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Adjustable Beam Expander

CASTECH's adjustable beam expanders have a conventional working wavelength of 355nm, the magnification can be 2-10 times. It has many advantages, such as compact, divergent angle adjustable and the diameter of the output beam is large. It is widely used in laser processing. The product also has standard thread interface. In addition, it also can be customized to the working wavelength and appearance according to customer demand.


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      Beam expanders are optical devices used to increase the diameter of a collimated input beam to a larger collimated output beam. CASTECH's adjustable beam expanders have a conventional working wavelength of 355nm, the magnification can be 2-10 times. It has many advantages, such as compact, divergent angle adjustable and the diameter of the output beam is large. It is widely used in laser processing. The product also has standard thread interface. In addition, it also can be customized to the working wavelength and appearance according to customer demand.

 

Features:                                                 Applications:

◆ Fixed magnification                                                        Short pulse lasers

Compact beam expanders                                            Ultra-short pulse lasers

For large beam diameters                                             Laser scanning

Customized design available

 

Specifications:

Material

Fused Silica

Wavelength

355nm

Magnification

2, 3, 4

5, 6, 7, 8, 10

Clear Input Aperture

12mm, 8mm, 8mm

8mm

Clear Output Aperture

26mm, 26mm, 20mm

31mm

Max. Input Beam Diameter

10mm, 6mm, 4mm

6mm, 4mm, 4mm, 3mm, 3mm

Outside Diameter

42mm

46mm

Total Length

58mm

86mm

Screw Thread

M30×1

M30×1

Transmission

>98%

>98%

Divergence Adjustable

Yes

Yes

Product specifications are subject to change without notice;

Customized (Wavelength, Dimension, Power Handling , etc) are available;

Note:All products are RoHS compliant.

 

 

Order No.

Magnification

Material

C.A.(φ)

mm

Max exit(φ)mm

Outside

(φ)mm

Length

(mm)

Thread

Adjustable range(mrad)

BE355-2-30-A/B

2

Fused silica

12

26

42

58

M30×1

0.02-2.6

BE355-3-30-A/B

3

Fused silica

8

26

42

58

M30×1

0.03-3.6

BE355-4-30-A/B

4

Fused silica

8

20

42

58

M30×1

0.05-5.2

BE355-5-30-A/B

5

Fused silica

8

31

46

86

M30×1

0.02-36

BE355-6-22-A/B

6

Fused silica

8

31

43

80

M22×0.75

0.03-43

BE355-6-30-A/B

6

Fused silica

8

31

46

86

M30×1

0.03-43

BE355-7-30-A/B

7

Fused silica

8

31

46

86

M30×1

0.09-50

BE355-8-22-A/B

8

Fused silica

8

31

43

80

M22×0.75

0.07-62

BE355-8-30-A/B

8

Fused silica

8

31

46

86

M30×1

0.07-62

BE355-10-30-A/B

10

Fused silica

6

31

46

86

M30×1

0.1-70

 BE-355-2-30-B:

BE-355-5-30-B:

Beam expanders are optical devices used to increase the diameter of a collimated input beam to a larger collimated output beam. Beam expanders are used in applications such as laser scanning, laser cutting, interferometry, and remote sensing. The most common type of beam expander is derived from the Galilei telescope which usually has one negative input lens and one positive output lens, as shown in the following figure.

 

 

As shown in figure, the lens1 focuses the laser beam onto the front focuses plane and the new beam waist ω’0 and divergence angle θ’ can be represented as:

 

whereω(l) is the radius of the beam input the lens1, l is the distance  between the lens1 and the beam waist ω0 , and f1 is the focal length of the lens1. Since ω’0lies on the back focus plane of the lens2 with a longer focal length f2, the Gaussian beam with a beam ω’0will be collimated by the beam expander. The collimation ratio of the beam expander for a Gaussian beam is as follows:

where T1 =f2/f1. The beam waist ω”0 and divergence angle θ” after the beam expander are:

Substituting Equation(1) to Equation(5), the following expression can be obtained:

 

From Equation(4)-(7), it is concluded the beam expansion ratio and the collimation ratio  for a Gaussian beam depend not only on the specifications of the beam expander, but also on the laser beam parameters as well as the positions of the lenses.

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