Figure 4: The second low-thermal lensing mirror with a GDD of -3,000 fs2 exhibited a 20K temperature change throughout the test, which also did not lead to any detectable performance reduction due to thermal lensing even though it was double that of the other low-thermal lensing mirror

Simple DMXController

More than 32 fixtures in a DMX line:The maximum number of devices for a DMX line is 32. If you exceed this limit, it is better to use a splitter to ensure your signal remains strong and your fixtures work optimally.

There is a small tradeoff in reflectivity when using a highly-dispersive mirror optimized for thermal lensing, as they achieve reflectivities around >99.5% compared to 99.8% for other highly-dispersive mirrors. However, this tradeoff could be very worth it in high-power systems where thermal lensing threatens to destabilize the laser and potentially prevent mode-locking. This allows these systems to push to limits of what peak powers are achievable.

Thermal lensing is a phenomenon where heat buildup in laser gain media reduces the performance of solid-state lasers, particularly when they are operating at high powers. The density of the gain medium may decrease as temperature increases, causing components closer to the beam axis to become more curved than areas further away from the beam. This curvature gradient can misalign the laser's resonance cavity, generate unwanted laser mode profiles, and lead to drifts in the laser's beam pointing. These effects become even more of an issue at higher repetition rates. A portion of these effects can be controlled through careful design of the resonator, but there are not many steps that can be taken to change thermal behavior inherent to the gain medium.2

Due to continuous improvements and innovations, Specifications may change without notice at any time. All specifications are indicative, download the photometric files for actual values.

Lighting Controller

Figure 3: The first low-thermal lensing mirror with a GDD of -1,000 fs2 exhibited a 10K temperature change throughout the test, which did not lead to any detectable performance reduction due to thermal lensing

MIDILighting Controller

Written by Cory Boone, Technical Marketing Manager, and Vladimir Pervak, Head of Optical Coatings at UltraFast Innovations, Edmund Optics

The versatility of DMX-controlled lighting allows it to be used in a wide range of applications. Among the most common applications are theatres, concerts, and clubs. However, DMX can also be used in museums, churches, shops, TV studios, and hotels. The possibilities are endless. The greatest advantage of DMX-controlled lighting is that it offers full control. You can program LED lighting to create any desired effect. You can control and adjust the intensity, color, and other parameters in a fraction of a second.

Example: You have 4 fixtures. Fixture 1 has 4 colours, RGBA. Fixture 2 has 4 colours, RGBW. Fixture 3 has 3 colours, AWB. Fixture 4 has 1 colour, W.

When your DMX line needs to cover a long distance, the signal can become too weak. A DMX booster ensures that the signal is amplified, allowing it to be transmitted further. Multiple boosters can be used in a DMX line. For this purpose, you can also use a splitter.

Concertlighting

To verify whether these mirrors really do reduce thermal lensing, an infrared camera (FLIR SC305) measured temperature fluctuations while they were they were used to reflect a Yb:YAG thin disk laser operating at continuous wave (CW) mode. Their performance was compared with other highly-dispersive mirrors without the coatings designed to minimize thermal effects. Figure 2 shows a temperature change of 57K of a dispersive mirror without the new, low-thermal lensing coating. This mirror features reflectivity >99.8% and a GDD of -3000 fs2 for wavelengths from 1010 and 1050nm. This increase in temperature led to deterioration of the laser mode and oscillator stability. Figures 3 and 4 show the measured temperature for two highly-dispersive mirrors with the novel reduced thermal lensing coatings. They featured GDD values of -1000 fs2 and -3000 fs2, respectively, and slightly lower reflectivities of >99.5% over a comparable waveband. They exhibited temperature changes of 10K and 20K, which is significantly lower than that of the first mirror. No detectable changes in laser mode and oscillator stability were observed, so system performance was unaffected by thermal lensing. This allowed the system to maintain desired performance.

DMX512 is the most common DMX protocol. DMX512 utilizes a data signal to control lighting. The data signal is transmitted via a cable from the DMX controller to the DMX fixtures.

BandLighting

Figure 2: The mirror without the coating optimized for thermal lensing exhibited a 57K temperature change during the test, which reduced system performance

Thermal expansion can also induce stress and warp intracavity optics. If thermal lensing is severe enough to change the radius of curvature of the mirrors making up the resonance cavity, the laser may not be able to achieve mode-locking and generate ultrafast pulses. This would essentially render the laser useless. Thankfully, selecting the proper intracavity optics can prevent thermal lensing and maintain desired performance.

Theatrelighting

Every fixure has its own number of channels needed to be able to use every function. When you start programming all of your fixtures, check the amount of channels needed when you add more than 1 fixture to your Universe, because if you address your fixtures immediately after each other, it is possible to adjust the settings on fixture 1 when you want to adjust the settings on fixture 2.

Advancements in ultrafast coating technology have thankfully resulted in novel highly-dispersive mirrors with negligible thermal lensing, allowing ultrafast laser systems to reach higher powers without thermal lensing destabilizing the system (Figure 1). They still achieve a broad bandwidth and highly-negative GDD, but they also have minimized thermal lensing thanks to unique coating designs and precise control of the coating deposition process. This allows for them to be used in high-power ultrafast systems without suffering from thermal lensing. The coatings can be designed to work with a wide variety of different laser types such as Er:YAG, Yb:YAG, holmium, and thulium laser sources.

Isolating Devices:When the controller is disconnected from the network, the DMX line becomes vulnerable to interference because the line can float. If a splitter is present, you can remove the controller but the DMX line remains powered from the splitter. This is a good solution when a DMX controller is not always present.

Effectslighting

Fixture 2 needs 4 channels, but fixture 1 also needed 4. To make every function of fixture 1 work by only altering the designated colour, you cannot program it on a channel it is using, so you need to start after those. Of course, you can program them directly after one another, but the result will not be as nice to see. If you programmed fixture 2 on channel 2, you would alter the green colour on fixture 1, and the red colour on fixture 2 simultaneously. That is why it is commonly chosen to program fixture 2 on address 5. Because it has 4 functions, it gets channel 5-8.

Negligible thermal lensing coatings are not required for all ultrafast applications. Ti:sapphire lasers usually do not reach powers high enough for significant thermal lensing to be an issue. Fiber lasers do not use solid-state resonance cavities, so this technology is also not needed in these systems. Other types of highly-dispersive mirrors are sufficient and can allow for slightly higher throughput because of their higher reflectivities. However, high-power, solid-state ultrafast laser systems could benefit from reducing thermal lensing. High-power Er:YAG, Yb:YAG, holmium, and thulium laser sources can take advantage of low-thermal lensing coating technology to beat the heat and maintain system stability and performance.

To make it easier to control multiple fixtures at the same time, you can program them on the same channel. When you alter the settings for a fixture, all fixtures on the same address listen to your commands. This way you only need the amount of channels the fixture needs once, so for example with 2 fixtures that both need 4 channels, you only need 4 to control both of them, instead of 8.

DMXLightingControllers

If it is challenging to connect each device with cables, a solution may be to send a signal wirelessly. This can be useful when the existing setup does not allow for adding a physical data line. Wireless DMX is the quicker and more cost-effective option in such cases. It is also easy to use in places like churches or other locations where new cabling is not desired to maintain the appearance of the venue. However, there are risks, especially in areas with a lot of airborne signals. Creating a stable wireless signal is therefore more effortful than using a cable. Our advice is that if you can use a cable, this is always preferable.

When you’re going to calculate which address to program, to be able to use every function, you need to look at the amount of channels.

To prevent unstable operation due to reflections, you can use terminators on your last device. You can terminate the signal with a 120 Ohm resistor.

Pulse compression optics such as highly-dispersive mirrors are critical for compensating for the positive group delay dispersion (GDD) inherent to most optical media. Left unchecked, this would elongate pulse durations, reduce peak powers, and reduce system performance. Pulse compression optics have a negative GDD that balances out this positive dispersion, resulting in short laser pulses. Highly-dispersive mirrors feature several advantages over other pulse compressing optics like gratings and prisms including negative GDDs with a high magnitude, large bandwidth, low levels of loss, and compact size.3 However, thermal lensing can warp these mirrors as described earlier.

If you want to add more fixtures to your DMX-Universe, you need to program it on address 13, to be able to use every function of device 4.

Image above: Highly-dispersive mirrors with negligible thermal lensing allow ultrafast laser systems to achieve high powers without becoming destabilized by heat buildup and thermal lensing

A DMX address, also known as a start address, indicates from which channel in a block the data is used by a fixture. If the fixture is an RGBW fixture with a start address of 10, it will retrieve the value of red from channel 10, green from channel 11, blue from 12, and white from 13.

Want to know more about DMX? Look at our product pages to see which products are compatible with DMX, or contact us. We are happy to help. You can leave your question in the form below, and we will do our best to get back to you within 24 hours.

The short pulse durations and high peak powers of ultrafast lasers make them beneficial for laser materials processing, multiphoton microscopy, and a wide range of other applications, but these systems are particularly sensitive to thermal lensing.1 Heat can build up and change the geometry of optical components in the laser, destabilizing the system and potentially even preventing it from generating ultrafast pulses. Thankfully, new low-thermal lensing, highly-dispersive mirror technology can minimize thermal lensing while still maintaining high reflectivities and dispersion control.

Using Y-cables allows for a quick split in a DMX line. However, this is discouraged due to potential interference and signal attenuation. This can result in an unstable network. While it might work initially, it is highly susceptible to external interference. This can lead to occasional unresponsiveness.

There are several types of splitters, with the non-isolated and isolated being the most well-known. The non-isolated splitter is preferred. It ensures that any potential interference or overvoltages on one DMX line are not passed on to the other DMX line.

A DMX512 universe has 512 channels. All these channels are controlled by the controller. Each channel can have a value from 0 to 255. All 512 channels are transmitted in one block, sequentially. On average, a block is transmitted 33 times per second.

DMX lighting is a type of digital lighting control. DMX stands for Digital Multiplex and is a system that allows multiple fixtures to be affected by a single controller. DMX lighting uses a data signal to precisely control the intensity, colour, and other parameters of LED lights. That makes DMX-controlled lighting versatile. You can create any look you want and be entirely in control of your lighting.