Design and construction of a microscope-based Raman system

Abstract

A relatively inexpensive micro-Raman system featuring confocal imaging, holographic optics, and CCD detection is described in detail. The construction of a confocal filter is discussed, along with the depth of field and spatial rejection expected. Limitations of the system such as low-frequency signal rejection by the holographic optics and wavelength calibration are also discussed. Spectra are shown giving examples of the capabilities of the system and the signal-to-noise ratio expected for typical liquid and solid samples.

Identification of insulin variants using Raman spectroscopy

“…Two micro Raman spectrometers of similar design were used for all DCDR measurements [23]. Unless noted otherwise, all measurements were performed using a 633-nm HeNe excitation laser (Spectra Physics model 127) with between 10 and 30 mW directed at an approximately 2-lm diameter spot on the deposited protein sample.…”

“…Either an 80· or a 100· objective (Olympus MDPlan80 or LMPlanFl) was used for both laser illumination and Raman back scattering detection. Exposure times (CCD integration times) of between 60 and 100 s were used to collect all Raman spectra (unless noted otherwise) [23]. The bovine insulin solution and DCDR results shown in Fig.…”

Characterization of select members of the Taxane family using Raman spectroscopy

“…A liquid N 2 cooled charge-coupled device (CCD) detector (Princeton Instruments Inc., LN/CCD-1152E) with 1152 ð 298 pixels and a spectrograph of 320 mm focal length with a 600 grooves/mm grating were employed. 32 In this work, we focused on the fingerprint region of approximately 600-1700 cm 1 , where the most important vibrational bands of the analytes are located. Spectra were recorded at a resolution of 5 cm 1 .…”

A microlens to improve the optical signal from a diamond anvil cell

“…The fact that the diamonds are transparent enables one to investigate the sample with optical techniques, in particular micro-Raman spectroscopy. 2 Usually, the most important limitation for a good performance is that the frame pressing the diamonds is only permitting a small ''window'' to the outside. Moreover, near the diamond the hole in the metal support ͑A in Fig.…”

“…Further, if it is needed to place the DAC in a thermostat or cryostat, the working distance might be larger than 100 mm, which is ten times larger than usual. 2 Therefore, we have tested the idea of placing a planoconvex microlens against the surface of the diamond nearest to the optical equipment ͑see Fig. 1͒.…”