Smartphones become photonics hardware

John Wallace Senior Editor Laser Focus World johnw@pennwell.com

As Laser Focus World readers know, the use of the iPhone in photonics is growing. Examples include the iPhone as a source of info (geometrical optics guide; colorimetry color and measurement values) and the iPhone as a hardware/software photonics system (holographic microscope; 3D image capture). Earlier this month I posted a news story to the Laser Focus World home page on another example of the iPhone as photonics system: a microscope using a ball lens and the iPhone's camera to image blood cells.

I personally have an Android phone instead of an iPhone. Since Android is actually more popular than iOS for phones, I've been waiting for more Android photonics apps and such to appear (there are some already, such as a fluorochrome search app from Chroma Technology).

Yesterday, John Canning of the University of Sydney let me know that the use of Android devices as photonics hardware is advancing, as illustrated by an experiment in which he and his colleagues use an Android smartphone (the HTC Desire) as the light source for a fluorescence-microscope setup.¹ The blue light is from the phone's OLED screen, and a freely downloadable color-flashlight app from the Android market is the spectral control.


Specimen under Android phone illumination:
(a) white light (RGB); (b) blue; and (c) excited
by blue and filtered to pass only fluorescence.
(Images: University of Sydney)

The specimen is placed on a slide directly atop the OLED screen; the blue emission, which peaks at 445 nm, excites the fluorone dye Rhodamine 123 inside a silica mesostructure sphere. A green filter passes only the resulting fluorescence to the microscope optics. The researchers believe that a custom app would raise the signal intensity and allow rapid modulation for fluorescence-decay measurements. In addition, modifying the setup to use the phone's own camera will further simplify the device raising its potential for use in remote areas.

The authors point out that a big advantage of Android is its open access, which allows total software control, making it straightforward to integrate the phone with other hardware.

REFERENCE:

1. John Canning et al., Sensors, 11, p. 7055, 6 July 2011; doi:10.3390/s110707055.