Spectroradiometers play an important role in the field of remote sensing, helping applications measure spectral signatures of elements from any given distance. While they have been around for at least two decades now, their usage has only increased tremendously over the past few years. Thanks to the research development in building devices that have a bunch of extra features like built-in computer programming, direct display, sampling functions, and portability. The latter has given rise to what are known as field spectroradiometers (as opposed to laboratory version of these devices which are relatively larger) which can be used to make spectral measurements of light sources such as plants and canopies as well as military purposes.
All of this highlights the significance of spectroradiometers in modern-day remote sensing and spectral power distribution (SPD) measurements. This article hopes to shine more light into why these light-calibrating devices are important by focusing on the latest trends in remote light sensing and its myriad of applications today.
Operating Principle of a Spectroradiometer
Before digging deep into the recent trends, it is important to understand the basic premise of spectroradiometers. In simple words, it is a device used to measure certain spectral values such as luminance, irradiance, chromaticity, and radiant intensity in different sources of light. The information collected through this spectral measurement can be used to characterize and calibrate the sources of light, thereby giving us a complete scope and description of the light’s source. In most cases, an integrating sphere or a blackbody is used for the calibration purpose.
A spectroradiometer is made up of several components, four of the most important ones are listed below:
- Input optics – to gather the source’s electromagnetic radiation
- Monochromator – to collect the source’s wavelength information
- Detector – to detect and sample this collected information
- Analyzer – to control, analyze, and log data that may be used at a later stage (in a process)
Considering its chief components, its USP is the ability to work independently without the need for external control or analysis system. It is a standalone device that works effectively on its own and provides data that can be easily sampled onto third-party devices such as external displays. This is also the basic premise of a field spectroradiometer where it can be used for any type of external application and still provide highly accurate data while preventing errors (atmospheric).
When compared to a spectrometer, this device measures all types of radiometric, photometric, and colorimetric elements, thus giving a blanket approach at light measurement. It must be seen as a hybrid between a spectrometer and a radiometer which provides quick and accurate measurements with added portability and affordability.
Some of the spectroradiometers’ most common applications are CFL testing, LED measurement, and display measurement (televisions and monitors). Today, field spectroradiometers are used for traffic lights, daylight measurement, and architecture models. As it becomes a more essential part of such applications, it signifies the need for more development.
So, let’s have a look at the main trends that are governing research and development in the field of spectroradiometry.
Latest Trends in Remote Sensing and Spectroradiometry
The world is going digital. And, so increased the need for such instruments to adapt to these digital systems. In a way, this need to sync with users’ advancing requirements has resulted in a spurt in how technology develops itself. And the biggest evidence we have in this regard is a spectroradiometer itself.
The Advent of Digital Devices
The first trend is its standalone ability – without the need for an external computer – to measure spectral values. Moreover, certain models in the market even have touch-screen displays attached to these devices that only increase their usability in an environment that is continuously looking at reducing overhead costs. The advent of electronic and digital devices to complement analog activities like spectroradiometry is one of the most interesting trends seen in the current landscape.
A good example of this is Konica Minolta’s CS-100 spectroradiometer that has a spectraval CAM with a touch-screen display. Compare that with CI Systems’ flagship SR-5000N – one of the most resilient devices for remote sensing in the market today – and it is clear that a hybrid of these two devices is likely the industry’s next lucrative target.
Powerful New Interfaces
This complements the first trend where new interfaces like Bluetooth and NFC are being equipped in complicated systems to aid in measurement, data collection, and data transmission. WLAN is another interface that has given the maximum output in this field which has made it convenient for technicians to obtain measuring data almost instantaneously.
Miniaturization
This not only deals with the form factor of the spectroradiometer. It also has to do with data transfer through miniature functions like the popular USB. Smaller devices mean more convenience as they can be attached to a production line for constant capturing, analysis, and communication.
Imagine a bio-plant factory where there is a need to analyze plant activity every minute of the day. A miniature field spectroradiometer that can be attached to the assembly line and be used to obtain data in real time would come in very handy for this purpose. And that is where most manufacturers are focusing presently. From ground-based applications to underwater remote sensing, this can have a massive impact on how luminance data is collected and transmitted.
Multichannel Spectroradiometers
This is probably the most obvious trend. The luxury of measuring multiple, different objects simultaneously using a single device is something that can be a boon to the industry. It will not only bring down R&D and production costs but will also lead to much more complex processes. Especially because it has its own set of disadvantages (varied measuring time and switching errors).
While the disadvantages are not terrible deal breakers, it makes sense to consider them while attempting to break the status quo of these sensing devices.
Thanks to the constantly changing landscape of this volatile industry, it is safe to say that there will be a few more trends ready to unleash themselves, surrounding spectroradiometers and remote sensing.