Product Description

1.5LRB Length Reference Bar

Use an Invar length reference bar with your tracker

Our 1.5LRB Length Reference Bar provides a NIST-traceable length for use during laser tracker or scanner jobs. Use it to establish system scale when using single measuring instruments or when bundling multiple instruments together. Or use it to verify system accuracy and stability during a measurement job. Many of our customers shoot a length reference bar at the beginning, middle, and end of a job to gain confidence that nothing moved or changed during the shoot.

The 1.5LRB consists of a single length of our Invar tubing outfitted with two permanently mounted, 1.5INV magnetic SMR nests for a 1.5″ SMR. (SMRs not included.) Also included are two 15199 Invar system “feet”, positionable at your discretion.

The 1.5LRB is available in customer-specified lengths, English or metric (90″ or 2.3m maximum). Actual length will be within ±1/32″ (0.8mm) of requested length, but our calibration lab will provide a certificate with NIST-traceability indicating the actual length of the assembly within ±0.0001″ (0.003mm).

Invar is an excellent material for this application due to its extreme stability over a wide temperature range. Take a look at the table below to see the stability of Invar reference bars compared with other materials.

Deviation in Length of 80″ Reference Bar
at Various Temperatures
Tempature °F Steel Aluminum Invar
40° -0.0180″ -0.0292″ -0.0015″
50° -0.0116″ -0.0188″ -0.0010″
60° -0.0052″ -0.0084″ -0.0004″
68° (std) ±0.0000″ ±0.0000″ ±0.0000″
70° +0.0012″ +0.0020″ +0.0001″
80° +0.0076″ +0.0124″ +0.0007″
90° +0.0140″ +0.0228″ +0.0012″


Note: If you don’t need NIST-traceability of a given dimension, but just require a consistent length for system checks, you may want to build your own reference bar using our Invar system and related targets.

May Be Used With

Any 1.5″ SMR


Length accuracy:
NIST-traceable certification to ±0.0001″ (0.003mm); length of bar will be within ±1/32″ (0.79mm) of requested length
Maximum length: 90″ (2.3 m)
Case: High impact plastic.
Case only included for the 1.5LRB-1050mm bar.