with image processing software. For best results, the camera’s exposure settings (e.g., shutter speed) may need to be adjusted to sharpen the laser’s appearance in footage.
Parallel Line Variation
When configured as a parallel line laser, users can establish scale anywhere in the frame, even if the camera is tilted relative to the target. This is particularly useful for oblique angles, diver deployments, drop or tow camera systems where the imaging plane isn't perfectly aligned.
Common uses:
Surface profiling and deformation detection
3D model generation and point cloud capture
Structural inspection of subsea assets
Capturing consistent scale in angled footage
Grid Lasers
Grid lasers project a matrix of dots, such as a 10x10 array, across the field of view. These provide multiple redundant points for spatial reference, making them ideal for complex geometry capture and photogrammetry.
Grid patterns enable researchers and engineers to calculate distances, build 3D models, or compare surface changes over time with high precision.
Common uses:
Photogrammetry and 3D model reconstruction
Mapping irregular coral reefs or archaeological sites
Supporting research-grade habitat analysis
Enhancing visual geometry capture in video-based workflows
How to Choose the Right Laser Type
Before choosing a laser, clarify what you're trying to achieve:
Need to measure or estimate size? Use a parallel dot laser for scale, or a grid laser for multiple reference points.
Need to highlight contours or structural detail? Use a line laser to reveal profile distortions across the scene.
Need both? You may benefit from using multiple laser types—especially in longer-term or multipurpose monitoring.
Some setups, like SubC’s Rayfin camera systems, allow flexible integration of different laser modules to match your inspection goal.
Matching Laser Types to Your Subsea Deployment Platform
Laser performance and integration depend heavily on how and where you’ll deploy them:
ROVs and AUVs: Require compact, rugged lasers with consistent alignment to the camera’s field of view. Cable routing and mounting hardware should be secure and vibration-resistant.
Drop, tow, or diver camera systems: Simpler mounting systems may suffice. Laser mounts or bracketed arms are often used to maintain fixed spacing and alignment.
Permanent observatories: Lasers must maintain long-term alignment and withstand corrosion and biofouling. Reliability over thousands of hours is key.
SubC lasers are depth-rated to 6000m and built with Grade 5 titanium for maximum durability in harsh marine conditions.
Underwater Laser Comparison Table
Here’s a quick comparison of underwater laser types, their use cases, and how they integrate with different subsea platforms.
| Laser Type | SubC Product | Visual Output | Measurement Use Case | Best For | Camera Alignment |
|---|---|---|---|---|---|
| Parallel Dot | MantaRay Mk2 | 2 green dots | Simple size/distance estimation | Still imagery, vertical drop or tow cameras | Perpendicular to target |
| Line | Skate Mk2 (line config) | 1 green beam | Surface profiling, point cloud | Deformation, welds, terrain mapping | Perpendicular for best accuracy |
| Parallel Line | Skate Mk2 + dual mount | 2 green lines | Consistent scale across image | Oblique imaging, angled surface shots | Not dependent on camera tilt |
| Grid | Skate Mk2 (grid config) | Dot matrix | Complex 3D modeling, photogrammetry | Irregular surfaces, dense structure scans | Perpendicular or slightly angled |
All SubC lasers shown above are FDA Class 3R compliant and qualified for international deployment.
Consider Environmental Conditions
Laser visibility and stability are directly influenced by the underwater environment:
Turbid water or poor visibility: Green lasers (520nm) penetrate murk better than other wavelengths and remain visible over longer distances.
Deep or dark environments: Higher output lasers improve visibility, but exposure settings on the camera may also need adjusting (e.g., shorter shutter speeds for line sharpness).
Reflective surfaces or bright lighting: You may need to adjust the beam angle or reduce intensity to avoid scatter and flare.
All SubC lasers operate at 520nm (green) and are optimized for visibility in challenging subsea conditions.
Understand Laser Safety and Compliance
Safety is a key concern when working with lasers, especially in subsea environments. SubC lasers comply with FDA Class 3R and international standards.
Best practices include:
Use fixed-focus, non-adjustable beams to reduce risk
Equip systems with TTL or relay-based control for safe activation
Avoid direct exposure or use laser warning overlays in real-time feeds
SubC Imaging’s MantaRay and Skate Mk2 lasers are fully compliant and qualified for international shipment and operation.
Capturing Scalable Data with Subsea Lasers
To ensure your laser imagery is measurable and consistent:
Keep lasers within the camera’s field of view at all times
Maintain consistent spacing and alignment through calibrated mounts
Choose software that supports laser-based measurement or annotations
For long-term deployments, ensure mechanical stability and alignment over time
Rayfin camera systems are factory-calibrated to work seamlessly with SubC lasers, reducing setup time and increasing measurement confidence.
Build the Right Imaging Setup
The laser is just one part of your subsea imaging toolkit. To get reliable data from inspections or surveys, your laser, camera, lights, and deployment platform need to work together as a system.
Whether you're documenting marine growth, performing asset integrity inspections, or capturing benthic survey footage, choosing the right laser improves the clarity, accuracy, and value of your data.
Need help choosing the right laser for your inspection or survey?
SubC Imaging can help you select the best laser type and configuration—dot, line, grid, or parallel dot—for your platform, environment, and data needs.
