Optical: systems and elements – Polarization without modulation – Polarization by scattering
Reexamination Certificate
1999-10-20
2001-08-14
Spyrou, Cassandra (Department: 2872)
Optical: systems and elements
Polarization without modulation
Polarization by scattering
C359S483010, C359S506000, C356S021000, C033S231000, C033S277000, C033S277000
Reexamination Certificate
active
06275337
ABSTRACT:
FIELD OF INVENTION
The present invention relates generally to methods and devices that minimize the effects of reflections from a transparent surface and more particularly to methods and devices that minimize the effects of reflections from a transparent surface while viewing an object or target through such reflective surface by a weapon sight without affecting the projected point of impact of the projectile from the weapon using the sight.
BACKGROUND OF THE INVENTION
The reflections
2
(
FIG. 1
) of the sun
2
, sky or other bright source from a surface
4
of a transparent member, such as a window of a building or motor vehicle (e.g., automotive windshield) have long been a problem in a number of cases because they tend to obscure the target or object one is attempting to view through the reflective surface. For example, when a police officer, federal law enforcement official or other authorized person (e.g., soldier) is trying to view a target area that is behind the transparent member, the view is obscured by the reflections
6
. This obstruction of the view occurs because such reflections
6
of the sun
2
or the sky can be much brighter than the image of the target area that lies behind the transparent member surface
4
.
This obstruction of the view is particularly dangerous in hostage type of situations because the reflections
6
can obscure the police officer's, federal official's or military personnel's view of the target area. This problem can be especially dangerous during situations such as hostage crisis area, because it can prevent the police officer, federal official or soldier from determining who is a hostage and who is the hostage taker.
The reflections
6
of the sun
2
from the surface
4
are mainly in the form of linearly polarized rays
8
. Accordingly, one method for reducing or eliminating the effect of such linearly polarized reflections or rays
8
from the transparent surface
4
involves placing a polarizing filter in front of the optical device or optical lens assembly being used to view the target area. The polarizing filter suppresses the reflections and provides a clearer view to the subject beyond the surface causing the reflections. For example, fishermen use polarized sunglasses to suppress the reflections from the water's surface so they can better see their prey. In another example, photographers use a polarizing filter mounted on the front of the camera lenses to suppress reflections from building windows.
When this particular technique is applied to a sight for a weapon such as a rifle of a police officer or federal official, which is the common practice, other problems can arise. For example, when a polarizing filter is mounted in front of an optical system of the weapon sight, the polarizing filter can act like an optical wedge, thus refracting the light rays entering the optical system of the weapon sight thereby causing the image to be shifted slightly. Because this image shifting occurs before the image gets to the reticle or reticule provided within the optical system of the weapon sight, this shifting changes the point of impact for a projectile fired from the weapon as projected by the weapon sight. This can result, consequently, in the shooter not hitting the intended target at all or where intended or possibly striking another when the intended target is missed altogether (e.g., wrong target or bystander).
A missed shot or not hitting the target where intended can be dangerous particularly such as when dealing with a hostage crisis. This also applies in the case where a shot is not taken at all because of the targeting uncertainty created by the particular method or device used to attenuate the surface reflections. In such cases the inability or failure to take a shot or to take the intended shot can lead to the loss of life or serious injury to the hostages or innocent bystanders.
It thus would be desirable to provide a new method, technique and device that reduces or attenuates the reflections from the surface of a transparent member. It would be particularly desirable to provide new methods and devices that minimize the effect of such reflections while viewing an object or target through the reflective surface of the transparent member by a weapon sight without affecting the projected point of impact of the projectile from the weapon sight or other telescopic viewing mechanism. Such methods and devices preferably would be simple in construction and would not require highly skilled users to utilize the device or require sophisticated or detailed procedures for using such a device in the field.
SUMMARY OF THE INVENTION
The present invention generally features a method and device that minimize the effects of reflections from a surface of a transparent member while viewing an object or target area through the reflective surface of the transparent member. In particular, when viewing an object or target when using a sight for a weapon, such as a telescopic weapon sight, without affecting the sight's projected point of impact of the projectile that can be fired from the weapon.
According the present invention there is featured a method for viewing an object from a first side of a transparent medium, the first side being a reflective surface, when the object is located on an opposite side of the transparent medium. The viewing method includes the steps of providing a telescopic viewing mechanism, mounting a filter at an exit aperture of the telescopic viewing mechanism and passing light from the object through the telescopic viewing mechanism and through the polarizing filter. The filter also is configured to significantly attenuate light being reflected from the transparent member first side and in a particular embodiment is a polarizing or polarizer filter. The method further includes filtering the light being reflected from the transparent member first side and passing through the telescopic viewing mechanism using the filter.
In this way, the internal sighting or aligning mechanism (e.g., reticle) provided or included with the telescopic viewing mechanism will not be shifted from the point of impact because of the image being shifted by the refraction of the front mounted filter. Rather, mounting the filter at the exit aperture results in the image and the internal sighting mechanism (e.g., reticle) being shifted at the same time.
In particular embodiments, the telescopic viewing mechanism is a telescopic sight for a weapon and wherein the step of mounting includes disposing the filter optically behind the weapon sight, more specifically the eyepiece of the weapon sight. More particularly, the filter is disposed optically behind the internal image and reticle of the weapon sight. In this way and as also described above, the reticle of the weapon sight and image being viewed shift at the same time. Consequently, the point of impact for the projectile (e.g., bullet) fired from the weapon does not change from that being shown by the weapon sight.
According to the present invention there also is featured a method for attenuating light being reflected from a reflective surface of a transparent member while viewing an object located opposite to the reflective surface using a telescopic viewing mechanism. This light attenuating method includes mounting a polarizing filter proximal an exit aperture of the telescopic viewing mechanism such as the sight for a weapon, filtering the light being reflected by the reflective surface and passing through the telescopic viewing mechanism using the polarizing filter and passing light from the object through the telescopic viewing mechanism and the polarizing filter for viewing.
When the telescopic viewing mechanism is a telescopic sight for a weapon, the filter is mounted so that it is located optically behind the weapon sight. More specifically behind the eyepiece of the weapon sight, and more particularly, the filter is disposed optically behind the internal image and reticle of the weapon sight. In this way, the reticle of the weapon sight and image being viewed
Corless Peter F.
Curtis Craig
Dike Bronstein, Roberts & Cushman IP Group, Edwards & Angell, LL
Hazzard Lisa Swiszcz
Spyrou Cassandra
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