US4872743A — Varifocal optical element

Claim 1

Independent Claim 177 words

An optical element having a variable focal length, comprising: a medium the refractive index of which varies with temperature, said medium passing an incident light beam therethrough; a plurality of independently controllable heating means for imparting heat to said medium to create a single continuous index gradient due to a temperature distribution resulting in said medium as a consequence of heat being imparted thereto, wherein said plurality of independently controllable heating means comprise an annular heater and a central heater provided at the center of said annual heater, wherein the heating of said annular heater and said central heater is capable of being selectively controlled by control means to thereby produce concave and convex lens functions of the index gradient formed in said medium, and wherein said plurality of independently controllable heating means is disposed in a plane crossing the light beam; and control means for independently controlling the amount of heat being imparted to said medium by each of said plurality of heating means to vary the shape of the index gradient formed in said medium.

Claim 2

Dependent Claim 177 words

An optical element having a variable focal length, comprising: a medium the refractive index of which varies with temperature, said medium passing an incident light beam therethrough; a plurality of independently controllable heating means for imparting heat to said medium to create a single continuous index gradient due to a temperature distribution resulting in said medium as a consequence of heat being imparted thereto, wherein said plurality of independently controllable heating means comprise an annular heater and a central heater provided at the center of said annual heater, wherein the heating of said annular heater and said central heater is capable of being selectively controlled by control means to thereby produce concave and convex lens functions of the index gradient formed in said medium, and wherein said plurality of independently controllable heating means is disposed in a plane crossing the light beam; and control means for independently controlling the amount of heat being imparted to said medium by each of said plurality of heating means to vary the shape of the index gradient formed in said medium.

Claim 3

Dependent Claim 115 words

An optical element the focal length of which is variable, said element comprising: a medium the refractive index of which varies with temperature, said medium defining a light beam incident plane and passing a light beam therethrough; a plurality of heating means for respectively imparting heat to different portions of said medium to form a plurality of index gradients in said medium, said plurality of heating means being disposed in a plane crossing the light beam; means for controlling the amount of heat imparted by said plurality of heating means; and means for selectively illuminating areas of said light beam incident plane excluding at least those areas in which said plurality of heating means lie.

Claim 4

Dependent Claim 115 words

An optical element the focal length of which is variable, said element comprising: a medium the refractive index of which varies with temperature, said medium defining a light beam incident plane and passing a light beam therethrough; a plurality of heating means for respectively imparting heat to different portions of said medium to form a plurality of index gradients in said medium, said plurality of heating means being disposed in a plane crossing the light beam; means for controlling the amount of heat imparted by said plurality of heating means; and means for selectively illuminating areas of said light beam incident plane excluding at least those areas in which said plurality of heating means lie.

Claim 5

Dependent Claim 30 words

An optical element according to claim 2, wherein said plurality of heating means comprise ring-shaped heat-generating resistance members imparting amounts of heat which are electrically controllable by said controlling means.

Claim 6

Dependent Claim 91 words

An optical element according to claim 3, further comprising a plurality of light-intercepting means provided correspondingly with said plurality of heating means, said light-intercepting means being formed to intercept the passing of the light beam that has passed through said ring-shaped resistance member when a corresponding one of said plurality of heating means is in a heated condition and to permit the passing of the light beam that has passed through said ring-shaped resistance member when a said corresponding one of said plurality of heating means is in an unheated condition.

Claim 7

Dependent Claim 154 words

An optical device comprising: a light source; a light receiving surface for receiving a light beam from said light source; spot forming means for forming a beam spot on said light receiving surface by use of a light beam from said light source; scanning means for relatively scanning the beam spot formed by said spot forming means on said light receiving surface; a medium the refractive index of which varies with temperature, said medium being disposed at a position where the light beam from said light source enters between said light source and said light receiving surface; heating means for applying heat to said medium in order to generate a refractive index distribution accompanied with a temperature distribution in said medium; and controlling means for controlling said heating means so as to vary a diameter of said beam spot, scanned on said light receiving surface, by varying said refractive index distribution in said medium.

Claim 8

Dependent Claim 154 words

An optical device comprising: a light source; a light receiving surface for receiving a light beam from said light source; spot forming means for forming a beam spot on said light receiving surface by use of a light beam from said light source; scanning means for relatively scanning the beam spot formed by said spot forming means on said light receiving surface; a medium the refractive index of which varies with temperature, said medium being disposed at a position where the light beam from said light source enters between said light source and said light receiving surface; heating means for applying heat to said medium in order to generate a refractive index distribution accompanied with a temperature distribution in said medium; and controlling means for controlling said heating means so as to vary a diameter of said beam spot, scanned on said light receiving surface, by varying said refractive index distribution in said medium.

Claim 9

Dependent Claim 16 words

An optical device according to claim 5, wherein said light receiving surface comprises a photosensitive body.

Claim 10

Dependent Claim 23 words

An optical device according to claim 6, wherein recording is performed on said photosensitive body by scanning by use of said scanning means.

Claim 11

Dependent Claim 29 words

An optical device according to claim 7, wherein said controlling means records a change of a density of the beam spot by changing said diameter of the beam spot.

Claim 12

Dependent Claim 15 words

An optical device according to claim 8, wherein said light source comprises a semiconductor laser.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-10-09	1993-04-10	1993-10-10	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-10-09	1997-04-10	1997-10-10	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-10-09	2001-04-10	2001-10-10	$7700.00	Window Closed / Lapsed

Varifocal optical element

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