LED Array Light Source
- LED Array Comprised from 20 High Brightness LEDs
- Longer Lifetime than Traditional Light Sources (up to 100,000 hours)
- LED Array Output can be Modulated
- Fits Many Commercially Available Camera Illumination Units
- Compatible with Thorlabs' 30 mm Cage System
Thorlabs' LED array light sources are available in four different colors: red, green, blue, or white, with intensities up to 1700 μW/cm2. Conviniently mounted in a Ø1.5" housing, these light sources can be used for a variety of lighting applications. The housing can be readily secured into most optical mounts used in camera illumination units. Additional mounting options include two threaded holes on the rear of each housing, one M4 and one 8-32, as well as grooves running the length of the housing that allow the LED unit to be placed in a 30 mm cage system. The LED unit will be suspended by the cage rods but not restrained from moving along the optical axis of the cage system as shown above in the application photograph. To fix the position of the LED unit, sandwich it between two fixed cage elements (see the Additional Images tab for a possible solution).
Each LED unit consists of 20 individual bright LEDs. When operating with 100 mA of current, the Red, Green, and Blue LED units have an output intensity of 600 µW/cm2 while the white LED unit has an output intensity of 1700 µW/cm2 when measured 100 mm away from the LEDs. During normal operation, the temperature of the LED housing can increase by as much as 25 °C.
A seperate power supply, LIU-PS, can be purchased to power these LEDs. For specific applications, a 2 m long power cord with an M8 connector is also available. Thorlabs also provides a mounting adapter (AD38) for these LEDs to be mounted in our 2" mirror mounts such as the KS2 as shown above.
|Pin||Specification||Wire Color on PAA630 Cable|
|4||LED Ch2 (for future use)||Black|
Note. The pin diagram above is viewed looking into the plug. And the above color scheme is standard for M8 connectors and should be used for any external wiring applications. When the PAA630 cable is plugged into an LIU series unit, the table above relates cable wire color to unit pin number.
Typical Control Circuit
The LIU series LED's intensity can be modulated with the control circuit demonstrated below. The LED brightness is controlled by the variable controlled current device (shown as the arrow in a circle). For every 10 mA of current flowing through the LED, 1 kΩ of resistance develops across pin 1 and pin 3, e.g., LIU001 has a 120 mA current limit, if 120 mA is flowing throught the LED, 12 kΩ is developed across the two pins. A sample current is generated (bias voltage/developed resistance) and can be measured out of pin 3 to ground, e.g., (24 V/ 12 kΩ=2 mA). The voltage across R can be monitored to indicate the current rating of the LED unit (e.g. for the LIU001, with a 24 VDC supply the current through R is around 2 mA, and the voltage measured would be around 20 V). A system can use this sample voltage as a feedback to determine if the LED is at max current or some brightness in-between.
The image above shows the backside of the LIU LED array unit. The threaded mounting holes and power terminal are visible from this angle.
The image to the right shows an LIU004 LED array unit in a 30 mm cage system application. The white (LIU004) LED array is sandwiched between a CFW6 (30 mm cage filter wheel) and a CP03 (30 mm cage plate) so that it cannot slide along the cage rods. The Ø35 mm aperture of the CP03 cage plate allows for easy access to the power terminal located on the rear of the unit.
In this application, the CFW6 was loaded with Ø1" diameter dichroic filters (FD1R, FD1G, FD1B, FD1M, FD1Y, and FD1C, which correspond to a red, green, blue, magenta, yellow, and cyan, respectively). This allows the user to illuminate the sample/object/subject with any of the primary or secondary colors by simply rotating the filter wheel.
For automated applications, the CFW6 can be replaced with a motorized filter wheel. In addition, if the motorized filter wheel is not directly compatible with our 30 mm cage system, an SM1T2 and a CP02 cage plate will be required to connect the 30 mm cage system to any SM1 compatible motorized filter wheel.