In this International Year of Light 2015 blog entry written by Abhijeet Phatak is a final year undergraduate student at the Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi, India, different lighting technologies paired with smartphones are explored.

Smartphone technology is getting better and cheaper with each passing day. People have developed interesting apps and technologies smartly using the hardware. The smartphone app industry is projected to be at least US $77 billion industry by the end of 2017 (1). This burgeoning market has greatly influenced and instigated a sense of competition among other industries as well. The development of Smart TV’s can serve as a good example to how versatile and useful modern day smartphones have become (2).

Smartphones have indeed become an integral part of our lives!. (Photo courtesy of:  https://pixabay.com/en/smartphone-photo-phone-mobile-623722/)

Smartphone manufacturers consistently try to improve existing hardware without increasing the cost of the device. Better and more accurate accelerometers, gyroscopes have been integrated for better gaming experience. Magnetic sensors, compass, GPS and many other components have made exploring new places easy. High resolution and energy efficient displays have been developed by their R&D teams. NFC along with the already existing Bluetooth and Wi-fi technologies have led to interesting everyday applications. The high-end models also have a heart beat monitor, pressure and temperature sensors for monitoring human health and also the surroundings (3).

With this burgeoning smartphone market, we can definitely expect cooler applications in the future. In this article, I would like to focus primarily on simple applications which would be made possible by the simple inclusion of laser diodes in our smartphone hardware. There are definitely some legal issues and challenges with this idea but there are no limits to imagination. Also, the applications I have quoted in this article might need some other changes in software and hardware.

Health

Recently there have been some cool products developed with the help of lasers for medical applications. One good example is a vein finding device (4), which uses an near infrared (NIR) laser. This device is particularly useful for the obese, dark-skinned or elderly patients where it becomes difficult to locate the veins for intra-venal medication. There are various research groups who are aggressively working to develop what is known as telemedicine. One such research group is led by Prof. Ozcan at UCLA (5). Devices that use an NIR laser to detect body temperature have already become common in the medical industry. However, they are also being used in industrial and other scientific applications. We have already started experiencing a drastic change in fitness monitoring with the advent of wearable technology like smart watches, smart bands , etc.

LUCAS, A lens-free imaging technique using cellphones for better health monitoring. (Photo courtesy of: http://newsroom.ucla.edu/releases/cell-phone-prototype-of-lensless-77054)

Integration of laser diodes into the current architecture of smartphones and other IoT (Internet of Things) based wearable devices will definitely add to their functionality for better health monitoring and sensing. In the future, we can expect to see a number of microfluidic chip based devices that might be used for detecting diseases eliminating the need of costly diagnosis especially in the poorer regions of the world (6). Who knows what functionality a laser in a common smartphone might add to such devices?

Security

Optical holograms and barcodes have already been implemented to thwart fake or duplicate products. However, there are still piracy related issues. We can design specific technologies which are hard to replicate, the authenticity of which can be tested with the help of your smartphone laser. Laser based anti-theft systems have been popularized by action movies. What if one could make such a system for a nominal cost all by themselves! (7)

Optical data security has also attracted a lot of research interest (8). Digital holography for information security and encompasses: Optical information encryption, Optical information hiding, Optical information verification, Optical information watermarking, Information sharing, Optical authentication, Multiple information security technology.

Although both physical security and data/information security schemes based on optical techniques have been implemented to a certain extent, there is still a lot of work to be done.

Sensing

Light has been used to sense and detect motion, chemical and physical attributes of matter. Our understanding of time is also based on the speed of light and vice a versa. Spectroscopy is a tested technique to detect hazardous chemicals and drugs. It is non-contact, non-invasive method which primarily is based on the interaction of electro-magnetic radiation with matter. Mach Zehdner interferometers, waveguides and other devices are some examples of sensors based on light. Some light based sensors are already embedded in our smartphones, for instance take proximity sensors, ambient light sensors, etc. However, they do not provide an opportunity to experiment and know more about our surroundings. Laser diodes embedded in the smartphone might enable us to monitor pollution in air and water. This might not be completely useful to all of us but would go a long way in real-time monitoring and helping us track the changes in our surroundings. It might indirectly help us in staying healthy. There are already some products developed for this purpose (9). But, what if we can achieve the same without the need of buying anything else? Also, body temperature monitoring will become easier.

SPIKE, a laser accurate smartphone based measurement system.(Photo courtesy of http://www.ikegps.com/spike/)

LIDARs and other optical ranging systems are widely used in surveying, construction and other field work. There are products which are trying to integrate smartphone tech with laser rangefinders to create an accurate measurement system (10). With laser diodes embedded in our smartphone, we might have standalone smartphone based measurement systems!

Communications

Optical communication systems, also known as Visible Light Communication (VLC) are still in their infancy. However, there is a rapid progress in this field. Philips, GE and bytelight are some of the companies working aggressively in this field. Philips recently developed an indoor positioning system which uses simple LED bulbs to communicate with the smartphone user’s front camera to guide through the supermarket (11).

What will happen if we have a laser in our smartphone? Can we somehow enable such short distance communication at high speeds? Though the history of such VLC based communication dates back to the year 1880 when Alexander Graham Bell invented the photophone, there has been little progress. This photophone used sunlight as the source of light. One more interesting version of the photophone is a private communication line that can be made for less than 5$ at our home (12). It uses a simple laser diode with Amplitude Modulation driven by the sender’s voice. At the receiver end, this modulated signal is demodulated with the help of a photocell. Such simple communication systems can have a very large impact in areas where there is no cellular network coverage. One can also think of a cell phone based communication system that can be used on a optical fiber network maybe in offices or public places. The possibilities are endless.

Entertainment, Experience and Education

Probably the most important reason behind this smartphone boom is the many options a smartphone can offer when you are bored. Be it games, applications, surfing the internet, photography, watching videos, etc. The possibility of smartphone based projectors and secondary displays have also been explored (13). However, with coherent light, things become more interesting. We can think of advanced holographic art forms and laser based visualizations along with music! Lasers can cause damage to the human vision without proper protective glasses. This is one reason why there has not been much use of lasers in educating young people. However, they can enhance learning in enabling students to perform simple experiments. One can hardly imagine the possibilities.

More Information

1 –  http://www.entrepreneur.com/article/236832
2 – https://en.wikipedia.org/wiki/Smart_TV
3 – https://www.qualcomm.com/news/snapdragon/2014/04/24/behind-sixth-sense-smartphones-snapdragon-processor-sensor-engine
4 – http://www.google.co.in/patents/US20080147147
5 – http://innovate.ee.ucla.edu/
6 – https://www.ted.com/talks/manu_prakash_a_50_cent_microscope_that_folds_like_origami?language=en
7 – http://www.instructables.com/id/Laser-Tripwire-Alarm/
8 – Wen Chen, Bahram Javidi, and Xudong Chen, “Advances in optical security systems,” Adv. Opt. Photon. 6, 120–155 (2014)
9 – http://www.origins-china.com/
10 – http://www.ikegps.com/spike/
11 – http://www.lighting.philips.com/main/cases/cases/food-and-large-retailers/carrefour-lille.html
12 – http://makezine.com/projects/make-16/simple-laser-communicator/
13 – http://www.androidcentral.com/lenovo-unveils-smart-cast-smartphone-concept

Abhijeet Phatak, a final year undergraduate student at the Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi, India (www.iitbhu.ac.in).

Abhijeet Phatak is a final year undergraduate student at the Department of Ceramic Engineering, Indian Institute of Technology (Banaras Hindu University), Varanasi, India (www.iitbhu.ac.in). His research interests include optics, photonics, materials science, ceramic materials, nanotechnology, semiconductors, energy, metamaterials, quantum effects, computational physics and other sciences. Pursuing further research, he wishes to do something that will have a great and positive impact on the society.