• DMc150 compact double monochromator

Comprising twin 150mm focal length Czerny Turner single monochromators operating in tandem with additive dispersion, the DMc150 offers exceptional optical performance within a small footprint.

Compatible with the full range of sources, detectors and entrance optics of the Bentham portfolio, the DMc150 is at the heart of many of our light measurement solutions including those for:-

  • Type-testing of tanning appliances
  • Accurate dosimetry of sources used in phototherapy (including PDT and PUVA)
  • Monitoring of solar UV irradiance
  • NVIS compatibility testing



  • Comprises twin 150mm focal length monochromators
  • Built in a single casting, for optimised rigidity and robustness
  • Stepping motor and sine bar driven diffraction gratings
  • Predictable sinusoidal wavelength accuracy
  • One entrance and up to two exit ports with automated mirror-based port selection for use of multiple input/ output configurations
  • Control electronics integrated and fully automated via USB 2.0 interface

Optical Layout

Configuration Pair symmetrical Czerny Turner monochromators, additive dispersion
Focal length Total focal length: 300mm
Individual Units: 150mm
Grating mount Kinematic
Number of gratings 1 pair
Grating size 33x33mm
Aperture ratio f/4
Number of entrance/exit ports 1 entrance, 1-2 exits
Spectral range Within range 200nm-2400nm


Wavelength scanning By integrated stepping motor and micro-stepping drive electronics
Slit type Fixed, micrometer or motorised variable
Slit width & height 10µm-10mm (W) x 20mm (H)
Filter size - 6 position filter wheel : 25mm diameter
- 8 position filter wheel : 22mm diameter

Optical Performance (quoted for typical 2400 g/mm gratings)

Spectral range 200-600nm
Linear dispersion 1.35nm/mm
Wavelength accuracy ± 0.15nm, ± 0.05nm with software correction
Wavelength reproducibility ± 0.05nm
Resolution full/reduced slit height 0.25/0.1nm
Stray light rejection at 2.5 FWHM 10-8
Wavelength acquisition speed 30nm/s


Computer interface USB 2.0
Software control BenWin+/SDK

Diffraction Gratings

A range of gratings are available depending on the spectral range of consideration. Diffraction gratings are supplied in pairs, on kinematic mounts to permit easy installation in the DMc150 without compromising the wavelength calibration.

Grating Line density (g/mm) Grating type & Blaze wavelength Maximum wavelength range (nm)
GA-G1524H0U25 2400 Plane holographic, 250nm blaze 200-600
GA-G1518H0U25 1800 Plane holographic, 250nm blaze 200-800
GA-G1518R0U5 1800 Plane ruled, 500nm blaze 200-800
GA-G1512R0U4 1200 Plane ruled, 400nm blaze 300-1,100
GA-G1512R0U5 1200 Plane ruled, 500nm blaze 300-1,100
GA-G1512R0U75 1200 Plane ruled, 750nm blaze 450-1,100
GA-G15083R1U2 830 Plane ruled, 1.2µm blaze 650-1,700
GA-G1506R1U25 600 Plane ruled, 1.25µm blaze 800-2,400
GA-G1506R1U6 600 Plane ruled, 1.6µm blaze 800-2,400

Order Sorting

A filter wheel is located behind the entrance slit of the DMc150 to accommodate a shutter and long pass filters as required for the spectral range of operation. A six position filter wheel, for 25mm diameter filters is fitted as standard. An eight position filter wheel, for 22mm diameter filters is required where more positions are required.

Spectral range Required OS filter
<400 nm Under standard conditions- none required
Under purged operation OS310
400-700nm OS400
700-1250nm OS700
1250-2000nm OS1250
2000-3600nm OS2000

Slit Configuration

The DMc150 can be configured in the compact, in-line or dual layouts. In the latter case a solenoid-driven programmable swing away mirrors (SAM), controlled by the internal drive electronics, is fitted for port selection.

Slit Type

The dimension of the largest of the entrance/ exit slits defines the bandwidth of the monochromator. Fixed, micrometer variable and motorised variable slits are offered, with a slit height of 20mm. For tuneable light source applications a range of exit slit apertures are available. Please enquire for further information.

Slit type Features
Fixed slits (FSS) - Manually controlled
- Spring leaf to ensure the correct placement of the slit
Micrometer variable slits (VSS) - Manually controlled
- Bi-lateral slits
- Variable from 10µm to 10mm
Motorised variable slits (MVSS) - PC control via USB
- Driven via internal monochromator electronics or external MAC electronics bin
- Comprising stepping motor driven bi-lateral slits
- Variable from 10µm to 10mm

Further Options

Neutral density filters A range of metallic neutral density filters, for installation in the IDR150 filter wheel, are available for the purposes of signal attenuation.
Purge port Installation of purge ports on IDR150 to enable purging of the space within the monochromator for VUV work.

Monochromator Dimensions

DMc150 double monochromator front dimensions
DMc150 monochromator profile - Front profile
DMc150 double monochromator side dimensions
DMc150 monochromator profile - Side profile
DMc150 double monochromator top dimensions
DMc150 monochromator profile - Top profile

Software Control

The DMc150 may be controlled over the USB 2.0 interface using our Windows application Benwin+ or by user written code based on our SDK on a wide range of platforms (Labview, Matlab, C++ etc. Using configuration files, both applications allow:

  • Accessing grating, filter wheel and slit properties
  • Wavelength selection
  • Spectral measurements

Benwin+ includes higher functionality including:-

  • Easy system calibration
  • Obtain spectrally integrated (and weighted) quantities
  • Instantly obtain colorimetric data
  • Perform transmission, absorption and reflection measurements
  • Perform simple arithmetic functions
  • Utilities for control of translation stages, goniometers, RSB, data acquisition from other instruments etc.

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