Laser Attenuators

A laser attenuator is a device that is used to reduce the power or intensity of a laser beam. The primary use of a laser attenuator is to prevent damage to optical components or human eyes that can occur due to exposure to a high-powered laser beam.

Customization

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Part No.Wavelength (nm)Clear Aperture (mm)Attenuation RangeOptimizationDimensions (mm)
ATTN-3553552.0-10.05% - 95%Transmission88 x 93.5 x 79
ATTN-5325322.0-10.05% - 95%Transmission88 x 93.5 x 79
ATTN-106410642.0-10.05% - 95%Transmission88 x 93.5 x 79
ATTN-940094002.0-10.05% - 95%Transmission80x 84 x 95
ATTN-10600106002.0-10.05% - 95%Transmission80 x 84 x 95
ATTP-35535514.00.5% - 95%Transmission78 x 87 x 75
ATTP-53253214.00.5% - 95%Transmission78 x 87 x 75
ATTP-1064106414.00.5% - 95%Transmission78 x 87 x 75

  • Laser Attenuator (Polarization Insensitive)

The laser attenuator is especially useful for laser sources with fixed output powers. There are both fixed and variable laser attenuators depending on the intended attenuation required. Variable attenuators are readily available with either manual adjustment or motorized adjustment. The laser attenuator in no way affects the direction of the beam propagation after attenuation.     

  • Polarizing Laser Attenuator

Precision laser applications require fine power control. A variable attenuator with a large dynamic range and precision control is designed to fulfill this purpose. It is suitable for intensity attenuation over a wavelength range from UV to IR.

  • Laser Attenuator (Polarization Insensitive)

Laser Attenuator Diagram

  • Polarizing Laser Attenuator

Polarizing Laser Attenuator Diagram

  • Laser Attenuator (Polarization Insensitive)

Item No.: ATTN-10600-WC-V1
Wavelength: 10.6μm
Clear Aperture: Up to 19mm (Customizable)
Transmission Range: 10 – 90%
Damage Threshold: 1MW/cm^2
Resolution: 5%

  • Polarizing Laser Attenuator

Wavelength: 355/532/1064nm
Type: Transmission Mode
Clear Aperture: 14mm
Beam Shift: 0.5mm
Extinction Ratio: >200:1
Attenuation Range: 0.5%-95%
Damage Threshold: >5J/cm2@1064nm, 20ns, 20Hz
Weight: <300g

Laser & Variable Attenuators Application Note

Laser-Optics-Laser-Attenuator
Image of a laser attenuator

Part 1: Controlling the Output Power using Laser Attenuators

A laser attenuator is an optical device capable of reducing the optical power or intensity of the incoming laser beam. This is especially useful for laser sources with fixed output powers. There are both fixed and variable laser attenuators depending on the intended attenuation required. Variable attenuators are readily available with either manual adjustment or motorized adjustment. The laser attenuator in no way affects the direction of the beam propagation after attenuation.

Operation Principle

The laser attenuator optics works on the principle of reflection where a percentage of light is reflected off the surface of the optics, which is dielectric coated and the remainder is transmitted through. The angular rotation of the optics changes the angle of the incident light on the optics which in turn causes a change in the transmission ratio which ultimately changes the attenuation level. Due to the angular rotation of the optics, the laser beam passing through the optics undergoes refraction which changes the path of the outgoing laser beam. In order to correct this issue, a second optic is used in sequence and the two optics are moved in tandem to not alter the direction of the beam propagation as seen in Figure 1.

Figure 1.

The key specifications of the Bessel Lens are listed below. Compared with similar products in the market, we offer a larger aperture for larger beam diameters and an efficient operation at high power.

Item No.ATTN-10600-WC-V1
Wavelength10.6μm
Clear ApertureUp to 19mm (Customizable)
Transmission Range10 – 90%
Damage Threshold1MW/cm^2
Resolution5%
Table 1. Key specifications of ATTN-10600-WC-V1

*The attenuator is available for operation at 9.4μm.

The architecture of the laser attenuator allows for larger beam input without the worry of beam clipping during transmission and the water cooling channels allow for constant cooling throughout the operation to prevent any damage or beam manipulation at any point in time. The design of the laser attenuator can be seen in Figure 2.

Figure 2. Design features of ATTN-10600-WC-V1

Applications

The internal design of the laser attenuator allows for efficient absorption of reflected light. It is designed for attenuation of collimated beam outputs and not focusing beams. The laser attenuator can be implemented into any laser system with the purpose of precise control or reduction of the output beam power.

Figure 3. ATTN-10600-WC-V1 outline

The compact design, as seen in Figure 3, allows for ease of integration into laser systems and the base plate allows for easy manufacturing of holders or adapters for mounting the laser attenuator. A motorized version is also available upon request.

Part 2: Precision Control by the Principle of Polarization using Variable Attenuators

Precision laser applications require fine power control. A variable attenuator with a large dynamic range and precision control is designed to fulfill this purpose. It is suitable for intensity attenuation over a wavelength range from UV to IR.

Operation Principle

This variable attenuator consists of a specially designed optomechanical adapter and a precision optomechanical holder. The key optics involved are a half-wave plate and a thin film polarizer. The half-wave plate is usually made of birefringent crystal cut parallel to the optical axis. It is used to change the polarization direction of the incident beam.

Figure 1. Principle of polarization attenuator

A thin film Brewster-type polarizer placed after the half-wave plate reflects s-polarized light while transmitting p-polarized light. The intensity ratio of s-polarized to p-polarized beams may be continuously varied by rotating the wave plate. The intensity of either the exit beam or their intensity ratio can be controlled over a wide dynamic range. P-polarization can be selected for maximum transmission. A full range of attenuation from maximum to minimum can be achieved by rotating the half-wave plate from 0 to 45 degrees. For constant monitoring of power, the beam dump can be replaced with a power meter.

Figure 2. The layout of the polarization attenuator

The key specifications of the polarization attenuator at different operating wavelengths are listed below. Compared to similar products in the market, we offer a large dynamic range of attenuation, which is useful for precision laser process control.

Wavelength355/532/1064nm
TypeTransmission Mode
Clear Aperture14mm
Beam Shift0.5mm
Extinction Ratio>200:1
Attenuation Range0.5%-95%
Damage Threshold >5J/cm2@1064nm, 20ns, 20Hz
Weight<300g
Table 1. Key specifications of polarization attenuator

Applications

The following listed characteristics enable the polarization attenuator to precisely control the laser intensity with fine adjustment steps. Using a suitable type of polarizer, this principle can be realized at very high-power levels.

  • Divides laser beam into two parallel beams of the manually adjustable intensity ratio
  • Large dynamic range
  • Negligible transmitted beam deviation
  • High Optical damage threshold
  • Transmission attenuation range 0.5% – 95.0%

The application of polarization optics design is not limited to attenuation of laser intensity; other applications include phase control (phase retarding), interferometer, etc.

Figure 3. Varieties of polarization laser optics

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FAQ

What is the use of an attenuator in the laser micromachining process?

Attenuators are used in laser micromachining to control the intensity of the laser beam that is used to cut or ablate material.

The intensity of the laser beam is important because it determines the amount of energy that is delivered to the material being processed. If the intensity is too high, it can cause damage to the material or create unwanted side effects such as thermal stress, melting, or vaporization. On the other hand, if the intensity is too low, it may not be sufficient to achieve the desired material removal rate or precision.

Attenuators work by reducing the power of the laser beam without altering its spatial profile or beam quality. This allows the user to precisely adjust the energy delivered to the material being processed, which in turn can improve the quality and precision of the micromachining process.

Attenuators can be either passive or active. Passive attenuators use filters, glass planes, or polarizers to absorb or reflect some of the laser light, while active attenuators use devices such as electro-optic modulators or acousto-optic modulators to vary the laser power in real-time. The choice of attenuator depends on the specific requirements of the micromachining process, including the laser wavelength, power, pulse duration, and repetition rate.

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