Gabriel Lippmann (pronounced LIP-muhn; August 16, 1845 – July 12, 1921) was a French scientist who worked on practical physics problems. He won the Nobel Prize in Physics in 1908 for creating the Lippmann plate, a way to make color images using photographs based on how light waves interact.

Biography

Gabriel Lippmann was born on 16 August 1845 to French Jewish parents in Hollerich, Luxembourg. His father owned and managed a business that made gloves.

In 1848, Lippmann’s family moved to Paris. He first learned from his mother before starting school at the Lycée Napoléon (now called the Lycée Henri-IV) in 1858. He was described as a student who sometimes seemed distracted but was deep in thought, with a strong interest in mathematics. In 1868, he entered the École normale supérieure. However, he did not pass the agrégation examination, which would have allowed him to become a teacher. Instead, he chose to study physics.

In 1873, the French government sent Lippmann to Germany to learn about science teaching methods. He worked with scientists Wilhelm Kühne and Gustav Kirchhoff at the University of Heidelberg. In 1874, he received a doctorate with the highest honors. The next year, he visited Hermann von Helmholtz at the University of Berlin before returning to Paris. On 24 July 1875, he presented his doctoral thesis on electrocapillarity to the Sorbonne.

In 1878, Lippmann became a member of the Faculty of Science at the Sorbonne. In 1883, he was named Professor of Mathematical Physics, and in 1886, he became Professor of Experimental Physics. That same year, he took over as Director of the Research Laboratory, which was later moved to the Sorbonne.

In 1888, Lippmann married the daughter of the novelist Victor Cherbuliez.

Lippmann died at sea while traveling back from Canada to France on 12 July 1921, at the age of 75.

Inventions and theories

One of Lippmann's early discoveries was the connection between electricity and capillary actions, which helped him create a sensitive tool called the Lippmann electrometer. This tool was used in the first ECG machine. In a paper presented to the Philosophical Society of Glasgow on January 17, 1883, John Gray McKendrick described the device as follows:

In 1881, Lippmann predicted the opposite effect of electricity and pressure.

Most importantly, Lippmann is best known for inventing a method to reproduce colors using photography, based on how light waves interact. This work earned him the Nobel Prize in Physics in 1908.

In 1886, Lippmann focused on a way to capture the colors of the solar spectrum on a photographic plate. On February 2, 1891, he told the French Academy of Sciences, "I have successfully created an image of the spectrum with its colors on a photographic plate. The image stays fixed and can remain in daylight without fading." By April 1892, he reported that he had produced color images of a stained glass window, a group of flags, a bowl of oranges with a red poppy, and a multicolored parrot. He shared his theory about using the interference of light waves for color photography in two papers, one in 1894 and another in 1906.

The interference of light waves happens when light reflects off a surface and creates standing waves, similar to ripples in water that bounce back from a wall. In normal light, these standing waves are only visible in a very thin area near the surface.

Lippmann used this idea by projecting an image onto a special photographic plate that could record details smaller than the wavelengths of visible light. Light passed through a thin glass sheet and into a transparent photographic emulsion containing tiny silver halide grains. A temporary mirror made of liquid mercury reflected the light back through the emulsion, creating standing waves. These waves formed layers of silver grains, which stored color information. The spacing between these layers matched the wavelengths of the light recorded. Longer wavelengths, like red, had wider spacing.

To view the image, the plate was lit from the front with white light. At each point on the plate, light with the same wavelength as the original image was strongly reflected back, creating a full-color image. Other wavelengths passed through the emulsion and were absorbed by a black coating on the back of the plate.

In practice, the Lippmann process was difficult to use. The special photographic plates were less sensitive to light, requiring long exposure times. A camera with a large lens and a bright subject could sometimes capture an image in less than a minute, but exposures often lasted minutes. The process produced vivid pure colors but struggled with the complex color patterns of real objects. It could not make color prints on paper, and copying a Lippmann image by rephotographing it was not possible, so each image was unique. A prism was often attached to the plate to reduce reflections, but this limited the size of the images. Early Lippmann photographs were 4 cm by 4 cm, later growing to 6.5 cm by 9 cm. The lighting and viewing setup needed to see the colors clearly made the process impractical for casual use. Although special plates and equipment were sold around 1900, even experts had trouble achieving consistent results. The process remained a scientific curiosity but inspired further research into color photography.

Lippmann’s method was similar to laser holography, which also uses standing waves in a photographic material. Denisyuk reflection holograms, sometimes called Lippmann–Bragg holograms, have structures that reflect specific wavelengths. In these holograms, laser light creates standing waves in a large area, eliminating the need for the light to reflect immediately next to the recording material. However, lasers, the subject, and the recording material must stay stable during exposure to ensure clear results.

In 1908, Lippmann introduced a technique he called "integral photography." This method used a flat array of tiny spherical lenses to capture a scene from many slightly different angles. When the images were corrected and viewed through a similar lens array, each eye saw small parts of all the images, creating a single 3D image that appeared life-sized and realistic. This idea of using multiple lenses to record a "light field" is the basis for modern light field cameras and microscopes.

When Lippmann explained his "integral photography" in March 1908, he could not yet show results because the materials needed to make a proper lenticular screen were not available. In the 1920s, experiments by Eugène Estanave using Stanhope glass lenses and Louis Lumière using celluloid showed promise. Lippmann’s work laid the foundation for research on 3D and animated lenticular images, as well as color lenticular processes.

In 1895, Lippmann developed a method to remove human error in timing measurements by using photography. He also studied ways to fix irregularities in pendulum movements.