1. Introduction
The RETRA (L) Light Engine consists of 1 or 2 individually addressable solid-state light sources with integrated
electronic control systems. The constituent light sources may be LEDs, luminescent light pipes or lasers. Optimal
internal operating temperature is maintained by negative pressure air cooling with the air intake at the front of the
light engine and the exhaust fan at the the rear. The outputs of the constituent light sources are refined by
bandpass filters and merged into a common optical train directed to the light output port on the front panel. The
light output port has a built-in adapter for connection to an SMA-terminated optical fiber or a liquid light guide
(LLG). An onboard photodiode continuously monitors the light output and generates a reference signal that is
applied to the constituent sources in a feedback loop to maintain constant light output over time. The light
sources within the RETRA (L) Light Engine
®
are controlled by software via one of two serial interfaces, USB/
RS-232 or TCP, to the on board computer operating Lumencor firmware. The user can enable or disable each
source independently by serial commands as well as change the intensity of each source independently. The
RETRA (L) Light Engine can either be controlled by a Lumencor GUI, by third party microscopy data acquisition
software or by a LAN connection to an onboard computer with an embedded command library. Alternatively, the
light sources may be turned on and off by TTL inputs from a trigger device such as a camera. The only manual
control is the master power switch on the front panel to turn on/off the electrical power into the unit.
RETRA (L) Light Engine Manual 57-10025
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