1. Colour Holography Hans I
Colour Holography Hans I. Bjelkhagen Professor of Interferential Imaging Sciences
Centre for Modern Optics
Colour Holography Jan 2004

2. Colour Holography by Bjelkhagen
Recording materials: silver halide or photopolymer
Laser wavelengths: three RGB
Setup: Denisyuk hologram
Processing: development and bleaching
Reconstruction: illuminating light source
Colour Holography Jan 2004

3. Holographic Recording Materials
Panchromatic materials required
Low light-scattering emulsions needed to record blue light
Relatively high sensitivity to record large holograms
Possible materials:
Silver-halide (SH) emulsions (grain size < 10 nm)
DCG emulsions (sensitized to red laser light)
Photopolymer materials (panchromatic)
Colour Holography Jan 2004

4. Recording Material Resolving Power Requirement
The recording material must be able to resolve the highest spatial frequencies of the interference pattern created by the maximal angle θ between the reference and the object beams in the recording setup. If λ is the wavelength of the laser light used for the recording of a hologram, n the refractive index of the emulsion then the closest separation de between the fringes in the interference pattern in the emulsion is λ
de =
2nsin(θ/2)
For a colour reflection hologram recorded in blue light (λ = 400 nm) with an 180-degree angle between the beams, a minimum resolving power of 7600 lines/mm is needed.
Colour Holography Jan 2004

5. Slavich Panchromatic SH Emulsions
The recording of high-quality large-format reflection colour holograms in a single-layer ultrahigh-resolution silver-halide emulsion was performed by Bjelkhagen and Vukičević in 1995
A specially prepared Slavich panchromatic SH emulsion was supplied for tests at Université Louis Pasteur in Strasbourg, France
Three laser wavelengths were used: 633 nm, 532 nm and 488 nm for the first tests
H. I. Bjelkhagen, D. Vukievi, in Fifth Int'l Symposium on Display Holography, ed. by T. H. Jeong. Proc. SPIE 2333, (1995)
Colour Holography Jan 2004

6. First Successful Holograms 1994 Recorded in a Single-Layer SH Emulsion
Colour Holography Jan 2004

7. Slavich PFG-03c Panchromatic Emulsion
Emulsion thickness 7 μm
Grain size nm
Resolution 10000 lp/mm
Blue sensitivity  mJ/cm2
Green sensitivity  mJ/cm2
Red sensitivity  mJ/cm2
Colour sensitivity peaked at 633 nm, and 530 nm
Colour Holography Jan 2004

8. Laser Wavelength Selection Using the CIE 1976 Chromaticity Diagram
Colour Holography Jan 2004

9. Colour Hologram Definition
Hubel and Solymar gave a quantitative and exact definition of what is regarded as a colour hologram: "A holographic technique is said to reproduce 'true' colors if the average vector length of a standard set of colored surfaces is less than chromaticity coordinate units, and the gamut area obtained by these surfaces is within 40% of the reference gamut. Average vector length and gamut area should both be computed using a suitable white light standard reference illuminant."
P.M. Hubel, L. Solymar, Color reflection holography: theory and experiment, Appl. Opt. 30: 4190 (1991)
Colour Holography Jan 2004

10. Denisyuk Hologram Recording Principle
Colour Holography Jan 2004

11. Wavelengths from CW Lasers
Wavelength Laser Single line
[nm] type power [mW]
442 Helium cadmium < 100
457 DPSS Blue < 500
458 Argon ion < 500
468 Krypton ion < 250
476 Krypton ion < 500
477 Argon ion < 500
488 Argon ion < 2000
497 Argon ion < 500
502 Argon ion < 400
514 Argon ion < 5000
521 Krypton ion < 100
529 Argon ion < 600
531 Krypton ion < 250
532 Nd:YAG (frequency doubled) < 400
543 Green neon < 10
568 Krypton ion < 100
633 Helium neon < 80
647 Krypton ion < 2000
Colour Holography Jan 2004

12. Elephant Test Target with the 1931 CIE Chromaticity Diagram
Colour Holography Jan 2004

13. Recording of the Elephant CIE Test Target
The target is positioned upside- down in the recording setup (to easily get an overhead reference beam for the illumination of the recorded hologram)
The target is illuminated with the “white” laser light from the three lasers
Then, the red, green and blue beams are individually measured and adjusted to obtain good white balance in the colour hologram
Colour Holography Jan 2004

14. Three-Laser Colour Holography Setup
Colour Holography Jan 2004

15. Measurement of RGB Power Densities at the Position of the Recording Plate
Colour Holography Jan 2004

16. Colour Holography Processing Steps.
1. Tanning in a Formaldehyde solution 6 min
2. Short rinse sec
3. Develop in the CWC2 developer min
4. Wash min
5. Bleach in the PBU-amidol bleach 5 min
6. Wash min
7. Soak in acetic acid bath min
8. Short rinse min
9. Wash in distilled water with wetting agent added 1 min
Colour Holography Jan 2004

17. Prehardening Bath Distilled water 750 ml
Formaldehyde 37% (Formalin) ml (10.2g)
Potassium bromide g
Sodium carbonate (anhydrous) g
Add distilled water to make l
The prehardening time in this solution is 6 minutes.
The Slavich emulsion is rather soft, and it is important to harden the emulsion before the development and bleaching takes place.
Colour Holography Jan 2004

18. CWC2 Developer Distilled water 750 ml Catechol 10 g Ascorbic acid 5 g
Sodium sulfite (anhydrous) g
Urea g
Sodium carbonate (anhydrous) g
Add distilled water to make l
The developing time is 3 minutes at 20oC.
Colour Holography Jan 2004

19. PBU-(amidol) Bleach Distilled water 750 ml Cupric bromide 1 g
Potassium persulphate g
Citric acid g
Potassium bromide g
Add distilled water to make l
After the above mentioned chemicals have been mixed, add 1 g amidol [(NH2)2C6H3OH.2HCl, 2,4-diaminophenol dihydrocloride].
Bleaching time is about 5 minutes.
Colour Holography Jan 2004

20. Spotlight for Illuminating Colour Holograms
The selection of a suitable lamp for the reconstruction (illuminating) of colour holograms is much more important than the selection of lamps for monochrome hologram display. The colour balance for the recording of a colour hologram must be adjusted with the type of spotlight that is going to be used for the display of the finished hologram in mind. The colour reproduction in a reflection hologram is only correct when the light is illuminating the hologram or film at a specific angle. A suitable spotlight to illuminate colour holograms is a 12-Volt 50-Watt narrow-beam halogen lamp.
Colour Holography Jan 2004

21. Spectrum of Philips 6438 GBJ Halogen Light
Colour Holography Jan 2004

22. Measurement of Holographic Colour Rendering with PR-650 Photo Research SpectraScan Equipment
Colour Holography Jan 2004

23. Measurement of White Area of the Hologram
Colour Holography Jan 2004

24. MacBeth ColorChecker® White light RGB laser light Colour hologram
Colour Holography Jan 2004

25. Measurement of MacBeth Target
Colour Holography Jan 2004

26. Holographic MacBeth Colour Rendering
Colour Holography Jan 2004

27. Fish Broach Hologram Laser-illuminated object Hologram
Colour Holography Jan 2004

28. Displaying Colour Holograms
It is important to remember that the holographic plate or the film is only one part of the holographic display system. The other part is the light source which is actually generating the image in the hologram. In a reflection hologram the image consists of almost an infinite amount of reflected images of the light source itself. Therefore, the apparent source size has an influence on the resolution of the displayed image. The hologram plate or film itself, without correct illumination, is of no interest on its own. The correct illumination of the final colour hologram is extremely critical as well as competing ambient light, etc.
Colour Holography Jan 2004

29. The Display of Reflection Holograms One point source
The Display of Reflection Holograms One point source Wide area spotlight Multiple spotlights
Colour Holography Jan 2004

30. Displaying Colour Holograms
The next thing is how the light source is going to be arranged in relation to the hologram. It seems that fixed installations are the only possible ones, e.g., wall mounted holograms with overhead track lighting or holograms in special display devices with integrated illumination. Sometimes extended arms from the hologram frame have been used to hold the lamp at the right position and distance. However, such arrangements are normally not aesthetically acceptable and, when displaying large-format holograms, the arm has to be ridiculously long.
Colour Holography Jan 2004

31. HOLOSHOW Display Case
Colour Holography Jan 2004

32. HOLOSHOW Features
Providing correct illumination for the hologram with a folded reference beam illumination
Containing two lamps positioned next to each other; if one fails the other one is automatically switched on
The top of the display device acts as a shield for ambient light
The hologram is exhibited at a 45-degree position. The advantage is that independent of whether the viewer is short or tall, the best viewing position is found by walking toward or away from the display device, not to have to move up and down which is the case for wall-mounted holograms
The outside walls of the display unit can have conventional advertising material attached associated with the hologram on display, such as photos, text with product information, etc.
Colour Holography Jan 2004

33. 3-D Art Reproductions
Here we can mention 3-D reproductions of beautiful artifacts, for example Farbegé Eggs. There are many other examples of how museums and exhibitions could benefit from employing colour holograms. Exhibitions could be promoted by using holograms of one of the most impressive pieces in a collection to be shown in hotel lobbies, tube stations, airports, etc. Another important application here is in the field of art education. Art schools around the world could give students the opportunity to see a collection of the most famous art objects in the world, all easily accessible for them within the institute. Also exhibitions of art pieces, all in the form of colour holograms, could be on display in a museum. This means that an artist’s entire work of art which may be located in different museums around the world could be on display in one single museum, or simultaneously in many museums.
Colour Holography Jan 2004

34. Display of Artifacts in Museums
Colour holography is a suitable 3-D imaging technique for the display of unique and valuable artifacts in museums and public exhibitions
In most cases in museums , the objects are placed behind glass to protect them. Colour holography can provide a perfect replica of an object, not possible to distinguish from the real object
Colour Holography Jan 2004

35. Chinese Vase 12” by 16” Hologram Hologram Setup
Colour Holography Jan 2004

36. Cunieform Colour Holograms
Colour Holography Jan 2004

37. Colour Holograms
Colour Holography Jan 2004

38. More Examples of Colour Holograms
Colour Holography Jan 2004

39. Large Russian Egg Hologram Hologram Recording setup
Colour Holography Jan 2004

40. 2-D Art Reproduction
It may sound strange, but actually, colour holography may become an important reproduction technique for 2-D objects as well, such as, e.g. oil paintings. Holographic reproductions provide extremely realistic-looking images, showing the texture details such as brush strokes and the painter's signature. In addition, they will not fade or change colour even if they are continuously on display. This fact is of importance from an archival point of view as well. Insurance companies may require holographic reproductions of very expensive works of art in case they are stolen or damaged. If perfect colour rendering can be obtained in colour holography, 2-D art reproduction may become important.
Colour Holography Jan 2004

41. Reproduction of An Oil Painting using. Colour Holography. Original
Reproduction of An Oil Painting using Colour Holography Original Hologram
Colour Holography Jan 2004

42. Enlarged Areas of the Painting. Upper: Original. Detail from Hologram
Enlarged Areas of the Painting Upper: Original Detail from Hologram Lower: Hologram
Colour Holography Jan 2004

43. Colour Hologram of Parrot
Education. Rare birds and other endangered species can be holographically recorded and then copied in large quantities for schools and universities.
30 cm by 40 cm colour hologram
Colour Holography Jan 2004

44. Advertising and POP Displays
In particular colour holograms are suitable for the expensive antique and jewellery market. It will make it safer and less expensive to exhibit the items in various places even in places that would be out of question for displaying the real product. Unique items of which only one of its kind exists can be exhibited simultaneously in many places. New places to advertise expensive items could be in airplanes, trains and buses, all equipped with special hologram display devices.
Colour Holography Jan 2004

45. Colour Hologram of Expensive Watches
Colour Holography Jan 2004

46. Promotional Colour Holograms
Colour Holography Jan 2004

47. Chrysler VIPER Colour Hologram
Colour Holography Jan 2004

48. Coca Cola 12” by 16” Colour Hologram
Colour Holography Jan 2004

49. Holograms of Food, Chocolate, etc.
Even less expensive products may be of interest to display as colour holograms. Here one can mention products that quickly deteriorate or otherwise become affected by long term display, such as food, chocolate, flowers, etc.
Colour Holography Jan 2004

50. The Future of Colour Holography
The virtual colour image behind the holographic plate represents the most realistic-looking image of an object that can be obtained today. The extensive field of view adds to the illusion of beholding a real object rather than an image of it. The wavefront reconstruction process recreates accurately the light scattered off the object during the recording of the colour hologram. Such a remarkable 3-D image has many obvious applications as explained in this presentation.
Colour Holography Jan 2004

51. The Future of Colour Holography
Today, it is technologically possible to record and replay acoustic waves with very high fidelity. Hopefully, holographic techniques will be able to offer the same possibility in the field of optical waves, wavefront storage, and reconstruction. Directly recorded and computer-generated holographic images would make it possible to display extremely realistic full-parallax 3D colour images.
This century may also see the possibility to generate true-holographic 3D color images in real time, provided that computers become faster and possess greater storage capacity. However, the most important issue is the development of very high-resolution electronic display devices that are needed for electronic holographic real-time imaging.
Colour Holography Jan 2004

52. Professor Hans I. Bjelkhagen
Contact Details
Professor Hans I. Bjelkhagen
Colour Holography Jan 2004