Difference between holographic paper and diffraction gratings?

[James2018]

TL;DR

What is the difference between holographic paper sold in decorative shops and professional diffraction gratings? What about the difference between pearlescent decorative tape and professional dichroic mirrors?

These photos show pearlescent tape that changes color when observed from different angles. Either it's the full rainbow like in the third, fifth and seventh images I displayed here or just a few colors like in the other images, they still change color and are called "iridescent decorative tapes". How do they compare to professional diffraction gratings and professional dichroic mirrors which are more expensive? Do they work on the same principles in physics or on different principles?

 

[kuruman]

Yes, all these items rely on the same principle of wave interference when light is scattered (or transmitted) by microstructures. These, like the examples you list are human made, but they also occur naturally. This Wikipedia article mentions all that. The morpho butterfly is my favorite example of structural wave interference (see video below.)

 

[BvU]

with

professional diffraction gratings

you can do actual measurements. With a butterfly that's not so realistic

$\$

 

[James2018]

with you can do actual measurements. With a butterfly that's not so realistic

$\$

One of the teachers at my university thought that diffraction gratings and dichroic mirrors are expensive and that me and him could never afford one. He thought about using a CD for a diffraction grating. Yet I found these in a decorations shop - holographic paper and pearlescent tape. I guess they can replace the professional dichroic mirror and diffraction grating?
One such PVC film does completely block a red laser pointer and " is widely applied in decoration of bags, shoes and clothes".

 

[James2018]

Is it true that these plastic dichroic films are created by melting plastic (polyester or polyvynil chloride) together with mica flakes coated with thin films of titanium dioxide?

 

[kuruman]

One of the teachers at my university thought that diffraction gratings and dichroic mirrors are expensive and that me and him could never afford one.

When I was in charge of introductory physics lab at my University we had two experiments in "modern physics" in which students used gratings. The first week they used the spectrum of hydrogen to determine the Rydberg constant. The second week they used the measured wavelengths from the previous week in a photoelectric experiment to determine $h/e.$ They got decent results.

The gratings they used were mounted on cardboard slides (I don't remember the spacing). Through Amazon.com you can get these for $2.99 ea., these for $9.90 ea. and these for $43.30 ea.

Edmund Scientific has pricier gratings in the $100-200 range that might not be prohibitively expensive for your teacher and you. The adage "you get what you pay for" is almost always the case but, of course, what you should get is what you need to do the job adequately.

 

[James2018]

When I was in charge of introductory physics lab at my University we had two experiments in "modern physics" in which students used gratings. The first week they used the spectrum of hydrogen to determine the Rydberg constant. The second week they used the measured wavelengths from the previous week in a photoelectric experiment to determine $h/e.$ They got decent results.

The gratings they used were mounted on cardboard slides (I don't remember the spacing). Through Amazon.com you can get these for $2.99 ea., these for $9.90 ea. and these for $43.30 ea.

Edmund Scientific has pricier gratings in the $100-200 range that might not be prohibitively expensive for your teacher and you. The adage "you get what you pay for" is almost always the case but, of course, what you should get is what you need to do the job adequately.

I observed that dichroic mirrors and their plastic pearlescent tape imitations become like a metallic silver mirror in appearance when irradiated only with the wavelength they reflect. When irradiated with the wavelength they transmit they appear completely transparent like window glass, or at least translucent. So do crystals like moonstone or labradorite which also use thin-film interference in multiple layers. Although labradorite is gray so it does not become transparent under transmitted light.
For example, this is a iridescent Christmas tree star decoration which reflects yellow and transmits blue:

 

[James2018]

Is this the element behind the pearlescent plastic effect?

https://nihonkoken.co.jp/en/pearl

 

[AlexisBlackwell]

Holographic paper from decor stores is usually a simple imitation of the holographic effect and does not have true holographic properties like professional diffraction gratings. Mother-of-pearl decorative tape changes color at different angles due to the interference of light on the surface, while dichroic mirrors have a special coating that transmits or reflects certain colors of light. Although both phenomena are based on the interference of light, they use different principles of physics and have different properties.

 

[James2018]

"The holographic effects are created by metalizing the surface with a thin layer of shiny silver aluminum. The holographic patterns are embossed into the aluminum surface, which forms millions of pixels in microscopic grooves and valleys. This embossed surface diffracts the light into many colors and reflects the light."

Source:
https://www.novavisioninc.com/pages/learn_more_holographic_paper.html

Interference Pearls are made by mica coated with titanium dioxide. When you look at them straight on they appear more whitish. When viewed at an angles you see glorious irridescent colors. The presence of the difference colors is due to the thickness of the titanium dioxide coating. By varying the coatings you get all the wonderful colors of the rainbow.

Important things to know when working with interference pigments. (other tradenames may be "hilites" or,"intervals")

They are very translucent.

The particular color effect is angle dependent.

The Strongest color effect is with a thin application over a dark valued color, such as black.


Source:

https://justpigments.com/collections/interference-mica-powder

 

[James2018]

Holographic paper from decor stores is usually a simple imitation of the holographic effect and does not have true holographic properties like professional diffraction gratings. Mother-of-pearl decorative tape changes color at different angles due to the interference of light on the surface, while dichroic mirrors have a special coating that transmits or reflects certain colors of light. Although both phenomena are based on the interference of light, they use different principles of physics and have different properties.

OK some pearlescent tapes I am using have a thin layer on the surface like soap bubbles that varies in thickness

but other ones I am using have many layers of interference pigment (mica powder coated with titanium dioxide) inside the plastic matrix so they block yellow light or green light and transmit their complementary colors.

Can you see the difference?

 

[James2018]

Grating based holographic images and patterns are widely used in
packaging to catch the eye of the consumer. The characteristic
rainbow-like reflection of light from holographic papers can be
used either by itself or with a print to create interesting
contrasts and optical effects. Holographic patterns are also used
for purposes of authentication to protect products and documents
from counterfeiting.

A grating based holographic paper consists of separate areas of
reflective diffraction gratings, which disperse polychromatic
light into its constituent monochromatic components depending on both illumination and observation angles, and the physical
structure of the grating. Due to the angle-dependent nature of the
holographic patterns, conventional measurement methods for paper products cannot be used"

Source:
"Method for the Characterisation of Grating Based0Holographic Paper", Max Karlsson, Uppsala Universitet

 

[James2018]

My final guess is that the Chinese manufacturers include these pigments to achieve either 2D holographic or pearlescent effect. I am not sure but they could be mixed with molten plastic with a rotating drum so that they disperse evenly in the molten plastic,which is then extruded into foils or shaped using molds. This is just a guess I am not sure. What do you think?

 

[James2018]

Holographic paper under the microscope -> YouTube Microscope - Holographic Paper. Seems to have some parallel lines, maybe these diffract light?
\

 

[James2018]

OK, the tapes are iridescent and based on thin film interference. The pearlescent plastic with mica flakes has a more sparkly diffuse reflection like nacre.

 

[James2018]

 

[James2018]

Explain

The colour changing film is made of many different layers, laminated together to form a sheer film that changes colour as you move around it. As light reflects at different angles the colours glide through rainbows of colour.

http://m.hologramsmanufacturers.com/iridescent-laser-hula-hoop-tape-2069589.html

https://fancy-tapes.co.uk/products/magic-colour-changing-film

Many different layers?

 

[James2018]

Here is what gives iridescent sequins their iridescence. I melted it, seems to be a thin film of transparent plastic.

Before melting, sequins are iridescent

After melting, the sequin loses its iridescence and looks like a ball of translucent plastic:

There is no mica flakes in it coated with titanium dioxide, else it would still be iridescent because these flakes are inorganic and do not melt.

How do you explain this?

 

[James2018]

"

• Made with PET material, the colour film is made by the superposition of hundreds of layers of polyester film by co-extrusion technology.

"

https://resinsupplies.co.za/product/holographic-iridescent-self-adhesive-sheets-2-pack/

https://plasticfilmchina.en.made-in...idescent-Film-for-Printing-and-Packaging.html

What does it mean co-extrusion? And how can they superpose hundreds of layers of the same material - PET to achieve iridescence? I thought two materials with different refractive indices were needed.

 

[James2018]

"
Controlling light waves as they pass through or bounce off of hundreds or thousands of layer interfaces is defined by the refractive index of the adjacent polymers. The larger the difference in refractive indices of adjacent polymer layers, the brighter the reflection off their interface. The reflection is also brighter with more layers in the stack.

Decorative films alternate layers of two polymers, typically a polyester like PET with a refractive index of 1.8 and an acrylic like PMMA with a refractive index of 1.5. The reflected-color effect varies as the viewing angle onto the film changes.

Birefringence is caused by the difference in refractive index between polymers at different viewing angles. Birefringent polymer pairs in microlayer films typically leak light when they are tilted and reflect only within a specific range of viewing angles. From all other angles, the interface appears transparent.



3M discovered that different layer thicknesses in a stack could create highly sophisticated patterns of reflections, capable of passing some waves of light through while stopping other wavelengths, and creating structures that reflect equally well from any viewing angle."
https://www.ptonline.com/articles/microlayer-films-new-uses-for-hundreds-of-layers

 

[James2018]

Opalescent and iridescent glitters exhibit effects where colour can only be seen when viewed from a particular angle. This effect is know as a colour travel effect, where the colour observed changes depending upon which angle the glitter is viewed. Opalescent and Iridescent glitters utilise the manipulation of light through refraction and reflection to achieve this effect.

In an iridescent glitter, light is refracted and essentially spun back on itself back. Iridescent glitters are created by micro layering more than one hundred alternate layers of two different type of plastics with complementary refractive indexes. The microlayer film is created by using hi-tech plastic extrusion techniques of the two colourless synthetic plastic polymers. Iridescent glitters are transparent, unlike metallic and holographic which have a reflective aluminium layer and are opaque. Refractive index is the value given relating to a materials’ ability to bend light when light enters it. Refection is the effect seen when light is bent moving from one medium into another, for example from air into water.

These types of plastic glitter do not contain any pigment or aluminium layer and are completely transparent. The intensity of the iridescent effect is increased by using these types of glitters against a dark or black background.

The Structure of Plastic Iridescent Effect Glitter

Source:
https://www.bioglitter.com/glitter-colour-effects-how-are-they-created/

 

[James2018]

Holographic effect glitters exhibit a spectacular rainbow effect, created by splitting light into its individual component parts. Each glitter particle acts as little prism splitting light. The structure of a holographic glitter is similar to a metallic glitter in that it has a very thin aluminium layer to reflect, with the addition of a microscopic structural pattern to diffract the light.

In non-diffuse direct light, for example, direct sunshine or LED lights, these products really excel, producing an eye-catching kaleidoscope of dazzling colour.

As holographic glitters contain an aluminium layer, like metallic glitters 2500 times thinner than a human hair, they are opaque, diffusing and reflecting the light that hits them.

Source:

https://www.bioglitter.com/glitter-colour-effects-how-are-they-created/

 

[James2018]

Iridescent glitter exudes a soft, pearlescent shine, adding a touch of magic to any project. It's revered for its subtle, shimmering quality that emanates a soft, captivating glow. On crafts, it grants a gentle sheen that changes color as light hits it from different angles. This captivating effect is achieved by layering multiple transparent colors over a reflective base.

The process of making iridescent glitter involves depositing thin layers of metallic oxides onto a substrate, often a polyester film. These layers interact with light, causing interference and diffraction that results in the shifting colors. This type of glitter is made using precision coating techniques to ensure consistent layer thickness and optimal color play. The final iridescent glitter product consists of a polyester film coated with metal oxides, typically titanium dioxide or similar materials.

The creation of holographic glitter involves impressing microscopically fine patterns onto a reflective film. These patterns diffract light, splitting it into a spectrum of colors that shift as the viewer's perspective changes. Quality holographic glitter requires precision imprinting techniques to ensure intricate and consistent patterns.

Source: https://www.boujipanda.com/blogs/cr...m-iridescent-holographic-and-metallic-glitter

 

[James2018]

https://epdwindowfilm.com/why-dichroic-glass-is-so-expensive-and-the-best-alternative/

Seems they made a cheap replacement for the expensive glass dichroic mirror.

 

[James2018]

What do you think of my dichroic mirror and diffraction grating?

Diffraction grating 600 lines / mm, PET, 5.90$; dichroic mirror reflects cyan (~490 nm) and transmits red (~644 nm), 4.76 $, K9 glass.

I think the transmitted color is best seen on a white background and the reflected color on a brown background for the dichroic mirror. The dichroic mirror did not have wavelength specifications but I used RGB to wavelength conversion online.

 

[Gleb1964]

Suitable for applications with low requirements, certain types of illumination optics, and demonstrations.

Not suitable for a serious device, as the wavefront will experience many wave aberrations and irregularities. Astigmatism will be one of the main issues.

 

[James2018]

Suitable for applications with low requirements, certain types of illumination optics, and demonstrations.

Not suitable for a serious device, as the wavefront will experience many wave aberrations and irregularities. Astigmatism will be one of the main issues.

This is how the combined pattern looks like for that dichroic filter and diffraction grating looks like in front of a white LED source:

 

[sophiecentaur]

What does it mean co-extrusion? And how can they superpose hundreds of layers of the same material - PET to achieve iridescence? I thought two materials with different refractive indices were needed.

Two lumps of slightly different plastic then: Fold and stretch, fold and stretch - just like flaky pastry and Damascus Steel swords.I guess.

 

[James2018]

Suitable for applications with low requirements, certain types of illumination optics, and demonstrations.

Not suitable for a serious device, as the wavefront will experience many wave aberrations and irregularities. Astigmatism will be one of the main issues.

Perhaps, but my 5$ plastic diffraction grating is labeled as "Professional". You can see this in the photo below on the package label:

 

[James2018]

Ok it's 6.5 dollars not 5 dollars. Perhaps it's because it's available in a stock of 10,000 pcs every month and it's made of a cheap material - PET plastic?