The Lambda DG-4 Plus offers unprecedented speed and versatility for experiments requiring rapid light wavelength switching. It offers all the advantages of interference filter-based systems, yet eliminates the temporal constraints imposed by filter switching devices. Switching between any two wavelengths is achieved in less than the 1.2msec vertical retrace period of a video signal, allowing you to perform real-time video imaging. For dual wavelength ratio imaging studies, the Lambda DG-4 enhances your ability to follow fast changes in ion concentrations by acquiring a ratio pair in two consecutive video frames.
Narrow bandpass systems, such as single cavity interference filters, grating monochromators, and A.O. modulators, will, by their nature, pass harmonics of the desired wavelength. With variable wavelength devices, it is not always possible to obtain sufficient blocking of out-of-band wavelengths. Modern interference filters, as used in the Lambda DG-4, have integral blocking characteristics 1000 times better than typical monochromator systems. In addition, it is difficult to adjust the intensity of one wavelength relative to another in a traditional system with a single optical path and a variable wavelength device. The dual galvanometer design of the Lambda DG-4 eliminates this problem.
This unique optical design of the Lambda DG-4, is based on dual scanning galvanometers. The wavelength selection is done by interference filters. The standard version of the instrument, the Lambda DG-4, can host up to four 25mm interference filters. A five filter version (two 25mm and three 18mm), Lambda DG-5 is also available.
The light coming from the 175W xenon arc lamp is focused on the first galvanometer mirror. The light is then directed, via a parabolic mirror, through one of the optical channels that may contain an interference filter. The light passing through the filter is collected by another parabolic mirror and sent to a second scanning mirror that directs it to a liquid light guide.
The light guide can be coupled to the illumination port of an instrument (e.g. epi-illumination port of a microscope). The intensity of the output can be modulated by controlling the relative orientation of the two scanning mirrors. Thus this system can provide narrow band excitation at selected wavelengths over a range of intensities or can rapidly turn off the light. Dwell time at any wavelength is arbitrarily set by the user. Transitions are achieved in less than 1.2msec.
FEATURES > LAMBDA DG-4
*Complete system for wavelength switching
A built-in 175 or 300 Watt ozone-free xenon arc lamp makes the Lambda DG-4 a complete excitation system, and eliminates problems associated with device integration. Four or five interference filters can easily be installed in the DG-4 or DG-5, respectively. An additional standard neutral density filter can be inserted in the common path of the light. The light guide output from the Lambda DG-4 provides uniform spatial illumination, as well as vibration isolation from your microscope.
*Integral shuttering The Lambda DG-4 provides a high speed shutter function with open/close times of 500 s. The shutter can be enabled between filter transitions to prevent light transmission through intermediate filters.
*Integral neutral density filtering Neutral density filtering is achieved under program control by offsetting the output galvanometer such that light is not centered on the liquid light pipe. Up to 15 logical filters can be defined with this method. Due to the scrambling effect of the light guide, the output still has excellent uniformity. Direct insertion of neutral density optical filters is also possible in the filter holders at any of the four optical channels. A final neutral density optical filter can be placed in the exiting light path which will reduce the light output from all 4 optical channels.
*Two outputs for monitoring filter position A 4 bit TTL signal transmits the current optical channel (filter) position. A digital-to-analog converter (DAC) output produces a voltage showing which filter is in use.
METHODS OF CONTROL > LAMBDA DG-4
*Direct Computer Control via Parallel or Serial Interface
When operated in these modes, the Lambda DG-4 control commands are a subset of our Lambda 10-2 controller and will operate with software written for the Lambda 10-2. If you plan to control the DG-4 with other interfaces, please contact Sutter for specific issues.
*Strobe-Pulsed Ring Buffer Control A sequence of up to 32 filter values can be downloaded into a ring buffer via keypad or computer. The system will change to the next filter in the buffer on a strobe pulse. Each subsequent pulse will cause a move to the next filter in the buffer on a TTL level strobe (trigger) pulse. After executing the last filter change in the string the system resets to the first filter and continues.
*Video Sync Pulse A video sync pulse can be used to initiate the filter change for each sequence stored in the ring buffer. Stand-alone operation of the Lambda DG-4 is achieved in this mode using only a video sync input.
*Video Sync with Strobe Low The system will implement a filter change on the video sync pulse, but only if the strobe line is held low. This allows a computer to override the sync pulse.
SPECIFICATIONS > LAMBDA DG-4
Output Range 330nm to 700nm - Ozone free, 300nm to 700nm - Full spectrum (requires ozone removal)
Lamp Type 175 Watt ozone free or full xenon arc bulb spectrum
Lamp Lifetime Expected lifetime 1,000 hours (All bulbs warranted for 500 hours.)
Power Consumption 350 Watts
Filter Diameter DG-4: Four, 25mm (1 in) DG-5: Two, 1in (25mm) and Three (18mm)
Dimensions 10in x 10in x 19in, 25cm x 25cm x 48cm
Light Guide 2 meters long, 3mm diameter
Weight 45lbs, 20kg
Electrical 115/230 Volts, 50/60 Hertz power line
The DG-4/OF includes a Lambda DG-4 unit, full spectrum 175W bulb, 4 slide-in filter holders, 1 neutral density filter holder, power cord, serial and parallel cables, liquid light guide, spanner wrench, and manual.
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Download a brochure at http://www.autom8.com/pdfs/optical/AM-Optical.pdf