We report a demonstration of laser Doppler holography at a sustained acquisition rate of 250 Hz on a 1 Megapixel complementary metal-oxide-semiconductor (CMOS) sensor array and image display at 10 Hz frame rate. The holograms are optically acquired in off-axis configuration, with a frequency-shifted reference beam. Wide-field imaging of optical fluctuations in a 250 Hz frequency band is achieved by turning time-domain samplings to the dual domain via short-time temporal Fourier transformation. The measurement band can be positioned freely within the low radio-frequency (RF) spectrum by tuning the frequency of the reference beam in real-time. Video-rate image rendering is achieved by streamline image processing with commodity computer graphics hardware. This experimental scheme is validated by a non-contact vibrometry experiment.

A brief review of acquisition and rendering methods of optically-acquired holograms in frequency-shifting and off-axis conditions is presented. Applications to laser Doppler imaging in angiography are reported, as well as our latest technical developments in auto-focusing, adjustable magnification, and video-rate implementation of numerical image reconstruction.

We report a demonstration video-rate heterodyne holography in off-axis configuration. Reconstruction and display of a one megapixel hologram is achieved at 24 frames per second, with a graphics processing unit. Our claims are validated with real-time screening of steady-state vibration amplitudes in a wide-field, noncontact vibrometry experiment.

We report new results in angiographic mapping of microvessels in vivo with a wide field optical detection scheme, enabling blood flow contrast measurements in minimally invasive conditions without exogenous marker.

We report laser Doppler ophthalmoscopic fundus imaging in the rat eye with near-IR heterodyne holography. Sequential sampling of the beat of the reflected radiation against a frequency-shifted optical local oscillator is made onto an array detector. Wide-field maps of fluctuation spectra in the 10 Hz to 25 kHz band exhibit angiographic contrasts in the retinal vascular tree without requirement of an exogenous marker.

Ce travail presente le developpement d'une nouvelle technique d'imagerie thermique utilisant une nanoparticule fluorescente comme capteur de temperature. La particule est fixee a l'extremite d'une pointe de microscope a force atomique. En contact avec une surface ou un dispositif plus ou moins chaud, la fluorescence de la particule varie et permet de determiner la temperature. La particule utilisee contient des ions de terres rares (erbium et ytterbium) dont certaines raies d'emission sont en equilibre thermique. La mesure de l'intensite relative de ces raies permet de determiner la temperature absolue du materiau, et donc de la surface avec lequel il est en contact. Nous avons tout d'abord utilise cette technique pour etudier l'echauffement de pistes resistives (aluminium et nickel) parcourues par un courant continu. Dans le cas de pistes d'aluminium, la resolution laterale thermique que nous avons obtenue est d'environ 250 nm, de l'ordre de la taille de la particule fluorescente. Nous avons ensuite utilise cet instrument pour observer l'echauffement de pistes parcourue par un courant alternatif. Ce mode permet d'observer ou sont localisees les variations de temperature, mais ne permet pas pour l'instant de determiner la temperature absolue du dispositif. A l'aide de ce mode de fonctionnement, nous avons observe l'echauffement dans des pistes de nickel dont la largeur est de l'ordre de 200 nm. Enfin, en effectuant des courbes d'approche/retrait, nous avons aussi pu mesurer l'importance relative des differents mecanismes de transfert de chaleur entre la pointe et la surface. Dans le cas de pistes de taille submicronique, le transfert de chaleur par contact direct est de loin le plus efficace.

A scanning thermal microscope that uses a fluorescent particle as a temperature probe has been developed. The particle, made of a rare-earth ion-doped fluoride glass, is glued at the extremity of a sharp tungsten tip and scanned on the surface of an electronic device. The temperature of the device is determined by measuring the fluorescence spectrum of the particle at every point on the surface and by comparing the intensity variations of two emission lines. As an example, we will show some images obtained on a nickel stripe 1 microm wide, heated by an electrical current. A good agreement is observed with a simulation of the temperature field on the device.

Luminescence is light emission by materials after absorption of energy. Today, this effect has been made into a very powerful way of characterising materials in a whole range of different fields, across physics, biology, and chemistry. In terms of technological applications, luminescence is also on the point of replacing incandescence for short-range lighting purposes, e.g., pocket lamps, with the advent of white light-emitting diodes. In this chapter, we shall describe a specific application of luminescence to the development of thermal nanosensors. There are four sections. In the first two, we simply describe the luminescence phenomenon, along with several light-emitting materials used for thermometric measurements. In particular, we shall explain how the temperature of a material can be determined from data concerning its luminescence. In Sect. 17.3, we shall discuss the technique of scanning thermal microscopy with fluorescent nanoprobes, together with the experimental setup. In the last section, we shall discuss applications of this technique to image microelectronic devices. The characteristics of the probes and their advantages and disadvantages as compared with other near-field probes will be described in some detail.

We have developed a scanning thermal microscope (SThM) that uses a fluorescent particle glued at the end of an atomic force microscope tip as a thermal sensor. When a temperature change occurs, a modification of fluorescence is detectable, enabling measurement of local temperatures and rendering of thermal images. We describe the technique and demonstrate its capability to map surface temperatures by measuring the local resistive heating in a 500nm wide nickel wire.

We study the Joule heating of a 1.25 μm wide aluminum microstripe excited by an electrical current. The temperature changes are measured with a scanning thermal microscope that uses a small fluorescent particle as a sensor. The lateral resolution observed for this sample is better than 300 nm. We have compared the temperature distribution in the stripe with a simple analytical model of heat propagation in the wire and the substrate. A good qualitative agreement is observed, although the measured temperature is much smaller than the estimated one, showing that the heat transfer between the hot wire and the fluorescent probe is not fully efficient.

We have developed a scanning near-field optical microscope that uses a subwavelength-sized silica sphere covered with CdSe∕ZnS quantum dots as a fluorescent optical detector. Due to the good photostability of these semiconducting particles, we are routinely able to perform several successive scans without a noticeable decrease of fluorescence signals. As an example, we will show some images of the light immediately transmitted through 300nm wide slits made in a thin gold film. We will also discuss the advantages of such fluorescent probes compared to other near-field optical techniques.