HoloLens 2

HoloLens 2
Basic Info
VR/AR	Mixed Reality
Type	Head-mounted display
Subtype	Standalone AR
Platform	Windows Mixed Reality
Creator	Microsoft
Developer	Microsoft
Manufacturer	Microsoft
Announcement Date	February 24, 2019
Release Date	November 7, 2019
Price	$3,500 (device only), $5,199 (Development Edition)
Website	https://www.microsoft.com/hololens
Versions	HoloLens 2, HoloLens 2 Industrial Edition, HoloLens 2 Development Edition
Requires	Microsoft account or Azure Active Directory
Predecessor	Microsoft HoloLens 1
System
Operating System	Windows Holographic
Chipset	Qualcomm Snapdragon 850
CPU	8-core Kryo 385 (4×2.96 GHz Gold + 4×1.7 GHz Silver)
GPU	Adreno 630
HPU	Holographic Processing Unit 2.0 (custom Microsoft)
Storage
Storage	64GB UFS 2.1
Memory	4GB LPDDR4x
SD Card Slot	No
Display
Display	2× MEMS Laser Scanning waveguide
Subpixel Layout	N/A (laser scanning)
Peak Brightness	500 nits
Resolution	2048 × 1080 per eye (2K 3:2 displays)
Pixel Density	47 PPD
Refresh Rate	60Hz
Persistence	N/A
Image
Field of View	52° diagonal
Horizontal FoV	43°
Vertical FoV	29°
Average Pixel Density	47 PPD
Foveated Rendering	No
Optics
Optics	See-through holographic waveguide lenses
Ocularity	Binocular
IPD Range	51-74mm (automatic via eye tracking)
Adjustable Diopter	No (glasses compatible)
Passthrough	Native see-through (optical)
Tracking
Tracking	6DoF inside-out
Tracking Frequency	1000Hz IMU
Eye Tracking	Yes (Azure Kinect DK sensor)
Face Tracking	No
Hand Tracking	Yes (fully articulated)
Body Tracking	No
Rotational Tracking	Yes
Positional Tracking	Yes
Play Space	Unlimited (world-scale)
Latency	<10ms hand tracking
Audio
Audio	Built-in spatial speakers (bone conduction optional)
Microphone	Yes (5-channel microphone array)
3.5mm Audio Jack	Yes
Camera	8MP stills, 1080p30 video, 4× environment understanding cameras
Connectivity
Connectivity	Wi-Fi 5 (802.11ac 2×2), Bluetooth 5.0
Ports	USB Type-C
Wired Video	No
Wireless Video	No
WiFi	Wi-Fi 5 (802.11ac 2×2)
Bluetooth	Bluetooth 5.0
Power	Internal battery
Battery Capacity	N/A
Battery Life	2-3 hours active use
Charge Time	~2 hours
Device
Dimensions	Adjustable
Weight	566g
Material	Carbon fiber, aluminum
Headstrap	Dial-in fit system
Haptics	No
Color	Black
Sensors	Accelerometer, gyroscope, magnetometer, 4× visible light cameras, 2× IR cameras, 1MP ToF depth sensor, ambient light sensor
Input	Gaze, gesture, voice, hand tracking
Compliance	FDA, CE, FCC

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The Microsoft HoloLens 2 is a standalone mixed reality head-mounted display developed by Microsoft, announced at Mobile World Congress on February 24, 2019, and released on November 7, 2019 at a starting price of $3,500. Building upon the original HoloLens, the second generation device features more than double the field of view (52° diagonal compared to 34°), improved comfort through a redesigned form factor with carbon fiber construction, fully articulated hand tracking replacing the limited gestures of its predecessor, and eye tracking for automatic IPD adjustment. Powered by a Qualcomm Snapdragon 850 processor and Microsoft's second-generation Holographic Processing Unit (HPU 2.0), the HoloLens 2 targets enterprise applications including manufacturing, healthcare, education, and remote collaboration.

History and Development

Background and Genesis

Following the success of the original HoloLens released in 2016, Microsoft embarked on developing a successor that would address the primary criticisms of the first device: limited field of view, uncomfortable weight distribution, and the restrictive gesture-based input system. Alex Kipman, the technical fellow who led HoloLens development, described the goal as creating a device that felt as natural to use as a pair of glasses.

Mobile World Congress 2019 Announcement

Microsoft unveiled HoloLens 2 at Mobile World Congress in Barcelona on February 24, 2019. The announcement emphasized three major improvements: a dramatically expanded field of view, a completely redesigned comfort system, and breakthrough hand tracking technology that could recognize each finger's position and movement without controllers.

Azure Integration

Microsoft positioned HoloLens 2 as a cloud-connected device deeply integrated with Microsoft Azure services. Azure Kinect sensors, Azure Spatial Anchors, and Azure Remote Rendering expanded the device's capabilities beyond its onboard processing power.

Enterprise Focus

Unlike consumer-focused VR headsets, Microsoft targeted HoloLens 2 exclusively at enterprise customers from launch. Major deployments include surgical planning in healthcare, assembly line guidance in manufacturing, remote assistance in field service, and training simulations across various industries.

Industrial Edition

In late 2020, Microsoft introduced the HoloLens 2 Industrial Edition, designed for use in controlled environments such as clean rooms and hazardous locations. This variant carries ISO 14644-1 Class 5 certification and UL Class I, Division 2 certification for use in potentially explosive atmospheres.

Design and Hardware

Form Factor Revolution

The HoloLens 2 represents a complete redesign from its predecessor. The weight has been reduced and redistributed using a carbon fiber construction, with the primary mass moved to the back of the head for improved balance. The device now sits on the user's head like a visor, with the computing and display components positioned above the brow rather than directly in front of the face.

Carbon Fiber Construction

The use of carbon fiber for the headband significantly reduced weight while maintaining structural rigidity. The material choice also improved heat dissipation, addressing the thermal concerns of the original HoloLens during extended use sessions.

Dial-In Fit System

A precision dial mechanism at the rear of the headband allows users to quickly adjust the fit for their head size. Combined with adjustable brow and back pads, the system accommodates a wide range of head sizes and shapes while maintaining consistent optical alignment.

Flip-Up Visor

The HoloLens 2 introduces a flip-up visor design that allows users to quickly transition between holographic and unobstructed views of the real world. This feature addresses a key workflow limitation of the original device, where users had to remove the headset entirely to focus on physical tasks.

Glasses Compatibility

The optical system has been redesigned to accommodate users wearing prescription eyeglasses, with sufficient space between the waveguide displays and the user's eyes. This represented a significant improvement over the original HoloLens, which many glasses-wearing users found uncomfortable.

Display System

MEMS Laser Scanning Technology

The HoloLens 2 utilizes a revolutionary display technology based on Micro-Electro-Mechanical Systems (MEMS) laser scanning. Rather than using traditional LCD or OLED panels, tiny mirrors rapidly scan RGB laser light across the waveguide displays, creating images point by point. This approach enables:

Exceptional clarity and color accuracy
Lower power consumption than panel-based displays
Compact form factor
Reduced heat generation

Waveguide Optics

The see-through holographic lenses use waveguide technology to project computer-generated imagery while allowing the user to view the physical world through the same optical elements. Light from the MEMS laser system is coupled into the waveguide and directed toward the user's eyes through diffractive optical elements.

Expanded Field of View

The HoloLens 2's 52-degree diagonal field of view represents more than double the visible holographic area of the original HoloLens (34 degrees). This expansion addresses one of the most significant criticisms of the first-generation device, allowing larger and more immersive holographic content.

Horizontal FoV: 43°
Vertical FoV: 29°
Diagonal FoV: 52°

Resolution and Pixel Density

Each eye receives a 2048 × 1080 pixel image through the 3:2 aspect ratio displays, resulting in approximately 47 pixels per degree—described by Microsoft as "retina resolution" for holographic content. This density ensures that holographic text remains legible and detailed imagery appears sharp.

Color and Brightness

The laser-based display system produces vibrant, accurate colors with peak brightness of approximately 500 nits. Unlike the first HoloLens which struggled in brightly lit environments, HoloLens 2's improved brightness makes holograms visible in more lighting conditions.

Processing Architecture

Dual-Processor Design

The HoloLens 2 employs a unique dual-processor architecture:

Qualcomm Snapdragon 850: General-purpose computing, running Windows Holographic OS
Holographic Processing Unit 2.0: Dedicated silicon for sensor processing, tracking, and holographic operations

Snapdragon 850

The Qualcomm Snapdragon 850 provides the main computing power:

8-core Kryo 385 CPU (4× Gold cores at 2.96 GHz, 4× Silver cores at 1.7 GHz)
Adreno 630 GPU
Hexagon 685 DSP
4GB LPDDR4x RAM
64GB UFS 2.1 storage

This mobile platform was selected for its balance of processing power, energy efficiency, and Windows on ARM compatibility.

Holographic Processing Unit 2.0

Microsoft's custom-designed HPU 2.0 represents a significant advancement over the original HPU. This second-generation coprocessor handles:

Real-time processing of sensor data from all cameras
Hand tracking algorithms with full finger articulation
Head tracking and spatial mapping
Eye tracking for gaze input and automatic IPD adjustment
Seamless offloading from the main CPU

The HPU 2.0 processes data from 12 cameras, 5 sensors, and 6 microphones simultaneously while maintaining sub-millisecond latency for tracking operations.

Tracking and Sensors

Inside-Out Tracking

HoloLens 2 uses markerless inside-out tracking with no external sensors required. The tracking system maintains positional awareness across large spaces, enabling world-scale experiences that persist between sessions.

Spatial Mapping

Four visible light cameras continuously scan the environment to create and update a real-time 3D mesh of the physical space. This mesh enables:

Hologram placement on physical surfaces
Occlusion of holograms behind real objects
Physics-based interactions between virtual and physical worlds
Spatial sound reflections

Time-of-Flight Depth Sensor

A 1-megapixel time-of-flight depth sensor based on Azure Kinect technology provides accurate depth information for:

Hand tracking
Scene understanding
Precise surface detection
Near-field spatial mapping

Eye Tracking

Integrated eye tracking enables several important capabilities:

Automatic IPD Adjustment: The system automatically adjusts the display positioning based on measured IPD (51-74mm range)
Gaze Input: Users can select objects by looking at them
Foveated Rendering Potential: While not actively used, the system supports future optimization
User Attention Analytics: Applications can track where users look for training and evaluation purposes

Hand Tracking

The fully articulated hand tracking system represents one of HoloLens 2's most significant advancements:

Recognition of both hands simultaneously
Tracking of all 25 joints per hand
Natural gesture recognition (grab, pinch, touch)
Direct manipulation of holographic content
No controllers or markers required
Works in various lighting conditions

The hand tracking system uses both depth and visible light camera data, processed by the HPU 2.0, to achieve latency under 10 milliseconds.

Inertial Measurement

High-frequency IMUs (accelerometer, gyroscope, magnetometer) provide 1000Hz rotation and position data, enabling smooth tracking even during rapid head movements.

Input Methods

Gaze and Dwell

The eye tracking system enables gaze-based selection where users look at a target and dwell (hold gaze) to select. This complements the hand tracking system for situations where hand input may not be convenient.

Articulated Hand Gestures

Unlike the limited air-tap and bloom gestures of HoloLens 1, the second generation supports natural hand interactions:

Grab: Close hand to grasp holographic objects
Pinch: Touch thumb and index finger to select
Poke: Touch holographic buttons directly
Manipulation: Move, rotate, and resize holograms with both hands
Scroll: Swipe through content naturally

Voice Commands

Cortana integration and voice recognition enable hands-free operation:

System-level commands ("Select", "Go back", "Start")
Application-specific voice controls
Dictation for text input
Natural language processing for queries

Virtual Keyboard

A holographic keyboard appears when text input is required, supporting both hunt-and-peck finger input and gaze-based selection.

Audio System

Spatial Audio Speakers

Built-in speakers positioned near the ears deliver spatial audio without covering the ear canal, allowing users to hear both holographic audio and environmental sounds simultaneously. The audio system supports:

3D positional audio tied to hologram locations
Head-related transfer function (HRTF) processing
Environmental audio passthrough

Microphone Array

A 5-channel microphone array enables:

Clear voice command recognition
Noise cancellation for calls
Spatial audio capture
Voice-based identity verification

Audio Jack

A 3.5mm audio jack accommodates headphones for private listening in noisy environments or when enhanced audio quality is required.

Connectivity

Wireless

Wi-Fi 5 (802.11ac 2×2) for high-bandwidth data transfer and cloud services
Bluetooth 5.0 for accessory connectivity

USB Type-C

The USB Type-C port supports:

Device charging
Data transfer
Connection to desktop applications
Ethernet adapter connectivity

Power and Battery

Battery Life

The internal battery provides 2-3 hours of active use depending on workload intensity. The improved thermal design allows extended sessions without the overheating issues that affected the original HoloLens.

Charging

The device charges via USB Type-C, reaching full charge in approximately 2 hours. The HoloLens 2 supports charging while in use for all-day deployment scenarios.

Software Platform

Windows Holographic

HoloLens 2 runs Windows Holographic, a specialized version of Windows optimized for mixed reality:

Universal Windows Platform (UWP) application support
Azure Active Directory integration
Mobile Device Management (MDM) compatibility
Windows Update deployment

Development Platforms

Developers can create HoloLens 2 applications using:

Unity: Most popular development environment
Unreal Engine: High-fidelity graphics support
MRTK (Mixed Reality Toolkit): Microsoft's open-source UX framework
OpenXR: Cross-platform VR/AR standard
Web technologies: WebXR for browser-based experiences

Azure Services Integration

Deep integration with Microsoft Azure expands HoloLens 2 capabilities:

Azure Spatial Anchors: Persistent world-scale positioning
Azure Remote Rendering: Stream high-quality 3D content from the cloud
Azure Object Anchors: Align holograms to physical objects
Dynamics 365 Remote Assist: Enterprise remote collaboration
Dynamics 365 Guides: Interactive work instructions

Enterprise Applications

Manufacturing

Assembly guidance with step-by-step holographic instructions
Quality inspection with AR-assisted measurement
Training simulations for complex procedures
Remote expert support for troubleshooting

Healthcare

Surgical planning and navigation
Medical education with 3D anatomy visualization
Remote consultation during procedures
Physical therapy guidance

Architecture and Construction

BIM model visualization at full scale
On-site construction verification
Design review with stakeholders
Clash detection in physical space

Field Service

Remote assistance with live video and annotations
Equipment maintenance with overlaid instructions
Parts identification and inventory
Knowledge capture and transfer

Versions and Pricing

Version	Price	Features
HoloLens 2	$3,500	Standard device for enterprise deployment
HoloLens 2 Development Edition	$5,199	Includes $500 Azure credits, 3-month trials
HoloLens 2 Industrial Edition	$4,950	Clean room and hazardous environment certified

Technical Specifications Summary

Specification	Details
Display	MEMS laser scanning waveguide
Resolution	2048 × 1080 per eye
Field of View	52° diagonal (43° H × 29° V)
Pixel Density	47 PPD
Refresh Rate	60Hz
Processor	Snapdragon 850 + HPU 2.0
Memory	4GB LPDDR4x
Storage	64GB UFS 2.1
Eye Tracking	Yes
Hand Tracking	Full articulated (25 joints/hand)
Voice Input	Yes (Cortana)
Audio	Built-in spatial speakers
Battery Life	2-3 hours
Weight	566g
Connectivity	Wi-Fi 5, Bluetooth 5.0, USB-C
Price	$3,500+

References