Uses of PHOTONICS in Road Transportation

Transportation technologies have changed dramatically over the last 20 or 30 years. Traffic flow in and around urban areas is increasing steadily, thus asking for more demanding solutions in terms of infrastructure inspection and maintenance, traffic flow monitoring, safety and smart driving.

Photonics is ideal for precise, remote and contactless measurements in harsh conditions. Thanks to major breakthroughs in the technologies involved, optical sensing is becoming more compact, robust and affordable. In particular, we will consider four types of situations, like:


Traffic monitoring implies the estimation of microscopic as well as macroscopic parameters of the traffic flow. Microscopic monitoring deals with the counting and classification of individual vehicles in each lane. Photonics can be used for traffic monitoring at both levels.

For measuring macroscopic parameters of the traffic conditions, a network of video cameras provides useful information in particular on the traffic in urban highways. Reliable solid state CCD and CMOS cameras and recent progress in computing technology, INO has been able to develop a real-time video-based automated traffic analysis system which can detect traffic incidents in a highway scene independently of the illumination conditions. The incidents detected by the system comprise slowdowns, traffic jams and stopped the vehicle.


Each year a substantial amount of money is being spent for the inspection of the road network showing the need for an automatic and objective assessment of road pavement conditions. Road surface inspection is a very demanding application involving a large and relatively flat surface. INO has developed two technologies aimed at inspecting the road surface.

  • 3D laser-based triangulation system designed to detect and characterized pavement rutting.
  • The second technology is a unique multi-function pavement distress characterization system based on custom high performance 3D laser scanners.


Photonics can be used in the context of smart cars and intelligent vehicles in three application fields. Like, (a) in information systems, (b) in distributed communications and (c) in instrumentation. Fiber optics has several advantages such as compactness, high bandwidth, lightness and immunity to EM interferences, over conventional wires to distribute signals and information from different locations in the vehicle. A system for real-time automatic detection and recognition of road signs is currently being developed at INO. Images of traffic scenes are acquired by a color camera mounted on a vehicle. Two main stages are involved in the processing of these images.

  • Detection of regions potentially containing road signs using chiefly color information.
  • Recognition and classification using digital and optical template matching.

Recognition and classification are carried out using template matching and rule-based techniques with a reference database of standard traffic road signs.


Photonics can play other roles in road transportation applications. For example, the real-time video system that is being developed at INO for road signs detection and recognition could also be applied for inventory purpose. Regular inspection of road signs infrastructure over the road network. OCR is also an active area of R&D applied to the tolling problem for reading car plates on pay highways and bridges.

Finally, other photonic technologies such as thin film coating, solid-state LED light sources and flat panel display based on liquid crystal light modulators are being investigated for use in improving reflectance of panels as well as for enhancing contrast in programmable display panels and traffic lights.

Uses of PHOTONICS in Space, Air, Water and Railway

Currently, many of applications are implemented using some form of discrete (free-space) optics, much can be gained from a transition to Photonics Integrated Circuits. This follows the trends in the electronics industry where highly integrated electronic circuits have allowed the combination of many different functions in a small form factor. Just as it has done for the electronics industry, integrated optics will lead to smaller, cheaper, more reliable and more user-friendly devices. Which become very helpful for space, air, and water and railway transportation.

  • Photonic Integrated Circuits (PICs)
  • Photonic Integrated Circuits (PICs) are devices on which several or more optical components are integrated; often together with electronic components..
  • PICs technology for visible light

Photonics technologies currently used are typically categorized as Silicon Photonics, III-V Materials, and Dielectrics. Silicon Photonics, using Silicon-on-Insulator, offers passive light manipulation at a very small footprint, allowed by the relatively high contrast index of silicon.

The III-V Materials technology platform offers light amplification and detection, next to passive light manipulation as filtering, splitting or interfering. The Dielectrics technology platform offers light manipulation with very low transmission and fibre coupling losses, given the refractive index match of Silica. Also referred as Planar Lightwave Technology (PLC).

Interfacing to PIC Devices

To interface with the optical system, the visible light PICs can be equipped with optical fibre connections or be used as a free- space optical component. Hybrid configurations with both fibre connections as well as free-space interfaces on the same device are also possible. The devices based on the PIC for visible light have no moving parts, are robust and stable over a very wide temperature range, do not need optical adjustment and can be very compact in size.

Variable Optical Attenuator

Another example of using PIC technology for visible light is the Variable Optical Attenuator (VOA) for visible wavelengths. This VOA enables to decrease the output power of any input laser in a measurement setup, while the laser operates at standard high output powers. This increases the stability of the total system as the lasers prefer operation at their sweet-spots, which typically are high power. Lowering the power of the laser directly increases the noise as they no longer operate at their preferred operation point. The VOA for visible wavelengths offers the possibility to run a laser at its preferred output state and the power can be adjusted to match the level of the specific measurements.

Fringe pattern generator

An application demonstrating how PICs can be used in cooperation with free space optics a fringe pattern generator is developed. As the phase of the light can be controlled very accurately on the visible PIC, fringe patterns can be made and control that are projected on a surface. These are using for communication, signaling, route mapping and controlling, distance measurement, sea level & depth measurement, surface mapping etc.

Above we have presented few examples of optical and photonic systems that have been developed for transportation applications. All these examples indicate that photonics has an immense potential which is still largely unused for transportation applications. Advances in precision, speed and repeatability are occurring rapidly in the photonics industry and this can be applied to good use for low-cost efficient instrumentation applied to transportation.