Portable Raman Equipment is distinguished from “Handheld” on the basis of it being larger and generally offers higher spectral resolution. In addition, the equipment almost always uses a fiber coupled Raman probe rather than an open beam (although some SERS based portable systems are open beam, and a small number of suppliers offer integrated portable Raman systems with open beam excitation & collection. Portable Raman is also associated with “Modular Raman”.
IPS lasers are well suited for portable Raman applications and generally fall into 2 categories:
- Multi-Mode sources – Used for fiber coupled probe-based systems. Key characteristics are high power (typically >350 mW) and a homogenous output. Power stability is becoming very important in this space since many OEM customers use modular Raman systems as their initial starting place while developing a Custom Built for Purpose (CB4P) system that can be used in process environments. IPS’s new ultra-stable MM laser design “-ET-HPU” is a great choice for portable/modular for this reason! In addition, these lasers are easily power adjustable by either changing drive current or using Pulse Width Modulation. This is helpful in applications where customers may change between samples that are power sensitive and liquid samples that are not.
- Single mode sources – The SM lasers offer very high-power density – so they can generate a LOT of Raman in a small area, but they can burn samples easily and they focus to extremely small spots. Systems that move the beam can take full advantage of the small form factor and high-power density…but other systems that don’t move the beam could focus to a tiny spot interstitially between grains of a sample and have poor Raman signal generation and can burn samples. In cases where customers are using open beam and cannot move the beam around, the STUB laser is an alternative since it offers lower power density, a homogenous intensity profile and a larger spot.