Cornerstone 260 1/4 m Monochromator with a detector mounted to each output port
The Oriel Cornerstone 260 1/4 m Monochromators are economical, fully automated, multi-grating instruments with dual output ports and exceptional optical performance. We offer a dual grating and a triple grating model; both were designed for fast, automated, continuous scanning over a broad spectral range. Simply program your filter, grating, and port changeover points, and walk away while Cornerstone 260 automatically scans from the UV through the far IR. Other standard features include a built-in electronic shutter, filter wheel control, and a family of interchangeable gratings and slits.
Superior performance and ease of use at an economical price make the Cornerstone 260 Monochromator one of the best choices for UV-IR spectroscopy and radiometry. The dual grating instruments offer improved resolution, over the triple grating instruments. The grating mounts are interchangeable, so if you currently have a triple grating Cornerstone, you can easily convert it to a dual grating instrument for improved resolution in your spectral range of interest.
Fig. 1 shows the asymmetrical in-plane Czerny-Turner optical configuration of the Cornerstone 260. The input F/number is F/3.9. The resolution is 0.10 nm (dual grating instruments with a 1200 l/mm grating and 10 µm x 2 mm slit). Throughput is high and stray light is very low. We relied on our extensive research on optical flat black paints and baffles, and the use of high efficiency spherical mirrors and gratings to minimize surface reflections, and thus, stray light.
Cornerstone 260 uses a stepper motor drive to change wavelengths and to switch gratings. This direct drive mechanism slews at a maximum rate of 205 nm/s (with a 1200 l/mm grating). Wavelength precision with a 1200 l/mm grating is 0.08 nm. Switching from one instaleed grating to the next takes only 10 seconds.
Stray light is very low in the Cornerstone 260 Monochromator. shown aret two stray light tests. Both measurements were made using a UV-VIS photomultiplier, model 77340 .
Using an Oriel Deuterium Source, measurements were made with and without a glass plate in the beam. The glass blocks all radiation below 320 nm. At 250 nm, the stray light signal was only 3 x 10-4 of the unblocked signal.
Using a HeNe laser at 632.8 nm focused on the slit in an F/4 cone, the average of the stray radiation readings at 612.8 and 652.8 nm was 1.5 x 10-5 of the signal at 632.8 nm. A 1200 l/mm, 500 nm blaze ruled grating was used.
The Cornerstone 260 has two output ports to allow continuous scanning over a broad wavelength range without breaking down the instrument to switch detectors. This flip mirror is commanded through the Cornerstone 260 software or hand controller. Note that with the help of model 77713 Motorized Beam Steerer, it is also possible to turn the monochromator into a dual input instrument.
We offer Cornerstone 260 Monochromators with USB 2.0 or with RS232 and IEEE-488 interfaces. You can communicate with any of the Cornerstone 260 instruments in one of 3 manners.
The 74009 Hand Controller is a dedicated interface just for the Cornerstone Monochromator Family. There is no need to memorize commands or key sequences; the 24 keys are clearly labeled with functions like Step Up, Go Wave, and Shutter. The backlit LCD display provides constant information on grating lines/mm, filter wheel position, current wavelength, and shutter status. The 74009 provides intuitive access to nearly all the functionality of the Cornerstone 260.
The computer interface was also designed for simplicity and ease of use. The Cornerstone ASCII command set is simple to use via RS 232, USB, or GPIB. For example, close the shutter is SHUTTER C and change to the second grating is GRAT 2.
We offer various software applications for Cornerstone
The Cornerstone 260 holds two or three gratings simultaneously. Each is mounted in an individual, prealigned mount. Simply drop it in place, and program the grating specifications into the Cornerstone through the Control/Utility Program or Hand Controller. If you intend to use the Cornerstone 260 as a triple grating instrument, choose your gratings from the Triple Grating Assemblies list in Table 1. If you intend to use the instrument as a dual grating monochromator, order two gratings from the Dual Grating Assemblies list.
You can add and change gratings in the field without changing the instruments grating turret. However, you may have to replace your current grating assemblies. If you want to change a dual grating instrument into a triple grating instrument, you cannot simply order a third grating; all three of your gratings need to be Triple Grating Assemblies. Similarly, if you wish to convert your triple grating Cornerstone 260 to a dual grating Cornerstone 260 (to improve resolution), you cant simply remove one grating; you will need to order two new Dual Grating Assemblies.
These gratings are mounted in pre-adjusted holders that can be inserted and removed, at any time, from the Cornerstone 260.
We offer four types of slit assemblies for the Cornerstone 260. Choose the same size and type of slit for the input and output of your monochromator. All our slit assemblies have a 1.5 Inch Series male flange.
This is our most versatile slit assembly. Change your instruments resolution by varying the slit width from 6 µm to 2 mm, in 6 µm steps. To operate a motorized slit, you also need the 74116 Slit Control Board; this board operates up to three motorized slits. Control is via the 74009 Hand Controller, or software. Input and output motorized slits are slightly different due to the mounting blocks. Please order motorized slits at the time you order the monochromator, so that we may factory install them. We do not recommend the installation of motorized slits in the field.
The 74001 is a more economical choice than the motorized assembly, if you need to change resolutions frequently. It uses a precision micrometer drive to adjust the slit width from 4 µm to 3 mm.
The 77269 is a rotating disc with eight highly repeatable fixed slit positions. A manual wheel rotates the disc to the desired slit width; each position has a positive detent for high repeatability.
Choose the 74010 Motorized Filter Wheel to hold order sorting or neutral density filters. The 74010 holds six 1 inch (25.4 mm) diameter filters with no reduction in F/# (clear aperture, 0.87 inch (22 mm). Cornerstone 260 controls the 74010 . Filter changeover is only 1.5 seconds for adjacent filters.
With most filter wheels, you have to break down the setup to change filters, but with the 74010 , the filters are held in individual mounts that snap into place from the top of the wheel. Six individual filter holders are included with each 74010 Filter Wheel.
If you only need a few slit sizes, this is the most economical choice. These are precision slits fixed on a machined slide. You need the 77294 Fixed Slit Holder to hold the slit and mate it to the monochromator.
We built a rugged, 0.5 Hz repetition rate shutter into the Cornerstone 260. The instrument drives the shutter; it is commanded via software or the hand controller. In addition to measuring background levels, the shutter is a convenient safety feature. You can close it when changing gratings or filters to protect your detector.
Cornerstone 260 is heavy enough (21 lbs; 9.5 kgs) to stand on its own with accessories mounted to the 1.5 Inch Series input and output slit assemblies. To simplify alignment of optical trains, order the 74105 Mounting Plate that bolts the Cornerstone 260 to inch (1/4-20) or metric (M6) optical surfaces. If you are coupling an Oriel Light Source into Cornerstone 260, order one of these kits: