The design of the laser source is described at Laser4DIY Micro Chip Laser. Here we focus on assembling the laser source

Micro Chip Laser Block

The Micro Chip Laser block is our pulsed IR laser source and integrates several functionalities into one assembly:

  • Mounting points for the needed optical components, namely laser diode, GRIN lens and laser crystal (including passive Q switch and vapour-deposited mirrors)
  • Heat spreader for laser diode and laser crystal
  • integrated peltier element for thermoelectric cooling
  • water cooling block (hot side of peltier element)
  • mounting bracket to be used on the Laser4DIY base plate or standard optical bread boards

Apart from the optical components, it consists of several parts, most of them are machined, either from copper (Cu), aluminum (Al) or acrylic (PMMA). These need to be mounted in the following order (bottom-to-top):

  • baseplate (Al)
  • plexi spacer (PMMA)
  • cooler (Al)
  • Peltier element 20W, 15V
  • MC-heatspreader (Cu)
  • MC-bracket-A (Cu)
  • MC-bracket-B (Cu)
  • MC-lensbar (Al)

Additionally, the following is also needed

  • an thermistor (connected to the TEC controller for reading the temperature)
  • 2 tube fittings (for connecting the water cooling)

The STEP files for the machined parts can be found on github:
Details on the other parts can be found in the BOM below.

For now, we only assembly the cooling stack. The optical components are added later, when the electrical and cooling setup is working.

Assemble the pieces in the order as listed above. Do not add optical components yet. The stacked parts are hold together by 4 M3 screws. MC-bracket-A and -B are hold by 2 M4 screws. Just screw them in loosely now, we will have to add the crystal later.

Setting Up Optical Components

For setting up the optical components, we have chosen to use a custom bread board made from 8mm thick aluminum:

It features a grid of holes with M6 threads that allow the use of standard fixtures for optical components. The micro chip laser block is designed to be placed directly on the bread board as well, the height of the optical axis matches the one of standard components.

There is a 1 inch wide hole in the board, which can take up a beam expander mechanic and a lens. There the laser beam is mirrored downwards and focused onto the PCB lying on the table below.

The bread board is laser cut, you can find the dxf for it in the github repository:

Optical components are very sensitive!

  • Handle them with care!
  • Do not touch the active surfaces of lenses and crystals with your fingers! It will leave finger prints.
  • Do not touch the active surfaces of lenses and crystals with tools either! This may cause scratches that could ruin the coating. Always touch them on sides only
  • Make sure they don't get dusty.  Keep them in their packages as long as possible. Build your setup in a room that is not too dirty and cover a build in progress when not working to protect it from dust.

Now we start setting up the components for the laser source:

  • Use the annotated images and the BOM to see where the parts go to
  • Start with the large components, the micro chip laser block is the first you should add
  • If possible, use the same position for the components. Use the same hole for screwing them down (count the holes in the grid). We will do a fine adjustment later, but now we have to make sure everything fits on the base plate.
  • The images show the copper block for the optical amplifier. This is an optional piece, that is not covered yet by this assembly guide. Simply leave it out. The water cooling just uses two tubes to the microchip laser, nothing more.
  • Make sure the cables and cooling tubes are not blocking the path of the laser beam.

ItemQtyDescriptionPartSupplier Comment

Optical Components

11Nd:Yag Resonator wit Cr:Yag
Coupletechcustom, specs see Laser4DIY Micro Chip Laser
31Pumping-DiodeWSLD-808-010-E.FACEQ Photonics
45Clamp bigCF175Thorlabs
51Clamp middleCF125Thorlabs
61Clamp SmallCF038Thorlabs
73Lens holding Assembly3 parts: PH20E/M + LMR1/M + TR20V/MThorlabs
81Clamp MicroCL8Thorlabs
92Beam Expander Mechanic2 parts: SM1L05 + SM1V05Thorlabs
105Mirror Holder with Post2 parts: KM100 + RS1P4MThorlabs
112Mirror 1" 1064nmNB07-K14Thorlabs
122Mirror 1" 532nmNB07-K12Thorlabs
13(1)Beamsplitter 1" 1064/808nmDMLP900ThorlabsOnly needed for version with optical amplifier (details to be added)
142Lens 1" f=50mm 1064nmLBF254-050-CThorlabs
151Lens 1" f=75mm 53nmLBF254-075-AThorlabs
161Mirror Holder DownwardsAB90A(M)Thorlabs
171Lens 1" F=25mm 532nmLB1761-AThorlabs
181Lens 1" F=-25mm 1064nmLD2297-CThorlabs
19(1)Amplifier Crystal Nd:Yvo4

Only needed for version with optical amplifier (details to be added)
201KTP Crystal SHG 1064nmKTP Crystal 5x5x10mmShalom EO
211Crystal holderAD5TThorlabs


1Peltier Element 70W, 15V, 30 x 30 x 4 mm

1NTC 10k, ring lug mounting

e.g. Vishay NTCALUG01T103G501


2Screw connection, angled, R1/8 , Ø 8 mmSMC KQ2L08-01AS reichelt

Other Components

1Indium Foil 50*50*0.1mm

Needed to wrap the laser crystal

30Cable holder, self-adhesive
reicheltAlso useful for cable management in the whole device

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