Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2001-01-09
2002-12-10
Kim, Robert H. (Department: 2882)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C359S493010
Reexamination Certificate
active
06492635
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to techniques for controlling a polarizing filter and, more particularly, to a method and device for automatically controlling a polarizing filter. The method and device feature automatically sensing, measuring, and analyzing at least one parameter associated with direction of a polarizing filter by an electronic direction/motion sensing mechanism, receiving a signal from the electronic direction/motion sensing mechanism relating to the at least one parameter associated with direction of the polarizing filter by a rotation control circuit, and receiving a signal from the rotation control circuit relating to the at least one parameter associated with direction of the polarizing filter by a polarizing filter rotating mechanism for automatically rotating the polarizing filter.
Basic principles and details relating to propagating electromagnetic radiation and to polarization of propagating electromagnetic radiation needed for properly understanding the present invention are provided herein. Complete theoretical descriptions, details, explanations, examples, and applications of these and related subjects and phenomena are readily available in standard references in the fields of physics, materials science, optics, photography, and photographic equipment. The present invention is primarily directed to applications of a polarizing filter in the field of photography, however, the present invention clearly can be directed to applications of a polarizing filter in a variety of other fields involving the use of polarized electromagnetic radiation for viewing, imaging and/or projecting through short or long distances, for example, involving the use of a microscope, binoculars, a telescope, or a laser beam device.
Electromagnetic radiation which is unaffected and untreated by external influences, in general, and unpolarized, in particular, such as that of unpolarized light or any other radiation, behaves as a propagating transverse wave vibrating equally and randomly in all directions perpendicular to the direction of propagation. Polarization is generally denoted as the uniform and nonrandom elliptical, circular, or, linear or planar, variation of the vibrational orientation of the wave motion of such electromagnetic radiation. Linear or plane polarized electromagnetic radiation occurs when all the vibrating electromagnetic field components of the propagating electromagnetic radiation are oriented in the same direction. A simple way of describing this phenomenon is by considering the wave motion of electromagnetic radiation as a vector sum of two such vibrations in perpendicular planes, vibrating perpendicular to the direction of propagation, whereby linear or plane polarized electromagnetic radiation results when one of the two components is partly or entirely removed from the propagating wave motion of the electromagnetic radiation.
Sources of unpolarized electromagnetic radiation can be naturally existing, such as the sun or the moon, or, can be man made, such as a manufactured electromagnetic radiation source, for example, a device generating a highly focused or coherent beam of electromagnetic radiation, such as a laser beam, or, a device generating spread out or diffuse electromagnetic radiation, such as an incandescent lamp, a fluorescent lamp, an infra-red lamp, an ultra-violet lamp, or, a device generating a combination of focused and diffuse electromagnetic radiation, such as a photographic flash lamp, spot light, or flood light. Unpolarized electromagnetic radiation can be linearly or plane polarized by any of various linear or plane polarizing mechanisms, the most well known and characterized being absorption, scattering, or reflection, each of which is basically described herein.
In the linear or plane polarizing mechanism involving absorption, unpolarized propagating electromagnetic radiation, originating from a natural source or a man made source, is directed into a medium having a unique structure which passes or transmits incident electromagnetic radiation polarized in one direction, commonly referred to as the ‘passing direction’, while strongly absorbing or ‘blocking’ electromagnetic radiation polarized in the perpendicular, or ‘blocking’, direction. Accordingly, such a linear or plane polarizing medium functions as a special type of filter, commonly referred to as a ‘polarizing filter’, for blocking or filtering out a selected part, or fraction, of the incident electromagnetic radiation. A single polarizing filter polarizes up to a maximum of half the intensity of unpolarized electromagnetic radiation, and, depending upon the relative angular orientation of the polarizing planes of two polarizing filters placed in series, transmission of electromagnetic radiation, initially unpolarized when directed into the first polarizing filter, successively passing through the second polarizing filter can be controlled down to a minimum of zero if the double polarization is complete, in accordance with the well known Malus cosine-squared law.
Different types of media, such as a polarizing prism, or, a polarizing sheet, which are widely used as polarizing filters, are known for producing absorption type of linear or plane polarization of electromagnetic radiation. A polarizing prism is made of a material, for example, calcite, whose crystal structure exhibits double refraction or birefringent characteristics, whereby the crystal structure has a different index of refraction for each direction or plane of polarization. Since electromagnetic radiation of one polarization is bent more strongly than the other, it is possible to separate the polarized components by total internal reflection, for example, by using a Nicol prism, or, a Glan-Thompson prism, or, by deviation in different directions, for example, by using a Rochon prism, or, a Wollaston prism. A polarizing sheet, for example, any one of the variety of different types of polarizing sheets manufactured by the Polaroid Corporation, USA, is made by aligning microscopic crystals of an appropriate material in a suitable base.
A special case of polarizing electromagnetic radiation is when linear or plane polarized electromagnetic radiation such as light traverses a crystal such as calcite perpendicular to its axis, the light is transformed into elliptically polarized, or, circularly polarized light.
In the field of physics, in general, and materials science, in particular, linear or plane polarizing media are used for producing a well defined and characterized source of polarized electromagnetic radiation, such as that produced by placing an appropriately designed and constructed polarizing filter in front of the beam of a source of electromagnetic radiation such as a laser device, for studying electronic structure, properties, and behavior of materials.
In the field of photography, propagating electromagnetic radiation in the form of scattered light, glare or intense light, and other strong reflections of light, often interfere with the photographic process and degrade photographs in many ways, for example, by diluting colors, by obscuring or distracting a photographer from important image details, or by forcing less than optimal exposure compromises. Fortunately, for photographers, such ‘interfering light’ is associated with varying degrees of polarization, and this association provides a relatively easy way to eliminate, minimize, or, exploit, the ‘interfering light’, by using a polarizing filter set at optimum or strategic polarizing angles, while capturing the remaining desired light required for the photographic process.
In the linear or plane polarizing mechanism involving scattering, unpolarized propagating electromagnetic radiation, originating from a natural source or a man made source, is directed into a medium which absorbs and re-radiates or scatters the incident electromagnetic radiation, such that the scattered electromagnetic radiation leaving the medium is strongly polarized in the direction perpendicular to the incident direction of propagation.
Friedman Mark M.
Kim Robert H.
Song Hoon K.
LandOfFree
Method and device for automatically controlling a polarizing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and device for automatically controlling a polarizing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and device for automatically controlling a polarizing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2988071