[Paper Review] Photographing by means of a diffractive axicon

José J. Lunazzi, Daniel Souza Ferreira Magalhães|ArXiv.org|Jan 19, 2007

Orbital Angular Momentum in Optics10 references3 citations

TL;DR

This paper demonstrates that a compact disc, acting as a diffractive axicon, can produce photographic images by diffracting light in a wavelength-dependent manner. The axial position of the focused image shifts with wavelength, enabling the CD to function as a simple spectral filter for visible light imaging.

ABSTRACT

In this paper we demonstrate that the light diffracted by a simple compact disc can be used to generate photographic images of a certain kind. Being the compact disc an axicon that generates a diffraction-free beam, we show that the focusing position of an image depends of the wavelength of the diffracted light, what makes possible its use as a spectral filter.

Motivation & Objective

• To explore the optical properties of a compact disc as a diffractive axicon for imaging applications.
• To demonstrate that the axial focus position of diffracted light varies with wavelength, enabling spectral filtering.
• To provide a low-cost, accessible educational tool for teaching diffraction and optical filtering using everyday materials.
• To illustrate the principles of axicon-based beam formation and diffraction-free propagation in a tangible, hands-on experiment.

Proposed method

• A standard compact disc (CD) is used as a diffractive axicon due to its periodic groove structure.
• Light from a white source is diffracted by the CD's grooves, producing a conical wavefront characteristic of axicons.
• The axial focus position of the diffracted beam is observed to vary with the wavelength of incident light.
• Photographic images are captured by placing a camera or film at different axial positions along the beam path.
• The wavelength-dependent focus shift is analyzed to confirm the spectral filtering capability of the CD.
• Experimental setups are designed to visualize and record the intensity distribution and focus shift across visible wavelengths.

Experimental results

Research questions

• RQ1 Can a compact disc function as a diffractive axicon to generate a diffraction-free beam?
• RQ2 How does the axial position of the focused image vary with the wavelength of incident light?
• RQ3 To what extent can a CD serve as a simple spectral filter in imaging applications?
• RQ4 What is the feasibility of using common optical components like a CD for educational demonstrations of diffraction and spectral filtering?

Key findings

• The compact disc produces a conical wavefront due to its periodic groove structure, confirming its behavior as a diffractive axicon.
• The axial focus position of the image shifts systematically with wavelength, demonstrating wavelength-dependent focusing.
• The system enables the formation of photographic images at different axial positions depending on the light's color, indicating spectral sensitivity.
• The observed wavelength-dependent focus shift confirms the CD's ability to act as a simple spectral filter in imaging.
• The experiment demonstrates a low-cost, accessible method for visualizing diffraction and spectral filtering using everyday materials.