US2302613A

US2302613A - Lamp

Info

Publication number: US2302613A
Application number: US349157A
Authority: US
Inventors: Edwin H Land
Original assignee: Polaroid Corp
Current assignee: Polaroid Corp
Priority date: 1940-08-01
Filing date: 1940-08-01
Publication date: 1942-11-17
Anticipated expiration: 1959-11-17

Description

Reference 2.3o2,e;

Nbv. 17 1942.

E. H. LAND LAMP Filed Aug. 1, 1940 BY. :NVE NTIOI'FLA ATTORNEY tion, an element I! which is adapted to polariz: 4o

Patented Nov. 17, 1942 UNITED STATES PATENT OFFICE LAMP Edwin 11.

Land, Boston, Mass, assignor to Polaroid Corporation, Dover, Del, a corporation of Delaware Application August 1, 1940, Serial No. 349,151

(Cl. aa-ss) 1 Claim.

' allel to said surface has been eliminated.

A further object of the, invention is to provide such a lamp whereinthe polarizing element or lements are so positioned that at least a part :f the=undesired component of the hght ls elimlnated by reflection from thtes surfaces of said larizin element or elemen 3 Other t ibjects of the invention will in part appear and in part be pointed out in the course of the following description of one embodiment the invention, which is given as a non-limiting example in connection with the accompanying drawing, which is a side elevation, partly broken away, of a lamp embodying a form of the infd lamp comprises an incandescent bulb or other suitable source of light 5, mounted in a column member i provided with a base I of any suitable shape. Shade or shell member i is mounted on column 6 in any desired manner, and a reflecting element i2 is preferably provided positioned to direct light incident thereon out of the open portion is of said shell. The inside of said shell will also preferably be lined with suitable light-reflecting material.

- In accordance with the practice of the inventransmitted light is positioned in open portion to polarize the light passing therethrough from bulb i and reflector It. said polarizing element ls preferably sheet-like in form and may adeously comprise dichroic, plastic materials Eris the polarizing materials made and sold under the trade name Pole-mid." Polarlzer It may be mounted in any convenient way such as by means of a series of projections Ii on the inside of shell II and screws or rivets it as shown.

user thereof. mat ll. The lamp of the invention is designed to emit only light vibrating in the plane of incidence of said light upon the surface to be illuminated, that is to say, light vibrating parallel to the plane of the paper in the drawing.

The component of the light vibrating parallel to the surface to be illuminated, which is the glare-producing component, is eliminated by means of the polarizing element 15.

In accordance with the practice of the invention, polarizing element i5 is so positioned in the lamp that at least a portion of the undesired component of the light from bu b i and reflector I2 is ehminated by reflection at the surfaces of said polarizing element. In a lamp used in the manner shown in the drawing, this will be accomplished by positioning said polarizing element with its surfaces substantially parallel to the surfaceto be illuminated. It will be seen that this condition will commonly be fulfilled by posltioning element IS with its surfaces substanlially parallel to the bottom of base element 0.

Dotted due 22 indicates the course of a ray of light polalized by the lamp of the invention. Said ray is nrst reflected from reflector l2 and is then incident on the upper surface of polarizer it, at which surface a portion of the horizontally vibrating component is reflected, indicated at 24. Since it is the Purp se of the lamp to eliminate this horizontally vibrating component and to racilltate transmission of the component vibrating at right angles thereto, this loss by renection aids the purpose of the lamp. Ray 22 then continues through polarizer l5 and in the course or its passage therethrough. the remainer or the horizontally vibrating component is absorbed by the dichroic material of the polarizer. The remaining component 25, which includes only light vlbrating parallel to its plane of incidence on element l5, continues on to illuminate surl'ace 20. It will be noted that the intensity of ray it depends upon the angle at which ray 2: is incident on polarizer l5, and that for maximum efliciency the elements of the lamp should be so arranged that as much of the light as posslble should strike the upper surface of the polarizer at angles approaching the polarizing angle of incidence.

It will be seen that the operation of the above described lamp is substantially the same whether or not element It comprises dichroio material. However, if it does comprise dichroic material,

it should be noted that said element be so positioned in the lamp that its transmission axis will be parallel to the plane of incidence thereon of ray :2. That is to say, said material should be positioned to transmit only that component of the light from bulb B which is vibrating parallel to the plane of the paper in the drawing and to absorb that component of said light which is vibrating parallel to its surface, that is, perpendicular to the plane of the paper in the drawing.

It should be pointed out that the lamp of this invention is capable of other uses in addition to that illustrated in the drawing. For example, it may be used to excellent advantage to illuminate such objects as paintings hanging as on a wall. In such case, said lamp will preferably be positioned with polarizing element l5 perpendicular to the horizontal, but the surfaces of element I! will still be parallel to the surface to be illuminated. Other such uses will doubtless be apparout to one skilled in the art and are to be construed as being within the scope of the invention.

Since certain changes may be made in the above construction and diilferent embodiments of the invention could be made without departing from the scope of the invention, it is intended -that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense. It is also to be understood that the following claim is intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

A lamp comprising, in combination, a base element having a substantially fiat bottom surface, a reflector-shield, a column element connecting said shield element with said base element, said shield element extending laterally beyond said column element, a source of light positioned within said shield substantially in line with said column element, a substantially sheet-like element of dichroic light-polarizing material mounted within said laterally extending portion of said shield with the surfaces thereof substantially parallel to said flat surface of said base element, and means for directing the light emanating from said source upon said polarizing element at relatively large angles of incidence, said polarizing element being arranged with the trans- 'mission axis thereof substantially parallel to the plane of incidence thereon of said light.

EDWIN H. LAND.