Portrait of Jose Carvajal-Beltran

Jose Carvajal-Beltran

Materials science undergraduate at MIT · Cambridge, MA

I study Materials Science & Engineering at MIT.

My current research is on nanocomposites, specifically on carbon nanotube/polysulfone composites. When mixed, the product of these two creates a conductive path, depending on the concentration of nanotubes. My goal is to find a sweetspot where these composites are most piezoresistive (have the biggest change in resistance due to strain).

Outside of research I play soccer, spend time with friends on campus, and build hardware projects for fun.

Resume

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Log

My problem with the current state of laser pointers.

Most of what is wrong with consumer laser pointers isn't a missing law or regulation. The law is already there, it's been there, and it is specific. The problem is that almost nobody checks whether the device in your hand actually obeys it.

Under 21 CFR 1040.10 and 1040.11, any laser product sold in the United States must meet a federal performance standard administered by the FDA's Center for Devices and Radiological Health. For anything sold as a pointer, that means Class 3R at most. Five milliwatts of visible output, with the far stricter Class 1 accessible emission limit governing everything past 700 nm in the infrared. Manufacturers certify their own compliance and file a report. There is no required independent test.

But what does the market look like in practice? The best answer available is still a NIST study from 2013. Joshua Hadler and colleagues built a deliberately cheap test bed and measured 122 commercially purchased pointers. Roughly 90 percent of the green units and 44 percent of the red units were out of compliance, and 52 percent of all devices tested exceeded the pointer power limit by a factor of two or more. The worst offender put out 66.5 milliwatts, more than ten times the legal ceiling. This essentially says there is a high probability that a handheld laser labeled Class 3R is in fact a Class 3B device.

I want to bring up the infrared point. A green pointer isn't a green diode. It's an 808 nm diode driving a neodymium crystal at 1064 nm, frequency doubled down to 532 nm. Everything upstream of that final conversion is invisible, and the only thing standing between it and your retina is a filter that costs the manufacturer money to install. NIST found green pointers routinely emitting unacceptable infrared levels alongside the visible beam. Your blink reflex answers to brightness. It doesnt react to 1064 nm.

This brings me to the actual failure point. The label is the only information a buyer has, and the label is the thing that is false. A consumer generally cannot measure output power, especially if it is an unknowing parent. They cannot detect infrared leakage. They read "Class IIIa, less than 5 mW," which is a legal claim made by a party with every incentive to make it and essentially no chance of being audited, and they reasonably believe it.

There are consequences. Pilots reported 10,994 laser strikes to the FAA in 2025, a 14 percent decrease from the previous year after 12,840 strikes in 2024. The agency has tracked 337 pilot injuries since it began collecting the data in 2010. Green is the most commonly reported color, which is exactly what you would predict from a category that is both the brightest per milliwatt and the least likely to meet spec.

What actually bothers me is that NIST survey is thirteen years old. It is still the most rigorous public characterization of the American pointer market. The market it sampled barely resembles the one we have now, where a listing can advertise burning through electrical tape as a selling point while the same product page claims a compliant five milliwatts, and where the seller can dissolve and relist under a new name faster than any enforcement action can land.

This summer I filed a Citizen Petition with the FDA under 21 CFR 10.30. It is docketed as FDA-2026-P-7822. The agency already has a valid, unambiguous performance standard, and it also has published federal measurement data showing a majority noncompliance rate against that standard. What it doesn't have is an enforcement posture built for a market that has shifted almost entirely to anonymous overseas sellers shipping directly to consumers, where manufacturer self certification is functionally an honor system with no honor in it. The petition asks the agency to stop treating the pointer category as presumptively compliant and to reconcile its enforcement approach with its own evidence.

I built it on the NIST measurements, on FAA strike data, and on the structure of the certification requirement itself, with fifteen supporting footnotes and a severability clause, because I would rather have the strongest request survive on its own than watch the entire petition get dismissed on the weakest one.

The obvious objection to a petition resting on 2013 data is that it rests on 2013 data. I agree, and that is the next step. The NIST apparatus was designed specifically so that other institutions could replicate it easily. A fresh random sample of what is actually being sold in 2026, measured properly, reported per unit across both bands, is a study one undergraduate can run, and it is one that apparently nobody has run in over a decade.

Redacted

This was a log entry that I deemed too 'bold' to have, for now.

Projects

ISEF: Potential Shift in Velocity as Temperature Changes

Motivated by the growing interest in drone delivery systems and rotor-based space capsules, this project used maple samara seeds as a physical analogue to study how temperature affects aerodynamic descent. I dropped 30 seeds twice each across three controlled-temperature rooms (180 total trials), recording fall times from 2.3 meters and computing terminal velocity, energy equilibrium, and Reynolds numbers for each condition.

The results showed a clear shift: at 27 °C terminal velocity exceeded 1 m/s, while at 20 °C it stayed below that threshold. The higher-temperature runs also yielded lower Reynolds numbers, indicating a more laminar flow regime. The data point to a positive correlation between ambient temperature and descent velocity, and suggest that future work with more temperature points could sharpen these findings considerably. This project won a CIA award

ISEF: Dynamics of Space Capsule with Rotors

Despite decades of NASA interest in rotor-equipped re-entry capsules, the literature rarely drills down to the rotor geometry itself. This project set out to fill that gap, testing the hypothesis that a larger chord length produces superior autorotation performance. I ran a CFD simulation of the NACA 4412 airfoil to map pressure distributions across the blade, then applied Momentum Theory to derive closed-form autorotation equations and estimate Reynolds numbers under idealized assumptions.

A Blade Element Momentum (BEM) simulation revealed a counterintuitive result: the efficiency curve is actually wider — meaning more forgiving across a range of conditions — for shorter chord lengths than for longer ones. Supplementary heat-flux analyses of the capsule outer surface produced consistent results across two independent runs. The overall conclusion is that a rotor-based space capsule is plausible, but optimal performance likely favors thinner, high-strength blades and a coaxial rotor arrangement to manage the highly turbulent Reynolds regime predicted during descent. This project won a full tuition scholarship to F.I.T.

Custom Air Hockey Table

Watch on YouTube

In this project, Diego Salcedo and I were both in the same Edgerton (Makerspace at MIT) section for Interphase Edge. We decided that it would be a great idea to build an air hockey table with a unique V shape. After going through many iterations, we found that it would be virtually impossible to create what we wanted to within a very short timespan and while taking many difficult courses.

Instead, we created our own air hockey table from scratch, with Diego working on the machining aspects and myself working on the electronics components. I configured a 120V AC OEM blower to the table and hooked it up to power and an e-stop to blow air through the many holes Diego drilled. After this, I used a protoboard and infrared sensors to create a beam-break sensor and a scoreboard to track who is winning.

All-in-all, this is definitely the most fun I have had creating a project!

8.012 Final Project

Download Report (PDF)

This was my final project for 8.012, it was revolving a problem from a Problem Set that felt very counterintuitive even if the math checked out. We made a physical model and coded a simulation (with a BIT of exaggeration) to see if the phenomenon was real and if it could be explained better. The problem was of two beads on this ring, it is said that if the beads were a certain mass or greater, then the ring would 'jump' up at a certain angle. We tested this in real life (after hours of making models that didn't work and using ancient scales) and found that the phenomenon did actually happen, seeing it made it feel more intuitive. We submitted our report and ended up getting selected to present in front of the entire class (Shoutout to Kaku & Ishan)!

Academics

8.012 Classical Mechanics

Definitely the hardest and most time-consuming endeavor so far in my journey (albeit the journey has just started). This class is informally called 'physics for masochists'. People would ask me all the time "why are you taking that class", and I genuinely had no response other than for curiosity. This class focused heavily on advanced calculus and vector algebra.

6.2020 Electronics Project Laboratory

One of the most interactive and interesting classes I've taken. Taught by Jim Bales, this class was an introduction to circuits and basic laws about electricity. We built many projects with protoboard and learned how to use new electrical components every week.

UROP: Optimal Orientation for VAM

How Volumetric Additive Manufacturing works, visualized.

This is a research project that i took part in, it involves a really cool 3D manufacturing technique that is known as Volumetric Additive Manufacturing (VAM). The most basic way to explain it is to say that light from a projector 'shoots' a bunch of 2D photos at a vat of resin that hardens with light. The vat spins and for each degree, a new photo is projected. All of these projections form a 3D object. What I set out to determine is whether the orientation ($\phi$ and $\theta$) have any effect on the resulting quality of the print due to dosage of light. I found that there was in fact a variation in the print quality, sometimes it was obvious, but othertimes it was not. I utilized a technique involving many iterations at a small scale (using less voxels) to see which angles looked promising. This almost always translated to the actual print having a higher quality as well, where quality is determined by measures of a histogram involving in-part and out-of-part voxels.

MIT MISTI Mexico

This is a project I am currently undertaking. I have made many castings of a Carbon Nanotube (CNT) and Polysulfone (PSF) nanocomposite. At different weight percentages (i.e. different amounts of CNTs), nanocomposites of these nature exhibit different properties. One of these is resistance and piezoresistivity. Essentially, as we deform this nanocomposite, its electrical resistance changes. This is exactly what I have been studying for the past month (one month left). I have mastered the art of creating these nanocomposites and aligning carbon nanotubes using an applied voltage, with the CNT/PSF mixture cast in between two electrodes. I will update this further as I learn many more cool things!