Many market surveys for optical sensors have been done over the past several years in the United States, Japan, and Europe. While the estimates vary considerably, owing to the variety of assumptions, they nevertheless agree in predicting a large and growing optical fiber sensor market over the next two decades. Shown in Figure 6.8 are data from a 1993 Frost and Sullivan Market Intelligence estimate (FSMI 1993) and also data from OITDA.
Best Performance Levels of Various Optical Sensor Types
Fig. 6.8. Optical sensor market survey.
The obvious differences between the U.S. and Japanese figures are thought to be a result of OITDA including more of the sensor systems in its numbers. OITDA's numbers are the sums of actual sales figures obtained from direct polling of member companies; likewise, future projections are the sums of estimates polled from OITDA members. (Newer OITDA projections were unavailable when this report was prepared.)
The FSMI report indicates that the unit price of sensors, a very important parameter, is currently about $300 and is expected to decline to about $150 by the year 2000. This would seem contrary to many reports. For example, major programs are in place to reduce rotation sensor prices below $1,000, aiming toward $500 (Elwood 1995). Reasons for this discrepancy include the mix of products being sold: many of the high-unit-volume sensors are low in cost. Additionally, many sensors used in medical applications are disposable, so that instrumentation unit costs are amortized over many sensor units.
The mix of sensor types has changed over the years as well. In the early days of sensor development, it was projected that displacement, position, and proximity sensors would constitute the majority of units sold. The segment occupied by these sensors today is small and decreasing. Today, temperature, pressure, and chemical sensors probably constitute the biggest segment of the sensor market. Of these three, chemical sensing, mostly associated with medical and biomedical applications, is showing the fastest growth. Another market area of considerable interest is automotive sensing. Potentially, the automotive sensor market could grow to several billion dollars over the next several decades if all the parameters to be sensed could be done cost-effectively in an optical format. However, this market is extremely price conscious, and it is not clear that optical techniques will be able to penetrate the market.
Another important market area for sensing is the civil infrastructure. The constantly aging system of bridges, highways, buildings, railroads, dams, pipelines, etc., continually suffer outages due to material fatigue. Increasingly, embedded fiber-optic sensors hold promise for more routinely monitoring this aging and offer the possibility of taking remedial action prior to catastrophic failure. A conference on the subject of "smart structures" was first held in 1992 (SPIE 1992) and has become an annual event. Issues associated with the technology for this market mostly have to do with packaging and attachment of the sensors. It is in these areas that much research is taking place, mostly at universities. The other issue is cost; currently optical sensors are as much as 100 times more expensive than corresponding mechanical or electronic sensors.