M74050
1/4M IMAGING SPECTROGRAPHS
27
7.1 DETERMINING RESOLUTION
All spectrographs featuring fixed slit holder(s) require fixed slits to be installed at the input port and
optional output ports. Fixed slits are ordered separately, and should be the same size at the input
and output ports. Micrometers adjustable slits allow for continuous variation of the width and height.
Use the table below for guidance on resolution vs. slit width.
Resolution is listed for each grating at the grating's blaze wavelength, i.e. the wavelength with the
greatest efficiency. Actual performance is determined by the spectrograph wavelength accuracy,
precision and calibration. Newport suggests having the spectrograph recalibrated annually by a
qualified service technician.
Unless otherwise stated, the values shown are for a 1024 array with 26 x 26 um pixels. For 200 um
high pixels (2048 element array), the resolution is half this value. All gratings used in the high
resolution configuration are 1200 lines/mm.
Calculation of Resolution Based on Fixed Slit Selection
Fixed Slit
Slit Width
Grating 1
Grating 2
Grating 3
High Resolution Configuration
77222
10 µm*
0.25 nm
0.25 nm**
0.25 nm
77220
25 µm*
0.35 nm
0.35 nm
0.35 nm
77725
77221
50 µm*
0.50 nm
0.50 nm
0.50 nm
77219
77728
100 µm
0.65 nm
0.65 nm
0.65 nm
77729
77730
200 µm
1.2 nm
1.2 nm
1.2 nm
77731
77732
500 µm
3.2 nm
3.2 nm
3.2 nm
* For slits with widths of 50 µm or less, aberrations begin to play a role in the actual achievable
resolution. Empirically measured resolution values shown which differ from calculations due to
aberrations present when using narrow slit widths.
** This value is achieved with either a 1024 or 2048 element array.