Advantages of MTI Instruments Non-Contact Laser Sensors

Interview conducted by Mychealla RiceDec 14 2016

Don Welch, Director of New Business Development at MTI Instruments talks to AZoSensors about the benefits and applications that MTI Instrument's Non-Contact Laser Sensors can be utilized in.

Can you please give a brief overview of the company and the work you do?

MTI Instruments is a worldwide supplier of precision non-contact physical measurement solutions; condition-based monitoring systems, portable balancing equipment, and semiconductor wafer inspection tools. MTI Instruments’ products use a comprehensive array of technologies to solve complex real-world applications in numerous industries including manufacturing, semiconductor, commercial/military aviation, automotive and data storage.

I am the Company’s Director of New Business Development. My position is responsible for developing new markets for existing products, developing new products for new markets, and working with customers to solve their technical requirements.

What is the difference between high-resolution sensors and proximity type laser triangulation sensors?

Proximity laser sensors use laser triangulation to detect the presence of objects with a go/ no-go output. High-resolution laser sensors measure the distance to a target and provide either an analog voltage proportional to the distance or a digital output that directly indicates the distance in engineering units such as mm or inches.

Please can you explain the advantages of non-contact vs contact sensors?

Contact sensors require touching the target to measure distance such as with an LVDT probe. Noncontact sensors, however, use either light reflected off the target or an electric field to sense the distance from probe or sensor to a target so there is no touching or loading on the target that could affect vibration or displacement.

Contact probes could restrict the target motion of dampening an oscillatory motion giving an erroneous result. Additionally, a contact probe would break if touching a rotation target that had an irregular or uneven surface.

What applications in the industrial sector would benefit from MTI’s laser sensors?

Laser sensors are typically good on opaque, nonshiny surfaces for various dimensions to about 1µm accuracy. The applications far outnumber most other conventional sensor applications.

They are ideal for measuring irregular surfaces where the sensor can't be close to the target. The laser sensor is also great for measuring the thickness of nonconductive materials such as plastics, paper, ceramics, etc..

Which laser sensor is best suited for dynamic measurements? Why?

All of our laser sensors are suited for dynamic measurements. They can measure at up to 20, 000 samples second. Our DTS sensors can provide direct digital measurements in mm or inches and the LTS series have analog outputs that can be used for process control.

For thickness and dimensional measurements, which MTI laser would you recommend using?

Typically for thickness measurements, you would want to choose an LTS 50-20 or DTS 50-20 sensor. It has a reasonable measuring range ( 20 mm / 0.8 inch) while not sacrificing resolution.

These sensors can give you about 1µm (0.00004 inches) resolution. Of course, we have larger sensors for applications that require larger measuring ranges,

Please explain your formula of Resolution = Sensitivity x Noise? Why is this important?

All sensors have residual noise in their analog output. This noise is random in nature and limits the sensor's resolution. Reducing the bandwidth of the sensor with the built-in low pass filters also reduces the noise and therefore can increase resolution. Users should choose the lowest filter setting for their application.

Typically the low pass filter setting should be 4-10 times greater than the speed of motion of the application.  

Is it possible for customers to write their own software for MTI’s laser sensor? How?  

Yes its possible MTI provides a software development kit (SDK) with examples of how to write code and we also have LabVIEW drivers if customers want to use the laser sensors with their LabVIEW software.

The SDK and drivers are provided free of charge at the time of order.

Is it possible for MTI’s laser sensor to be integrated with HMI or PLCs? How?

Typically customers use lasers with analog output for interface to a PLC using an analog input card. Our DLT (digital) series uses a USB port and can interface with digital PLC’s with a USB interface (not the programming port) or HMI’s with computational capability that have a USB 2 or USB 3 port.

The sensors get their power right over the USB port. Soon MTI Instruments will have DLT laser sensors and drivers with Ethernet capability so they can directly interface to PLC’s with serial Ethernet sensor capability.

Why is quality control important?

Quality control, especially in automation and manufacturing environment is the most important segment in any company. A failure in one of their production line could cause a company a significant part of their expenses. Without a proper QC, the company not only spend budget on recalls but also raw materials and time wasted on non-conformance products.

Nobody wants to buy a sensor and have it fail in their application. Failure could be poor performance due to a sensor flaw or outright sensor failure. Maintaining quality control over our supply chain and enacting rigorous sensor testing prevents poor quality and ensures a good out of the box experience.

Why is fixturing and environmental conditions important factors to consider? Can they affect results?

It’s necessary to hold the measuring sensor rigidly and properly over a target. I have seen customers design and implement sensor fixtures with long support arms that have vibration caused by their conveyor belts. The vibration then becomes mixed in with their target reading causing what could become a large error in say a thickness reading.

One customer blamed the sensor when it was their poor sensor arm design causing the problem. Also, it’s important to ensure the sensor doesn't become overheated or get wet. One customer mounted a laser sensor on a robot arm that had an integral glue heater.

The heater caused the laser's internal temperature to rise above 60 C causing the laser to extinguish. Isolating the laser from the heater solved the problem.

Where can our readers go to find out more?

Customers can visit http://www.mtiinstruments.com/ to look up product brochures for specifications and MTI University to get answers to some common applications. Additionally, they can contact us at [email protected] to get answers to application issues or help in finding the correct sensor for their application.

About Don Welch

Don Welch has been working at MTI Instruments for over 30 years, initially as a R&D engineer then Director of Engineering, then Director of New Business Development. Don enjoys working with customers to solve applications issues and has extensive industry experience with all types of sensors being used in a wide variety of industrial applications. Don holds a BSEE from Union College.