The Performance Edition uses a more powerful, ultra-narrow linewidth laser to achieve the best results. It is the recommended version for users that are serious about Raman spectroscopy. Check this page to compare the Performance Edition with the Starter Edition.
Although the Performance Edition is working, it is still considered a work in progress because it currently uses expensive lab drivers for TEC and LD control. We are currently putting all our best efforts to replace these drivers with much less expensive custom-made solutions to achieve a price below 3k€ for the complete unit (drivers included).
The Performance Edition uses the same components as the Starter Edition except the laser block is replaced by the new #2020-18/0 laser assembly (see below). If you do not own a Starter Edition, order all the components necessary to build one but remove the parts CPS532, LDS5-EC, and #2020-05 that are not necessary for the Performance Edition. The total price should be 2530.26€ without the laser and TEC drivers.
Download the files here: Laser Assembly (rev0).
The link contains all the drawings, STEP files, and BOM to reproduce the laser assembly. We recommend POM for the LD clamp part (#2020-12) but we obtained good results with standard resin 3D printing for that part (do NOT use filament nor SLS).
Assemble the components as described here below:
Step 1/ Remove the front panel of the Thorlabs LDM21 and the sticky foam that is on the Peltier cooler. Degrease the Peltier using gentle acetone and cottons swabs. Let the acetone completely dry out before proceeding to the next steps.
Step 2/ Check that the LD switch is on “AG” (Anode Grounded) mode and install the DJ532-40 laser with the middle pin oriented top.
Step 3/ Install the o-ring in the groove of the #2020-12 (LD CLAMP) part. Set the clamp in place using two 2-56×1/2″ screws. If the screws are too long, use one or two washers. Do NOT overtighten the screws. The goal is to maintain the LD in contact with the TEC element without forcing on it.
Step 4/ Re-mount the front panel of the LDM21 and place the laser assembly on the Starter Edition base plate using two 8-32×3/8″ DIN912 screws.
Step 5/ Assemble the rest of the spectrometer according to the instructions of the Starter Edition.
To power the laser, you will also need LD and TEC drivers. At the moment, we only offer a solution that uses expensive lab drivers from Thorlabs but we are working on much cheaper alternatives.
All the following instructions refer to the Thorlabs drivers LDC205C and TED200C that I was formerly using in the breadboard version. These drivers can be purchased either as part of the LTC56A/M kit or separately. When purchasing the drivers separately, you will also need a CAB400 cable and a CAB420-15.
The cables CAB400 and CAB420-15 are however too rigid to be set in place directly in the setup. You will have to make extension to those cables like in the picture on top of this page.
Soldering the cables is not difficult but you will need a soldering iron, some lead-free solder, cables and two pairs of SUB-D9 connectors (2 males and 2 females). You may also want to use some flux and heat-shrinkable tubing to achieve top-quality.
Thorlabs provide drawings of the pinout of their LDM21 part. The pins on your SUB-D9 connectors should be labeled accordingly. Double-check your connections if you don’t want to damage either your LD, LDM21, or drivers!
The overall concept is to connect the pin 1 or the male SUB-D9 connector to the pin 1 of the female SUB-D9 connector and so on. The male/female pinouts should be mirror images of each other. Use colored cables to avoid mistakes when connecting the cables and keep the cable length to 20 cm maximum.
I recommend twisting the pairs 3-7 for the LD controller and the pairs 2-3, 4-5 and 7-9 for the TEC controller. Twisting will help in having more stable signals, especially on high impedance inputs such as the thermistor.
Use 0.7 mm wires at the very least and 1.0 mm wires for the pairs 4-5 of the TEC driver as it may have high currents flowing through. When using Thorlabs drivers, I recommend connecting all cables except those marked as N.C. in the pinout drawings of the LDM21.
When operating the laser, always start the TEC driver first with a temperature set point to around 22.50°C. Once the temperature is stable, turn on the laser and gradually increase the current. If you don’t have a powermeter to control the actual output of the laser, I recommend not exceeding 300 mA for the LD.
Note that the LD output is strongly influenced by the temperature so it is mandatory to keep the TEC driver steady when performing your recording. In my experience, the LDM21 should regulate your LD at 300 mA to 22.50°C as long as the ambient temperature does not exceed 5°C from the set point. I have had some issues in the summer with that so be sure to install your setup in a room with controlled temperature.