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High-Aperture Compact Monochromator

Model ML44

High-Aperture Compact Monochromator ML44

The ML44 is a compact high-aperture short-focus monochromator operating in the spectral range of 190-1200nm. Complemented by a light source, the ML44 can be successfully used as a monochromatic illuminator for fluorescence excitation.

  • Extremely high aperture
  • Absence of astigmatism at the output
  • Change slits on the fly
  • Compact size and low cost
  • Extended delivery set, including condensers and fiber adapters



The ML44 monochromator comprises two diffraction gratings mounted on a single rotation axis. Spectrum scanning and diffraction grating change are automated. The wavelength for automatic gratings switching is set by the user in the instrument software.

Entrance and exit slits are changeable; they are mounted on two six-position discs. Each disc contains six spectral slits pre-aligned by the manufacturer. To change the slit width you just need to manually rotate the knob moving it to one of its six fixed positions. Two indicators on the ML44 housing show the widths of entrance and exit slits, and the software calculates the spectral width of the line separated by the monochromator.


compact monochromator ML44

The delivery set contains two optical fiber adapters and two fused silica condensers. Condensers and fiber adapters can be installed on the entrance and/or the exit slit. The condenser is used to focus the light onto the monochromator entrance slit, as well as to focus the light, coming from the monochromator, to the object. Fiber adapters allow to transfer the light to/from the monochromator via optical fibers (SMA-905 connectors). Optical fibers can be supplied upon your request.

Scanning control is performed from a computer via the serial RS-232 port. The delivery set contains a USB-RS232 adapter providing the USB interface.

The program DLL and/or LabView drivers are available at your request.

Option Value
Spectral range, nm 190-1200
Focal length of the collimator and camera lenses, mm 44.2
F/Number 1 : 2.9
Size, mm 25 * 20 * 6
Lines/mm 1200 600
Blazing wavelength, nm 270 700
Reciprocal linear dispersion (average), nm/mm 18.7 34.7
Operating spectral range, nm 190-600 450-1200
Wavelength of automatic change of grating, nm 600 (program controlled)
Tuning step by angle, deg 0,01875
Tuning step by spectrum, nm 0.125 0.25
Wavelength accuracy, nm ±1.0 ±1.5
Wavelength repeatability, nm ±0.25 ±0.5
Scanning speed, nm/s 200 400
Time required for wavelength tuning, s minimum maximum 0.001 38.4
Entrance/exit slits (changeable)
Slit width, mm 0.02; 0.05; 0.1; 0.25; 0.5; 1.0
Slit height, mm 3.0
Spectral interval (average) separated by ML44 at width of entrance and exit slits:
slits width 20µm 0.35nm 0.7nm
slits width 50µm 0.9nm 1.8nm
slits width 100µm 1.8nm 3.5nm
slits width 250µm 4.5nm 8.9nm
slits width 500µm 9.0nm 17.7nm
slits width 1000µm 18.0nm 35.5nm
Interface RS 232, USB
Computer requirements OS Windows 2000, XP, 7
Dimensions, mm
monochromator 154*114*147
driver 90*155*40
Weight, kg
monochromator 2.1
driver 0.6

A distinctive feature of the ML44 monochromator is the use of high-quality achromatic lenses as a collimator and a camera instead of mirror optics. This ML44 feature provides a number of its significant advantages over other short-focus monochromators:

  • the ML44 is extremely compact
  • as compared with mirror optics, lenses ensure better stray light rejection
  • lenses can provide higher apertures at short focal lengths
  • lenses are centered optical systems allowing aberrations compensation


High-Aperture compact monochromator model ML44

As a result of all these advantages the ML44 features exceptionally high aperture (F # 1:2.9), good line quality and does not have any astigmatism at its exit slit plane.

  • As an efficient spectral selector for investigation of detectors and light sources
  • As a tunable narrow-band filter for broadband fluorescence excitation sources
  • As an order separation pre-disperser in spectral instruments containing Echelle diffraction gratings
  • As part of other research and analytical equipment operating in the UV, visible and NIR spectral range
  • For spectroscopy education at colleges and universities
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