Tag: laser

Driving a green laser pointer with MicroManager

Reminder: green laser pointers have a ton of IR in them. It needs to be filtered out if you don’t want it. See this old (2011!) Labrigger post. I.e., Paul and Kurt are right (see above). The absurd amount of power you measure out of a “green” laser pointer is not because it is recklessly



Ripple noise on PMTs in 2-photon imaging – Part 2

The recent post on ripple noise generated some comments and additional discussion. Go check out the comments on that post. For example, Peter Rupprecht shared some snapshots an oscilloscope display showing the signal from the BNC connector at the back of the laser, in the presence of this ripple noise. The ripple is seen when



DIY 1060 nm fiber laser

For less than $13,000, you can build your own fiber laser and get pretty nice images with it.



Coolant lines for lasers

Many lasers have baseplates with channels through which chilled water is pumped to dissipate heat and stabilize the temperature of the system. I haven’t had much trouble with the chillers and baseplates of Newport/Spectra-Physics systems. However, most of the Coherent Chameleon systems I’ve worked with (3 out of 4) have had problems with the water



Inexpensive IR viewer options

From Benjamin Judkewitz: I needed an IR viewer to see a Ti:S beam and was really surprised to find that most viewers still sell for > 1000 € (or $). Visualizing NIR used to be really simple with smartphones (enabling public installations like this one by JPL/NASA), but that was before nearly all makers started



Photonics Handbook online reading

When you run out of catalogs to read, Photonics has some nice short articles. It’s all pretty basic, not too complicated. Good for training (e.g., Optical design software, Fiber lasers)



Time-bandwidth product

Ultrafast pulses are formed through interference of different wavelengths of light. Think of Fourier transforms, and how pulses can be generated through constructive and destructive interference of wavelengths with aligned phases. These wavelengths are close to the center wavelength, and spread over a wavelength bandwidth. Shorter pulses require wider bandwidths, and the product of pulse



Controlling a bunch of servos

A friend just asked a quick question: How can I make a bunch of cheap (not fast) laser shutters? Here’s a quick answer: For motors, servos are pretty easy to use. Put a piece of black material on the arm of the servo if the laser is weak and this is safe to do. Alternatively,



Damage thresholds and Ti:Sapph lasers

Recently, a moderately expensive optical element got fried at Labrigger. During the postmortem, we revisited our power and energy calculations, and our LIDT (laser intensity damage threshold) calculations. LIDT calculations remind me of radiation-health physics (e.g., how much radiation can a human be safely exposed to?). My nuclear physics professor, the excellent R.T. Carpenter, included



Smartport for open source handheld laser control

Wicked Lasers makes laser pointers. High quality, high power laser pointers that can be repurposed for other applications. In fact, some of their lasers should probably never be used as pointers (e.g., this 2 watt 445 nm laser). To aid in the re-application of their lasers, they have released the Evo, a 100mW 532nm laser



Autocorrelator for under $5k

Autocorrelators can be used to measure the pulse width of ultrafast lasers. This can be useful for troubleshooting dispersion in your 2-photon imaging system and generally troubleshooting laser issues. They are big ticket items and often cost over $15k (e.g.). Minioptic sells one for under $5k. Just run your beam into it and plug the



Pulsed laser power part 2

In a previous post, we discussed how peak power is computed. Although Ti:Sapph laser manufacturers typically quote the average power, peak power is the more relevant quantity for two photon excitation. Here’s a graph showing how narrow pulse widths can increase peak power. It takes about 3 watts of average power in a beam for



50% off at Edmund Optics

If you’re like most people, you can get the vast majority of your holiday shopping done at Edmund Optics. They’re having a Cyber Monday sale this Monday, November 26th. Use code Cyber12 at checkout. Here’s the deal, they’re offering 50% off of these product families: Clearance, Recertified, Anchor The first two categories are self explanatory,



Optimizing pulse frequency for 2p imaging

The lasers used in multiphoton imaging deliver their photons in pulses. Many commonly used systems pulse at 80 MHz. However, there are good reasons to try different frequencies. In 2007, Donnert, Eggeling, and Hell published a Nature Methods paper where they used low frequency pulses to get more fluorescence signal out of the preparation. The



Laser pointers and quantum mechanics

Laser pointers are handy sources for coherent light. The green and blue varieties are actually diode-pumped solid state lasers, all in a hand-held package. The IR wavelengths used for pumping are typically left in the beam, so your green laser pointer is actually a fairly bright IR laser with some green thrown in. This was