Raman spectroscopy requires a concentrated light source such as a laser to generate Raman signal from a sample, which is often referred to as a ‘Raman laser’ or ‘Raman excitation laser’. Its characteristics impact the quality of the Raman spectrum which can be acquired. This is why the lasers we offer are carefully selected based on their linewidth, stability, and power. Wasatch Photonics offers standalone benchtop lasers from several leading laser manufacturers for Raman spectroscopy (248 to 1064 nm), as well as a line of spectrometers and systems with integrated lasers, which offer unique benefits. Any laser wavelength can be used to generate a Raman spectrum as long as sufficient laser intensity is delivered to the sample. However, there are trade-offs between wavelength and background autofluorescence that determine the best choice for each sample type. When we work with you to configure a Raman spectrometer or system, we aim to balance these factors for the cleanest, strongest spectra.
At Wasatch Photonics, we highly recommend using a Raman system with an integrated laser, as this reduces size & cost and allows full laser control via software. We offer an integrated laser option for most of our WP Raman series (WP 633, 785, 830, and 1064 nm), and for all of our OEM modules: WP 785 XM, WP 830 XM, and WP 1064 X. Integrating the laser with the spectrometer in a Raman system offers many benefits over the use of a standalone or benchtop laser:
Some users prefer a fully modular Raman system for maximum flexibility, in which case we offer the benchtop lasers below for use with Wasatch Photonics spectrometers. (For individual laser purchase, please contact the manufacturer directly.) Note that benchtop or standalone lasers are not directly controllable from our ENLIGHTEN™ spectroscopy software, nor is their wavelength automatically detected to calculate Raman shift accurately. For external laser power control, please refer to the manufacturer’s operating manual regarding availability of control software or SDKs. A 105 µm core multimode fiber (0.22 NA) is often used for lasers with an FC-PC output, but contact us to discuss the best fiber choice and system configuration for your specific application and needs.
For the benchtop laser models we use lasers from the following manufacturers: Photon Systems (248 nm), Hubner Photonics (532 nm), Coherent (638 nm, 785 nm, 830 nm, 1064 nm).
Are you using your own laser for Raman spectroscopy, or buying one as part of a system? You’ll want to make sure it is appropriate for the unique needs of Raman. Here are the parameters we consider to be most important at Wasatch Photonics, and what we look for in any Raman laser we resell, recommend, or integrate:
It is essential to know the exact emission wavelength of the laser used for Raman excitation, as the output wavelength of a Raman laser may vary by up to 1 nm from the nominal wavelength. This value must be used in order to calculate the Raman shift in cm-1 accurately. Even a small, 0.1 nm difference in laser wavelength can result in a 1-15 cm-1 shift in the Raman spectrum (depending on excitation wavelength).
All Wasatch Photonics Raman spectrometers and systems provided with an integrated laser (or purchased from us with a standalone/benchtop laser as part of a configured modular system) already have the exact measured laser wavelength stored in EEPROM, which will be read automatically by our ENLIGHTEN™ software to calculate Raman shift. Note: If you are using any other laser, ENLIGHTEN™ software will assume that the laser wavelength matches the nominal excitation wavelength corresponding to the spectrometer in use (i.e., 785.0 nm for a WP 785 spectrometer). If you wish to write your own laser wavelength to a Wasatch Photonics spectrometer EEPROM.
We also advise performing a daily wavenumber correction to adjust for small changes due to temperature or laser drift.
When you are using a Raman spectrometer with an integrated or standalone laser, it is extremely important to follow all recommended safety precautions. You should also complete your organization’s laser safety training course, or seek one out independently. At a minimum, any Raman system operator should: