How to Choose Spectrometers and Detectors for Raman and Photoluminescence

Webinar

Choosing a spectrometer and detector for Raman or photoluminescence spectroscopy starts with your wavelength range, required spectral resolution, signal level and acquisition time. Grating, focal length, entrance slit and detector settings must work together to balance sensitivity, spectral coverage and measurement speed.

Abstract

Struggling to resolve closely spaced peaks, measure weak signals or accelerate spectral mapping? Your results depend on how the spectrometer, detector and collection optics work together.

In this webinar, HORIBA’s Philippe de Bettignies explains the principles of dispersive spectroscopy and the parameters that influence Raman and photoluminescence measurements. Discover how diffraction gratings, focal length, slit width and optical coupling affect spectral resolution, wavelength coverage and light efficieny.

The session also explores CCD, electron-multiplying CCD (EMCCD) and InGaAs detectors, including quantum efficiency, detector noise, cooling and acquisition modes. Practical examples explain why higher dispersion does not automatically deliver better resolution, when EMCCD detection can support shorter acquisitions, and how etalon fringing can affect spectral interpretation.

Watch the webinar to make more informed choices when configuring a spectroscopy system or optimizing an existing instrument for your application.
What you will learn

  • Distinguish spectral resolution from spectral dispersion and sampling.
  • Understand numerical aperture, f-number and optical étendue.
  • Select grating groove density and blaze wavelength for your spectral range.
  • Balance slit width, light efficiency and peak separation.
  • Compare detector technologies for different wavelengths and signal levels.
  • Understand read noise, dark noise and shot noise.
  • Choose acquisition settings for point measurements and spectral mapping.
     

Who should watch?

Researchers, laboratory scientists, engineers and students using Raman or photoluminescence spectroscopy, particularly those selecting instrumentation or improving measurement performance.

Watch the webinar

Language: English | Duration: Approximately 54 minutes

Frequently asked questions

Start with the wavelength range, spectral features you need to resolve and available signal. Then assess focal length, grating groove density, grating efficiency, entrance slit and detector compatibility together. The appropriate configuration depends on the balance you need between resolution, spectral coverage, sensitivity and speed.

Spectral dispersion describes how wavelength or Raman shift is distributed across the detector, often expressed in nanometers per pixel or inverse centimeters per pixel. Spectral resolution describes the ability to distinguish closely spaced spectral features. Finer sampling alone does not guarantee better optical resolution.

A narrower entrance slit can improve spectral resolution by reducing the width of the slit image on the detector. However, it can also reduce the amount of light entering the spectrometer. The best setting provides enough peak separation while retaining sufficient signal.

Higher groove density generally increases dispersion, spreading the spectrum across more detector pixels and reducing the spectral range captured in one acquisition. Grating efficiency also depends on wavelength and blaze design, so groove density alone is insufficient to select a grating.

An EMCCD amplifies the electron signal before readout, reducing the relative impact of read noise. This can help with weak signals and short integration times, including some Raman mapping measurements. Its benefit depends on the signal, background and acquisition conditions.

Etalon fringing results from interference caused by internal reflections within the detector’s silicon layer. It can introduce oscillations in broad spectra or modulate peak intensities. Detector design and treatments can reduce this effect, making it an important consideration for measurements at longer wavelengths.

Cooling reduces dark current and its associated noise. This becomes particularly important during longer exposures, when thermally generated charges accumulates. For short acquisitions, read noise may have a greater influence on performance.

InGaAs detectors are used for infrared measurements beyond the useful spectral response of silicon CCDs. Selection should account for the required wavelength range, quantum efficiency, dark current, cooling and exposure time.

About the speaker

Philippe de Bettignies works on new technologies at HORIBA France. At the time of this webinar, he had more than 15 years of experience at HORIBA, including a previous role as Raman Microscopy R&D Manager. In this session, he explains how spectrometer optics and detector characteristics influence practical Raman and photoluminescence measurements.

Related Information

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