# US 2021/0278680 A1 · Method to vary the diameter of a laser beam

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- Number: US 2021/0278680 A1
- Document ID: US20210278680A1
- Status: Published application
- Kind: A1
- Application number: 16/808,509
- Filed: 2020-03-04
- Published: 2021-09-09
- Earliest claimed: 2020-03-04
- Assignees: BAE Systems Information and Electronic Systems Integration Inc.
- Applicants: BAE SYSTEMS Information and Electronic Systems Integration Inc.
- Inventors: Philip R. Staver
- Web page: https://patentgrep.com/patent/US20210278680A1

## CPC

- G02B 27/0966: {Cylindrical lenses (cylindrical lenses per se G02B3/06)}
- G02B 9/60: having five components only
- G02B 26/0875: {by means of one or more refracting elements}
- G02B 27/0961: {Lens arrays (lens arrays per se G02B3/0006)}
- H01S 3/005: {Optical devices external to the laser cavity, specially adapted for lasers, e.g. for homogenisation of the beam or for manipulating laser pulses, e.g. pulse shaping (shaping laser beam for working metal or other materials B23K26/06; optical elements, systems or apparatus in general G02B)}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL

## Abstract

Techniques, systems, architectures, and methods for modulating the focal spot and/or divergence of a laser beam comprising the use of a collimated light source, a lens assembly disposed within an optical path corresponding to light emanating from the collimated light source wherein the lens assembly comprises two pairs of cross cylinder lenses having equal and opposite focal powers oriented with their neutral axes positioned orthogonally to each other; and a focusing objective lens assembly disposed within the optical path following the lens assembly, wherein each of the two pairs of cross cylinder lenses are configured for rotation about an axis defined by the point at which light from the collimated light source impinges on each of them.

## Claims

### Claim 1

An optical system for modulating the focal spot and/or divergence of a laser beam, the system comprising:
a lens assembly comprising a pair of cross cylinder lenses having equal and opposite focal powers oriented with their neutral axes positioned orthogonally to each other; and
a focusing objective lens assembly disposed within an optical path defined by the lens assembly,
wherein at least one of the pair of cross cylinder lenses is configured for rotation about an axis defined by the point at which the optical path impinges on each of them.

### Claim 2 (depends on 1)

The system of claim 1, further comprising a collimated light source configured to send collimated light down the optical path.

### Claim 3 (depends on 1)

The system of claim 1, wherein the cross cylinder lenses are square in shape.

### Claim 4 (depends on 1)

The system of claim 1, wherein the cross cylinder lenses are round in shape.

### Claim 5 (depends on 1)

The system of claim 1, wherein the cross cylinder lenses are rectangular in shape.

### Claim 6 (depends on 1)

The system of claim 1, wherein the cross cylinder lenses are Jackson cross-cylinder lenses.

### Claim 7 (depends on 1)

The system of claim 1, wherein each of the pairs of cross cylinder lenses is configured solely for equal and opposite rotation, relative to the other.

### Claim 8 (depends on 1)

The system of claim 1, wherein the focusing objective lens assembly is a single focusing objective lens.

### Claim 9 (depends on 8)

The system of claim 8, wherein the cross cylinder lenses and the focusing objective lens are made of Infrasil.

### Claim 10 (depends on 9)

The system of claim 9, wherein the cross cylinder lenses and the focusing objective lens are 4 mm thick and 20 mm wide.

### Claim 11 (depends on 10)

The system of claim 10, wherein the cross cylinder lenses are rectangular and the focusing objective lens is round.

### Claim 12 (depends on 11)

The system of claim 11, wherein the pair of cross cylinder lenses comprises a first pair of cylinder lenses and a second pair of cylinder lenses, the first pair of cylinder lenses comprising a first cylinder lens having an effective focal length of infinity in an X-axis and 10.00 in a Y-axis and a second cylinder lens having an effective focal length of −10.00 in the X-axis and infinity in the Y-axis, and the second pair of cylinder lenses comprising a third cylinder lens having an effective focal length of infinity in the X-axis and 10.00 in the Y-axis and a fourth cylinder lens having an effective focal length of −10.00 in the X-axis and infinity in the Y-axis.

### Claim 13 (depends on 12)

The system of claim 12 wherein the focusing objective lens has an effective focal length of 0.1 in the X-axis and 0.1 in the Y-axis.

### Claim 14

A method of modulating the focal spot and/or divergence of a laser beam, the method comprising:
providing an optical system comprising:
a collimated light source;
a lens assembly disposed within an optical path corresponding to light emanating from said collimated light source wherein the lens assembly comprises a pair of cross cylinder lenses having equal and opposite focal powers oriented with their neutral axes positioned orthogonally to each other; and
a focusing objective lens disposed within the optical path following the lens assembly,
wherein at least one of the pair of cross cylinder lenses is configured for rotation about an axis defined by the point at which light from the collimated light source impinges on it,
directing an output of the collimated light source through a central portion of the lens assembly corresponding to the optical path; and
rotating at least one of the pair of cross cylinder lenses about an axis corresponding to the optical path.

### Claim 15 (depends on 14)

The method of claim 14, wherein the collimated light source is a laser.

### Claim 16 (depends on 14)

The method of claim 14, wherein the cross cylinder lenses are rectangular and the focusing objective lens is round.

### Claim 17 (depends on 14)

The method of claim 14 wherein the cross cylinder lenses are Jackson cross-cylinder lenses.

### Claim 18 (depends on 14)

The method of claim 14, wherein the focusing objective lens assembly is a single focusing objective lens.

### Claim 19 (depends on 14)

The method of claim 14, wherein the cross cylinder lenses and the focusing objective lens are made of Infrasil.

### Claim 20

An optical system for modulating the focal spot and/or divergence of a laser beam, the system comprising:
a collimated light source;
a lens assembly disposed within an optical path corresponding to light emanating from said collimated light source wherein the lens assembly comprises a pair of cross cylinder lenses having equal and opposite focal powers oriented with their neutral axes positioned orthogonally to each other; and
a focusing objective lens assembly disposed within the optical path following the lens assembly,
wherein at least one of the pair of cross cylinder lenses is configured for rotation about an axis defined by the point at which light from the collimated light source impinges on it,
wherein at least one of the pairs of cross cylinder lenses is configured for rotation, relative to the other, and
wherein the cross cylinder lenses and the focusing objective lens are made of Infrasil.