US4942583A — Misalignment-tolerant, grating-tuned external-cav…

Claim 1

Independent Claim 260 words

A grating tuned laser system comprising: a laser amplifier (71) that emits a laser beam (75) along an optical axis A, said laser beam having a pair of lateral dimensions W P and W T where W P is measured along a direction parallel to an axis P perpendicular to optical axis A and W T is measured along a direction parallel to an axit T perpendicular to axes A and P, said lateral dimensions W P and W T being referred to herein as laser beam height and width, respectively; a grating (73) positioned in the path of said laser beam (75) and oriented relative to said laser amplifier to produce a diffraction order that retroreflects back to the laser amplifier (71), thereby forming an external cavity with said laser amplifier (71); wherein said grating (73) is rotatable about axis P to enable tuning of the laser amplifier (71); wherein said grating (73) contains a set of grating rulings (74) that are substantially parallel to axis P; and wherein a normal N to a front face (711) of the grating (73) at the intersection of the optical axis with the grating (73) makes an angle θ with the optical axis A at the grating; optical relay means, positioned in the path of said laser beam between the laser amplifier and the grating, for reducing the ratio of laser beam height to laser beam width to produce on said grating (73) a laser spot (710) having a ratio of height W P to width W T much less than 1.

Claim 2

Dependent Claim 260 words

A grating tuned laser system comprising: a laser amplifier (71) that emits a laser beam (75) along an optical axis A, said laser beam having a pair of lateral dimensions W P and W T where W P is measured along a direction parallel to an axis P perpendicular to optical axis A and W T is measured along a direction parallel to an axit T perpendicular to axes A and P, said lateral dimensions W P and W T being referred to herein as laser beam height and width, respectively; a grating (73) positioned in the path of said laser beam (75) and oriented relative to said laser amplifier to produce a diffraction order that retroreflects back to the laser amplifier (71), thereby forming an external cavity with said laser amplifier (71); wherein said grating (73) is rotatable about axis P to enable tuning of the laser amplifier (71); wherein said grating (73) contains a set of grating rulings (74) that are substantially parallel to axis P; and wherein a normal N to a front face (711) of the grating (73) at the intersection of the optical axis with the grating (73) makes an angle θ with the optical axis A at the grating; optical relay means, positioned in the path of said laser beam between the laser amplifier and the grating, for reducing the ratio of laser beam height to laser beam width to produce on said grating (73) a laser spot (710) having a ratio of height W P to width W T much less than 1.

Claim 3

Dependent Claim 25 words

A grating tuned laser system as in claim 1 wherein the ratio W P /W T is on the order of or less than 0.1.

Claim 4

Dependent Claim 39 words

A grating tuned laser system as in claim 1 wherein said optical relay means (72) produces a laser beam (75) having wavefronts (16) at the grating (73) that are tangent to the front face (711) of the grating (73).

Claim 5

Dependent Claim 54 words

A grating tuned laser system as in claim 3 wherein said grating (73) is a planar grating having parallel equally spaced grating rulings (74) and wherein said optical relay means (72) produces a laser beam (75) having at the grating (73) a waist (15) in both of its principal meridional planes (the xz-and yz-planes).

Claim 6

Dependent Claim 19 words

A grating tuned laser system as in claim 1 wherein the optical relay means comprises a cylindrical lens (77).

Claim 7

Dependent Claim 47 words

A grating tuned laser system as in claim 5 wherein the separation between the grating (73) and the cylindrical lens (77) along the direction of the laser beam is selected to maximize the average feedback of the external cavity over the tuning range of the laser system.

Claim 8

Dependent Claim 32 words

A grating tuned laser system as in claim 5 wherein said cylindrical lens (77) is substantially perpendicular to the optical axis A of the laser beam (75) at said cylindrical lens (77).

Claim 9

Dependent Claim 25 words

A grating tuned laser system as in claim 5 wherein said cylindrical lens (77) is substantially parallel to the grating (73) for all angles θ.

Claim 10

Dependent Claim 57 words

A grating tuned laser system as in claim 5 wherein said cylindrical lens (77) is oriented at a fixed angle Φ relative to optical axis A at the cylindrical lens (77), said angle Φ being selected to optimize, at a single wavelength within the tuning range of the laser, the degree of focus on the grating (73).

Claim 11

Dependent Claim 57 words

A grating tuned laser system as in claim 5 wherein said cylindrical lens (77) is oriented at a fixed angle Φ relative to said optical axis A of the laser beam at the cylindrical lens, said angle Φ being selected to maximize the average feedback of the external cavity over the tuning range of the laser system.

Claim 12

Dependent Claim 19 words

A grating tuned laser system as in claim 1 wherein the optical relay means comprises a conical lens (87).

Claim 13

Dependent Claim 47 words

A grating tuned laser system as in claim 11 wherein the separation between the grating (73) and the conical lens (87) along the direction of the laser beam (75) is selected to maximize the average degree of focus of the laser beam (75) onto the grating (73).

Claim 14

Dependent Claim 32 words

A grating tuned laser system as in claim 11 wherein said conical lens (87) is substantially perpendicular to the optical axis A of the laser beam (75) at said conical lens (87).

Claim 15

Dependent Claim 25 words

A grating tuned laser system as in claim 11 wherein said conical lens (87) is substantially parallel to the grating (73) for all angles θ.

Claim 16

Dependent Claim 45 words

A grating tuned laser system as in claim 11 wherein said conical lens (87) is oriented at a fixed angle Φ relative to optical axis A that optimizes the degree of focus on the grating at a wavelength within the tuning range of the laser.

Claim 17

Dependent Claim 59 words

A grating tuned laser system as in claim 11 wherein said conical lens (87) is oriented at a fixed angle Φ relative to said optical axis A of the laser beam (73) at the conical lens (87), said angle Φ being selected to maximize the average feedback of the external cavity over the tuning range of the laser system.

Claim 18

Dependent Claim 43 words

A grating tuned laser system as in claim 1 wherein the optical relay means (72) comprises: a beam expander (811) that expands the beam (75) at the grating (73) in a direction (T) substantially perpendicular to the rulings (74) of the grating (73).

Claim 19

Dependent Claim 23 words

A grating tuned laser system as in claim 1 wherein the optical relay means (72) further comprises a graded index rod lens (76).

Claim 20

Dependent Claim 26 words

A grating tuned laser system as in claim 1 wherein said optical relay means and grating (73) form a degenerate external cavity with the laser amplifier.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1993-07-16	1994-01-15	1994-07-17	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1997-07-16	1998-01-15	1998-07-17	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2001-07-16	2002-01-15	2002-07-17	$7700.00	Window Closed / Lapsed

Misalignment-tolerant, grating-tuned external-cavity laser

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