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Beam Blocks and Traps

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Beam Blocks and Traps

Item #Laser InputWavelength
Max Average
BT600(/M)CW200 nm - 3 µm80 WTrap
BT610(/M)CW & Pulsed400 nm - 2.5 µm30 WTrap
BT620(/M)CW & Pulsed1 - 12 µm50 WTrap
BTC30CW200 nm - 3 µm5 WTrap
LB1(/M)CWVisible10 WBlock


  • Laser Safety Devices Reduce Risk of Laser Damage
  • Solutions for up to 80 W or 40 J/cm2 (10 Hz) Beams
  • Post or 30 mm Cage Mounting

Thorlabs' selection of beam traps and beam blocks are common laser lab safety devices. They are designed to be the terminal piece of an optical system and absorb the incident laser beam. Our post-mounted beam traps are suitable for CW (BT600) or CW and pulsed (BT610 & BT620) beams up to 80 W. The BTC30 quick-release trap is suitable for 5 W CW lasers and can be easily inserted into and removed from existing 30 mm cage systems without disassembly. The LB1 beam block provides a large absorptive target area for CW beams up to 10 W.

Laser Safety and Classification

Safe practices and proper usage of safety equipment should be taken into consideration when operating lasers. The eye is susceptible to injury, even from very low levels of laser light. Thorlabs offers a range of laser safety accessories that can be used to reduce the risk of accidents or injuries. Laser emission in the visible and near infrared spectral ranges has the greatest potential for retinal injury, as the cornea and lens are transparent to those wavelengths, and the lens can focus the laser energy onto the retina. 

Alignment Tools
Laser Barriers
Enclosure Systems
Blackout Materials
Laser Glasses
Laser Viewing Cards
Laser Safety Signs
Shutter and Controllers

Safe Practices and Light Safety Accessories

  • Thorlabs recommends the use of safety eyewear whenever working with laser beams with non-negligible powers (i.e., > Class 1) since metallic tools such as screwdrivers can accidentally redirect a beam.
  • Laser goggles designed for specific wavelengths should be clearly available near laser setups to protect the wearer from unintentional laser reflections.
  • Goggles are marked with the wavelength range over which protection is afforded and the minimum optical density within that range.
  • Laser Barriers and Blackout Materials can prevent direct or reflected light from leaving the experimental setup area.
  • Thorlabs' Enclosure Systems can be used to contain optical setups to isolate or minimize laser hazards.
  • A fiber-pigtailed laser should always be turned off before connecting it to or disconnecting it from another fiber, especially when the laser is at power levels above 10 mW.
  • All beams should be terminated at the edge of the table, and laboratory doors should be closed whenever a laser is in use.
  • Do not place laser beams at eye level.
  • Carry out experiments on an optical table such that all laser beams travel horizontally.
  • Remove unnecessary reflective items such as reflective jewelry (e.g., rings, watches, etc.) while working near the beam path.
  • Be aware that lenses and other optical devices may reflect a portion of the incident beam from the front or rear surface.
  • Operate a laser at the minimum power necessary for any operation.
  • If possible, reduce the output power of a laser during alignment procedures.
  • Use beam shutters and filters to reduce the beam power.
  • Post appropriate warning signs or labels near laser setups or rooms.
  • Use laser sign lightboxes if operating Class 3R or 4 lasers (i.e., lasers requiring the use of a safety interlock).
  • Do not use Laser Viewing Cards in place of a proper Laser Barrier or Beam Trap.


Laser Classification

Lasers are categorized into different classes according to their ability to cause eye and other damage. The International Electrotechnical Commission (IEC) is a global organization that prepares and publishes international standards for all electrical, electronic, and related technologies. The IEC document 60825-1 outlines the safety of laser products. A description of each class of laser is given below:

ClassDescriptionWarning Label
1This class of laser is safe under all conditions of normal use, including use with optical instruments for intrabeam viewing. Lasers in this class do not emit radiation at levels that may cause injury during normal operation, and therefore the maximum permissible exposure (MPE) cannot be exceeded. Class 1 lasers can also include enclosed, high-power lasers where exposure to the radiation is not possible without opening or shutting down the laser. Class 1
1MClass 1M lasers are safe except when used in conjunction with optical components such as telescopes and microscopes. Lasers belonging to this class emit large-diameter or divergent beams, and the MPE cannot normally be exceeded unless focusing or imaging optics are used to narrow the beam. However, if the beam is refocused, the hazard may be increased and the class may be changed accordingly. Class 1M
2Class 2 lasers, which are limited to 1 mW of visible continuous-wave radiation, are safe because the blink reflex will limit the exposure in the eye to 0.25 seconds. This category only applies to visible radiation (400 - 700 nm). Class 2
2MBecause of the blink reflex, this class of laser is classified as safe as long as the beam is not viewed through optical instruments. This laser class also applies to larger-diameter or diverging laser beams. Class 2M
3RLasers in this class are considered safe as long as they are handled with restricted beam viewing. The MPE can be exceeded with this class of laser, however, this presents a low risk level to injury. Visible, continuous-wave lasers are limited to 5 mW of output power in this class. Class 3R
3BClass 3B lasers are hazardous to the eye if exposed directly. However, diffuse reflections are not harmful. Safe handling of devices in this class includes wearing protective eyewear where direct viewing of the laser beam may occur. In addition, laser safety signs lightboxes should be used with lasers that require a safety interlock so that the laser cannot be used without the safety light turning on. Class-3B lasers must be equipped with a key switch and a safety interlock. Class 3B
4This class of laser may cause damage to the skin, and also to the eye, even from the viewing of diffuse reflections. These hazards may also apply to indirect or non-specular reflections of the beam, even from apparently matte surfaces. Great care must be taken when handling these lasers. They also represent a fire risk, because they may ignite combustible material. Class 4 lasers must be equipped with a key switch and a safety interlock. Class 4
All class 2 lasers (and higher) must display, in addition to the corresponding sign above, this triangular warning sign Warning Symbol
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Posted Comments:
Poster: c.wedge
Posted Date: 2013-07-16 06:16:43.39
I want to use the BT610/M with a Nd:YAG laser giving 5ns pulses at 20Hz at both 532nm and 355nm. I notice the specifications give a wavelength range of 400nm upwards; is damage likely to result from use in the UV if I remain below the rated power density or will I just get increased back scatter?
Poster: jlow
Posted Date: 2013-07-17 16:34:00.0
Response from Jeremy at Thorlabs: Unfortunately we do not have complete material data below 400nm for the filter glass used in BT610(/M). However, it is estimated that no damage will occur if used at 355nm below the stated damage threshold.
Poster: s.greveling
Posted Date: 2013-04-04 04:22:03.153
I want to use the BT600/M for a 1064 nm cw laser with a 20 W output. I want to make sure the convection is at a mininum and notice from the specs that with an input power of 40 W the housing is heated over 100 Degrees. What will the heating be with an input power of 20 W?
Poster: tcohen
Posted Date: 2013-04-11 10:18:00.0
Response from Tim at Thorlabs: We have not tested at this power, but after modeling this (assuming 25C ambient) we would expect approximately 70C.
Poster: jlow
Posted Date: 2013-01-18 18:44:00.0
Response from Jeremy at Thorlabs: The LB1 would not function as a beam dump for NIR. It would block the NIR beam but there's nothing to capture the small reflection.
Poster: lundblad
Posted Date: 2012-12-07 12:24:37.353
Can I use the LB1 as a beamdump for 1064 nm?
Poster: tcohen
Posted Date: 2012-05-09 11:15:00.0
Response from Tim at Thorlabs: Thank you for your feedback! The 40J/cm^2 value is representative of a 10ns pulse duration at a 10Hz rep rate. Higher rep rates will decrease the max average energy density and past 20Hz CW values should be used. The different operating mechanisms of the BT600 and BT610 make the BT600 more resistant to CW and the BT610 more resilient against pulsed beams. Although 40J/s is 40W, the BT610 is much more suited to take 40J/cm^2 in a 10ns pulse at 10Hz over one second than it is to handle this average power density in CW operation (400W/cm^2).
Poster: Robert
Posted Date: 2012-05-09 07:26:43.0
Is there a typo in the spec for this? If the beam dump can take 40J/cm2, how come it can only take 15W/cm2 (unless the 40J the total energy for any exposure)? 40 Joules per second would be 40 Watts! Whatever the values are, do they apply to pulses in the nanosecond range?
Poster: Thorlabs
Posted Date: 2010-08-06 16:22:45.0
Response from Javier at Thorlabs to last poster: Thank you for your feedback. We have no tested the maximum power density that the LB1 can withstand. We would recommend using the 10 W guideline specification conservatively.
Posted Date: 2010-08-05 10:10:15.0
Hi Thorlabs, for the answer below, what would be the beam dia. for the 10W?
Poster: Thorlabs
Posted Date: 2010-08-03 19:12:10.0
Response from Javier at Thorlabs to last poster: Thank you for your feedback. We do not have precise data for the damage threshold of the black coating on the LB1. However, you can expect deterioration and damage to the coating once the 10 W maximum recommended input is exceeded.
Posted Date: 2010-08-03 16:09:57.0
Regarding your LB1, do you have a reference of damage threshold on the black coating?
Poster: Thorlabs
Posted Date: 2010-07-27 09:46:14.0
Response from Javier at Thorlabs to JMStettler: Thank you for your feedback. The links for the drawings and spec sheets of the beam blocks/traps have been fixed. They should work now. I will send you the specification sheet for the BT510.
Poster: JMStettler
Posted Date: 2010-07-26 14:47:02.0
The links for the spec sheets (under "Documents and Drawings") for BT510, BT600, and BT610 all seem to be broken. Where can I find this information? Under "Beam Trap Specs" I can find some information on the BT600 and BT610, but I dont see anything for the BT510. Is this information anywhere on your website? Thanks, JS
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Beam Traps
BT600 with SM05 Lens Tube
Click to Enlarge

Beam Trap Mounted on a Ø1/2" Post with a Ø1/2" Lens Tube Connected to the Input

Beam traps are common laser lab safety devices that are designed to absorb a laser beam's energy. Versions are offered here that can be used with either CW or pulsed laser beams. Simply align so the beam is directed into the entrance aperture.

These beam traps have internally SM05-threaded input apertures and are 30 mm cage system compatible. A Ø1/2" Lens Tube can be attached directly to the input aperture to shield the laser beam path (see photo to the right). An 8-32 (M4)-tapped hole on the bottom of the beam traps enables post mounting.

Please note that the BT620(/M) contains graphite and may not be suitable for all lab environments. All beam traps will become hot to the touch with beam powers above 10 W.

Item # Wavelength
Laser Type Max Average
Max Average
Power Densitya
Max Energy
Backscatterb Entrance
Max Acceptance
BT600(/M) 200 nm - 3 µm Anodized Aluminum CW 80 Wd 150 W/cm2 30 mJ/cm2 2 x 10-4 @ 633 nm Ø0.43"
(Ø11 mm)
BT610(/M) 400 nm - 2.5 µm Absorptive Neutral
Density Glass
CW and Pulsed 30 W 15 W/cm2 40 J/cm2 f 9 x 10-5 @ 633 nm
BT620(/M) 1 - 12 µm Graphite CW and Pulsed 50 We 25 kW/cm2 25 J/cm2 f 1 x 10-4 @ 633 nm
1 x 10-4 @ 3.39 µm
  • Performance of individual units may differ due to material variability.
  • Total integrated backscatter as a fraction of entrance beam power.
  • In order to ensure optimum performance, measured from the optical axis in any direction.
  • Housing temperature will exceed 100 °C above 40 W input power.
  • Housing temperature will exceed 100 °C above 35 W input power.
  • At 1064 nm, 10 ns, 10 Hz. Performance of individual units may differ due to material variability.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
BT600 Support Documentation
BT600 Beam Trap, 200 nm - 3 µm, 80 W Max Avg. Power, CW Only
BT610 Support Documentation
BT610 Beam Trap, 400 nm - 2.5 µm, 30 W Max Avg. Power, Pulsed and CW
BT620 Support Documentation
BT620 Beam Trap, 1 - 12 µm, 50 W Max Avg. Power, Pulsed and CW
+1 Qty Docs Part Number - Metric Price Available / Ships
BT600/M Support Documentation
BT600/M Beam Trap, 200 nm - 3 µm, 80 W Max Avg. Power, CW Only, Metric
BT610/M Support Documentation
BT610/M Beam Trap, 400 nm - 2.5 µm, 30 W Max Avg. Power, Pulsed and CW, Metric
BT620/M Support Documentation
BT620/M Beam Trap, 1 - 12 µm, 50 W Max Avg. Power, Pulsed and CW, Metric
Quick-Release Beam Trap for 30 mm Cage Systems
BTC30 mounted in 30 mm Cage
A BTC30 Beam Trap mounted onto a
30 mm Cage system.
Click to Enlarge
  • Scatters and Absorbs Laser Beam Energy
  • 30 mm Cage System Compatible
  • Quick-Release Flexure Clamping Mechanism for Secure Cage Mounting without Disassembly
  • Ø8 mm Clear Aperture

Beam traps are common laser lab safety devices designed to absorb laser beam energy. The Quick-Release Beam Trap offered here is optimized to accept CW laser beams of up to 5 W. It is equipped with a flexure-style clamp that snaps onto any two adjacent cage rods of a preassembled 30 mm cage system. To snap the beam trap onto the rods, ensure that the two 4-40 setscrews (0.050" hex) located on the sides of the trap are loose enough to allow the flexure mechanism to snap over the cage rods. Once positioned, these same two setscrews can be tightened to lock the beam trap's position along the rods. For small positional adjustments, slightly loosen the locking screws and slide the device along the cage rods.

Unlike the beam traps sold above, this beam trap is not equipped with a tap for direct post mounting. Caution should be taken when using this beam trap with laser beams above 2 W, as it will become hot to the touch.

Item # Wavelength RangeAbsorptive Material Laser Type Max Average
Max Average
Power Density
Max Energy
Backscattera Entrance Aperture
BTC30 200 nm - 3 µm Anodized
CW 5 Wb 150 W/cm2 c 30 mJ/cm2 b 5 x 10-3 @633 nm Ø0.315"
(Ø8 mm)
  • Total integrated backscatter as a fraction of entrance beam power.
  • Housing temperature will exceed 40 °C above 2 W input power.
  • Performance of individual units may differ due to material variability.
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
BTC30 Support Documentation
BTC30 Customer Inspired! 30 mm Cage-Compatible, Quick-Release Beam Trap, 5 W CW Max Avg. Power
Beam Blocks
LB1 Mechanical Drawing
  • Absorbs up to 10 W CW
  • 3" (75 mm) Long, Ø1/2" Post Included
  • Large, 1.4" x 0.7" (35.6 mm x 17.8 mm) Target Area

The LB1 Beam Block absorbs CW visible laser beams. It is recommended for a maximum power of 10 W. These beam blocks are pre-mounted on a 3" (75 mm) long, Ø1/2" post. The post is easily interchangeable with other Ø1/2" posts or Ø1" posts with 8-32 (M4) taps.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal/Imperial Price Available / Ships
LB1 Support Documentation
LB1 Beam Block (Active Area: 0.7" X 1.4"), Includes TR3 Post
+1 Qty Docs Part Number - Metric Price Available / Ships
LB1/M Support Documentation
LB1/M Beam Block (Active Area: 18 mm X 36 mm), Includes TR75/M Post
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