Cairn OptoLed Lite Instruction Manual

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OptoLed Lite

Instruction Manual

Specialists in Fluoresence Microscopy - DESIGN TO INTEGRATION

Important Information

Please Read Before Installing and

Operating Your OptoLED Lite

For maximum reliability and safety we recommend using the equipment
within certain guidelines. If in any doubt, then please feel free to contact
our technical support department (e-mail [e-mail]).

The following points should be considered when using the OptoLED for the
first time:

1. The OptoLED is capable of producing very intense illumination. The LED
heads should NEVER be viewed directly. If testing the LEDs then ALWAYS
shine them at a white surface and view the resultant reflection or
fluorescence. This is especially important with ULTRAVIOLET LEDs which
will not appear bright to the human eye, but can cause permanent
damage if not used with care.

2. Our standard LED heads have built in protection to avoid damage,
however if in any doubt then please check with Cairn as to the rated
power of the supplied heads, and use accordingly.

3. The OptoLED is typically supplied in conjunction with our modular
microscope coupling system. Please refer to the separate
documentation regarding your particular configuration.

4. The OptoLED system supports a vast range of different LEDs and LED
arrays. Different sized LEDsrequire different condenser lenses. We
always try to optimise the condensers for the LEDs ordered, but if you
require help with optimisation then please ask.

Contents

1 Introduction 1

2 Installation Guide
3 Technical Summary 4

4 Specifications 6

5 Appendix 7

5.1 LED Head Connections 7

5.2 Overload Protection 8

6 Technical Support 11

1 Introduction

The Cairn OptoLED Lite is capable of driving an LED over a wide range of
currents. The standard operating current range, which is set either by a front
panel control or by an external control voltage, is 0-2 amps (A). This current is
limited by components in the interchangeable LED heads, above which the
current driver will temporarily shut down in order to protect the LED from
damage. However, since LEDs can be transiently overdriven above their
continuous current limit (which is usually determined by thermal
considerations), the protection circuitry also allows a higher transient current
limit to be set. By incorporating the protection-setting components in each LED
head, they can be tailored to match the maximum safe levels for that type of
LED.

In addition, digital inputs are provided to switch the LED on and off with rise
and fall times of just a few microseconds (for faster requirements you will
need the full OptoLED). The operation of the unit will now be described, first
with reference to the front and rear panel facilities, and then with reference
to the further facilities available internally on the circuit boards.

Some more general notes on LED operation will follow after that. Finally, for
users who wish to try out alternative LEDs, the necessary information for
constructing or modifying LED heads is given in the Appendix.

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2 Installation Guide

Depending on the required configuration the LED head may have been
pre-installed in a microscope coupling (described in a separate manual), or it
may be a discrete unit. Either way we would recommend connecting the LED to
the controller box using the DIN plugs provided and pointing the LED (or output
of coupling) at a piece of white paper (NEVER VIEW THE LEDS DIRECTLY).
Next connect the power supply to the mains, and read the following description
of the controls before verifying operation.

The front and rear panel controls are described in detail below, but if the user
bears in mind that the LED has independent controls to set whether it is on or
off and to set the intensity, and that either of these can be applied from the
front panel or externally (e.g. from a PC) then operation is quite intuitive.

‘OFF / EXT/ON’ switch

This switch allows the LED to be permanently 'ON', permanently 'OFF' or
digitally controlled 'EXT’. The digital signal is applied via the TTL (5V) 'EXT'
socket on the rear panel and allows the LED to be switched between on and off
very rapidly. When the switch is in the on or off position, this digital signal is
overridden.

‘CURRENT’ Control

This control sets the LED drive current when the 'INT/EXT' switch on the front
panel is in the 'INT'ernal position (otherwise control is via an external voltage).
The current can be set between 0 and 5A, but the protection circuit in the LED
head will usually limit maximum current.

‘LED ON’ Indicator

This indicator is illuminated whenever the corresponding LED is on. If it is lit and
there is no light at the LED head then it is probably because the intensity level
is set to zero on the front panel or the applied intensity voltage is 0V (if using
the device under external intensity control). Since its status is affected by the
digital control signals, this indicator may appear to be illuminated more or less
brightly if the applied signals are changing too rapidly to be followed by eye.

‘OVERLOAD’ Indicator

If either the steady or the transient power through the LED exceed values
preset by components within the LED head, this indicator will illuminate for
about 1 sec, during which time the drive current will be switched off to protect
the LED. Resetting is automatic, but the overload condition will keep re
triggering for as long as the power remains above these values.

For users who, at their own risk of course(!), wish to experiment with the
overload parameters, and/or wish to make their own custom LED heads, the

necessary information for how to do this is given in the Appendix.

‘POWER ON’ Indicator

This indicator is illuminated when the power is turned on both at the main
socket as well as the power on switch located on the rear panel.

‘INT/EXT’ Switch

This switch controls whether the current applied to the LED is set from the
front panel dial or referenced to an external voltage applied to the rear panel.

‘TTL INPUT’

This is a logic-level (i.e. 0V or +5V) input, which determines whether the LED is
on or off when in the 'EXT' mode. This input is at a logic low level by default if it
isn't connected to a suitable drive signal.

‘EXT LEVEL’

This is an external analogue input for the LED drive level where the input range
is 0 to +5V. Each change in 1V corresponds to a change in 1A.

‘ROTARY DIN’ Socket

This is an 8-pin locking DIN socket for connection to the LED head. In case you
would like to make up your own custom LED heads, the connections are
described in the Appendix.

‘POWER’ Switch

This switch needs to be turned on for the machine to operate

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