OBB Monochromator

Monochromator Hardware


This extremely rugged monochromator is built from a single solid metal casting that includes the base plate, optical mounts and all four sides of the unit. Inside the monochromator has extensive baffles to reduce stray light. There is an entrance and exit baffle box at the entrance and exit silts, as well as a center baffle that separates the input side from the exit side of the monochromator.

The monochromator has four optional ports that can be utilized for two inputs and two outputs. In the standard configuration it comes with one entrance and one exit port. This gives you a choice of four different input/output geometries:

180° Straight Line – with folding mirrors on entrance and exit

90° Right Angle – with folding mirror on the exit side

90° Left Angle – with folding mirror on the entrance side

360° – with no folding mirrors

Straight Line Right Angle

180° Straight Line

90° Right Angle

Left Angle 360 Degree

90° Left Angle



You can also elect as an option to have two entrance ports or two exit ports. This option adds an appropriate flipping mirror(s) and slit assemblies. The flipping mirror is manually switched to receive light from either entrance port, or to deliver light to either exit port depending on the configuration.

Dual Exit Ports Dual Entrance Ports Dual Entrance and Exit Ports

Dual Exit Ports

Dual Entrance Ports

Dual Entrance and Exit Ports



The monochromator slits are continuously adjustable manual slits with micrometers for adjustment from 0 to 6 mm. The micrometers have a digital readout of the physical slit size selected. The slit housing also has a manually sliding shutter to quickly shut off or open the light path. This manual slider also has a wedge height adjustment to allow you to select a slit height anywhere from 0 to 21 mm.

digital slit

digital slit

M3 mounting screws on slit assembly


There is a wide selection of gratings to choose from depending on the optical requirements. All gratings are 50 x 50 mm flat gratings. The Ruled gratings have better optical throughput and the Holographic gratings have improved stray light characteristics. Ruled gratings have two fundamental parameters to choose from; the groove density, expressed in grooves (or lines) per millimeter, and the blaze angle which nominally refers to the peak reflectance wavelength expressed in nanometers. The groove density affects the resolution and mechanical scanning range of the monochromator. Below is a reference chart showing the affect groove density has on the mechanical scanning range of the monochromator as well as the reciprocal linear dispersion of the slits.


Groove Density

Mechanical Scanning Range (nm)

Reciprocal Linear Dispersion (nm/mm)

2,400 g/mm 0 to 550 nm 2 nm/mm
1,200 g/mm 0 to 1,100 nm 4 nm/mm
600 g/mm 0 to 2,200 nm 8 nm/mm
300 g/mm 0 to 4,400 nm 16 nm/mm

150 g/mm

0 to 8,800 nm 32 nm/mm


An optional dual grating mount allows you to select two different gratings, say to optimize throughput in different wavelength ranges. The gratings are positioned back to back and a switch dial is available at the top of the monochromator to manually choose which grating is to be used.

Below is a list of our standard gratings. Other gratings are also available upon request.

Available Gratings

Part #


Grating Curve

200 600 g/mm, 1,250 nm blaze Download Curve
201 1,200 g/mm 300 nm blaze Download Curve
202 1,200 g/mm 400 nm blaze Download Curve
203 1,200 g/mm, 500 nm blaze Download Curve
204 Holographic grating 300–800 nm Download Curve
205 75 g/mm 10.0 µm blaze Download Curve
206 150 g/mm, 4.0 µm blaze Download Curve
207 300 g/mm, 2.0 µm blaze Download Curve
209 600 g/mm, 750 nm blaze Download Curve
211 600 g/mm 1.0 µm blaze Download Curve
212 1,200 g/mm, 600 nm blaze Download Curve
213 1,200 line/mm, 750 nm blaze Download Curve


Wavelength Control

The monochromator wavelength is controlled with a manual dial and readout. The readout is designed to be in true wavelength in nanometers for the 1,200 g/mm grating. For other gratings you have to multiply the dial readout by a factor depending on the actual grating resolution. For example with the 600 g/mm grating you multiply the digital readout by 2 to arrive at the true wavelength position of the monochromator in nanometers.


Computer Control

An optional computer control accessory is available. It includes a stepper motor assembly, an MD-2000 USB motor controller interface box and a LabVIEW* driver for computer control of the monochromator wavelength with LabVIEW software from National Instruments.

A very simple software package is also provided by OBB to remotely select the wavelength and control the shutter. Requires Windows 2000 or Windows XP operating system.

Software Screen Shots
Click to enlarge

Monochromator Software Monochromator Software


Top View

Top View


Side View

Side View

digital slit

M3 mounting screws on slit assembly


For more information on OBB's Monochromator visit the Monochromator Specifications page.

*LabVIEW is a trade mark of National Instruments

OBB has a policy of continuous product development and reserves the right to amend part numbers, descriptions and specifications without prior notice.

Monochromator Quick Links





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HORIBA Scientific
Optical Building Blocks
3880 Park Avenue
Edison New Jersey

Tel: 732-494-8660
Fax: 732-623-8129