Three Extended Range Gratings

Extended MS260i imaging spectrographs come with three general purpose ruled gratings that are installed and aligned on a triple grating mount. A high precision motor is used to select the desired wavelength and switch between three diffraction gratings quickly, without sacrificing performance.

Optical Design

The optical design of the MS260i is based upon an asymmetrical in-plane version of a Czerny-Turner monochromator. The input is f/3.9, and the input and exit focal lengths are 220 nm and 257 nm. The MS260i produces a flat, 28 x 28 mm image plane for use with multichannel detectors. Toroidal mirrors are used to produce accurate images of the input slit in the flat output plate. The optical configuration is designed to ensure high resolution and maximum throughput. This spectrograph is optimized to provide excellent stray light rejection while minimizing aberrations. Spatial and spectral resolution are measured independently and optimized by Newport during the instrument calibration process. The exceptional flat field and minimal optical aberrations of the MS260i mean that the resolution is very nearly constant across the entire focal plane. The MS260i magnifies the image by a factor of 1.1 horizontally, and a factor of 1.6 vertically.

Fixed Slit Versions

Fixed slits should be used for the utmost accuracy and repeatability, especially at high resolution. Fixed slits are the best option when only a few slit sizes are required, as they are less expensive. The fixed slits slide into the holder at the input port, as well as the holder at the lateral output port on dual output models. The width and height cannot be adjusted, but may be individually replaced with other slit sizes. Individual fixed slits are required and sold separately to allow customized choices based on the needs of the application (see accessory section). Order one fixed slit for single output port models, and two identical fixed slits for the dual output port spectrographs. The slit width is one of the factors determining the resolution and throughput of the instrument, with a narrow slit providing higher resolution and lower throughput.

A fixed slit is shown installed into the fixed slit holder.

Micrometer Adjustable Slit Versions

Micrometer adjustable slits offer flexibility and high throughput, but are not as accurate or repeatable as fixed slits. The micrometer adjustable slit assembly is continuously variable from fully closed to 3 mm width. The narrowest practically achievable width is 4 µm. A height adjustment slide allows variation in the height from 2 to 12 mm. This type of slit is designed primarily for versatility and convenience in changing resolution and throughput. The micrometer adjustable slit assembly is pre-installed at the input port on the single output port models, as well as at the lateral output port on dual output models.

Motorized Slit Versions

A motorized slit installed at the input port allows control of the slit width of the input port through the utility software, an optional hand controller, or the optional TracQ Basic software. This enables automated slit control or hands-off operation. The motorized slit assembly may be adjusted from 6 µm to 2 mm width in 6 µm steps. An advantage of using a motorized slit is that in addition to setting the slit width manually, the software can be configured with an automatic bandpass setting. The software adjusts the slit width to maintain the chosen bandpass as the wavelength range is changed. Manual calculation of the slit width for a desired resolution is valid at the peak wavelength for a grating. The software performs additional mathematical calculations to take into account any change in wavelength away from the blaze wavelength. The motorized slit is installed only at the input port.

Optional Hand Controller

All models include a connector to utilize the optional 74009 Hand Controller for manual operation without a computer. The display provides information on the grating selection, active filter position, current wavelength, shutter status, and more.

LineSpec CCD Array Detector Mounting

The axial output port on the MS260i includes a mounting flange used to connect the model 78855 LineSpec CCD Array Detector that can be ordered separately. This flange may be removed and the mounting holes utilized to install another detector, if desired. The LineSpec CCD detector’s spectral responsivity range is from 200 to 1100 nm. Pixels are 200 µm high x 14 µm wide on 14 µm centers, with 2048 total pixels. The LineSpec includes an easy-to-use spectroscopic data acquisition software package, while the MS260i includes utility software to control the spectrograph.

Motorized Filter Wheel Accessory Control

The MS260i is capable of automatically controlling the optional model USFW-100 filter wheel. These filter wheels hold up to six 1-inch diameter filters. Neutral density filters can be used for intensity adjustment. Order sorting filters may be installed to block higher order diffraction. The filter wheel can be mounted to the male flange of the spectrograph slit or slit holder. The filters are mounted external to the spectrograph.

Single or Dual Output Ports

The MS260i is available with a single output port or dual output ports. A single output port is the most economical choice, and the simplest arrangement when using a single array detector. It is equipped with a mounting flange for installing a LineSpec™ Array Detector. This flange may be removed by the user and replaced with another camera-mounting flange, if desired. If more than one detector is required for the application, the use of a single output port instrument results in the experiment needing to be stopped to switch detectors. In order to address this problem, dual output port versions are available. A dual output port model has the same mounting flange at the axial output port as the single port offering. A matching slit type of the input port is mounted at the lateral output port. The slit size should be matched to the one installed at the instrument’s input port. This allows the instrument to be used as a monochromator at the lateral output port. A flip mirror inside the instrument is used to select the output port. This mirror is controlled through the spectrograph’s software, low-level commands or the optional hand controller. The lateral output port slit may be removed in the field to allow for installation of a camera flange in its location. Array detectors may then be mounted at both output ports to allow for extended wavelength measurements. Removal of the slit invalidates the calibration of the lateral output port. Newport offers recalibration services, if it is desired to reinstall the slit at a later date. Please note that a single output port model cannot be converted to a dual output port configuration.

LabVIEW™ Utility Software Included

LabVIEW™ based utility software is included at no extra cost with all MS260i models to control both the spectrograph and filter wheel accessory. An intuitive command set is provided for those wishing to create their own programming. A list of these commands is provided in the user’s manual included with the spectrograph. The Oriel MonoTERM utility is also provided for sending low-level commands to the spectrograph. This is very convenient for assisting programmers in their software development efforts. The MonoTERM utility was developed in National Instruments LabVIEW™. It is open source code, so it may be used to provide LabVIEW™ programming examples.

USB or GPIB/RS232 Communication Interfaces

MS260i imaging spectrographs are offered with a USB or GPIB/RS232 communication interface. The utility software provided with the spectrograph includes USB drivers for Windows 7 32-bit and 64-bit operating systems. GPIB communication offers the distinct advantage of being able to connect multiple devices to a single GPIB port, provided the computer contains a GPIB adapter card. Both GPIB and RS232 communication methods simplify low-level communications, as there is no driver or dll file. USB versions include the USB cable. For RS232/GPIB spectrographs, cable 70040(RS232) or 70038 (GPIB) may be ordered separately.

Built-In Shutter

An electronic shutter is integrated into the MS260i spectrograph's housing for the many spectroscopic applications that require the use of a shutter. For more information, please refer to the technical note entitled Shutters for Spectroscopic Applications.

Delivered Fully Assembled and Aligned

The MS260i is factory assembled and pre-aligned so it is ready for immediate use. The three diffraction gratings are installed on a triple grating mount and factory aligned. A manual slit, motorized slit, or fixed slit holder is installed to the input port. Dual port versions include a fixed slit holder on the lateral output port. A mounting flange is installed on the axial output port to attach a LineSpec™ CCD camera. Also included with the MS260i is LabVIEW™ based utility software and API with examples. MonoTerm low-level command software, users manual and certificate of calibration. A DC power supply and line cords for US and Europe are also included.

Spectrograph Mounting

The optional 74105 mounting plate can be used to secure a MS260i imaging spectrograph to an inch or metric optical table. The ability to mount the spectrograph simplifies setup and alignment of the optical system. The mounting plate also helps ensure consistent results over time, as the spectrograph cannot be accidentally moved out of position. The plate adds 0.25 inch [6.35 mm] to the optical height. Threaded holes on the mounting surface of the spectrograph also allow the instrument to be optical rod mounted, if desired.

Long Life Instrument

These instruments continue to function for many years. With proper care, they only require periodic maintenance to ensure gears are lubricated, spring tension is correct, etc. It is suggested to send the spectrograph to Newport annually for recalibration, in order to meet its performance specifications. During recalibration, the instrument is thoroughly examined and routine maintenance services are performed. In addition to this service, Newport is also able to reconfigure the grating selection, slits and communication electronics if desired. Contact Newport Sales for more information.