White-light laser is basis of new optical tweezers and microscope

May 27, 2005

Penn State engineers have used a "white-light laser" to produce a new type of optical "tweezers" that not only traps, holds and moves microscopic objects but also can perform characterization of the object via spectroscopy at the same time.

Dr. Zhiwen Liu, assistant professor of electrical engineering who leads the project, says, "Our team is among the first to demonstrate the 3-dimensional trapping and manipulation of microscopic objects using white laser light. Our novel tweezers, thanks to the broadband nature of white light, also have the potential to perform optical scattering spectroscopy of the trapped object over a broad wavelength range."

Through optical spectroscopy, researchers can probe the trapped particle's size, shape, refractive index and chemical composition. In experiments, so far, the team has demonstrated the tweezers's capabilities with three kinds of polymer microspheres of different sizes.

The new tweezers were described Friday, May 27, in a paper, “White Light Supercontinuuum Optical Tweezers,” presented at the Conference on Laser and Electro-Optics/Quatum Electronics and Laser Science in Baltimore Md. The authors are graduate students Peng Li and Kebin Shi as well as Liu. The tweezers were also described in the paper, “Manipulation and Spectroscopy of a Single Particle by Use of White-light Optical Tweezers,” published earlier this year in Optics Letters.

The Penn State researchers have also incorporated a white light laser into a confocal microscope system to speed image production while retaining the image clarity and ability to observe the object in layers available in conventional instruments. Images that require a second or more to be produced with a conventional confocal microscope need only tens of milliseconds in the white-light instrument.

Liu notes that many biological processes occur in milliseconds or less and the new confocal microscope has the potential to film them as they happen. He expects both the new tweezers and microscope to have applications not only in the biological and medical sciences but also in the microcircuit chip industry.

Propagating short laser pulses of infrared light, for example, in a photonic crystal fiber broadens its spectrum dramatically and generates supercontiuum white light. The white light produced in this way can be focused to a tiny spot just like a normal laser.

The Penn State researcher notes, "The broad spectrum of supercontinuum white light increases its information capacity and offers new opportunities for next generation optical information systems. "

The microscope was described in the paper, “Chromatic Confocal Microscopy Using Supercontiuum Light,” published last year in Optics Express.

The research was supported by start-up funds from Penn State's College of Engineering and Department of Electrical Engineering.

Source: Penn State

Explore further: Crystal unclear: Why might this uncanny crystal change laser design?

Related Stories

Silicon nanoparticles trained to juggle light

August 24, 2016

A team of physicists from ITMO University (Saint Petersburg) and Moscow Institute of Physics and Technology (MIPT) has demonstrated the potential of silicon nanoparticles for effective non-linear light manipulation. Their ...

Measuring tiny forces with light

August 25, 2016

Photons are bizarre: They have no mass, but they do have momentum. And that allows researchers to do counterintuitive things with photons, such as using light to push matter around.

Physicists propose method for braiding light

August 22, 2016

(Phys.org)—Physicists have proposed a way to braid three beams of light by guiding the beams along swirling, vortex-shaped defects in the optical medium through which the beams travel. The braided light would have an unusual ...

Electrons at the speed limit

August 26, 2016

Electronic components have become faster and faster over the years, thus making powerful computers and other technologies possible. Researchers at ETH Zurich have now investigated how fast electrons can ultimately be controlled ...

NIST's compact gyroscope may turn heads

August 23, 2016

Shrink rays may exist only in science fiction, but similar effects are at work in the real world at the National Institute of Standards and Technology (NIST).

Recommended for you

Rosetta captures comet outburst

August 25, 2016

In unprecedented observations made earlier this year, Rosetta unexpectedly captured a dramatic comet outburst that may have been triggered by a landslide.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.