Wanting inside a laser measurer

Tape measures are proper up there with uncooperative-coiling (and -uncoiling) extension cords and backyard hoses on the checklist of “issues assured to boost my blood stress”. They don’t work reliably (because of gravity) past my arm span until there’s one thing flat beneath them for all the distance they’re measuring. Metallic ones don’t do effectively with curved surfaces, whereas material ones are much more gravity-vulnerable. Talking of which, the one option to maintain a cloth one neatly spooled when not in use is with a rubber band, which can inevitably slip off and go away a large number in no matter drawer you’re storing it in. And when steel ones auto-spool post-use, they inevitably slap, scratch, or in any other case maim your hand (or another physique half) enroute.

All of which explains why, after I noticed Dremel’s HSLM-01 3-in-1 Digital Measurement Instrument on sale at Woot! for $19.99 late final October, I jumped for pleasure and jumped on the deal. I ended up shopping for three of ‘em: one for my brother-in-law as a Christmas current, one other for me, and the third one for teardown for all of you:

The labeling on this extra inventory photograph could be useful in explaining what you simply noticed:

Right here’s a extra meaningful-info instance of the bottom unit’s show in motion:

The default laser configuration is claimed to work reliably for greater than 5 dozen ft, with +/- 1/8-inch accuracy:

whereas the Wheel Adapter allows measuring curved surfaces:

and the Tape Adapter (sure, I didn’t fully escape tape, however no less than it’s non-obligatory and nonetheless is smart in some conditions) is extra correct for assessing round-trip circumference (and sure, they spelled “circumference” mistaken):

I imply…look how completely satisfied this man is together with his!

Apologies: I dilly-dally and digress. Let’s get to ripping down, lets? Right here’s our sufferer, starting with the compulsory outer field photographs:

And right here’s what the within stuff appears to be like like:

Right here’s a part of the literature suite, together with the included two AAA batteries which I’ll put to good use elsewhere:

Know-how licensed from STMicroelectronics? Now that’s intriguing! Maintain that thought.

Right here’s the rest of the paper:

And right here’s the laser measurer and its two-accessory posse:

This snapshot of the highest of the machine, as common accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for dimension comparability functions:

is nearly as good a time as any to conceptually clarify how these gadgets work. Wikipedia extra usually refers to them as laser rangefinders:

A laser rangefinder, often known as a laser telemeter, is a rangefinder that makes use of a laser beam to find out the space to an object. The commonest type of laser rangefinder operates on the time of flight precept by sending a laser pulse in a slender beam in direction of the article and measuring the time taken by the heartbeat to be mirrored off the goal and returned to the sender. As a result of excessive pace of sunshine, this method isn’t acceptable for prime precision sub-millimeter measurements, the place triangulation and different strategies are sometimes used. It’s a sort of scannerless lidar.

The essential precept employed, as famous within the earlier paragraph, is named “time of flight” (ToF), one of many three most typical approaches (together with stereopsis, which is employed by the human visible system, and structured gentle, utilized by the unique Microsoft Kinect) to discerning depth in laptop imaginative and prescient and different functions. Within the earlier photograph, the laser illumination emitter (Class 2 and <1mW) is on the proper, with the picture sensor receptor at left. Sure, I’m guessing that this explains the sooner STMicroelectronics licensing reveal. And the three steel contacts mate with matching pins you’ll quickly see on the no-laser-necessary adapters.

The underside is admittedly much less thrilling:

As are the textured and rubberized (for agency consumer grip) left and proper sides (the two-hole construction on the backside of the left aspect is presumably for a not-included “leash”):

I deliberately shot the entrance a bit off-center to get rid of reflections-of-self from bouncing off the shiny show and case end:

The duller-finish bottom offered no such reflectance considerations:

I don’t know what that white rectangular factor was contained in the battery compartment, and I wasn’t courageous sufficient to chop it open for a extra thorough inspection (an RFID monitoring tag, perhaps, readers?):

This closeup of the again label does double-duty as a pictorial rationalization of my preliminary disassembly step:

Screws beneath, simply as I suspected!

what comes subsequent…

Liftoff!

We will already see an outline of the laser transmitter perform block (full with a heatsink) at higher proper and the receptor counterpart at higher left. Seems, in reality, that all the inside meeting lifts proper out with no additional unscrew, unglue, and so forth. effort at this level:

From an orientation standpoint, you’re now wanting on the inside the entrance portion of the outer case. Word the steel extensions of the three earlier famous topside steel contacts, which seemingly press towards matching (flex? seemingly) contacts on the PCB itself. Once more, maintain that thought.

Now we will flip over and see the (much more naked) different aspect of the PCB for the primary time:

This can be a perspective you’ve already seen, this time absent the case, nevertheless:

Three extra views from totally different angles:

And as you’ll have already guessed, the show isn’t connected to the PCB aside from by way of the flex cable you see, so it’s straightforward to flip 180°:

Talking of flipping, let’s flip all the PCB again over to its again aspect, now unencumbered by the case that beforehand held it in place:

Once more, some extra views from totally different angles:

See these two screws? Eradicating them didn’t by itself get us any additional alongside from a disassembly standpoint:

However unscrewing the 2 different ones up high did the trick:

Flipping the PCB again over and inserting a “wedge” (small flat head screwdriver) between the PCB and ToF subassembly popped the latter off straightaway:

Right here’s the now-exposed underside of the ToF module:

and the seen-before frontside and finish, this time absent the PCB:

Newly uncovered, beforehand beneath the ToF module, is the system processor, a STMicrolectronics (shock!…not, when you recall the sooner licensing literature…) STM32F051R8T7 based mostly on an Arm Cortex-M0:

And in addition newly revealed is the laser at left which feeds the same-side ToF module optics, together with the picture sensor at proper which is fed by the optics within the different half of the module (understand that on this orientation, the PCB is upside-down from its normal-operation configuration):

I nearly stopped at this level. However these three steel contacts on the high rim of the bottom unit intrigued me:

There have to be matching electrical circuitry within the adapters, proper? I figured I would as effectively fulfill my curiosity and see. In no specific order, I began with my longstanding measurement-media nemesis, the Tape Adapter, first. Entrance view:

High view:

Backside view, revealing the beforehand foreshadowed pins:

Left and proper sides, the latter giving our first glimpse on the end-of-tape tip:

And two extra tip views from the again:

Peeling off the label labored final time, so why not strive once more, proper?

Revealed have been two plastic tabs, which I unwisely-in-retrospect instantly forgot about (keep tuned). As a result of, in any case, that seam alongside the highest seemed mighty attractive, proper?

It admittedly was an efficient transfer:

Right here’s the within of the highest lid. That groove you see within the center mates up with the top of the “spring” aspect of the spool, which you’ll see shortly:

And right here’s the within of the underside bulk of the outer case. See what appears to be like like an IC on the backside of that round gap within the middle? Hmmm…

Now for the spool usually in-between these two. Right here’s a high view first. That coiled steel spring usually suits fully contained in the plastic piece, with its finish becoming into the beforehand seen groove inside the highest lid:

The underside aspect. Hey, no less than the tape isn’t flesh-mangling steel:

A aspect view, oriented as when it’s put in within the adapter and in use:

And by the way in which, in regards to the spindle that matches into that spherical gap…it’s metallic. Once more, maintain that thought (and keep in mind my earlier remark about utilizing a rubber band to maintain a cloth tape measure neat and tidy?):

Right here’s the half the place I elaborate on my earlier “forgot in regards to the plastic tabs” remark. At first issues have been going nice:

However at this level I used to be caught; I couldn’t muscle the inside meeting out any extra. So, I jammed the sooner seen flat head screwdriver in a single aspect and wedged it the remainder of the way in which out:

Sadly, within the course of mangling one of many ICs on the PCB within the course of:

Had I simply popped each plastic tabs free, I might have been residence free. Reside and be taught (as soon as once more maintain that thought). Happily, I may nonetheless discern the package deal markings. The bigger chip can also be from STMicroelectronics (no shock once more!), one other Arm Cortex-M0 based mostly microcontroller, this time the STM32F030F4. And whereas at first, reflective of my earlier close-proximity magnetic-tip remark, I assumed that the different IC (which we noticed earlier than on the backside of that spherical gap) could be a Corridor impact sensor, I used to be close-but-not-quite: it’s a NXP Semiconductors KMZ60 magnetoresistive angle sensor with built-in amplifier usually meant for angular management functions and brushless DC motors. On this case, the consumer’s muscle is the motor! Fascinating, eh?

Now for the opposite, the Wheel Adapter. Entrance:

High:

Backside (pins once more! And word that the mysterious white strip seen earlier was pressed into service as a prop-up machine under the angled-top adapter):

Left and proper sides:

And label-clad again:

I’m predictable, aren’t I?

Word to self: do NOT overlook the 2 now-exposed plastic tabs this time:

That went a lot smoother this time:

However there are TWO mini-PCBs this time, one down by the contact pins and one other up by the wheel, linked by a three-wire harness:

Sadly, within the strategy of eradicating the case piece, I someway snapped off the connector mating this specific mini-PCB to the harness:

Let’s return to the bigger decrease mini-PCB for a second.  I received’t fake to feign shock as soon as once more, because the redundancy is probably going getting tiring to the readers, however the principle sliver of silicon right here is one more STMicroelectronics STM32F030F4 microcontroller:

The mini-PCB on the opposite finish of the harness pops proper out:

Kinda appears to be like like a motor, doesn’t it, however this time fed by the human-powered wheel versus a tape spool?

So, a conceptually comparable method to what we noticed earlier than with the opposite adapter, albeit with some implementation variation. I’ll shut with just a few photographs of the now-separate female and male connector pair that I mangled earlier:

And now, passing by means of 2,000 phrases and frightened of the mangling that Aalyia would possibly topic me to if I ramble on additional, I’ll shut, as-usual with an invite in your ideas within the feedback!

—Brian Dipert is the Editor-in-Chief of the Edge AI and Imaginative and prescient Alliance, and a Senior Analyst at BDTI and Editor-in-Chief of InsideDSP, the corporate’s on-line e-newsletter.

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