In my line of work in Life Sciences, we often deal with liquid media and bubble detection evaluation through a vessel or a tube. This can be done by using the absorption principle or the refraction principle with through-beam-configured optical sensors. These are commonly embedded in medical devices or lab instruments.
This configuration provides strong benefits:
-
- Precise sensing
- Ability to evaluate liquid media
- Detect multiple events
- High reliability
How does it work?
The refraction principle is based on the media’s refraction index. It uses an emitted light source (Tx) that is angled to limit the light falling on the receiver (Rx, Figure 1). When the light passes through a liquid, refraction causes the light to focus on the receiver as a beam (known as a “beam-make” configuration). All liquids and common vessel materials (silicon, plastic, glass, etc.) have a known refraction index. These sensors will detect those refraction differences and output a signal.
The absorption principle is preferred when a media’s absorption index is high. First, a beam is established through a vessel or tube (Figure 2). Light sources in the 1500nm range work best for aqueous-based media such as water. As a high absorption index liquid enters the tube, it will block the light (known as a beam-break configuration). The sensor detects this loss of light.
Discrete on-off signals are easily used by a control system. However, by using the actual light value information (commonly analog), more data can be extracted. This is becoming more popular now and can be done with either sensing principle. By using this light-value information, you can differentiate between types of media, measure concentrations, identify multiple objects (e.g., filter in an IV and the media) and much more.
There is a lot to know about through-beam sensors, so please leave a comment below if you have questions on how you can benefit from this technology.
It’s a new world for real-time, point-of-use information. Stacklights and indicators can provide much more feedback to operators and plant floor managers than ever before.
We have also seen customers mixing their own colors to achieve a level of differentiation. This differentiation could be simple appearance preference or adherence to their corporate color identity. All very achievable with the new class of smart, LED based stacklights and indicators.
possible to define the segments as you see fit. It works by taking control of every LED element. Each SmartLight segment is comprised of four LED elements that can be controlled anyway you want (see Figure 1). For example, with the 3-segment SmartLight, you actually have 12 LED elements that you can organize any way you want. In Figure 2, we only use three LED elements per SmartLight segment, making it a four segment SmartLight. By using two LED elements we create six segments. Figure 3 is even more interesting, in this example we can see the size of the segments are sized by the intended users. Forklift Drivers need a larger light due to the distance and the fact that they are moving. Operators are closer than the forklift drivers, so their segment can be smaller, and maintenance can use the smallest segments because they are closest to the SmartLight when working on the machine.
in close proximity, usually within the work envelope of the operators. In the example shown, the SmartLight is used in a socket tray application. The SmartLight indicates to the operator which socket is required for a specific task. Inductive proximity sensors connected to an IO-Link Hub verify the correct socket was pulled. The photo is showing an All-Call (all lights lit). Here you can see the unique LED element grouping only available with the new Flexible mode. Other applications for operator guidance are essentially endless. There are no technical limitations to your creativity.