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Optical Measurement

The Polaris Vega® and Polaris Vicra® optical measurement solutions work by using near-infrared (IR) light to wirelessly detect and track navigation markers attached to OEM surgical instruments. They do so over a large measurement volume, and with exceptional tracking accuracy and precision. Optical measurement technology is also known—and trusted—for its reliable tracking performance in almost any clinical environment.

Every advancement of the Polaris® product suite represents new opportunities for medical device OEMs to innovate ever-more-complex surgical navigation systems and approaches. Where today’s technology breakthroughs become tomorrow’s standard of care. It’s why the Polaris solutions have been integrated into the workflows of OEM surgical navigation systems for more than 20 years.

Polaris Vega

Our advanced optical measurement solution, with three models of optical trackers that deliver unrivalled measurement performance and versatility for emerging OEM surgical navigation applications.

Polaris Vicra

Bring exceptional measurement accuracy and reliability to confined tracking areas with our compact optical tracker: Polaris Vicra.

Passive Marker Sphere

Choose from two passive marker spheres, each with a special retro-reflective surface that consists of tens of thousands of microbeads to reflect IR light during tracking.

How Optical Measurement Works*

The Polaris® optical measurement solution consists of two core components that work together: the optical tracker (sometimes known as a ‘camera’) and navigation markers; e.g. passive marker spheres, Radix Lenses, retro-reflective discs. The optical tracker uses IR light to pinpoint and triangulate the real-time X-Y-Z coordinates of the instruments (via the markers) in 3D space. Tracking occurs within a pre-calibrated measurement volume, as reported in the Polaris’ global coordinate system.

Coordinate data are calculated as transformations; i.e. positions and orientations. Similar in concept to vehicle GPS navigation, tracking data can be used to visualize the surgical instrument’s location relative to patient image sets, and to plan and navigate the instrument’s path to the target/treatment site. Each instrument has a unique array of markers that distinguishes one instrument from another within the OEM surgical navigation interface.
  1. Markers can be attached to OEM surgical instruments.

  2. The Polaris optical tracker floods the measurement volume with infrared (IR) light.

  3. This light is reflected from the markers back to IR sensors on the Polaris optical tracker.

  4. The points where the light intersects are used to triangulate the markers’ 3D (X-Y-Z) coordinates within the measurement volume.

  5. Coordinate data are mapped to the associated instrument and used to calculate the transformations (poses) of the instrument.

  6. Tracking data are communicated to the host application for real-time visualization and navigation of instruments relative to patient image sets.

Polaris Vega® and Polaris Vicra® Comparison

The Polaris Vega and Polaris Vicra share the same trusted optical measurement performance; where they differ is their size and accuracy. The larger Polaris Vega provides tracking of larger OEM surgical instruments within a larger measurement volume. It has a measurement rate that is—at a minimum— triple that of the Polaris Vicra (depending on the Polaris Vega model). The volumetric accuracy of the Polaris Vega is also two times more accurate than the Polaris Vicra.

However, the small size and small measurement volume of the Polaris Vicra makes it a powerful optical measurement solution for tracking smaller tools within confined areas. The compact form factor of the Polaris Vicra also allows it to be mounted almost anywhere on the OEM medical system or within the operative suite.


Polaris Vega XT

Pyramid Volume (RMS)

Polaris Vicra

Vicra Volume (RMS)

Volumetric Accuracy1,20.12 mm0.25 mm
95% Confidence Interval1,20.20 mm0.50 mm
Maximum Frame Rate250 Hz20 Hz
Measurement VolumePyramid
Extended Pyramid (optional)


Polaris Vega XT

Polaris Vicra

Dimensions (LxWxH)591 x 103 x 106 mm273 x 69 x 69 mm
Weight1.7 kg0.8 kg
MountingFour M4 x 0.7 mm pitch x 10 mm deep threaded holes, rear mount¼” thread tripod mount or secured via three M3 x 0.5 mm pitch x 9.0 mm deep threaded holes, rear mount

Tool Tracking

Polaris Vega XT

Polaris Vicra

Tool Types PassivePassive, Active Wireless
Maximum Number of Tools Load up to 25 tools (maximum of 6 active wireless)Load up to 15 tools; simultaneously track up to 6 passive and 1 active wireless
Maximum Number of Markers per Tool 6 single-face/20 multi-face6 single-face/20 multi-face

Data Communication

Polaris Vega XT

Polaris Vicra

Data Communication Gigabit EthernetUSB
Network Synchronization Precision Time Protocol (PTP)Precision Time Protocol (PTP)
Data/Power Interface Ethernet, RJ45Host USB Convertor

*Example of an original equipment manufacturer’s use of Polaris in its medical device system.
1Based on a single marker stepped through more than 900 positions throughout the measurement volume using the mean of 30 samples at each position at 20°C.
2Accuracy stated based on overall volume.

Compare Optical and Electromagnetic Tracking Technology

Technology Comparison

Compare our Electromagnetic Tracking and Optical Measurement Solutions.

Legal Disclaimer
NDI tracking and measurement products are general metrology components that can be integrated into customer products, research experiments, and/or as components of medical devices that require precision measurement and tracking. While NDI components and technology can be integrated into original equipment manufacturer (OEM) medical devices, they are not specifically intended for a given application and, as such, have not been developed or manufactured in accordance with medical device standards. It remains the responsibility of the OEM customer or end-user to determine and test the suitability of NDI components and technology for their intended use, including performing any required ethics approval, verification, and validation required to demonstrate suitability and compliance. System-level testing, certification, and validation are the responsibility of the original equipment manufacturer or the applicable end-user and should be completed prior to the use of NDI products or technologies in any application.