TGLED and LLED-xxx-yz User Guide

ASI LED illuminators are designated by the part number LLEDxxx-yz.

• xxx indicates the approximate central wavelength in nanometers, or WHT for white. The LED wavelengths listed below can be used with any of the drive electronic types.
• y is a letter code indicating the type of drive electronics
  • R for regulated, which accepts a digital TTL signal to turn on the LED. Dimming can be accomplished by pulse width modulation (PWM). ASI firmware generally can drive this with a TTL output signal with dimming accomplished with PWM frequency ~1kHz, which leads to perceivable flicker with fast camera exposures. One LED per TTL signal.
  • A for analog, which uses the TGLED card on Tiger controllers (up to 4 separate LEDs) or WK-DUAL-LED-BRD on MS-2000 stand-alone controllers (up to 2 separate LEDs). Much of this document is regarding this drive electronics, which has per-LED analog PWM too fast to be perceived by microscope cameras in typical operation.
  • S for “Stabilight” analog control with feedback for stabilizing the intensity over time, introduced in 2022. In mid-2022 the Tiger card TGLED_S is available but no equivalent is yet available for MS-2000 controllers.
• z is a letter code to designate whether an iris is included
  • I for iris
  • N for no iris

All LED illuminators come with axial adjustment between the LED and the collimating lens, often used to achieve Kohler illumination. Furthermore the LED can be moved slightly laterally so that multiple LEDs can be co-aligned.

• Drives up to 4 ASI LEDs
• Up to 1.2A max current per LED
• Hot plugging safe, but need to respect ordering instructions below
• Brightness of each LED can be individually set
• High PWM Frequency of 97KHz
• LEDs can be controlled through TTL, Serial commands, and Micro-Manager

TGLED is a Tiger(TG-1000) plug-in card that can drive up to 4 of ASIs LLEDxxx-Az (high brightness LED units with analog control).

TGLED Connects to LLEDxxx-Az using a 3.5mm Mono Plug.

Its safe to hot-plug LED illuminators to TGLED card as long as you never connect an “empty” cable to the TGLED card. For example, if you are going to change which LED illuminator is connected to a particular channel you should first unplug the cable from the TGLED card, then change the illuminator before plugging the cable back into the controller. This is because the regulator onboard the TGLED is programmed to keep a certain amount of current flowing as long as the cable is plugged in. When a cable plugged in with an open circuit the regulator attempts to increase the applied voltage to compensate, and the voltage might get high enough to damage some critical components. There is an overvoltage detection circuit that prevents damage to the card, but once it is engaged the controller will need to be power cycled for the card to work normally again. In contrast, if the plug to the TGLED card is disconnected first, the card shuts off that connector and routes the current through another path.

Figure 1: Proper way to disconnect LED illuminator is to disconnect plug attached to TGLED card first.

Here are the options available for LLEDxxx-yz Lamps. Contact ASI if your required wavelength isn't yet listed and we will be happy to look into it.

1) LED powered with a TGLED card, 900mA current and 100% duty cycle
2) TBD - To be tested
3) Version without lens, expect lens to be brighter because of better capture efficiency
4) Lens assembly used to measure the Power mimics the condenser assembly on a microscope. This was done to better estimate the power the LED would deliver to the Objective.

Note that for fluorescence imaging the addition of an excitation filter is usually required to make sure that the LED illumination does not overlap with the fluorescence band. This can have the effect of greatly reducing the illumination intensity if the LED wavelength does not match well with the excitation bandpass.

ASI can place excitation filters inside the LLEDxxx-yz unit, inquire when placing the order. However, it is more common for the user to place an appropriate (often multi-band) excitation filter in the main microscope, e.g. just before the dichroic used to reflect the illumination to the objective. Some suggested filter sets can be found in the Lumencor SpectraX documentation.

Control of the TGLED card is similar to any other plug-in card of the TG-1000 system. This means most of the commands work (e.g. CDATE, BUILD X etc.). However as TGLED doesn't control an actuator, all of the motion commands are not implemented as they are not applicable incase of LEDs (e.g. MOVE, WHERE, SPEED, etc)

Below are some TGLED-related commands, including some that are “recycled” for a different use than for motion axes.

LEDs of the TGLED card can be turned ON/OFF through TTL pulse on TTL IN connector. When serial command [Addr#]TTL X=20 is issued, TGLED will turn off all the LED channels, then on the Rising Edge of every TTL pulse received on TTL IN connector, TGLED card will turn on all the LED channels to their set values for a specific duration set with the [Addr#]RT Y command. Then when serial command [Addr#]TTL X=0 is issued. All the LEDs will turn ON to their set percentages.

Units of RT Y command are in milliseconds. Smallest acceptable value is 1 milliseconds, and largest is 65000 milliseconds or 65sec. The timing may be off by around 0.25 milliseconds to 0.5 milliseconds. Maximum TTL frequency for which TGLED will reliably work is around 200Hz.

Example:

1LED X=30 Y=50 Z=0 F=0

The brightness of LEDs connected to Channel #1 and #2 is set to 30% and 50% respectively. LEDs connected to channel #3 and #4 will be turned off.

1RT Y=100

LED ON duration is set to 100 milliseconds.

1TTL X=20

TGLED card is put in TTL mode, all LEDs channels are turned OFF. On the rising edge of Every TTL Pulse received on TTL IN connector, LEDs connected to channel #1 and #2 turn ON for 100 milliseconds for 30% and 50% brightness respectively. Channel #3 and #4 will remain OFF.

1TTL X=0

TGLED card TTL mode is disabled, LEDs connected to Channel #1 and #2 turn ON and stay ON at 30% and 50% brightness respectively. Channel #3 and #4 will remain OFF. TTL pulses received on TTL IN will be ignored.

In this mode, for every TTL Trigger (Rising Edge Pulse on TTL IN connector). Only one LED channel turns ON for a fixed duration (Set with the RT Y command). Then On the next TTL trigger, the next LED channel turns ON for the same fixed duration. If a LED brightness is set to ZERO, then that channel is skipped and the next channel is turned ON instead. Example:

1LED X=30 Y=50 Z=0 F=0

Brightness of LEDs connected to Channel #1 and #2 is set to 30% and 50% respectively. LEDs connect to channel #3 and #4 will be turned off.

1RT Y=100

LED ON duration is set to 100millisec.

1TTL X=21

TGLED card is put in TTL mode #21, all LEDs channels are turned OFF. On the rising edge of FIRST TTL Pulse received on TTL IN connector, LED connected to channel #1 turns ON for 100 milliseconds for 30% brightness. Channel #2, #3 and #4 will remain OFF.

On the Second TTL Pulse, LED connected to Channel #2 turns ON for 100 milliseconds for 50% brightness. Channel #1,#3 and #4 will remain OFF.

On Third TTL Pulse, As Channels #3 and #4 are both set to 0% brightness, routine skips then and instead turns ON Channel #1 instead for 30% brightness and milliseconds. Channel #2, #3 and #4 will remain OFF.

On the Forth TTL Pulse, LED connected to Channel #2 turns ON for 100 milliseconds for 50% brightness. Channel #1, #3 and #4 will remain OFF.

And So on…

1TTL X=0

TGLED card TTL mode is disabled, LEDs connected to Channel #1 and #2 turn ON and stay ON at 30% and 50% brightness respectively. Channel #3 and #4 will remain OFF. TTL pulses received on TTL IN will be ignored.

Starting v3.24, when RBMODE's mode byte is set to Repeat autoplay mode RM F=3, the TGLED card cycle through the all LED channels without waiting for a TTL trigger. LED turns for the duration set by RT Y, the turns OFF, then the next LED channel turns ON.

TGLED card is supported onMicroManager 1.4.23 (or on Nightly builds built after 1st Dec 2015) as a shutter device under ASITiger.

Each TGLED card supports upto four LED illuminators. MicroManager automatically detects this, and implements them as 4 different shutter devices.

Below is a brief description of the device functions and properties,

SetOpen(bool open = true), Use to turn ON or OFF the LED. Brightness is set according to the

LED Intensity(%) property. True for ON, False for OFF

GetOpen(bool& open), Query the current LED state. ON or OFF.

Fire(double /*deltaT*/), not implemented.

LED Intensity(%), set the PWM dutycycle of the LED.

State, Can be set as Open or Closed to turn the LED ON or OFF respectively.

Current Limit in milliamps, Set the TGLED cards maximum current. This is a card wide settings, so it affects the brightness of all LEDs run from the same card. This property can also be used to adjust the LED brightness.

SaveCardSettings, a write only property, which lets the user save the current settings into the TGPMT cards's memory, or restore everything to factory defaults.

Listed below are some common issues when using the TGLED card and how to fix them.

This happens when TGLED card detects an over voltage. It disables the power supply and shutdown to prevent damage. A system Reset or Restart will bring the TGLED card back on, however if the over voltage persists cards will shut off again. One of the causes of overvoltage is when a LED Lamp is disconnected from the TGLED card by unplugging the plug from LED Lamp end first. This is seen by the Regulator on the TGLED card as a open circuit or huge resistance. It tries to maintain the current flow by ramping up the voltage. To avoid this disconnect the Led LAMP by unplugging it from the TGLED card side first. Refer to Connecting TGLED to MIM-LED-LAMP-NR section for more details. To Fix this, unplug all the LED Lamp plugs from TGLED card, Restart the system, and plug in one LED LAMP at a time. If Plugging in a LAMP causes the issue, there might be a problem with the LAMP. Contact ASI to discuss a replacement.

LED Lamps color changes when they experience high temperature for extended period of time. Running the LEDs at 100% brightness causes them to dissipate a lot of energy and generate heat. Contact ASI to discuss a replacement. Avoid running the LEDs at 100% brightness for extended period of time. Or turn them off when not in use.