Laserex LDP-400UB Laser Diode Pointer, retail AU$21.97 (US$20.00)*
Manufactured by Laserex Technologies (
Last updated 05-28-14

The Laserex LDP-400UB Laser Diode Pointer is a red-emitting laser pointer. It comes in a handsome plastic body, and can feed itself from either three N cells or two AAA cells.

It is labelled as the, "Presenter".

I used to have their LDP-300UB in the very late-1980s, so when I saw this one being sold as new on Ebay not long ago (late-May 2014), I jumped right on it.

*Pricing is accurate as of 05-27-14.
Please go to to convert Australian dollars to US dollars.

 Size of product w/hand to show scale SIZE

To get the laser to turn on, first be certain that there are a pair of AAA cells or a trio of N cells installed. If there isn't, then install them (see directly below; they're included), and THEN you can go irradiate something.

Press & hold down the button on the upper side of the barrel near the front for as long as you want or need the laser spot (a red, "emissions indicator" LED located just forward of the pushbutton will come on at this point), and release pressure on the button to neutralise it.

To change the batteries in your spiffy new (or dull, scratched-up old) Laserex LDP-400UB Laser Diode Pointer, slide the lower portion of the top of the case back (as you see in the photo directly below), buy yourself an airline ticket and fly to Sydney Australia, drive it to the Sydney Opera House, and huck it under one of the bass violinist's instruments so that the musician will step on and subsequently cause it to become busted...
O WAIT!!! YOU'LL NEED THAT!!! So just set it aside instead.

Remove the used AAA or N cells, and dispose of or recycle them as you see fit.

Insert two new AAA or three new N cells into the chamber, orienting them so that their nipple-ends (+) positives face the rear of the laser.

Finally, slide that battery door back on until it stops moving and fits flush with the rest of the laser pointer's body.
Aren't you glad that you didn't chuck that battery door into the orchestra pit at the Sydney Opera House now?

This is a self-contained laser , and not a flashlight meant to be carried around, thrashed, trashed, and abused - so I won't try to drown it in the toliet tank, bash it against a steel rod or against a concrete porch, let my mother's big dog's ghost, her fuzzbombs (kitties), my sister's kitty cats, or my own precious little furkid piddle (uranate) on it, run over it with a 450lb Celebrity motorised wheelchair, stomp on it, use a small or medium ball peen hammer in order to bash it open to check it for candiosity, fire it from the cannoñata, drop it down the top of Mt. Erupto (I guess I've been watching the TV program "Viva Piñata" too much again - candiosity is usually checked with a laser-type device on a platform with a large readout (located at Piñata Central {aka. "Party Central"}), with a handheld wand that Langston Lickatoad uses, or with a pack-of-cards-sized device that Fergy Fudgehog uses; the cannoñata (also located at Piñata Central) is only used to shoot piñatas to piñata parties away from picturesque Piñata Island, and Mt. Erupto is an active volcano on Piñata Island), send it to the Daystrom Institute for additional analysis, or perform other indecencies on it that a flashlight might have to have performed on it. So this section of the web page will be ***SIGNIFICANTLY*** more bare than this section of the web page on a page about a flashlight.

This is a directly-injected laser though, who's active components are the inverter circuit, the laser diode, and the collimating lens. So it should withstand accidents better than a DPSS (diode pumped solid state) laser - the type of laser assembly found in yellow (593.5nm), green (532nm) and blue (473nm) laser pointers. These lasers have several additional components (crystals, filters, etc.) in the optical train, and you can knock them out of alignment by doing little more than looking at them the wrong way. And if any of these components are nocked out of whack, you'll no longer get your yellow, green, or blue laser beam.
Though you still do not want to intentionally drop your red-emitting laser because it's a precision optical instrument -- and a rather expen$ive one too as red diode laser pointers go.

Power output peaks at 0.950mW with 3 N cells.

Power output peaks at 0.9063mW with 2 AAA cells.

These tests were conducted on a Sper Scientific Pocket Laser Power Meter # 840011 because my LaserBee 2.5W USB Laser Power Meter w/Thermopile is on the rag and this laser's power output is too low to be measured on this instrument anyway.

Beam terminus photograph on the test target at 12".

Beam terminus photograph on a wall at ~8 feet.

Spectrographic analysis
Spectrographic analysis of this laser.

Spectrographic analysis
Spectrographic analysis of this laser; spectrometer's response narrowed to a band between 635nm and 645nm to pinpoint wavelength, which is 642.240nm.

The raw spectrometer data (tab-delimited that can be loaded into Excel) is at

USB2000 Spectrometer graciously donated by P.L.

A beam cross-sectional analysis would normally appear here, but the ProMetric System
that I use for that test was destroyed by lightning in mid-July 2013.

Test unit was purchased on Ebay on 05-23-14, and was received at 2:08pm PDT on 05-27-14.

UPDATE: 00-00-00

Properly labelled for wavelength & CDRH classification (this is a Class II laser product)
Can use either N cells or AAA cells
Product is made in Australia (this typically signifies higher quality than might be found in products manufactured in other foreign countries)


Has a bit of a 'chintzy' feel; this was not expected from a Laserex product
Has some minor artifacts outside primary beam

    MANUFACTURER: Laserex Technologies
    PRODUCT TYPE: Handheld laser pointer
    LAMP TYPE: Diode laser
    No. OF LAMPS: 1
    BEAM TYPE: Very narrow spot
    SWITCH TYPE: Momentary pushbutton on/off on product's body
    CASE MATERIAL: Plastic
    BEZEL: Plastic; laser diode & lens recessed into a hosel for them
    BATTERY: 2x AAA cells or 3x N cells
    CURRENT CONSUMPTION: Unknown/unable to measure
    WATER- AND URANATION-RESISTANT: Very light splatter-resistance at maximum
    ACCESSORIES: 3x N cells, hard-sided storage case
    SIZE: 170mm L x 23mm W x 21mm D (at its deepest part)
    WEIGHT: 57.50g (2.030 oz.) with N cells, 45.80g (1.620 oz.) with AAA cells
    WARRANTY: 1 year


    Star Rating

Laserex LDP-400UB Laser Diode Pointer *

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