Optical spectrometer and raman microscope comprising such a spectrometer

An optical spectrometer (10) comprising:

• at least one aperture (13) configured to receive a source light beam, a first optical system (18), a planar diffraction grating (22), a second optical system (28) and an image sensor (32), the first optical system (18) being arranged and configured to receive the source light beam and to form a collimated light beam directed towards the diffraction grating (22), the diffraction grating (22) being positioned so as to receive the collimated light beam and configured to form a diffracted light beam, and the second optical system (28) being arranged and configured to form an image of the diffracted light beam on the image sensor (32),
• wherein:
• the image sensor (32) is a CMOS sensor including pixels (34) arranged in N rows oriented in a direction that is inclined at most by an angle alpha with respect to the spectral diffraction direction of the image of the diffracted light beam, where the angle alpha is less than 10 degrees, N being an integer higher than or equal to 3, each pixel (34) has a height h and a width w defining a pixel aspect ratio R=h/w, wherein the pixels (34) all have the same height h and the same width w and the pixel aspect ratio R is higher than 2.