Apparatus for carrying out spectroscopy

An apparatus for carrying out Raman spectroscopy on a sample,

• the apparatus comprising an optical system which is configured to guide a first portion of a laser beam to a sample and a second portion of the laser beam to a reference sample,
• wherein a first spectrum beam is generated from an interaction between the first portion of the laser beam and the sample and a second spectrum beam is generated from an interaction between the second portion of the laser beam and the reference sample;
• the optical system being configured to guide the first spectrum beam and the second spectrum beam to a diffraction element, wherein the diffraction element is configured to split the first spectrum beam into a first spectrum of spatially separated wavelength components associated with the sample and to split the second spectrum beam into a second spectrum of spatially separated wavelength components associated with the reference sample;
• the apparatus comprising a detector with an array of pixels for detecting the first and second spectrum on the array of pixels;
• wherein the sample and the reference sample are placed in different positions in the optical system;
• and
• wherein the optical system comprises an optical filter having a surface facing a grating and a surface facing at least one of the sample and the reference sample, the optical filter being reflective for the first portion of the laser beam and the second portion of the laser beam and transmissive for the first and second spectrum beams, wherein the reference sample is arranged on one of the surfaces of the optical filter,
• wherein the optical system is configured to guide the first portion of the laser beam such that it is reflected from the optical filter and incident on the sample, wherein the first portion of the laser beam is bypassing the reference sample;
• wherein the optical system comprises an optical slit through which the first and second spectrum beams are guided by the optical system,
• wherein the optical slit formed by a separate optical element is arranged between the optical filter and the grating, and
• wherein the optical element forming the optical slit is movable such that the optical slit can be aligned in at least one direction in a plane perpendicular to an optical axis of the optical system.