Optical system for forming non-circular image of like-wise shaped light source on workpiece located in waist of laser beam

Patent metadata

Field	Value
Publication number	US-9618754-B2
Application number	US-201414551152-A
Country	US
Kind code	B2
Filing date	Nov 24, 2014
Priority date	May 29, 2013
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

An optical system for forming a final image of a non-circular light source on a workpiece with a desired non-circular cross-section and desired size B includes a plurality of spaced lenses. The plurality of lenses are arranged with spaced upstream and downstream lenses which are configured to transmit the beam emitted by the light source. The optical system is configured with an F-theta lens spaced downstream from the downstream lens and converging the beam incident thereon so that the beam has a final waist. The F-theta and downstream lenses are spaced apart so that
F ⁢ ⁢ 4 Fth = A B ,
wherein F 4 a positive focal length of the downstream lens, Fth is the negative focus of the F-theta lens, B is the desired size of the final image, and A is a size of a preliminary noncircular image of the source different from the desired size B.

First claim

The invention claimed is:

1. An optical system for forming a final image of a non-circular light source, outputting a beam along a path, on a workpiece, wherein the final image has a desired non-circular cross-section and a desired size B, the optical system comprising:
a positive lens processing the beam such that an initial waist of the beam and an initial non-circular image of the non-circular light source are formed along the path with the initial non-circular image being spaced downstream from the waist at a desired distance;
an optical telescope including spaced upstream and downstream lenses which are located along the path downstream from the initial non-circular image, the upstream lens being configured to form an imaginary image of the non-circular light source and an imaginary waist of the beam, wherein the desired distance between the initial image and waist is such that the imaginary image and waist are substantially coplanar upstream from the downstream lens, the imaginary image being formed with a size A different from the desired size B; and
an F-theta lens spaced downstream from the downstream lens of the telescope along the path so that

F
⁢

⁢
4

Fth

=

A
B

,

 with F 4 and Fth being focal lengths of respective downstream and F-theta lenses, wherein the F-theta lens converges the beam incident thereon so that the final image and a final waist of the converged beam are formed such that the final image is formed in a focus of the F-theta lens and spaced from the final waist at a distance d 1 not exceeding ±5% of the Rayleigh range.

2. The system of claim 1 , wherein the upstream lens of the telescope is negative.

3. A kit comprising:
at least one upstream lens converging a beam from a non-circular light source such that an initial image of the non-circular light source and an initial waist of the beam are spaced from one another along a path;
intermediary upstream and downstream lenses forming an optical telescope downstream from the initial waist and initial image, and
an F-theta lens spaced downstream from the telescope; and

a positive lens insertable between the upstream lens and telescope and in optical communication therewith, the positive lens being configured to space the initial image and initial waste from one another at a desired distance,
the intermediary upstream lens of the telescope being a negative lens configured to form an imaginary image of the non-circular light source and an imaginary waist of the beam, wherein the desired distance between the initial image and initial waist is such that the imaginary image and waist are substantially coplanar upstream from the downstream lens of the telescope, wherein the intermediary image has a size A different from a desired size of the non-circular light source on a workpiece,
the F-theta lens being operative to transmit the beam so that the beam has a final waist downstream from the F-theta lens and form a final image of the non-circular light source having a desired size B in a focus of the F-theta lens and spaced from the final waist at a distance d 1 not exceeding ±5% of the Rayleigh range
provided that

F
⁢

⁢
4

Fth

=

A
B

,

 wherein F 4 a positive focal length of the downstream lens of the telescope, Fth is a negative focal length of the F-theta lens.

4. The kit of claim 3 further comprising a pigtailed optical component configured with:
a first housing which encases the upstream lens of the first optical system,
a second housing spaced from the first housing and encasing the telescope and the F-theta lens, and
a third housing coupled to the first and second housings and enclosing the positive lens.

5. The kit of claim 3 further comprising an additional upstream lens.

Assignees

• Ipg Photonics Corp

Inventors

• Erbatov Timur

Classifications

• B23K26/20

  Bonding (soldering by means of radiant energy B23K1/005) · CPC title

• G02B6/262

  Optical details of coupling light into, or out of, or between fibre ends, e.g. special fibre end shapes or associated optical elements · CPC title

• G02B27/0927

  Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat · CPC title

• B23K26/064

  by means of optical elements, e.g. lenses, mirrors or prisms · CPC title

• B23K26/0652

  comprising prisms · CPC title