Gemma Church examines how custom laser diode module solutions can add value across multiple applications
In our day-to-day lives, tailored solutions are usually regarded as the most expensive option – but in the world of laser solutions, the opposite can actually be true. Jeremy Lane, managing director of ProPhotonix, explained: ‘Our custom laser modules are designed and developed for specific customers and for the particular needs of their applications.
‘While a few of those custom laser solutions may be based on completely new design concepts, in most cases customisation means drawing from our extensive design database, which includes several thousand laser module designs and then making one or two, sometimes relatively minor changes, or perhaps combining elements of two or three existing designs.’
This is an important point and the company has been developing specialist solutions for its customers for more than 25 years. It is an established designer and manufacturer, specialising in laser modules, LED lighting solutions and laser diode distribution. ‘ProPhotonix is quite unique in offering its customisation service for both our laser and LED technologies,’ Lane added.
The company produces a range of plug-and-play solutions within the laser arm of its business, combining the optics, drive electronics, mechanical components and other parts to create modules that incorporate semiconductor direct laser diodes. These work across wavelengths from 375 to 1550nm with output power between 30μW and 1W.
ProPhotonix focuses on semiconductor laser modules within its product range. Lane said: ‘The range of applications for semiconductor laser modules is extremely broad, and actually that’s one of the most exciting things about this business – that no two of our customers have exactly the same applications.’
For example, these lasers may be used for alignment applications or to analyse materials for sorting or quality assurance purposes. In another group of applications, lasers are used as the light source for precision measurement or imaging across sectors including the medical and industrial. In other applications, such as fluorescence microscopy, for example, lasers are used to photochemically induce a response in a material.
In truth, the list of applications is endless and if a standard laser solution is used across any of these applications then this will involve ‘some compromise in terms of performance properties,’ according to Lane, who added: ‘It’s also very likely that if performance falls a little short in some areas, the standard product may be over-specified. In others, a custom solution may be able to provide exactly the performance needed at a very attractive cost.’
Specific solutions
There is a long list of laser module specification parameters to consider and balance when creating a custom solution. In a recent whitepaper, ProPhotonix examined five, key parameters to create a cost-effective, specialised solution. These include the boresight accuracy, mechanical integration, laser life, laser diode selection and beam quality.
These parameters do not exist in isolation, as Lane explained: ‘These various parameters are interlinked and the right decisions about laser module specification for your application may sometimes be counterintuitive.’
Let’s consider boresight accuracy. This is a measure of the degree of alignment between the laser propagation axis and the mechanical axis of the laser module. For some applications, such as laser surveying, a very high degree of alignment precision is needed over long distances. For other applications, such as dental X-rays, the working distance is short and precise alignment is not required.
Lane said: ‘The important message here really is that you can minimise overall cost by having either the laser module manufacturer take care of laser alignment or take care of it yourself during your assembly process, but not both. Counterintuitively, the apparently high-performance laser module may not be the best or the most economical choice.’
This is because different parameters depend on one another. Let’s examine the mechanical integration element now. When mounting a laser module in an OEM system you can potentially introduce a pointing error without active alignment. This may be very important in some applications and much less important than others. In other words, the mechanical integration affects the boresight alignment.
The mounting mechanism also needs to hold the laser module securely and resist any shocks or vibrations it may be subjected to, as well as providing thermal stability when the laser module invariably generates heat. This heat then needs to be dissipated through the module and clamp to maintain a constant temperature. This parameter is increasingly important with high-power lasers and active cooling systems may need to be included to maintain optimal and stable laser performance.
‘An effective partner can advise on the most suitable mounting for your application, taking into account the ease and cost of assembly, any space constraints in your design, the operating environment or who the assembly is carried out by,’ Lane explained.
The minimum expectation should be that the clamp holds the laser module securely in the correct position, provides adequate heat dissipation and ensures output stability of the laser module. But a custom laser module design can provide something more.
Let’s look at an example. Recently, ProPhotonix helped a customer develop a system where a line-generating laser module is integrated into a warehouse robot with a camera. This vision system can detect any obstacle in front of the robot by projecting a laser line with a wide fan angle downwards onto the floor. When the line is broken or distorted, an obstacle is present and the robot stops or moves around it.
The customer came to ProPhotonix with a prototype system that used a cylindrical laser module mounted to a flat part of the robot’s chassis using a U-shaped clip and two screws. While the component cost of the clamp was small, the combined cost of the clamp and the labour to assemble and precisely align the laser was significant, requiring the use of a camera and software.
Working closely with the customer, ProPhotonix devised an alternative solution, designing a laser incorporating a flange so the laser line could be aligned with the flaps of the flange during the laser module assembly and test process. This simplified the assembly process where the customer now just needs to quickly screw that system to the robot chassis. ProPhotonix also adapted other parameters to further reduce the cost. Lane explained: ‘For our customer, the cost of the laser module did increase slightly, but we kept that to a minimum by switching to lower cost materials for the housing brass rather than anodised aluminium. So, the total saving for our customer in terms of component cost and labour was very significant.
‘The takeaway here is that even something as simple as a minor modification to the mechanical housing of the laser module, its clamping and its integration into your product can deliver real added value,’ he added.
This is just one application example, highlighting how any vision system’s parameters require careful consideration to lower the cost of the laser diode module and create a value-added solution. To find out more about how ProPhotonix is helping customers create cost-effective and specialised laser diode modules, download the company’s latest whitepaper.
