— Variable Wavelength Fiber Optic Module — RS System - Modular VIS-NIR Recording Spectrophotometer — Tunable Grating Filter

VARIABLE WAVELENGTH FIBER OPTIC MODULE

Optometrics’ Variable Wavelength Fiber Optic Module is a rugged, low cost compact instrument that produces monochromatic light out of a fiber optic bundle. Operation is as simple as turning on the lamp and rotating a dial until the desired wavelength appears on the four digit counter. The module can be used for remote spectroscopic sensing or in any application requiring monochromatic radiation that cannot be obtained easily by conventional methods.

The module is comprised of a 20 watt tungsten halogen source, a digital or scanning digital monochromator and a five foot fiber optic bundle. The fiber bundle end is formed into a rectangular array that plugs directly into the monochromator, functionally replacing the exit slit. It is supplied with a 600 micron slit assembly for use on the entrance side. The other end terminates in a conventional circular bundle. Choose either the Digital Mini-Chrom or the Scanning Digital Mini-Chrom monochromator.

MLM-2 MONOCHROMATIC LIGHT MODULE
Optometrics' Monochromatic Light Module (MLM-2) offers a low-cost, high performance alternative for spectroscopy applications requiring easy component integration. The MLM- 2 was developed for use in research, teaching and quality control but can also be used as a component in a variety of sophisticated analytical and biomedical equipment such as HPLC detectors, UV-VIS-NIR spectrophotometers and clinical chemistry analyzers. It is ideally suited for quick and easy changing of monochromators, sample compartments and detectors. Three (3) choices of wavelength ranges are available, from 300 nm to 1.7 microns. The MLM-2 is CE Approved.

The MLM-2 consists of:

• Tungsten light source and power supply;
• Variable aperture assembly and shutter;
• Scanning Digital Mini-Chrom Monochromator;
• Integrated Stepper Motor Controller and Driver to run the scanning monochromator;
• Windows®-based software to easily control wavelength scanning and selection;
• Built-in Wavelength Scanning
• 3 Choices of Wavelength Ranges, from 300 nm to 1.7 microns
• Includes Tungsten Light Source and Variable Aperture
• Software to Control Scanning Models Via Stepper Motor

SCANNING SPECIFICATIONS
Stepper Motor: 400 steps per revolution

Scanning Resolution:
nm/rev: 50 (100 for Model B,C)
half step: 0.063 nm (0.125 for Model B,C)
half step multiplier: 16 (8 for Model B,C)

Scanning Speeds:
Minimum: 0.313 nm/min (0.625 for Model B,C)
Maximum: 250nm/sec (500 for Model B,C)

LAMP SPECIFICATIONS
Type: 20 W Tungsten halogen in quartz envelope
Color Temperature: 32000 K
Spectral Output: 340 to 3000

The MLM-2 can be programmed via a CRT, serial keyboard or computer through an RS-232 interface and comes with Windows®-based software to easily control wavelength scanning and selection. Over 25 different commands are available including initial and final velocities, move distance, ramp slope, half or full step operation, time-out pauses, etc. with stepping speeds of from 5 to 15,000 steps per minute. Data can be sent or received at any time during operation.

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RS System - Modular VIS-NIR Recording Spectrophotometer

Designed for the research and educational market, the RS System gives you the flexibility to choose the components you need to fit your application. The complete system includes a control module, tungsten lamp module, choice of monochromator and detector and the WinRS software that automates scanning and data capture and provides the spectroscopist with a range of software tools to analyze and store data.

• Design Your Instrument to Match Your Requirements
• Choose From Our Monochromators and Detectors to Build Your System
• WinRS Software Provides Control and Data Analysis

RS Systems are designed around the Mini-Chrom monochromator, a product proven by sales of over 20,000 units to leading manufacturers of analytical and biomedical instrumentation. The simplicity, versatility and low cost of Optometrics’ modular units allow the user to “customize” a recording spectrophotometer for a single application or a variety of experiments. Other modular units, under development, will expand current system capabilities.

Detectors and monochromators can be easily changed to enhance overall performance in selected spectral regions.

Basic system includes your choice of Scanning Digital Mini-Chrom Monochromator, Silicon Detector, Sample Chamber or Specular Reflectance Sample Chamber, Tungsten Halogen Light Source, Variable Light Aperture, Control Module with integral stepper motor controller and all required power supplies, Data Acquisi- 16 RS System - Modular VIS-NIR Recording Spectrophotometer tion Board, Adapter plate, all cables, WinRS System Software and full operating manual.

Instrument Features:

• Wavelength range: 375 nm to 1200 nm
• Interchangeable slits for resolution optimization
• Interchangeable detectors for signal optimization
• Varying detector ports for both in-line and 900 measurements in transmission and reflectance
• Perform reflectance, absorbance, transmission and concentration measurements
• May be used for excitation scanning or fixed wavelength fluorescence

Software Features:

• Quick Read Mode for immediate sample readings
• Wavelength Scanning Mode including 1st and 2nd derivatives, peak pick, peak integration and data smoothing
• Timebase Reading Mode to monitor chemical reactions against time. Includes calculation of reaction rate using linear fit
• Concentration Mode for direct reading of concentration of samples using a standard curve or calculation factor
• Other software features include storage of instrument parameter setup files, data storage and report printouts in both graphical and tabular formats.

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Tunable Grating Filter

The Tunable Grating Filter is a low cost optical instrument that is capable of selecting both the wavelength and bandwidth of a variety of ultraviolet, visible and near infrared sources. Designed for use with collimated radiation, the instrument is compatible with both CW and pulsed lasers.

Applications include the elimination of unwanted radiation due to laser discharges as well as fluorescence from dye lasers. The Tunable Grating Filter can replace a multitude of interference filters. It can also be used as a laser line selector for Argon, Krypton and other multiple line lasers. All optical components are made to withstand the high incident energy from lasers.

OPERATION
The Tunable Grating Filter is comprised of two modules, an optical unit with a high efficiency replicated grating, grating drive mechanism and folding mirrors and a separate variable aperture on a base plate. The wavelength is selected by turning a calibrated micrometer drive that rotates the grating. The wavelength is read directly from the micrometer.

Bandwidth is a direct function of grating groove spacing and aperture diameter and is inversely proportional to the distance between the aperture and the grating. Since focusing optics are not used, reducing the aperture smaller than the laser beam diameter will reduce the throughput. The aperture diameter and distance from the grating are both variable, allowing the bandwidth required for a specific application to be easily set. The Tunable Grating Filter is designed for in-line use with collimated light and does not displace the beam. It is easily mounted on an optical bench, rail or table.

CALCULATING BANDWIDTH (Δλ)

where:
λ = Selected wavelength
d = The grating constant, i.e. peak to peak width of a single groove
A = Selected diameter for the aperture
D = Distance from the exit slit to the variable aperture

Example: With an 1800 g/mm grating, 500 nm selected wavelength, 3.0 mm aperture diameter, 1500 mm from the exit aperture.

Specifications  Wavelength Readability: UV-VIS - 1.0 nm NIR - 2.0 nm (0.002 μ) Input Beam Diameter - 3 mm maximum Variable Aperture Diameter - 1.0 to 12.7 mm  Damage Threshold CW Laser - 250 W/cm2 Pulsed Laser (200 nsec. pulse) - 3.5 joules/cm2

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