Spectrometers> Multichannel Spectrometers

Description

Many applications require acquisition of signal from more than one source at a time. This is especially important in process line control, biomedical applications, microscopy, aerial imaging or hyperspectral imaging. P&P Optica has designed a line of high performance spectrometers which can image up to 140 separate channels simultaneously using a single, low cost, high spectral resolution instrument. The unique multichannel spectrometers use volume phase holographic (VPH) transmission diffraction gratings, and refractive optics to provide high resolution, low noise spectral acquisition in the 350 to 2500 nm spectral ranges.

P&P Optica's multichannel spectrometers use multi fiber input, whose disperesed spectra are projected onto a two dimensional detector. This creates a separate spectrum for each fiber, thereby allowing each fiber to be considered as a separate channel. The number of channels thus available is limited by the length of the slit which can be imaged on the detector array, the diameter of applied fibers and the distance between the fibers selected to ensures acceptable cross-talk level between the spectra of corresponding fibers. The cross-talk strongly depends on the performance of the spectrometer and has been dramatically reduced by proper design and selection of the applied optical elements.

The images below illustrate a multichannel application where six separate fibers were simulteneously collecting radiation from a pencil mercury spectral lamp at several points along its length. The top image shows all channels as registered on a 2D detector, with corresponding normalized spectra for a few of these channels shown below.

More information regarding the design and performance of the P&P Optica line of spectrometers can be obtained in the following white paper: Multichannel Imaging Spectrometers.

Available Systems

Product Name Spectral
range
[nm] 		Slit
length
[mm]		 Slit
width
1[µm]		 High spec.
res. 2
[nm]		 Specral
resolution3
for 0.1mm fiber
[nm]		 Bit
depth
[bit]		 Dynamic
range
/pixel 		Number of
channels4		 Dynamic
range
per chan.		 Frame
rate
[fps]
From To
MSPPEC BB -15-1.47
380
1150
4.0
13
1.5
4.5
16
4,800
15
15,000
1.4
MSPPEC UVI1-15-1.4
350
680
4.0
13
0.7
2.1
16
5,500
15
15,000
1.4
MSPPEC VIS1-15-1.4-HS
380
740
4.0
13
0.8
2.1
16
5,500
15
15,000
1.4
MSPPEC VIS1-30-30
380
740
8.0
5
0.4
1.9
12
2,200
30
15,400
30
MSPPEC VIS1-30-18
380
740
8.0
5
0.2
1.3
12
2,800
30
19,600
18
MSPPEC VIS1-30-8
380
740
8.0
5
0.2
1.3
12
2,000
30
14,000
8
MSPPEC VIS2-15-1.4-HS
400
780
4.0
13
0.7
2.1
16
4,800
15
15,000
1.4
MSPPEC VIS2-15-1.4-LN
400
780
4.0
13
0.7
2.1
16
5,500
15
21,000
1.4
MSPPEC VIS2-30-30
400
780
8.0
5
0.4
2.1
12
2,200
30
15,400
30
MSPPEC VIS2-30-18
400
780
8.0
5
0.2
1.4
12
2,800
30
19,600
18
MSPPEC VIS2-30-8
400
780
8.0
5
0.2
1.4
12
2,000
30
14,000
8
MSPPEC VIR1-15-1.4-HS
455
885
4.0
13
0.8
2.4
16
4,800
15
15,000
1.4
MSPPEC VIR1-15-1.4-LN
455
885
4.0
13
0.8
2.4
16
5,500
15
21,000
1.4
MSPPEC VIR1-30-30
455
885
8.0
5
0.4
2.4
12
2,200
30
15,400
30
MSPPEC VIR1-30-18
455
885
8.0
5
0.3
1.6
12
2,800
30
19,600
18
MSPPEC VIR1-30-8
455
885
8.0
5
0.3
1.6
12
2,000
30
14,000
8
MSPPEC VIR2-15-1.4-HS
490
955
4.0
13
0.9
2.6
16
4,800
15
15,000
1.4
MSPPEC VIR2-15-1.4-LN
490
955
4.0
13
0.9
2.6
16
5,500
15
21,000
1.4
MSPPEC VIR2-30-30
490
955
8.0
5
0.5
2.6
12
2,200
30
15,400
30
MSPPEC VIR2-30-18
490
955
8.0
5
0.3
1.7
12
2,800
30
19,600
18
MSPPEC VIR2-30-8
490
955
8.0
5
0.3
1.7
12
2,000
30
14,000
8
MSPPEC VIR4-15
575
1120
4.0
13
1.1
3.1
16
5,500
15
21,000
1.4
MSPPEC NIR1-20
875
1700
5.0
34
5.2
8.9
12
1,000
20
2,000
50
MSPPEC NIR1-30-12B
875
1700
8.0
14
2.6
7.1
14
2,700
30
8,100
30
MSPPEC NIR1-30-14B
875
1700
8.0
14
2.6
7.1
14
2,800
30
8,400
120
MSPPEC NIR3-20LR
1105
2155
5.0
21
8.3
15.1
14
8,000
20
16,000
100
MSPPEC NIR3-25
1105
2155
6.8
34
6.6
14.2
16
6,700
25
13,400
100
MSPPEC NIR3-20HR
1105
2155
6.0
5
3.3
12.6
16
6,000
23
24,000
120
MSPPEC NIR4-20LR
1285
2500
5.0
21
9.5
15.1
14
8,000
20
16,000
100
MSPPEC NIR4-25
1285
2500
6.8
34
7.6
14.2
16
6,700
25
13,400
100
MSPPEC NIR4-20HR
1285
2500
6.0
5
3.8
12.6
16
6,000
23
24,000
120

1Maximum slit width for full spectral resolution.

2Highest spectral resolution achieved. Spectral resolution is determined by the slit width and instrument performance (such as here). Many systems on the market erroneously present spectral resolution as dispersion per pixel, giving misleading information.

3Spectral resolution achieved when fiber with 0.1mm core diameter is used instead of the slit.

4Number of bright fibers 0.12mm of external diameter separated by dark fibers of the same diameter (provides minimal crosstalk and optimal signal strength.) This can be doubled by reducing the collection fiber diameter to 0.06 mm. If crosstalk is acceptable, further channel increase is possible.

5The minimum distance between two bright points so that they are resolved as defined by the Releigh criterion.

6As obtained after performing a subtraction of noise averaged along a column.

7System without suppression of second order effects.

Please contact us at sales@ppo.ca for more information about the above systems, higher channel counts or other specifications.

Technical Specifications

Parameter Value
size 32cm L x 12cm W x 10 cm H
weight typically <4 kg
F/number F/3
Spectral range (free of second order effects) 90-95% of an octave in the 350 nm to 2500 nm range
Spot diameter 19 µm @ 1000 nm in 25.4 x 9 mm2 area
Spectral resolution (0.024 mm wide pixels) 0.5 nm @ 400 nm and 2 nm @ 2000 nm
Linear dispersion 90%-95% of an octave per inch
Maximum detector size 25.4 x 12.7 mm
Dynamic range of a single 0.024 by 0.024 mm 2 pixel > 3,000 (typical TE cooled silicon detector)
Number of channels Up to 144, depending on the wavelength, acceptable cross-talk, input fiber and detector

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