Veiling glare control holographic windshield

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG.
2 illustrates a veiling glare control holographic windshield 50 in accordance with this invention.
The windshield 50 comprises inner and outer singlets 52 and 54 in the conventional manner.
Typically at least one singlet is fabricated of a tinted glass or other windshield material.
The windshield 50 has incorporated therein between the singlets 52 and 54 a zero-degree mirror reflection hologram 56 whose bandwidth is as broad as 100 nm or more, and whose high reflectance zone is in the visible at normal incidence.
A zero-degree mirror reflection hologram is a mirror reflection hologram with fringes parallel to the hologram surface.
This hologram is preferably made of photopolymer film.
The HRF600 and the HRF700 films produced by E.
I.
duPont de Nemoirs Company, or the DMP182 film produced by Polaroid Corporation are suitable for the purpose of fabricating the zero-degree mirror reflection hologram.
The hologram 56 is embedded within the windshield between the singlets 52 and 54.
Since this hologram layer does not need to perform any imaging function it will typically not be necessary to protect it with any polyvinyl alcohol (PVA) barrier layer to prevent "orangepeel" corrugation or peak wavelength positive shift from occurring due to contact with the polyvinyl butyral (PVB) layer conventionally disposed between the singlets.
However, such a barrier layer can be included in the windshield.
The solar control hologram 56 exhibits a reflectance versus wavelength spectrum that is characterized by a high reflectance over a well-defined wavelength band.
This reflectance is a maximum at the "reflection peak" or "efficiency peak.
" The reflectance is defined as the reflected energy divided by the total energy.
The wavelength at which the reflection peak occurs is called the "peak wavelength" or "hologram center wavelength.
" The peak wavelength varies with incident angle; as the incident angle moves away from normal, the peak wavelength drops.
FIG