Optical polarization spot size changing devices

Claim 2

In an optical system having a light source for producing an essentially coherent polarized light beam with a first beam waist therein, and having focusing means for forming a focused light spot, apparatus for selectively changing the spatial pattern of the focused light spot by selectively directing the light beam to traverse either a first or a secOnd path, the focused light spot having a first spatial pattern when the light beam traverses the first path and a second spatial pattern different from the first spatial pattern when the light beam traverses the second path, the apparatus comprising: first polarization changing means for controllably changing the polarization direction of the polarized light beam from a first polarization direction to a second polarization direction, first polarization sensitive means having an entrance window, and first and second exit windows, the first polarization sensitive means constructed and arranged to direct a light beam entering the entrance window to emerge from the first exit wondow if the light beam has a first polarization direction and to emerge from the second exit window if the light beam has a second polarization direction, second polarization sensitive means having first and second entrance windows and an exit window, the second polarization sensitive means constructed and arranged to direct a light beam entering the first entrance window to emerge from the exit window if the light beam has a first polarization direction, and to direct a light beam entering the second entrance window to emerge from the exit window if the light beam has a second polarization direction, beam directing means positioned to receive a light beam emerging from the second exit window of the first polarization sensitive means and to direct the light beam toward the second polarization sensitive means such that the light beam enters the second polarization sensitive means through the second entrance window, whereby a light beam having a first polarization direction which enters the first polarization sensitive means through the entrance window traverses the first path, which comprises entering the entrance window, emerging from the first exit window of the first polarization sensitive means, entering the second polarization sensitive means through the first entrance window, and emerging from the exit window of the second polarization sensitive means toward the focusing means, and a light beam having a second polarization direction which enters the first polarization sensitive means through the entrance window traverses the second path, which comprises entering the entrance window of the first polarization sensitive means, emerging from the second exit window, entering the second polarization sensitive means through the second entrance window, and emerging from the exit window of the second polarization sensitive means co-linear with the first path.

Claim 3

The invention as described in claim 1 and further comprising spatial filtering means positioned in the second path for altering the spatial pattern of the light beam traversing the second path.

Claim 4

The invention as described in claim 1 wherein the first and second paths represent different optical distances from the first beam waist to the focusing means.

Claim 5

The invention as described in claim 3 and further comprising spatial filtering means positioned in the second path for altering the spatial pattern of light beam traversing the second path.

Claim 6

The invention as described in claim 4 wherein the spatial filtering means is constructed and arranged to create a second beam waist in the second path at an optical distance from the focusing means essentially equal to the optical distance from the first beam waist to the focusing means over the first path, the second beam waist having a spatial pattern which is different from that of the first beam waist.

Claim 7

The invention as described in claim 1 wherein the first polarization changing means comprise an electro-optic crystal for selectively changing the polarization direction of the polarized light beam from the first polarization direction to the second polarization direction in response to an applied electric field.

Claim 8

The invention as described in claim 6 wherein the electro-optic crystal is positioned essentially at the first beam waist.

Claim 9

The invention as described in claim 1 and further comprising: second polarization changing means positioned between the second polarization sensitive means and the focusing means for controllably changing the polarization direction of the light beam from the second polarization direction to the first polarization direction when the first polarization selecting means changes the polarization direction of the light beam from the first polarization direction to the second polarization direction.

Claim 10

The invention as described in claim 8 wherein the first and second polarization changing means comprise electo-optic crystals.

Claim 11

In an optical system having a light source for producing an essentially coherent polarized light beam with a first beam waist therein, and having focusing means for forming a focused light spot, apparatus for selectively changing the spatial pattern of the focused light spot by selectively directing the light beam to traverse either a first or a second path, the focused light spot having a first spatial pattern when the light beam traverses the first path and a second spatial pattern different from the first spatial pattern when the light beam traverses the second path, the apparatus comprising: first polarization changing means for controllably changing the polarization direction of the polarized light beam from a first polarization direction to a second polarization direction, polarization sensitive means having an entrance window, an exit window, and first and second auxiliary windows, the polarization sensitive means constructed and arranged to direct a light beam entering the entrance window to emerge from the exit window if the light beam has a first polarization direction and to emerge from the first auxiliary window if the light beam has a second polarization direction, to direct the light beam entering the first auxiliary window to emerge from the second auxiliary window if the light beam has a first polarization direction, and to direct the light beam entering the second auxiliary window to emerge from the exit window if the light beam has a second polarization direction, beam directing means positioned to receive a light beam emerging from the first auxiliary window and to direct the light beam to enter the second auxiliary window with a second polarization direction, whereby a light beam having a first polarization direction which enters the polarization sensitive means through the entrance window traverses the first path, which comprises entering the entrance window, and emerging from the exit window toward the focusing means, and a light beam having a second polarization direction which enters the polarization sensitive means through the entrance window traverses the second path, which comprises entering the exit window, emerging from the first auxiliary window, entering the second auxiliary window, and emerging from the exit window co-linear with the first path.

Claim 12

In an optical system having a light source for producing an essentially coherent polarized light beam with a first beam waist therein, and having focusing means for forming a focused light spot, apparatus for selectively changing the spatial pattern of the focused light spot by selectively directing the light beam to traverse either a first or a second path, the focused light spot having a first spatial pattern when the light beam traverses the first path and a second spatial pattern different from the first spatial pattern when the light beam traverses the second path, the apparatus comprising: first polarization changing means for controllably changing the polarization direction of the polarized light beam from a first polarization direction to a second polarization direction, polarization sensitive means having an entrance window, an exit window, and first and second auxiliary windows, the polarization sensitive means constructed and arranged to direct a light beam entering the entrance window to emerge from the exit window if the light beam has a first polarization direction and to emerge from the first auxiliary window if the light beam has a second polarization direction, to direct the light beam entering the first auxiliary window to emerge from the second auxiliary window if the light beam has a first polarization direction, and to direct the light beam entering the second auxiliary window to emerge from the exit window if the light beam has a second polarization direction, beam directing means positioned to receive a light beam emerging from the first auxiliary window and to direct the light beam to enter the second auxiliary window with a second polarization direction, whereby a light beam having a first polarization direction which enters the polarization sensitive means through the entrance window traverses the first path, which comprises entering the entrance window, and emerging from the exit window toward the focusing means, and a light beam having a second polarization direction which enters the polarization sensitive means through the entrance window traverses the second path, which comprises entering the exit window, emerging from the first auxiliary window, entering the second auxiliary window, and emerging from the exit window co-linear with the first path.

Claim 13

The invention as described in claim 10 wherein the first polarization changing means comprise an electro-optic crystal for selectively changing the polarization direction of the polarized light beam from the first polarization direction to the second polarization direction in response to an applied electric field.

Claim 14

The invention as described in claim 11 wherein the electro-optic crystal is positioned essentially at the first beam waist.

Claim 15

The invention as described in claim 10 and further comprising: second polarization changing means positioned between the polarization sensitive means and the focusing means for controllably changing the polarization direction of the light beam from the second polarization direction to the first polarization direction when the first polarization changing means changes the polarization direction of the light beam from the first polarization direction to the second polarization direction.

Claim 16

The invention as described in claim 13 wherein the first and second polarization changing means comprise electro-optic crystals.

Claim 17

The invention as described in claim 10 wherein the beam directing means comprise: first reflective means positioned to receive a light beam emerging from the first auxiliary window and to reflect the light beam back toward the polarization sensitive means such that the light beam re-enters the first auxiliary window, first polarization shifting means positioned between the first auxiliary window and the first reflective means for changing the polarization direction of the light beam such that the light beam re-entering the first auxiliary window has the first polarization direction, second reflective means positioned to receive a light beam emerging from the second auxiliary window and to reflect the light beam back toward the polarization sensitive means such that the light beam re-enters the second auxiliary window, and second polarization shifting means positioned between the second auxiliary window and the second reflective means for changing the polarization direction of the light beam such that the light beam re-entering the second auxiliary window has the second polarization direction, and whereby the second path comprises entering the entrance window, emerging from the first auxiliary window, re-entering the first auxiliary window, emerging from the second auxiliary window, reentering the second auxiliary window, and emerging from the exit window co-linear with the first path.

Claim 18

The invention as described in claim 15 and further comprising spatial filtering means positioned in the second path for altering the spatial pattern of the light beam traversing the second path.

Claim 19

The invention as described in claim 16 wherein the spatial filtering means is constructed and arranged to create a second beam waist in the second path at an optical distance from the focusing means essentially equal to the optical distance from the first beam waist to the focusing means over the first path, the second beam waist having a spatial pattern which is different from that of the first beam waist.

Claim 20

The invention as described in claim 16 wherein the first reflective means and the spatial filtering means comprise a concave mirror.

Claim 21

The invention as described in claim 18 wherein the concave mirror is positioned at an optical distance from the first beam waist which is at least as great as the focal length of the concave mirror.

Claim 22

The invention as described in claim 18 and further comprising lens means positioned between the concave mirror and the polarization sensitive means.

Claim 23

The invention as described in claim 15 wherein the first and second polarization shifting means are quarter-wave plates.

Claim 24

The invention as described in claim 15 wherein the first and second polarization shifting means are 45* Faraday rotators.

Claim 25

The invention as described in claim 15 wherein the polarization sensitive means, the first and second reflective means, and the first and second polarization shifting means comprise a unitary body.

Claim 26

The invention as described in claim 23 wherein the unitary body further includes spatial filtering means positioned in the second path for altering the spatial pattern of the light beam traversing the second path.

Claim 27

In an optical system having a light source for producing an essentially coherent polarized light beam with a first beam waist therein, and having focusing means for forming a focused light spot, apparatus for selectively changing the spatial pattern of the focused light spot by selectively directing the light beam to traverse either a first or a second path, the focused light spot having a first spatial pattern when the light beam traverses the first path and a second spatial pattern different from the first spatial pattern when the light beam traverses the second path, the apparatus comprising: first polarization changing means for controllably changing the polarization direction of the polarized light beam from a first polarization direction to a secOnd polarization direction, polarization sensitive means having an entrance window, an exit window, and first and second auxiliary windows, the polarization sensitive means constructed and arranged to direct a light beam entering the entrance window to emerge from the second auxiliary window if the light beam has a first polarization direction and to emerge from the first auxiliary window if the light beam has a second polarization direction, to direct a light beam entering the first auxiliary window to emerge from the exit window if the light beam has a first polarization direction, and to direct a light beam entering the second auxiliary window to emerge from the exit window, if the light beam has a second polarization direction, first reflective means positioned to receive a light beam emerging from the first auxiliary window and to reflect the light beam back toward the polarization sensitive means such that the light beam re-enters the first auxiliary window, first polarization shifting means positioned between the first auxiliary window and the first reflective means for changing the polarization direction of the light beam such that the light beam re-entering the auxiliary window has a first polarization direction, second reflective means positioned to receive a light beam emerging from the second auxiliary window and to reflect the light beam back toward the polarization sensitive means such that the light beam re-enters the second auxiliary window, second polarization shifting means positioned between the second auxiliary window and the second reflective means for changing the polarization direction of the light beam re-entering the second auxiliary window to the second polarization direction, whereby a light beam having a first polarization direction which enters the polarization sensitive means through the entrance window traverses the first path, which comprises entering the entrance window, emerging from the second auxiliary window, re-entering the second auxiliary window, and emerging from the exit window toward the focusing means, and a light beam having a second polarization direction which enters the polarization sensitive means through the entrance window traverses the second path, which comprises entering the entrance window, emerging from the first auxiliary window, re-entering the first auxiliary window, and emerging from the exit window co-linear with the first path.

Claim 28

In an optical system having a light source for producing an essentially coherent polarized light beam with a first beam waist therein, and having focusing means for forming a focused light spot, apparatus for selectively changing the spatial pattern of the focused light spot by selectively directing the light beam to traverse either a first or a second path, the focused light spot having a first spatial pattern when the light beam traverses the first path and a second spatial pattern different from the first spatial pattern when the light beam traverses the second path, the apparatus comprising: first polarization changing means for controllably changing the polarization direction of the polarized light beam from a first polarization direction to a secOnd polarization direction, polarization sensitive means having an entrance window, an exit window, and first and second auxiliary windows, the polarization sensitive means constructed and arranged to direct a light beam entering the entrance window to emerge from the second auxiliary window if the light beam has a first polarization direction and to emerge from the first auxiliary window if the light beam has a second polarization direction, to direct a light beam entering the first auxiliary window to emerge from the exit window if the light beam has a first polarization direction, and to direct a light beam entering the second auxiliary window to emerge from the exit window, if the light beam has a second polarization direction, first reflective means positioned to receive a light beam emerging from the first auxiliary window and to reflect the light beam back toward the polarization sensitive means such that the light beam re-enters the first auxiliary window, first polarization shifting means positioned between the first auxiliary window and the first reflective means for changing the polarization direction of the light beam such that the light beam re-entering the auxiliary window has a first polarization direction, second reflective means positioned to receive a light beam emerging from the second auxiliary window and to reflect the light beam back toward the polarization sensitive means such that the light beam re-enters the second auxiliary window, second polarization shifting means positioned between the second auxiliary window and the second reflective means for changing the polarization direction of the light beam re-entering the second auxiliary window to the second polarization direction, whereby a light beam having a first polarization direction which enters the polarization sensitive means through the entrance window traverses the first path, which comprises entering the entrance window, emerging from the second auxiliary window, re-entering the second auxiliary window, and emerging from the exit window toward the focusing means, and a light beam having a second polarization direction which enters the polarization sensitive means through the entrance window traverses the second path, which comprises entering the entrance window, emerging from the first auxiliary window, re-entering the first auxiliary window, and emerging from the exit window co-linear with the first path.

Claim 29

The invention as described in claim 25 wherein the first and second paths represent different optical distances from the first beam waist to the focusing means.

Claim 30

The invention as described in claim 25 and further comprising spatial filtering means positioned in the second path for altering the spatial pattern of the light beam traversing the second path.