These two variations of illuminating light are confused as one another when people talk about them. There is a fundamental difference between the two types of colour shifting definitions. When people hear about holographic and iridescence effects it’s often used to describe makeup with colour shifting flecks that shine or pick up light. These are the definition and comparison between the two.
The definition of iridescent is the gradual change of colours when looking at a surface from different angles. There are many other properties that do that, for example, opalescent, pearlescent and luminescent. They all hold the same principles of colour shifting. The goniochromistic properties are the properties that make the colour shifting happen by the phenomenon of certain surfaces gradually changing in colour when the angle of view or the angle of illumination changes. The two ways iridescent effects happen are either interference (the small selection of colour shifting on a surface which based on the light available ) or diffraction (the full range of rainbow colours displayed from all angles). This is how we get the name iridescence from the Latin word iris meaning rainbow.
The colours on a peacock feather, in a bubble or in an oil slick light waves can interfere with another form causing the colour effects. Other examples of iridescence would be optically anisotropic effects when different optical properties of light have different directions.
The first use of iridescence in design
In the 9th century, a type of ceramic design was a type of pottery that used iridescent finish. This is called lusterware. This was a technique with Middle Eastern origins. There were different types of lusterware that had salts, golds and pieces of platinum for effect. A noticeable pottery ware that used this technique was the Hispano-Moresque ware in the 15th century Malagara, Spain.
Notable examples of iridescence:
- Plastic Clothing
Holographic are just holograms. Holograms are a photographic record that holds light from being scattered from an area without special lenses. They are various types of holographic techniques that exist; like, security labels which are rainbow holographic or objects that you can shine a light right through them to view an object through the other side which is transmitted holographic. Light would have to shine right through a holographic object to make the object have the three-dimensional effect.
The object would need a clear area for the light beams to interact and good material to help see the image. The light beam is split into two different types of lights an illuminating beam and an object beam. These two light beams are being directed into the object. This creates a reference beam that directed into the recording beam. The two beams interact and interfere with each other which creates a pattern with imprinted into the recording medium creating a holographic image.
The first holographic pictures
“The photographic record obtained with optical apparatus of [this] kind… has been termed a ‘hologram’ and this name will be used hereinafter.“Dennis Gabor, US Patent #2,770,166, 1951
It is noted that Hungarian born Dennis Gabor invented the first hologram while working in the United Kingdom researching optical physics and inventing experimental holographic work throughout the 1940’s to the 1950’s. He was always an inventor making new kinds of electron multipliers and cathode-ray tubes. Furthermore, he was always experimenting with photography and projection which influenced his invention of holography. He won a Nobel Prize for Physics in 1971 a few years after he retired in 1967. Lasers made holographic work more practical but it wasn’t used until the 1960’s.
The first holographic image that was created by a computer was in 1962 by Yuri Denisyuk from the Soviet Union and Emmett Leith and Juris Upatnieks from the University of Michigan. They developed a laser that recorded a three-dimensional object. This created the Denisyuk hologram which was a holographic object that can be viewed under white light through the use of the depth dimension of the emulsion.
Notable examples of holographics:
- Security labels
- Military mapping
- Digital storage discs (CDs and DVDs)
- Magnetic Resonance Imaging (MRI)
- Holographic projections for concerts
How the words holographic and iridescent are used in the marketplace
In the description boxes in makeup products that use “holographic” or “iridescent” are referencing the vibrancy of the colours. They both would be colour shifting and rainbow coloured prisms but it’s a difference between the deeply vibrant or the softly saturated. The vibrancy of colours makes a large difference when discussing depth.
Iridescent products have colour shifting properties because of plastics and other types of colourful particles used in the production process. Most iridescent products just have to show a simple display of colours shifting from a start point to an end point. When the object is moving to show the colour shifting properties it would show you the shape and edges of the design. The object would look flat because there’s no depth perception to see the form of the object just the edge of the design.
The holographic effect is created with the more vivid use of light to highlight areas closer to the light source. With the colour shifting properties of the material diffusing the gray tones into a rainbow of colours.