Light category

The New Light-responsive Nano LEDs

A team of researchers from the US and South Korea reported a unique type of NanoLEDs with unprecedented brightness levels, that excess 80,000 cd/m2, and also can operate both as light emitters and light detectors.

These new LEDs are about 50nm long and 6nm in diameter. As described in the paper, they included quantum dots of two different types, one of which can enhance radiative re-combinations (useful for LEDs) while the other type leads to efficient separation of photo-generated carriers.

Low- and high magnification scanning transmission electron microscopy images of DHNRs (right) magnified image of the region within the white dotted box on the left.

The research of this invention had been published in a paper titled “Double-heterojunction nanorod light-responsive LEDs for display applications“. The researchers consider the dual-mode LEDs will pave the way to new types of interactive displays.

As we head toward the “Internet of things” in which everything is integrated and connected, we need to develop the multi-functional technology that will make this happen. Oh et al. developed a quantum dot-based device that can harvest and generate light and process information. Their design is based on a double-hetero-junction nano-rod structure that, when appropriately biased, can function as a light-emitting diode or a photodetector. Such a dual-function device should contribute to the development of intelligent displays for networks of autonomous sensors.

The device can reach a maximum brightness in excess of 80,000 cd/m2 with a low turn-on voltage (around 1.7 V). It also exhibits low bias and high efficiencies at display-relevant brightness. The research team reports an external quantum efficiency of 8.0% at 1000 cd/m2 under 2.5 V bias.

Energy band diagram of DHNR-LED along with directions of charge flow for light emission (orange arrows) and detection (blue arrows) and a schematic of a DHNR.

One of the experiments was operating a 10×10 pixel DNHR-LED array under reverse bias as a live photodetectors, combined with a circuit board that supplied a forward bias to any pixel detecting incident light. And by alternating forward and reverse bias at a sub-millisecond time scale, light-detecting pixels could be “read out” as they illuminated the array.

Future applications of the DNHR LEDs include:

  • Translate any detected signal into brightness adjustments;
  • Automatic brightness adjustment in response to external light–intensity change;
  • Direct imaging or scanning at screen level;
  • Display-to-display data communication.
  • Displays can harvest or scavenge energy from ambient light sources without the need for integrating separate solar cells.

Sources: elektor, EETimes

LED Based Strobe For Entertainment, Events & Warning Signals

Strobe provides regular flashes of light. Usually Strobes are designed using Xenon Tubes. Here is LED based simple solution that can be used as strobe for entertainment and events and also as warning signals. Project is based on PIC16F1825 micro-controller with two digit frequency display.

Project provides TTL output signal, frequency 1Hz-25Hz, Tact switches provided to set the frequency.

This project works along with DC Output Solid State Relay

Features

  • Supply 4.5 to 5V DC
  • Frequency 1Hz To 25Hz
  • Easy Interface with Relay Board
  • Easy Interface with Solid State Relay
  • On Board Power LED
  • On Board Output LED
  • Onboard Switch to set the frequency
  • 2X7 Segment 0.5 Inch Display

LED Based Strobe For Entertainment, Events & Warning Signals – [Link]

iKeybo, The Advanced Projection Keyboard

Serafim is a company of some talents and experts in optoelectronics industry, and it aims to offer affordable, useful, and cool consumer electronics for a better computing experience. The latest amazing product by Serafim is: iKeybo!

iKeybo is a virtual projection multilingual keyboard that can turn any flat surface into a keyboard. iKeybo can work as a piano too.

Check this video to see iKeybo in action:

iKeybo uses a non-contact technology and has 90Hz frame rate. It turns your 5 inch display into 12 in a surface since the projection surface is 268*105mm. The keyboard consists of 78 keys where other competitors only have 66. It has a instant reaction around 11.11ms what makes it more convenient while using.You can use iKeybo with you PC, mobile devices and tablets since it works via Bluetooth and USB.

For developers, a SDK for iOS and Android is available! It supports all functions of touch screen which include single tap, double tap, rotate, press and drag, press and hold. Install the framework and make connections with your apps.

It differentiates from other laser projection keyboard because it implements a new patented technology that uses camera sensor and double linear sensors for faster calculation speed and less energy.

“What distinguish iKeybo from traditional projection keyboards is that it is the world’s first laser projection “piano” that allows users to create music instantly with piano, guitar, bass, or drums. When not in use, iKeybo can also serves as an external charger to power up devices with 10 hours of battery life. Its cellphone stand design is also perfect for desk or table to watch movies or start live streaming.“ – iKeybo team

iKeybo Features

4 Language Layouts you can choose from 4 different languages keyboard layouts (English, Spanish, Arabic, and Chinese) to type the language special characters that you need. You can’t add more language layouts to your iKeybo because each layout projection needs a different optical lens. Once you select a language edition or a bilingual one it will be fixed.

4 Musical Instruments with iKeybo you can play piano, guitar, bass and drums! Check this piano demo video:

Round Key Designs a special design to make it easier for typing. Other competitors use square keys with no space in between that make it possible to do a lot of typos.

Portable Charger & Cell Phone Stand  iKeybo also serves as an external charger to power up your devices with 10 hours of battery life. You can also use it as your cellphone stand to turn your mobile device into a computer within just a second.

iKeybo is not the first optoelectronics product by parent company Serafim. Check this page to know more about its products.

iKeybo is now live on a Kickstarter campaign and still has 10 days to go! You can pre-order your iKeybo with one language layout and piano for $89 and also you can get a bilingual iKeybo for $99. More information are available at the campaign page.

AS7221, An IoT Smart Lighting Manager

ams AG, a multinational semiconductor manufacturer and provider of high performance sensors and analog ICs, had announced the AS7221, an integrated white-tunable smart lighting manager that can be controlled through its network connection by means of simple text-based commands.

AS7221 Block Diagram

AS7221 is a networking-enabled IoT Smart Lighting Manager with embedded tri-stimulus color sensing for direct CIE color point mapping and control. IoT luminaire control is through a network connection, or by direct connection to 0-10V dimmers, with control outputs that include direct PWM to LED drivers and analog 0-10V to dimming ballasts. A simple text-based Smart Lighting Command Set and serial UART interface, enable easy integration to standard network clients.

Key features of AS7221:

  • Calibrated XYZ tri-stimulus color sensing for direct translation to CIE 1931/1976 standard observer color maps
  • Autonomous color point and lumen output adjustment resulting in automatic spectral and lumen maintenance
  • Simple UART interface for connection to network hardware clients for protocols such as Bluetooth, ZigBee and WiFi
  • Smart Lighting Command Set (SLCS) uses simple text-based commands to control and configure a wide variety of functions
  • Directly interfaces to 0-10V dimmer controls and standard occupancy sensors
  • Built-in PWM generator to dim LED lamps and luminaires
  • 12-bit resolution for precise dimming down to 1%
  • 0-10V analog output for control of conventional dimming ballasts in a current steering design
  • 20-pin LGA package 4.5mm x 4.7mm x 2.5mm with integrated aperture

“The next generation of lighting will be defined by three key characteristics: controllability, adaptation and connected architectures,” said Tom Griffiths, Senior Marketing Manager at ams. “Our new family of smart lighting managers meet those criteria. With this latest entry, we are addressing the luminaire manufacturers’ critical time-to-market challenge for developing and deploying a spectrally tunable luminaire that is cost-effective, accurate, and which smoothly integrates into the Internet of Things”.

The AS7221 is the first extension to ams’s recently announced Cognitive Lighting™ smart lighting manager family. The compact AS7221 will be available in a 5x5mm LGA package, for flexible integration into both luminaires and larger replacement lamps.

There are main domains of AS7221 applications, some of them are:

  • Smart home and smart building
  • Variable CCT general lighting industrial lighting
  • Retail and hospitality lighting with white-color tuning
  • LED tro ers, panel and downlights
  • LED replacement lamps (LED bulbs)
AS7221 Functional Diagram

Pricing for the AS7221 Spectral Tuning IoT Smart Lighting Manager is set at $3.13 in quantities of 10,000 pieces, and is available in production volumes now.

You can find AS7221 datasheet here.

Laser for sending music over a distance

Light is a very popular means of communication. Today, optical fiber communication is the backbone of telecommunication and internet. Light is guided through a fiber optic cable in such systems to achieve low-attenuation and high speed data transmission. Question is: Is it possible to use light for communication without a guiding medium? The answer is positive. Because of the highly collimated nature of the laser beam, it is feasible to use a laser output to transmit information without a guiding medium even in daylight, provided that the line of sight occurs between the sending and receiving units.

Armand & Victor from DIY Experiments Youtube channel illustrates a very simple example of modulating a laser diode output with an analog audio signal and sending it over a distance of more than 400 meters. The laser diode used in this project was of 250 mW capacity, which is ~ 100 times more powerful than a regular laser pointer. A single-transistor class-A amplifier circuit was used to amplify the audio input signal prior to use it for modulating the laser output light. A 1:25 turn ratio transformer is used as a coupling device between the audio and the laser module. The transformer is necessary to ensure only the AC variations (and blocks any DC component) in the audio signal will modulate the laser beam.

Circuit setup for modulating Laser with an audio signal

Circuit setup for modulating Laser with an audio signal

On the receiving end, the audio is reconstructed back by aiming the modulated laser beam at an array of four mini solar panels. The solar panel output voltage varies according to the signal variation contained in the laser and is directly fed to a high power (250W) guitar amplifier. The audio quality was quite remarkable for such a simple setup. Check out the following demo video of this project:

RELATED POSTS

Headlight Modulator for Motorcycle

boards

William Dudley @ dudley.nu has designed a motorcycle headlight modulator based on 555 timer IC and photoresistor. A headlight modulator will make the headlight to pulse during the day and be steady at night. He writes:

Unhappy with a headlight modulator I purchased, I decided to make my own. Even though it would be a trivial programming project to use an Arduino Teensy or similar to do this, I decided to do it the “old fashioned” way, using a 555 timer. The 555 is a clever chip; not only will it supply the oscillator for the flashing effect, it has a reset pin that can be used to force the output to a known state (low) when (other circuitry tells it that) it’s dark outside.

Headlight Modulator for Motorcycle – [Link]

DIY Sunlight Simulator – Light Therapy Light

DIY Sunlight Simulator Light Therapy Light banner

Luke Skaff @ lukeskaff.com decided to build a DIY Sunlight Simulator using wide spectrum filament lamp to be used as light therapy for Seasonal Affective Disorder. During the process he checks for various kinds of lamps and examines their light spectrum. He writes:

Sunlight simulation light boxes are commonly used as light therapy for treatment of Seasonal Affective Disorder (SAD). My mom has SAD and after seeing her wimpy light box I thought there had to be something better out there, after some research I was really surprised at the underwhelming sunlight simulator light therapy options on the market. When I started this project my parents lived in the Northern Virginia \ DC area of USA where there are many overcast days in the winter months. I love bright work lighting and lighting in general so part of me was happy that was not there was not a good option available on the market so I could be creative and make my own for her. Most light therapy boxes use fluorescent lighting which I have never liked due to its spikes in a few bands on the spectral power distribution (spectral distribution or emission spectra, discussed below). I love the full spectrum light of incandescent and halogens but to get a light bright enough to work for light therapy I needed a bulb in the 1100 watt halogen or 1500 watt incandescent range at minimum (likely much higher for ideal lumens) which is impractical in its power consumption and heat output. The best all around option is a high intensity discharge (HID) light such as a ceramic metal halide which have some of the best Color Rendering Index (CRI), spectral distribution, lifespan, and cost of any non-incandescent light source.

DIY Sunlight Simulator – Light Therapy Light – [Link]

Colour Injector lamp

Colour-Injector-by-Taras-Sgibnev_dezeen_sq

by Taras Sgibnev:

The colour of light emitted by this lamp can be controlled using syringes filled with red, green and blue ink. Russian designer Taras Sgibnev developed the interactive product as a physical expression of the way red, green and blue light are used in digital interfaces to create a full spectrum of different hues.

Colour Injector lamp – [Link]

Automatic Light Switching System with Dimmer

Manual switching of outdoor lights in houses or roadways can be sometimes really inconvenient especially when we are far away or still at work. Sometimes this becomes an opportunity for thieves to infiltrate houses or a possibility of accident in roadways if night comes and our outdoor lights are still OFF. That is why the goal of this circuit is to automatically switch ON outdoor lights when it senses that it is getting dark and switch OFF lights when it’s daytime.

This type of light switching system is what we can usually see installed in streetlights or houses that are implementing automatic switching of outdoor lights. The system is not just limited to switching ON/OFF lights, it can also adjust the brightness of the lights so that it can just supply the right amount of luminance on the area required. This system is composed of a photocell, a receptacle, a ballast (with dimming control), and a lamp powered by the 220VAC mains. The photocell measures the light intensity level in an area and sends this data in a form of voltages (ranging from 0-10VDC) for the dimming control of the ballast. Based on the level of light intensity sensed by the photocell, the ballast will adjust the brightness of the lamp.

The whole system is supported by the TE Connectivity dimming receptacle 2213362-1. The photocell and ballast are connected through this receptacle. This dimming receptacle supports ANSI standard dimmable photocells with 5 positions (3 power contacts and 2 dimming signal contacts). Its power contacts can handle voltages up to 480V AC/DC provided that the maximum current passing through it will not exceed 15A. The dimming contacts of this receptacle supports 0-10VDC dimming method with a maximum current of 0.10A

Automatic Light Switching System with Dimmer – [Link]