#fiber spectrometer

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Fiber Optic Spectroscopy

Optical spectroscopy refers to the techniques used for measuring light intensity in NIR, IR, UV, and VIS regions. A fiber spectrometer comes in handy for these high-end scientific applications.

Spectroscopy is generally the analysis of the interaction between matter and a portion of an electromagnetic spectrum. The technique has evolved from the study of the visible spectrum of light to new modules that allow for the study of x-rays, UV, and gamma rays thanks to technology advancements. Spectroscopic measurements are today valuable in many applications including among others concentration determination of chemical components, electromagnetic radiation analysis, and color measurements among others.

One of the most important industries that have benefitted from advanced spectroscopy is the photonics sector. Photonics revolves around the study and analysis of light generation, detection, and manipulation by taking into consideration emission, transmission, switching, modulation, signal processing, and amplification. Spectroscopy as such takes a central role in facilitating most of the analysis, which requires high-end instruments for accurate results. Photonics is mostly a horizontal industry given that since its foundation it has largely been an enabler for many other sectors and continues to accomplish this role to date.

A fiber spectrometer is a must-have tool for photonics applications as they provide easy and rapid measurements in a couple of minutes. Modern models are also very easy to set up and use making the expertise of their application simplified for even non-specialists. A whole array of fiber spectrometer is available for selection depending on the specifications you are after for an application. Before selecting, attention should be given to the brand which directly determines the efficiency of the equipment. Leading manufacturers have emphasized their production and quality assurance systems as such are always to be considered for their series of spectrometers.

Avantes is one of the leading innovators and manufacturers whose specialization in the development of miniature spectrometer has been above question. The company is ever at the forefront of introducing top class models with improved features to cater for all scientific and research application requirements. Avantes has over two decades experience in the industry providing optical sensing technologies and applied spectroscopy solutions. Their fiber optic spectrometers are famous for their compact build and speed of performance which is based on the latest technology solutions. To ensure compatibility with different systems and computers, they are delivered complete with Avasoft basic software, an extensive manual, and USB cable for connections.

The Starline series is one of the most sought-after fiber spectrometer as it offers an array of solutions for varied uses in the UV and VIS range. Its competitive pricing coupled with the high performance it provides users with makes it one of the best options you could ever settle for in the market. The series is used for a variety of applications including absorbance chemistry, high-speed measurements for process control, optical emission spectroscopy, and transmission measurements for optics, color measurements, & coatings. To find the perfect fiber spectrometer in the series all you have to do select the grit, grating, and detector that match your application and you have a ready tool for instant use.  With an integration time that can be as short as 1.1 milliseconds, your choice could not get any better.

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Choosing A Fiber Optic Spectrometer

Fiber optics direct light into optical detection systems like spectrometers through a total internal reflection process. Due to the fast speed of light, systems that integrate fiber optics are utilized for time-critical situations.

Introduction to fiber optic spectroscopy

Spectroscopic measurements are utilized in a range of applications, including in determining the concentration of chemical components, in color measurements and also in electromagnetic radiation analysis. A spectroscopic tool consists of an entrance slit, a detector, collimator, focusing optics and dispersive elements like a prism or grating. Monochromator systems feature an exit slit, and only a small part of the spectrum is projected on a one-element detector. The position of exit and entrance slits in monochromators is fixed and can be adjusted in width.

The 1990s development of the microelectronics for the multi-element optical detectors like Photo Diode (PD) Arrays and Charged Coupled Devices (CCD) Arrays enabled the manufacturing of affordable CCD cameras, scanners and more. Many companies, like Avantes, are integrating these PDA and CCD detectors into their line of fiber spectrometers, which ensures a fast scanning of the spectrum, without having to move the grating.

Factors to consider when choosing fiber optic

Core diameter

Since the core collects all the light in a fiber optic, its diameter is directly proportional to the amount of light that can be conveyed at any given time. Following this principle, you would expect that a core with a larger diameter will enhance the ratio of signal-to-noise as well as the sensitivity of a spectrometer. While this can hold true to some level, there are limiting aspects that need to be considered when selecting the right fiber optic, like the height the detector pixel.

The optical bench is meant to create the image of the slit on the detector plane. If the detector measures just 200 µm in height, and you pick a core fiber measuring 400 µm, then you’ll waste 50% of the light incident on the detector. If this happens, then you don’t gain from having a larger core. You can resolve this by integrating a spherical lens to the optical bench, on the front side of the detector. This will help to focus the slit’s image to the spectrum, without deforming the image along the axis parallel to the spectrum in the detector plane. The cylindrical lens directs all the light from the core to the detector pixel, which in turn, boosts the sensitivity of the entire setup.

Absorption properties 

This is another essential aspect to bear in mind. The fiber spectrometer won’t be able to detect any light if the fiber optic absorbs all of it. During the production of the optics, the plasma torches (used to soften the bulb) unintentionally dope OH negative ions. These ions form solid absorption bands in the NIR region which significantly impacts the ability to measure broadband through this region. Special low OH negative plasma torches are used to produce fiber optics to mitigate the problem in NIR spectroscopy.

On the other hand, UV array has exceptionally high absorption rates that result from solarization, which gets worse over time with extended UV exposure. That’s why it’s imperative that you pay close attention when selecting fiber for any given application.