• Rulers with Imperial and Metric Scales for Hands-Free Measuring
  • Mounting Bracket for Beam Height Rulers


Magnetic Measuring Tape


Mounting Bracket for Beam Height Rulers


6" (155 mm) Magnetic Beam Height Measuring Tool

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Thorlabs offers two solutions for hands-free measuring on an optical table or breadboard. First, our MFT1 Magnetic Measuring Tape lays flat on any magnetic surface to provide a reference for the position of components. Second, our BHM3 and BHM4 Magnetic Beam Height Rulers feature holes at 25 mm and 1" intervals to allow a laser beam to pass through. The rulers are laser engraved with both imperial and metric scales and are held onto any magnetic surface by two magnets in their bases.

A Mounting Bracket is also available that allows two beam height rulers (Item # BHM3 and BHM4) to be attached at a 90° angle. This allows for alignment of a laser beam horizontally in addition to measuring its height off the table.

Posted Comments:
Fatin Jalil  (posted 2020-09-09 19:29:42.96)
Please advise where I can distributor for this part number : MFT1 at Malaysia/Singapore? That because I just want to purchase for 5 unit only
YLohia  (posted 2020-09-10 10:23:27.0)
Thank you for contacting Thorlabs. Our list of international distributors can be found here: Our distributor in Singapore is Laser 21 Pte Ltd. (
Clément Jacquard  (posted 2020-08-12 11:04:23.153)
I am looking for such a product, although I align beams in the near IR. I would love to have smaller holes like 1mm diameter, every 2mm (yes that's a lot of holes, or even every 1mm with a lateral displacement instead of the inch scale) and a way to stick a VRC4 on the exit side of the holes in the back. This way I can precisely align my near IR beams. I would buy one and drill holes myself but I would have to anodize it again for the sake of safety.
DJayasuriya  (posted 2020-08-14 10:59:05.0)
Thank you for your inquiry. One of our application engineers will get in touch directly to discuss custom capability.
Nils Dessmann  (posted 2020-07-29 06:31:38.31)
The BHM is a super helpful tool. However, it seems that the alignment holes are shifted with respect to the ruler values. The one I use has an offset of less than, but not exactly 0.5mm (e.g. ruler at 200mm, center of hole at approx. 199.6±0.2mm). There are some occasions (aligning OAPs) where this really matters. Is that a fabrication or precisions issue? I can provide images of this.
DJayasuriya  (posted 2020-08-06 06:18:33.0)
Thank you for getting in touch with us. We have contacted you directly to resolve the issue and our quality team is looking into the fabrication process.
mojtaba.zamani.a  (posted 2017-08-19 08:14:20.493)
is it possible to buy MFT1 without your logo on it? we just need magnetic tape with its graduations.
nbayconich  (posted 2017-08-28 05:57:19.0)
Thank you for contacting Thorlabs. I will reach out to you directly about providing this as a custom option.
cbrideau  (posted 2013-06-03 18:24:11.48)
I would love to see a narrower version of this, say 1cm wide, to make it easier to use on a crowded optical table.
tcohen  (posted 2013-06-13 12:49:00.0)
Response from Tim at Thorlabs: Thank you for your suggestion. I agree this would be a convenient alternative for tight spaces and I am looking into offering this.

Magnetic Measuring Tape

Magnetic Ruler
Click to Enlarge

MFT1 Measuring Tape Covering One Row of Holes on an Optical Table
  • Magnetic Over Entire Backside of Ruler
  • Attaches to Optical Table or Breadboard for Hands-Free Measurement Guide
  • Flexible Material for Easy Rolling and Storing
  • Numeric Marks Every 1" and 1 cm, Tick Marks Every 1/8" and 1 mm
  • L x W x Thickness: 1 m x 1" (25.4 mm) x 0.03" (0.8 mm)

This vinyl magnetic measuring tape provides a convenient solution for determining approximate distances hands free on an optical table or breadboard. With a magnetic back that extends over the full length and width of the ruler, this measuring tape lays flat on any magnetic surface and features both imperial and metric scales, with numeric marks every 1" and 1 cm and tick marks every 1/8" and 1 mm. Only 0.03" (0.8 mm) thick, the ruler maintains a low-profile on the table. If a shorter length is desired, the ruler can be cut into segments. Please note that vinyl can stretch; consequently, this measuring tape should be used as an alignment aid and not as a precision measurement tool.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
MFT1 Support Documentation
MFT1Magnetic Measuring Tape, 1 m Long

Magnetic Beam Height Rulers

BHM Diagram
Click to Enlarge

Each ruler has holes next to the major ticks of the metric and imperial scales to allow a laser beam to pass through.
BHM3 Typical Application
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Light from a HeNe Laser Passing Through a Hole in a BHM3 Ruler
  • Imperial and Metric Laser Engraved Scales
    • 1.0 mm Metric Graduations
    • 1/16" Imperial Graduations
  • Facilitate Laser Beam Alignment Using Holes Spaced at 1" and 25 mm Intervals
  • Measure Beam Height on Magnetic Optical Tables or Breadboards
  • Neodymium Magnets Provide Holding Force
  • Homogeneously Diffusive Anodized Coating

Our BHM3 and BHM4 Magnetic Rulers measure beam heights up to 6" (155 mm) or 12" (305 mm), respectively. The front of the screen is laser engraved with 1.0 mm and 1/16" graduations for beam height measurement. A series of twelve or twenty four Ø2.0 mm (Ø0.08") holes (on the BHM3 and BHM4 respectively) are positioned next to the engraved numbers at 25.0 mm and 1.00" intervals to allow a laser beam to pass through the ruler.

The base of each ruler is fitted with either one or two neodymium magnets that hold the ruler to magnetic work surfaces and provide flexibility of movement when compared to an option that is bolted to the table. The BHM3 has one of these magnets, while the BHM4 has a pair. Both rulers are constructed from bead-blasted aluminum to remove any sharp edges and then anodized to create a homogeneously diffusive surface. The compact size allows the tool to fit into small gaps between components, enabling easy integration into a setup.

We also offer the BHMA1 bracket below for attaching two beam height rulers, allowing for the alignment of a laser beam horizontally in addition to measuring its height off the table.

Please note: Due to the presence of magnets, this ruler should not be used in the vicinity of pacemakers, credit cards, or other devices affected by magnetic fields.

Item # Ruler Surface
Dimensions (W x H)
(L x W)
Thickness Numbered
Graduations Hole Spacing Hole Diameter Damage Threshold
BHM3 30 mm x 160 mm
(1.18" x 6.30")
20 mm x 30 mm
(0.79" x 1.18")
2.0 mm
Every 1" and 10 mm 1/16" and 1.0 mm 1.00" and 25.0 mm 2.0 mm (0.08") >350 J/cm2
(1064 nm, 20 ns, 20 Hz, Ø1.14 mm)
BHM4 40 mm x 310 mm
(1.57" x 12.20")
20 mm x 40 mm
(0.79" x 1.57")
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
BHM3 Support Documentation
BHM36" (155 mm) Magnetic Beam Height Measurement Tool
BHM4 Support Documentation
BHM412" (305 mm) Magnetic Beam Height Measurement Tool

90° Mounting Bracket for Magnetic Beam Height Rulers

Click to Enlarge

BHM3 Ruler Mounted at 90° on a BHM4 Ruler Using the BHMA1 Bracket

Click to Enlarge

VRC4 IR Detector Card on a BHM3 Ruler
  • Mount Two Beam Height Rulers Perpendicularly
  • Ideal for Horizontal and Vertical Beam Measurements
  • Mount a Laser Viewing Card to a Beam Height Ruler
  • Built-In Spirit Level Simplifies Leveling of the Mounted Card or Ruler
  • Laser Engraved with 1.0 mm Graduations
  • Constructed From Black Delrin®*

Thorlabs' BHMA1 Mounting Bracket allows two beam height rulers to be attached at a 90° angle. This capability allows for alignment of a laser beam horizontally in addition to measuring its height off the table. As shown in the image to the right, the bracket can also be used to attach Laser Viewing Cards to a ruler, allowing for the viewing of UV, NIR, or MIR beams.

Click for Details

BHMA1 Mechanical Drawing

Constructed from durable black Delrin, this bracket contains a built-in spirit level (bubble level) for consistent leveling of the mounted part. When the bubble is centered between the two graduations the bracket is level. When the center of the bubble is under one of the graduations then the bracket is rotated by 31 arcminutes.

Laser engraved 1.0 mm spaced graduations are also included on three sides of the bracket. These markings can be used to indicate how far the mounted part has been translated horizontally or to repeatably add a ruler or viewing card into the setup. 

A through slot in the top of the bracket, shown in the drawing to the left, is shaped to fit over the top of the BHM3 and BHM4 rulers. Once fitted the bracket is free to translate vertically across the ruler. From here a second ruler or a viewing card is placed in the space between the first ruler and the front of the bracket. Everything is held in place by applying pressure using the thumbscrew on the front of the bracket.

Please Note: These brackets are created from Delrin and are not rated for laser safety.

*Delrin® is a registered trademark of DuPont Polymers, Inc.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
BHMA1 Support Documentation
BHMA190° Mounting Bracket for Magnetic Beam Height Rulers