Image of the Week

Striking images of optics and photonics, contributed by OPN readers

Rainbow Fiber Laser

A visible rainbow of hues in a near-infrared (NIR) continuous-wave Raman fiber laser, formed due to 2nd- and 3rd-harmonic conversion of the cascaded IR Stokes wavelengths traveling in the core of the fiber. The laser is pumped only by NIR sources and there is no visible light input. Image captured in the high-power lasers lab in CeNSE, IISc, using a standard DSLR camera with a 30-second exposure.

—Santosh Aparanji, Centre for Nano Science and Engineering, Indian Institute of Science, Bengaluru, India

28 Jan 2022

A Bacterial Colony

Recovered phase image―obtained using a lensless ptychographic sensor―of a live bacterial colony cultured on an uneven agar plate. The slow-varying phase with many 2π wraps is recovered over a cm-scale field of view with sub-micron resolution. [See Jiang et al., Biosens. Bioelectron. 196, 113699, (2022).]

—Guoan Zheng, University of Connecticut, USA

21 Jan 2022

A Volcano Track

A volcano track or plume rises over Mount Michael, an active stratovolcano on Saunders Island, about 1600 km from Antarctica. Acquired on 7 November 2021 with the Operational Land Imager (OLI) on Landsat 8, the false-color image was composed with a combination of shortwave infrared and blue light (OLI bands 7-6-2), to help distinguish the volcano track from the rest of the cloud deck.

—NASA Earth Observatory image by Lauren Dauphin, using Landsat data from the U.S. Geological Survey

14 Jan 2022

$On-Screen Diffraction$

On-Screen Diffraction

Solar illumination on a cell phone screen creates a beautiful diffraction pattern. The pattern is due to the pixelated nature of the screen. The reflection of the tree adds interest.

—Kamran Qaderi, Pacific Light & Hologram Los Angeles, CA, USA

07 Jan 2022

Polychromatic Sand

White sand from Chapoquoit Beach (Falmouth, MA, USA) in transmitted light under polychromatic polarization microscope, 4× objective lens (nature.com/ articles/srep17340).[OPN 2021 Photo Contest Third Place (tie)]

—Michael Shribak, Marine Biological Laboratory, University of Chicago, IL, USA

31 Dec 2021

How LEDs Really Work

LED holiday lights at the Smithsonian National Zoo, Washington, DC, USA, shot with continuous change in zoom lens focal length. The dashed nature of each LED indicates the LEDs are operated in a pulsed format, not continuously.

—Michael D. Duncan, Optica, USA

24 Dec 2021

Snow Summit

A vivid snow summit with a blizzard in dark night sky? Actually, it is the irregular border of a graphene oxide (GO) film (~140 nm) spin-coated on a silicon substrate (300-nm SiO2/Si) and captured by the KEYENCE VK-X1000 Laser Microscope.[OPN 2021 Photo Contest Third Place (tie)]

—Zhijun Xu, College of Science, Zhejiang University of Technology, Zhejiang, China

17 Dec 2021

OAM Beam Reconstruction

An orbital angular momentum (OAM) beam with charge L=2, reconstructed using the extended Gerchberg Saxton phase retrieval technique. In the image, brightness corresponds to intensity and hue to phase.[OPN 2021 Photo Contest Second Place]

—Matthew N. Jacobs, The University of Colorado Boulder, CO, USA

10 Dec 2021

Laser Engraving Fluorescence

Fluorescence of a laser engraving mark on a white plastic card shows how the laser modified the molecules to create a contrast in the zones of the laser mark. Image details: 20x/0.5 objective, 12V 100W Halogen Lamp and filter set Ex400-440 BS460 Em 470-900. The 697×526-μm image is an extended focus from 45 Z-Slides (65.13 μm in total).[OPN 2021 Photo Contest Winner]

—Jose Manuel Martinez Lopez, Quimica Tech, Chihuahua, Mexico

03 Dec 2021

Time-Resolved Emission

Fluorescent tubes go through one on-off-on cycle every 1/120 second. Each row of pixels is exposed sequentially, adding up to 1/30 second or four full cycles going from top to bottom. Purple light emitted early in the cycle comes from mercury and short-lived states in the phosphor mixture, and green light emitted late in the cycle comes from a long-lived Tb(3+) state in the phosphor mixture that continues emitting light at 542 nm for several ms after mercury emission turns off.[OPN 2021 Photo Contest Editors’ Choice]

—Dan Deptuck, CMC Microsystems, Ontario, Canada

26 Nov 2021

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Image of the Week

Rainbow Fiber Laser

A Bacterial Colony

A Volcano Track

On-Screen Diffraction

Polychromatic Sand

How LEDs Really Work

Snow Summit

OAM Beam Reconstruction

Laser Engraving Fluorescence

Time-Resolved Emission

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