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The Distinction of Holography and Ordinary Photography
The hologram unlike ordinary camera photography. Ordinary camera when the light emitted by objects or surface emitting and light refracted through the imaging lens , the light intensity recorded on the photosensitive film , showing a plane image of the object in the photographic paper . The hologram is a lensless imaging method , he used - amplitude and phase of all the information of the subject , so called hologram recorded in the hologram dry plate of the light interference principle . Holographic reproduction , see the objects are three-dimensional and vivid image .
Currently, hologram interferometry , information storage , optical information processing , non-destructive testing , stereoscopic display , the field of biology, medicine , and defense-related research has been quite widely used .
Ddistinction of holography and ordinary photography
To shoot a satisfactory hologram photo shoot system must meet the following requirements :
(1) The light source must be a coherent light source
Holography is based on the principle of interference of light, so they requested that the light source must have good coherence know by the previous analysis. The emergence of the laser light for the hologram of an ideal light source. This is good because the laser coherence, He-Ne laser used in the experiment, with its shooting small diffuse object, get a good spatial coherence and time of the hologram.
(2) the hologram system must have stability
Since the hologram recorded on the interference fringe, and is a thin, dense, interference fringes, minimal interference will cause the blurring of interference fringes in the photographic process, and even the interference fringes can not be recorded. Example, shooting film displacement of a micron, the stripes on a confusion, the hologram experiment station is shockproof. Table hologram optics magnetic firmly sucked on countertops steel. Further, the airflow through the optical path, the acoustic interference, and temperature changes will cause changes in the density of the surrounding air. Therefore, the exposure should prohibit loud noises, can not move around freely, the entire lab absolute quiet. Our experience is that each group a good tune the optical path, the students left the bench, stable after a minute, and then exposed at the same time, to get a better effect.
(3) the object beam and the reference beam should meet
Object light and reference light, an optical path difference should be as small as possible, preferably equal to the optical path of the two beams of light, up to not more than 2cm, adjusting the optical path with twine amount; the angle between the two light beams at 30 ° ~ 60 °, preferably at about 45 °, because the angle is small, interference fringes on the thin, so that the lower the resolution requirements of the system stability and the photosensitive material; two light beams of the light intensity ratio should be appropriate, generally requires can be between 1:1 to 1:10, the light intensity ratio measured with a silicon photovoltaic cell out.
(4) Use of a high-resolution hologram
Because recorded on the hologram backsheet is a thin, dense interference fringes, so the photosensitive material requires high-resolution. Ordinary photographic photosensitive film due to coarse particles of silver compounds can record only 50 ~ 100 stripes per millimeter, Tianjin photographic film plant the production of I-type hologram dry plate, with a resolution of up to 3 per mm? 000, can meet hologram request.
(5) the hologram photo washing process
The washing process is also critical. We follow the recipe requires dispensing with the developer, stop bath and fixer and bleach solution. The above several prescriptions are required to use distilled water, but the experiment proved successful with pure water preparation. The flushing process in the darkroom, the drug solution do not see the light, and kept at room temperature 20 ° C in the right rinse formulated liquid custody properly about a month.
Holographic characteristics and advantages:
1. A three-dimensional image of recycling out favor the preservation of precious art data collection .
2. shooting each point are recorded in any point of the hologram sheet , once photo damage little relationship .
3.Holographic photo scene three-dimensional sense of strong, vivid image , with the laser can be displayed in a variety of exhibitions , will get very good results . 
The use of hologram technology
In our lives , of course, are often able to see the use of hologram technology . For example , on some credit cards and banknotes , there is the use of the "rainbow" hologram on the full-color hologram technology invented in the 1960s , the Russian physicist Yuri Danny Suker the soft polyester film production . But these hologram image more just as a complex printing technology to achieve security purposes , their low sensitivity , color is also not enough realistic , far less than spurious realm . The researchers also tried to use the dichromate glue as photographic emulsion , used to make hologram identification equipment . In some fighter equipped with such equipment , they can make the driver's attention focused on the enemy .
Filmed some precious relics of this technology , when it was exhibited true stereo reproduction artifacts for visitors to enjoy , while the original is properly preserved , anti- theft the the large hologram can show cars, satellites and a variety of three-dimensional advertising , we can use pulse holography reproduction portraits , wedding photos . The small hologram can be worn on the neck, forming a beautiful decorative it reproducible favorite animal , colorful flowers and butterflies . Rapid development of molded rainbow hologram , can become vivid cartoons , greeting cards , three-dimensional stamp , also can be used as anti-counterfeit labels appear in the trademark documents cards, bank credit cards , and even banknotes . Decorative hologram three-dimensional photos in the book , as well as gift wrap shining hologram rainbow , make people appreciate the printing technology of the 21st century with new packaging technology leap .
In our lives , of course, are often able to see the use of hologram technology . For example , on some credit cards and banknotes , there is the use of the "rainbow" hologram on the full-color hologram technology invented in the 1960s , the Russian physicist Yuri Danny Suker the soft polyester film production . But these hologram image more just as a complex printing technology to achieve security purposes , their low sensitivity , color is also not enough realistic , far less than spurious realm . The researchers also tried to use the dichromate glue as photographic emulsion , used to make hologram identification equipment . In some fighter equipped with such equipment , they can make the driver's attention focused on the enemy .
Filmed some precious relics of this technology , when it was exhibited true stereo reproduction artifacts for visitors to enjoy , while the original is properly preserved , anti- theft the the large hologram can show cars, satellites and a variety of three-dimensional advertising , we can use pulse holography reproduction portraits , wedding photos . The small hologram can be worn on the neck, forming a beautiful decorative it reproducible favorite animal , colorful flowers and butterflies . Rapid development of molded rainbow hologram , can become vivid cartoons , greeting cards , three-dimensional stamp , also can be used as anti-counterfeit labels appear in the trademark documents cards, bank credit cards , and even banknotes . Decorative hologram three-dimensional photos in the book , as well as gift wrap shining hologram rainbow , make people appreciate the printing technology of the 21st century with new packaging technology leap . ...
Ultrasonic holography reproduction lurking in the three-dimensional pattern of underwater objects , and therefore can be used to conduct underwater surveillance and reconnaissance . Visible opaque objects , often transparent to ultrasonic , ultrasonic holography can be used for underwater military operations , and can also be used for medical perspective as well as the industrial NDT measurements .
In addition to the lightwave generated hologram has been developed to the available computer generated hologram . The hologram is very versatile and can be made ??of a variety of thin-film optical components such as lenses, gratings , filters , can overlap in space , is very compact , lightweight , suitable for space flight use . Use hologram storage of data , with a large capacity , easy to extract , anti-fouling , etc. .
The hologram methods from the field of optics extended to other areas . Microwave holography, acoustic holography been greatly developed and successfully applied in industrial and medical aspects . Seismic wave, the electron wave , X-ray , and other aspects of the hologram is also in-depth study . The hologram has an extremely wide range of applications . As used in the study of the shock wave of rocket flight , non-destructive inspection of the aircraft wing cellular structure . Now not only laser holography , and research the successful white hologram rainbow hologram , and panoramic rainbow hologram , so that people can see each side of the scene . Holographic three-dimensional display is the direction of the development of hologram color stereoscopic television and movies .
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