• TMc300 single monochromator
  • TMc300 single monochromator

This 300mm focal length Czerny-Turner monochromator includes a triple grating turret to permit flexible measurements across a range of 200nm-30µm.  A choice of up to two entrance and/or exit ports facilitate use of multiple input, output and detector configurations.

Compatible with the full range of sources, detectors and accessories of the Bentham portfolio, the TMC300 monochromator is the cornerstone of many proprietary light measurement systems ranging throughout the UV-vis-IR.

Core benefits


  • 300mm focal length single monochromator
  • Built in a single casting, for optimised rigidity and robustness
  • Up to three diffraction gratings permitting single–scan measurement over wide spectral range (200nm-30µm)
  • Up to two entrance and/or exit ports with automated mirror-based port selection
  • Fast wavelength acquisition with zero backlash
  • Large rectangular gratings enhances light throughput whilst optical layout minimises scattered light

Optical Layout

Configuration Symmetrical Czerny Turner
Focal length 300mm
Grating mount Triple grating turret
Number of gratings 1-3
Grating size 68 x 84mm
Aperture ratio f/4.1 (at all grating angles)
Number of entrance/ exit ports 1/2 or 2/1


Mechanical resolution drive 0.000072°/ step
Slit type Fixed, micrometer or motorised variable
Slit width & height 10µm-8mm (W) x 20mm (H)
Filter size 25/ 22mm diameter

Optical Performance (quoted for 1200 g/mm gratings)

Spectral range Within range 200nm-50µm
Linear dispersion 2.7nm/mm
Wavelength accuracy ± 0.2nm
Wavelength reproducibility ± 0.05nm
Resolution full/reduced slit height 0.3/0.1nm
Stray light rejection at 10x FWHM 5·10-5
Wavelength acquisition speed 1000nm/s


Computer interface USB 2.0
Software control BenWin+/SDK

Electrical/ Mechanical

Overall dimensions 316L x 354W x 209H mm
Optical height 115mm
Weight 14 kg
Power supply Mains input 110/220V 50/60Hz

Diffraction Gratings

A range of gratings are available depending on the spectral range of consideration. A range of gratings are available depending on the spectral range of consideration, with up to three diffraction gratings mounted to the turret of the TMc300.

Grating Line density (g/mm) Grating type & Blaze wavelength Maximum wavelength range (nm)
GA-T324R0U25 2400 Plane ruled, 250nm blaze 200-600
GA-T324H0U25 2400 Plane holographic, 250nm blaze 200-600
GA-T324H0U3 2400 Plane ruled, 300nm blaze 200-600
GA-T318H0U25 1800 Plane holographic, 250nm blaze 250-900
GA-T318R0U4 1800 Plane ruled, 400nm blaze 250-900
GA-T318R0U5 1800 Plane ruled, 500nm blaze 250-900
GA-T312H0U25 1200 Plane holographic, 250nm blaze 300-1,200
GA-T312R0U4 1200 Plane ruled, 400nm blaze 300-1,200
GA-T312R0U5 1200 Plane ruled, 500nm blaze 300-1,200
GA-T312R0U75 1200 Plane ruled, 750nm blaze 300-1,200
GA-T312R0U9 1200 Plane ruled, 900nm blaze 300-1,200
GA-T312R1U0 1200 Plane ruled, 1µm blaze 300-1,200
GA-T3083R1U2 830 Plane ruled, 1.2µm blaze 600-1,800
GA-T306R1U0 600 Plane ruled, 1µm blaze 800-2,500
GA-T306R1U25 600 Plane ruled, 1.25µm blaze 800-2,500
GA-T306R1U6 600 Plane ruled, 1.6µm blaze 800-2,500
GA-T306R1U9 600 Plane ruled, 1.9µm blaze 800-2,500
GA-T306R2U16 600 Plane ruled, 2.16µm blaze 800-2,500
GA-T304R1U6 400 Plane ruled, 1.6µm blaze 1,000-3,000
GA-T303R3U0 300 Plane ruled, 3µm blaze 1,500-5,500
GA-T303R4U0 300 Plane ruled, 4µm blaze 1,500-5,500
GA-T3015R4U0-AU 150 Plane ruled, 4µm blaze. Gold coated. 3,000-10,000
GA-T3015R6U0-AU 150 Plane ruled, 6µm blaze. Gold coated. 3,000-10,000
GA-T301R9U0-AU 100 Plane ruled, 9µm blaze. Gold coated. 4,500-16,000
GA-T30075R10U0-AU 75 Plane ruled, 10µm blaze. Gold coated. 6,000-20,000
GA-T30075R12U0-AU 75 Plane ruled, 12µm blaze. Gold coated. 6,000-22,000
GA-T3005R18U0-AU 50 Plane ruled, 18µm blaze. Gold coated. 9,000-30,000
GA-T3005R19U5-AU 50 Plane ruled, 19.5µm blaze. Gold coated. 9,000-30,000


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


An order sorting filter wheel is located inside the entrance port of the monochromator, fitted with 6 filters selected for the spectral range of use.

When measuring below 400nm, no filters are required as the corresponding wavelength of the subsequent diffraction order is less than 200nm, which is naturally blocked by the atmosphere.

Spectral range Required OS filter
<400 m None
400-700nm OS400
700-1250nm OS700
1250-2000nm OS1250
2000-3600nm OS2000
3.6-6 µm OS3600
6-10.5 µm OS6000
10.5-21 µm OS10500
> 21µm Please consult.

Further Options

ND/ BP filters Neutral density filters, used to attenuate optical signal level or band pass filters, to improve monochromator stray light performance, may be mounted in the filter wheel.
Purge ports Purge ports fitted to monochromator to allow purging with nitrogen to remove atmospheric absorbants which absorb in the UV (<200nm) and IR (Various absorption bands).
Toroidal mirrors Toroidal mirrors spherical mirrors replaced with toroidal mirrors for imaging applications.
Turret-mirror A mirror may be fitted on a free location on the turret for the purposes of relating un-diffracted light to the exit port.
418-INT 418 optical chopper mounted behind the entrance slit.
Interchangeable turrets For applications where very wide spectral range or regional optimisation is required, an interchangeable turret is available allowing the exchange of groups of three diffraction gratings to cover different spectral regions. In this case, the stepping motor in this case drives a platform to which is attached the grating assembly.
Shutter Solenoid-based shutter for timed exposure applications.

Monochromator Dimensions

TMc300 single monochromator front dimensions
TMc300 monochromator profile - Front profile
TMc300 single monochromator side dimensions
TMc300 monochromator profile - Side profile
TMc300 single monochromator top dimensions
TMc300 monochromator profile - Top profile

Software Control

The TMC300 may be controlled by PC, facilitated via a USB 2.0 interface by Bentham’s Benwin+ spectroradiometer software, responsible for:

  • Accessing grating filter wheel and slit properties
  • Identifying grating type and position
  • Wavelength selection and calibration
  • Spectral measurements
  • System calibration
  • Configuration files syntax

Alternatively, Bentham offers a comprehensive SDK for user-written programs, available across a wide range of platforms (LabVIEW, Matlab, C++, SPCI protocol, etc.).

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