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Projector
 Machine translation starting from :    
Contrary
to the anti-reflecting treatments by thin deposits of layers, the effectiveness of this
new anti-reflecting device is not deteriorated by impurities coming to be posed on the
protection of Holopanoragramme.
In this position apart from the large field of vision, this absorbing screen offers
moreover the utility to shelter by the top this holographic opening, as it can be made in
architecture above the external doors, or more recently above the banknote distributers.
It is it should be noted that with a slope of
the plane surface of a hologram with angle of vision reduced around the real image, the
horizontal black screen of this anti-reflecting device does not allow, because of its size
reduced and adapted to Holopanoragramme, this extinction of the reflections of the ambient
light for side positions and horizontal directions of observation of observers of various
sizes.
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Diagram of the device
running for the restitution of a hologram per reflection (H), plane and vertical, whose
ambient light (L) comes to obstruct the observation of the real image (M) by an observer
(D), especially on the dark parts of the image and in spite of the good output of
diffraction of the hologram (H) and the strong intensity of the point source of
restitution (S).
Anti-reflecting treatments on each polished and reflective surface of the support and its
protection by thin deposits of layers would remain ineffective for side directions of
observation moving away from the normal on the treated surfaces, with another disadvantage
that of being expensive. |
Moreover, these deposits of anti-reflecting
thin layers would require of the use too much maintenance whose the extinction would
depend on the parasitic reflections.
Indeed as on glasses of glasses or certain flat-faced screens, the least finger marks on
these thin layers cancel the extinction of the parasitic reflections of the ambient light.
Whatever the holographic
technique used, the artificial light of restitution will have to always pass only by one
specific opening of a lamp correctly positioned compared to the holographic support and in
a point of the space located in the same initial direction of the specific laser used at
the recording, this for the good restitution of a deep holographic image, which remains in
all the impossible cases using a broad source like a neon tube creating of the parasitic
images. |
Apparatus
of Mr. Lippmann to see
photographic negatives colors
(La Nature 1894)
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Indeed not to make fuzzy the image, all the
light of the volume of holographic space must pass as a preliminary through an opening of
a small diameter.
Compared to a hologram with reduced angle of vision diffracting the luminous rays in only
one direction, a hologram with great angle of vision without dead angles of course
requires more light intensity with the passage of this small opening.
And contrary to a poster, the luminosity of any holographic image decreases with the
increase in the intensity of the ambient light.
This is why, at the time of a presentation in full light of a hologram after an exposure
in an obscure room, the light intensity of its source of restitution must be
proportionally increased.
However, the diameter of this source of ordinary light increases with its intensity, which
results in to decrease the clearness of the in-depth image.
Therefore in holography of the precautions are to be taken to diffuse in full light of
clear information in all the directions as a poster with the minimum of light intensity.
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