Three-dimensional (3-D) imaging is an attractive subject in terms of scientific interest and potential practical applications. Although there are several 3-D imaging methods, most of them require rather complex image processing after acquiring data or some kinds of scanning, thus three-dimensional information cannot be obtained simultaneously. Simultaneous measurements are necessary for objects which are moving or changing their states.

Optical Measurement Section (Quantum Metrology Department) developed a new method for three-dimensional non-scanning imaging using the conversion between time and color axes, mediated by chirped ultrashort optical pulses.

Figure 1: Principle of the method.

The principle of the method is shown in Fig. 1. The chirped pulse in which the color of light is changing along the time axis illuminates the entire object and is reflected. Then the part of the beam is selected by the shutter, which shows a color distribution corresponding to the surface structure. Such a two-dimensional (2-D) color image corresponding to a 3-D image of the shape was detected.

The applicability of this method was demonstrated by measuring highly reflecting gauge blocks, using a self-mode-locked 100-femtosecond laser and a technique of optical Kerr shatter (Fig. 2). Also, the method is applicable to transmission and perfect diffusing objects.

Figure 2: One-shot imaging of 3D objects using the conversion between time and color by chirped ultrashort optical pulses. A sample is shown in the inset.