VCSELs, multiple applications

Vertical-Cavity Surface-Emitting Diode Lasers (VCSELs) are a relatively recent type of semiconductor lasers. VCSELs were first invented in the mid-1980’s. Very soon, VCSELs gained a reputation as a superior technology for short reach applications such as fibre channel, Ethernet and intra-systems links. Then, within the first two years of commercial availability (1996), VCSELs became the technology of choice for short range datacom and local area networks, effectively displacing edge-emitter lasers.

Today VCSELs aggressively move into various existing and emerging applications replacing conventional edge emitting diode lasers and LEDs.

Depth cameras

3D Imaging
One approach of 3D imaging uses a camera that measures the distance of an object based on the speed of light,measuring the time of flight of light from a laseremitter to the camera/detector after being reflected by the object under detection.

 Types of 3D imaging cameras uses the approaches of

  • Structured Light
  • Time-of-Flight (direct distance measurements)

Stereoscopic Imaging with multiple cameras VCSEL light can be spread over a large area and with enough intensity to be received by the camera even in ambient light.

Princeton VCSELs with special optics allow for a beam divergence up to 120×120 degrees covering a defined area.

Time of Flight System measures time for pulse (or flash of light) to hit the object and return to the camera and measured time reveals the distance to the object

Princeton VCSELs rise/fall time is on a level of 100 – 200 ps

Navigation
3D Imaging allows mapping of an environment. It will help an individual to navigate inside of a the building It enhances obstacle avoidance information and is very suited for input for robotics maneuvering and vehicle movement.

Virtual Reality
The return of the 3D mapped image such as the shape of a room, sofa, table and any of the objects on the table, can build a virtual world. That world can allow one to virtually place furniture in a room. Allowing for home decorating. Or it can allow gaming characters to transit and maneuver through the environment in a virtual conflict.

Infrared Illumination

Visible light is in the 380nm to 750nm range. When ambient visible light is no longer sufficient, IR Illumination can see through the darkness, fog and rain. IR Illuminators act as a spotlight for use with infrared sensors. IR Illuminators can enhance security cameras, automobile driving and navigation.

  • IR imaging technology improves vision in poor conditions
  • IR imaging cuts through the fog in day and night supporting weather independent vision
  • Can be scaled to provide greater distances by increasing radiated power and/or reducing the divergence angle
  • Better than traditional visible light “high-beam” which in fog results in blinding reflected light.

Princeton Optronics VCSELs Provide a Unique Solution for Illumination.

  • Wide Power Range 1mW-1kW
  • Wide Wavelength Coverage 650nm to 1064 nm
  • Fast Rise and fall times in Pulsed Operation, <1nsec
  • Customizable Emitter Area
  • High Conversion Efficiency
  • Low Speckle
  • Round Spot
  • Low-Cost High Volume Manufacturing-Similar to LEDs
  • High Reliability and Simple Packaging

Security and Surveillance Cameras
The growth in safety and security at the public and industry level has driven the need for usable camera imagery. This usable imagery may need to overcome poor weather conditions, sun glare and minimal lighting conditions.

IR Illuminators can enhance the image quality a camera sensor views without using external visible lighting. Camera systems with IR Illuminators can generate usable imagery in industrial and residential areas as well as city streets and institutional properties.

Driving Assistance at night and fog
Vehicle accidents are mostly attributed to driver carelessness or poor lighting conditions. In order to reduce these accidents cars are being equipped with IR Illumination systems. IR Illumination systems equip vehicle drivers with better vision while driving during night or in bad weather conditions. It also enables the driver to view the path which is beyond the reach of a vehicle’s headlight. Thereby increasing the time they have to react to people, obstacles or vehicles in the roadway and allowing them to take safe and evasive action.

LiDARs

LiDAR,  is a remote sensing technology that measures distance by illuminating a target with a laser and analyzing the reflected light.

One of the approaches to build LiDAR systems using laser beam steering by MEMS is empowered by high quality beam Princeton Optronics VCSELS . An alternative approach when no moving parts are used is also enabled by addressable VCSEL arrays from Princeton Optronics. The fast turn on/off individual VCSELs allows distance measurement at that spot.

Princeton Optronics offers:

Single emitter VCSELs

  • 100W peak power, 5 ns pulse
  • Multi-mode VCSEL : ~ 17 deg (full angle) divergence
  • Single-mode VCSEL with external cavity :
    divergence of 1 deg

VCSELs arrays

  • Addressable 8×8 arrays with each VCSEL
  • Tiling to up to 75×75 arrays

Anti Collision
Driver Monitoring Systems includes a camera placed on the steering column which tracks eyes of the drivers with infrared detectors. The system warns the driver by flashing lights and warning sounds if the driver loses attention on the road and a accident situation is detected. The system applies automatic brakes to the vehicle if the same is not done by the driver in accident situations. In addition, LiDAR Systems can warn the driver in the event of an impending collision, prepare the vehicle for emergency braking in a dangerous situation, assist the driver with braking and initiate automatic braking. The LiDAR monitored post-collision braking system reduces or prevents further contact with obstacles after an accident. Such multiple impacts otherwise occur in almost a third of all accidents involving personal injury. To prevent this, the anti collision braking system automatically initiates braking after a collision if the driver is not able to do so. 

Self Driving Cars
Legislation has been passed in a number of U.S. states allowing driverless cars. A autonomous vehicle needs to be able to detect and avoid vehicles and pedestrians as well as other roadside obstacles and keep itself safely on the roadway

These autonomous vehicles use an array of detection technologies including sonar devices, stereo cameras, lasers, and radar. All these components have different ranges and fields of view, but each serves a particular purpose. The LIDAR laser remote sensing system allows the vehicle to generate a detailed 3D map of its environment. The car then takes these generated maps and combines them with high-resolution maps of the world, producing different types of data models that allow it to drive itself.

Military
LiDAR bounces pulsed lasers off of objects as opposed to electromagnetic radiowaves of radar. They can create images in mapping modes and can saturate a target with laser pulses to develop a high resolution map.

Because it can detect much smaller particles in the atmosphere than radar. LiDAR can even be used for aerosol detection. But light detection and ranging (LiDAR), is a potential game changer. It’s said to yield data flows that are orders-of-magnitude quicker, more accurate and clearer than other mapping tools.

Other applications

Medical
Laser technology is gaining broad acceptance in the aesthetics of body contouring, vein elimination, skin rejuvenation and hair removal.

Material Processing
Laser Materials Processing, involves joining (plastic welding) and surface processing of structures.

Princeton Optronics high power devices with wavelengths from 650nm to 1064 nm allow you to weld devices by being transparent to the outer shell of the device but absorbing to the inner piece structure. Thereby heating the inner materials and developing a solid bond.

Pumping of Solid State lasers
VCSELs can be configured into high-power two-dimensional arrays and modules of arrays.
VCSELs emit in a circular, uniform beam which can greatly reduce the
complexity and cost of coupling optics. Their narrow and stable emission
spectrum is well suited to the narrow absorption spectrum generally
observed for solid-state gain media. The superior reliability of VCSELs
greatly enhances the robustness of solid-state laser systems and enables
high-temperature operation

Laser igniter
Princeton Optronics has demonstrated laser igniters for gasoline and natural gas engines. In addition to being able to focus the laser so that it ignites the fuel in the desired part of the combustion chamber, and can be used with lean and high compression ignition,, laser ignition can improve efficiency and reduced NOx emission. Results showed a 27% increase in combustion efficiency, leaner fuel ratio mixture and reduction in emissions.