Sol 1.7: High Performance Linear InGaAs Array Spectrometer

The Sol 1.7 from B&W Tek is a high-performance linear InGaAs array spectrometer that features 512 pixels with TE Cooling down to -5oC and provides large dynamic range and high throughput. Each spectrometer includes a built-in 16-bit digitizer and an SMA 905 fiber optic input, and is compatible with USB 2.0 plug-and-play.

The spectral acquisition software allows users to select between High Dynamic Range and High Sensitivity modes in pre-configured spectral range. Custom-made spectral resolution and application support are also available.

The Sol 1.7 NIR spectrometer features high resolution and extended wavelength options with deeper TE Cooling from +5 °C to -10 °C for better stability and lower noise. It includes additional grating options that allow for 18 additional configurations between 900 nm and 1700 nm, and resolution as fine as 0.35 nm.

Improved electronics allow the Sol 1.7 to function with a 5 VDC power supply, making it all the more suitable for OEM integrators and other similar end users.


The main applications of the Sol 1.7 NIR spectrometer are as follows:

  • NIR spectroscopy
  • Quality control
  • Process monitoring
  • Material identification
  • On-line analyzer


The key features of the Sol 1.7 NIR spectrometer are as follows:

  • Spectral range from 900 nm to 1700 nm
  • Resolution as fine as 0.35 nm
  • -20 oC thermoelectric cooling available
  • Built-in 16-bit digitizer
  • 256 and 1024 pixel configurations available
  • Two gain modes for specific application needs


The main specifications of the Sol 1.7 NIR spectrometer are as follows:

DC Power Input 5 V DC @ 3.5 Amps
AC Adapter Input 100 - 240 VAC 50/60 Hz, 0.5A @ 120 VAC
Detector Type Linear InGaAs Array
Pixels 512 x 1 @ 25 µm x 500 µm Per Element
Spectrograph f/# 3.5
Spectrograph Optical Layout Crossed Czerny-Turner
Dynamic Range High Dynamic Range Mode: 13,000:1
High Sensitivity Mode: 6,250:1
Digitizer Resolution 16-bit or 65,535:1
Readout Speed 500 kHz
Data Transfer Speed >200 Spectra Per Second Via USB 2.0
Integration Time 200 µs to >= 64 Seconds
External Trigger Aux Port
Operating Temperature 0 °C – 35 °C
TE Cooling -5 °C @ Relative Humidity = 90% (-20 °C Option Available)
Weight ~ 3.1 lbs (1.4 kg)
Dimensions 7.8 in x 4.3 in x 2.7 in (197 mm x 109 mm x 68 mm)
Computer Interface USB 2.0 / 1.1
Operating Systems Windows: 7, 8, 8.1 (32-bit or 64-bit)

Technical Details

1. Fiber Coupler

Secures Fiber to Ensure Repeatable Results

By combining a fiber optic with the SMA 905 adaptor, light will be directed to the slit and optically matched to ensure reproducibility. A diffuser or lens assembly can be fixed directly to the SMA 905 adaptor for free space sampling.

2. Entrance Slit

Determines Photon Flux and Spectral Resolution

A pre-mounted and aligned slit vignettes light that enters into a spectrometer’s optical bench. This ultimately determines the spectrometer’s spectral resolution and throughput after grating selection. B&W Tek offer a range of slit widths to match customers’ specific application requirements: from 25 µm to 100 µm wide, with custom slits available.

Slit Option Dimensions Approx. Resolution 900 -1700nm
25 µm 25 µm wide x 1 mm high ~4.0 nm
50 µm 50 µm wide x 1 mm high ~5.0 nm
100 µm 100 µm wide x 1 mm high ~8.4 nm
Custom Slit Widths Available

3. Collimating Mirror

Collimates and Redirects Light Towards Grating

Both mirrors are f/# matched focusing mirrors coated with a special coating that improves the NIR signal.

4. Diffraction Grating

Diffracts Light, Separating Spectral Components

The grating groove frequency determines two key aspects of the spectrometer’s performance: the spectral resolution and the wavelength coverage. When the groove frequency is increased, the device will achieve higher resolution, however, the wavelength coverage will decrease. Inversely, reducing the groove frequency increases wavelength coverage at the expense of spectral resolution.

The blaze wavelength or blaze angle of the grating is also a vital parameter in optimizing the performance of the spectrometer. The blaze angle determines the highest efficiency that the grating will have in a particular wavelength region.

Spectral Coverage (nm) Grating Approximate Resolution 25 µm Slit
1500 - 1600 1000/1310 0.35 nm
1260 - 1355 1000/1310 0.4 nm
1450 - 1650 600/1200 0.8 nm
1200 - 1400 600/1200 0.7 nm
900 - 1300 300/1200 1.5 nm
1200 - 1600 300/1200 1.5 nm
900 - 1700 150/1250 4.0 nm
Custom Configurations Available

5. Focusing Mirror

Refocuses Dispersed Light onto Detector

Both mirrors are f/# matched focusing mirrors coated with a special coating that improves the NIR signal.

6. Array Detector

Measures Entire Spectrum Simultaneously

The Sol™ 1.7 includes a 512 x 1 TE Cooled linear InGaAs photo diode array detector with 512 active pixels and 25 µm x 500 µm pixel dimensions. With BWSpec™, the detector mode can be switched between High Dynamic Range and High Sensitivity modes, allowing for better control over the detector’s sensitivity.

Wavelength Range 900 nm - 1700 nm
Pixels 256, 512 (standard), 1024
Pixel Size 25 µm x 500 µm
Well Depth High Dynamic Mode: ~100 Me-
High Sensitivity Mode: ~40 Me-
Digitization Rate 500 kHz

7. Thermoelectric Cooler

Reduces Dark Noise and Improves Detection Limits

Cooling an array detector using a built-in thermoelectric cooler (TEC) is an efficient way to decrease dark noise and current, and improve the dynamic range and detection limit.

When the InGaAs array detector is cooled by the TEC from a room temperature of 25oC to -10oC, the dark noise is reduced by 3.5 times and the dark current is reduced by 12.25 times. This enables the spectrometer to detect weaker optical signals and function at longer exposure times.

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