Lambda DG-4 Ultra High Speed Wavelength Switcher

Lambda DG-4 Ultra High Speed Wavelength Switcher

DG-4 ULTRA HIGH SPEED WAVELENGTH SWITCHER

The Lambda DG-4 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 band-pass systems, such as single cavity interference filters, grating monochrometers, and A.O. modulators, will, by their nature, pass harmonics of the desired wavelength. With variable wavelength devices, such as gratings, 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 monochrometer 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.

How it works:

This unique optical design of the Lambda DG-4 is based on dual scanning galvanometers. One galvanometer is placed at the focus of the arc lamp and is used to reflect the lamp output through one of four optical channels that may contain an interference filter. After the light passes through a filter, it is sent to a second scanning galvanometer mirror that directs the light to a light guide which provides spatial uniformity. The light guide can be coupled to the illumination port of an instrument (e.g. epi-illumination port of a microscope). By controlling the relative orientation of the two scanning mirrors, intensity of the output can be modulated. Thus this system can provide narrow band excitation at selected wavelengths over a range of intensities or can rapidly turn off the light source. Dwell time at any wavelength is arbitrarily set by the user. Transitions are achieved in less than 1.2msec.

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Features

Complete system for wavelength switching

• A built-in 175 Watt ozone-free xenon lamp makes the Lambda DG-4 a complete excitation system, and eliminates problems associated with device integration.
• Up to four standard interference filters (25mm diameter, 9mm thick) and neutral density filters can easily be installed in the system.
• The light guide output from the Lambda DG-4 provides the additional benefit of vibration isolation from your microscope .

Integral shuttering and filtering

• The Lambda DG-4 incorporates a high speed shutter with open/close times of 500us. 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 fiber optic light guide. Up to 15 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 acceptable in the filter holders at any of the four optical channels. A final optical filter can also 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

• Direct Computer Control via Parallel or Serial Interface

When operated in this mode, 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. (to take full advantage of the additional features of the Lambda DG-4, we recommend checking with your software vendor for the appropriate driver)

• Strobe-Pulsed Ring Buffer Control

Up to 32 filter sequences 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. 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

Ordering Information

BASIC SYSTEM

DG-4/OF Includes Lambda DG-4 unit, pre-aligned 175 Watt ozone free xenon bulb ,4 slide in filter holders, 1 neutral density filter holder, serial and parallel cables, liquid light guide, and manual

DG-4/FS Same as DG-4 but with 175W full spectrum bulb (note: full spectrum bulb produces ozone, and will require additional ventilation of the lamp exhaust. Contact our technical support staff for details) 

ACCESSORIES

O661176* Ozone free 175 Watt xenon bulb (attenuated output below 350nm, 80% at 340nm)

O661175* Full spectrum 175 Watt xenon bulb

DG-IF Interference filter holder

DG-ND Neutral density filter holder

X100160 Retaining ring

X100150 Filter spacer

* Please note that the above bulbs do not include the outer blue housing. If you need or want an extra housing, please contact us.

Mounting Adapters for Nikon, Zeiss, Leica and Olympus microscopes are available. Please call Sutter Instrument for pricing and further information. Also, please see the adapter list at the end of this section.

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Site by Rob Jones.
Copyright © 1999 Linton Instrumentation  . All rights reserved.
Revised: October 30, 2002 .