Components of MCV-500 laser calibration system. All the components, including the laser head, processor module retro-reflector and steering mirror, pressure and temperature sensors, and cables, fit in a small carrying case (in the background).

Why Laser Doppler Displacement Meter (LDDM) is better?

The performance is better and more flexible. The system is more efficient and easier to set up and operate.

What are the benefits?

It is more compact, lower cost, and a good return on investment (ROI).

How is LDDM more compact?

The exit laser beam and the return laser beam are co-axial. Therefore, the laser head and the retro-reflector are small and compact. In addition, all of the optical components are small.

What are the benefits?

The laser head is mountable directly on the machine and there is no need for a heavy tripod. The setup and alignment is relatively easy and fast. Movement and vibrations of the machine on its leveling pads or isolation foundation does not influence the measurements. The complete system can be fitted into a single small carrying case for easy transportation and storage.

Why is LDDM more efficient?

For MCV-2002, there are two laser interferometers in one head. Therefore, the displacement error and the angular error can be measured simultaneously. For MCV-500 or MCV-5000, the patented vector method can measure the 3D volumetric positioning errors, including three displacement errors, six straightness errors, and three squareness errors, in a few hours instead of a few days.
 

What are the benefits?

It automatically collects more data in a short time. Automatic data collection and on-the-fly data collection reduce the data collection time to a minimum. Therefore, it reduces expensive machine downtime.
 

Why is LDDM easier to setup and align?

The laser head is very small. With a magnetic holder, it can easily be mounted directly on the machine. There are only two elements to be aligned instead of three elements, therefore, the alignment is easier.
 

What are the benefits?

Reduction in expensive machine downtime and less training for the operator.
 

How is LDDM flexible?

The laser beam diameter can be large enough to resist air turbulence or small enough for multi-pass optics. It can also use a flat-mirror as target. Therefore, it is more flexible for various applications, such as sequential step diagonal measurement, non-contact laser ballbar, and nano-positioning with sub-angstrom resolution.
 

What are the benefits?

It can measure the static volumetric positioning accuracy, the dynamic contouring accuracy, and the spindle error motion. It can perform both calibrating and compensating the static positioning errors, and monitoring and optimizing the dynamic servo parameters.
 

Why is LDDM versatile?

With add-ons, it can perform different tasks on different machines.
 

Set up of a body diagonal displacement measurement on a DMG vertical machining center (top) and on a Giddings and Lewis horizontal machining center (bottom). The laser head is mounted on the machine bed and the flat-mirror target is mounted on the spindle.

What are the main versatility benefits?

One LDDM for all the machines is a savings of capital expenses.
 

How does the LDDM provide a longer range?

Since the laser head is single aperture, the laser beam can be collimated well and expand to very large diameter. In addition, the detector is more sensitive with higher signal bandwidth. The FM scheme is also more immune to noise. All these factors give the LDDM a longer range in a shop environment.
 

What are the benefits?

It can be used to calibrate very large machines in a vibrating and noisy environment.
 

Why does LDDM has greater resolution?

For an AM system, two detectors are needed to determine the direction of the displacement, while for a FM system, only one detector is needed. Therefore, the signal to noise ratio and the signal bandwidth are higher, and, in turn, the LDDM is more sensitive and higher resolution.
 

What are the benefits?

With large signal to noise ratio, the misalignment tolerance is large. Hence, it is easy to set up and align, and reduces the machine downtime.
 

Why is LDDM more accurate?

The laser frequency is frequency locked and the laser accuracy is traceable to NIST. Because of the two-frequency, FM, single-aperture and large beam diameter, it is less sensitive to environment interferences such as air turbulence and mechanical vibrations. Therefore, it is more accurate in the shop environment.

What are the benefits?

Meet the ASME B5.54 and ISO 230 standards, and traceable to NIST.
 

Why is LDDM faster?

The FM carrier frequency is very high. Therefore, the signal bandwidth is very high. It can reach a maximum velocity of 5m/sec or 300,000mm/min.
 

A dual beam laser system for rotary axis measurement. Both the linear displacement and the angular variations can be measured simultaneously. It is equivalent to two laser interferometers built in one.

What are the speed benefits?

With high speed and high data rate, it can be used for high-speed linear motor machine and machines with high resonance frequency.
 

Why is LDDM safer to the eye?

The maximum laser output power is less than 0.5mw. It is safer for the eye, when accidentally exposed to the laser beam.
 

What are the safety benefits?

No worries about personnel being affected by stray laser beams, and it easily meets laser safety requirement.
 

Why is LDDM Affordable?

It uses the latest technology such as Electro-Optic, Radio Frequency, and digital electronics, and with many patents. The performance to price ratio is very high, making it quite affordable.
 

What are the benefits?

Higher performance with lower cost.
 

What are the capabilities?

Since the laser head is single aperture, either a small retro-reflector, a flat-mirror, or any specula-reflecting surface can be used as target. Therefore, it has more capabilities.
 

What are the benefits?

It can be used to measure linear position errors, angular errors, straightness errors, squareness errors, master and slave axes, dynamic contouring errors, toolpath tracking, 3D volumetric positioning error measurement and compensation, and spindle error motion. One instrument for all the measurement saves on capital expenses. In addition, the sub-Angstrom positioning measurement and feedback can be used for nano-technology and MEMS applications.

Conclusion
With all the above features, benefits, and high performance to price ratio, the LDDM is the most cost effective and best capital investment. It minimizes the measurement time and machine downtime. It also improves the machine accuracy, quality, and productivity.

Optodyne, Inc.
Rancho Dominguez, CA
optodyne.com; optodyne-sh.com