要想使用欧里几德的C型探测器，玩家必须首先完成That Lucky Old Sun的任务，并在最后选择给阿基米德II充电。这玩意儿发射一次之后有24个小时的充能时间。由于测距仪本身没有任何威胁性，所以如果任務中没有给阿基米德II充电，那么它就只能当做一个收藏品放着了。
Euclid's C-Finder is not a weapon in its own right, but rather a targeting device, or "range finder," for the Archimedes II orbital laser platform. 这把武器伤害为0，所有的伤害都来自从天而将的激光冲击，所以在室内它也没有任何作用。
击发测距仪后，测距仪的屏幕上会反映出系统的各种计算数据，这需要大约5秒的时间。在这5秒钟内Euclid's C-Finder can be repositioned for a new target before the laser strikes. 而且能量武器的技能再高对其也没有任何增益。Pressing the trigger constitutes firing the weapon, which will alert nearby enemies before the actual laser hits. 敌人可能會跑出激光炮的攻击范围。
在自由城，两个小孩在追逐打闹，那个叫Max的小孩手里就拿着这玩意儿。Max thinks the weapon is actually just a toy, as it is reminiscent of the popular 1950s-60s toy laser guns for children. 交易技能45以上，20个瓶盖就可以买过来，否则要1000瓶盖。或者等那个熊孩子睡着了偷过来, followed by a loss of Karma. The game has been known to display "talk" rather than "pickpocket" Max when doing this. If you press the interact button it will take you into the pickpocketing menu where you can steal the gun. This will result in no loss of Karma.
- If you are under any effects of stealth field, firing Euclid's C-Finder will completely reveal you.
- Euclid's C-Finder cannot be used in V.A.T.S.
- If you have Veronica as a companion, she will respond "Yeah, I guess it works." when it is first fired.
- Though a heavy weapon of 15 lbs, Max, the child who owns it, has no problem holding it in one hand.
- If you fire the weapon during its recharge time, the positioning lasers will be seen but the weapon will not fire, however, the weapon will fire immediately after the recharge time is over.
- The weapon will not always fire if the recharge time of 24 hours is waited using the "wait" function instead of passing it in the game without the waiting function.
- Euclid's C-Finder's reloading animation is exactly the same as the alien blaster's (when multiple charges are possessed), save for the C-Finder having an orange power cell, as opposed to the alien blaster's blue.
- Euclid's C-Finder does not work indoors.
- The sun ray causes a knock down effect in a large AoE where it is blasted so be careful with friendly fire, as your companions can be easily crippled by it.
- Sometimes, around every two days, you may obtain another C-finder from Max if the player chooses to use the Barter check. This can be repeated up to four times.
- Even though Euclid's C-Finder is considered a unique weapon, there isn't a "normal" variant of it.
- If you pickpocket the weapon from Max instead of buying it, he will later reappear chasing Stacey. He will not have the weapon equipped, but if you talk to him he will pull it out. You can then wait until it gets dark and pickpocket another from him. This can be done infinitely.
- Max will appear with the gun again so and it can be purchased from him an unlimited number of times.
- If you Pickpocket it off Max and immediately talk to him, he says "I wish I had a gun." and goes back to sleep.
- If Veronica is with you when you buy the weapon from Max, she will say, "Wow, good thing the safety was on."
- After firing it for the first time, Mr. New Vegas will have a news article about the event on Radio New Vegas.
- If the player didn't direct the power to Archimedes II at the end of That Lucky Old Sun, this can be reverted through the console command set "e282d".nPowerConfiguration to 4.
Behind the scenes
- Euclid was a famous Greek mathematician, known as the originator of many basic geometric and mathematical principles. Euclidean geometry and Euclid's algorithm for calculating the greatest common divisor of two integers are both named for him.
- The name Euclid's C-Finder, and the graphics it shows the player while it is operating, are a reference to using Euclidean geometry to find the third point, C, of a triangle, given points A and B, and distances BC and AC. In this example B is the player's position on the ground, A is the position of the Archimedes II satellite, and C is the position of the target. The satellite gets distance BC from Euclid's C-Finder (which is described as a "handheld rangefinder" in the terminal notes at HELIOS One), and knows AC, one assumes, from radar height measurement. In practice, the satellite would also need to be able to determine the direction Euclid's C-Finder is pointing. Presumably, Euclid's C-Finder can only measure basic compass heading and range, leaving the satellite to calculate the target's elevation, unless it had an internal gyroscope and GPS, which would allow the elevation of the target to be calculated.
- Has platform::Playstation 3 After Exiting The Thorn or fast traveling with Euclid's C-Finder in your inventory, it may fire a beam with no warning, hitting The Courier, his/her companions and any other non-player characters in range. [已核实]
- Has platform::PC Has platform::Playstation 3 Has platform::Xbox 360 It is possible Euclid's C-Finder may re-spawn multiple times on Max. If you do not have the gun in your inventory and return to Freeside some time after acquiring it, Max will have another Euclid's C-Finder. This will also result in additional ARCHII charges added each day for each Euclid's C-Finder in the player character's inventory. [已核实]
- Has platform::PC Has platform::Playstation 3 Has platform::Xbox 360 If the player character has the Heave Ho! perk, firing Euclid's C-Finder may freeze the game. To fix this a player user can remove the perk using console commands, this will allow the player to fire the weapon without crashing. [已核实]
- Has platform::PC Has platform::Playstation 3 Has platform::Xbox 360 When trying to fire, the targeting laser may repeatedly play its animation without the laser firing. To fix, save the game with the gun drawn and firing and then quit the game completely back to the desktop/reset console. Restart, reload, and wait for the firing animation to complete. Ensuring to save far enough away from the target to not be hit, but close enough that the animation is still visible and playing. [已核实]
- Has platform::PC Has platform::Playstation 3 Has platform::Xbox 360 Sometimes the gun will not get any ammunition after activating Archimedes II, or it will fire a few times and then not get any more ammunition. To fix, save the game and then quit to the desktop/reset console. Reload the saved game and then after some time the charges will spawn as normal. [已核实]
- Has platform::PC Has platform::Playstation 3 Has platform::Xbox 360 Sometimes Euclid's C-Finder will not fire at all, despite the lasers being visible. However, the orbital strike will still take place some time after this at the intended location. Entering a building and waiting or sleeping until midnight followed by staying inside for 5-10 minutes will prevent the delayed strike from occurring as the gun cannot be fired inside.[已核实]
- Has platform::Playstation 3 Has platform::Xbox 360 The game seems to register kills with Euclid's C-Finder as "unarmed" kills as evidenced by getting the Beautiful Beatdown perk while using it. [已核实]
- Has platform::PC Has platform::Xbox 360 Obtaining Euclid's C-Finder before completing or at least initiating the quest I Could Make You Care, could bug the quest. See the quest page for details. [已核实]
- Has platform::Xbox 360 If aimed at a lake or body of water, there will be a bright flash of light, but no laser. [已核实]
- Has platform::Playstation 3 Euclid's C-Finder may disappear from the player character's inventory after being caught stealing from the Silver Rush in Freeside, even after killing them. [已核实]
- Has platform::PC Has platform::Playstation 3 Has platform::Xbox 360 If you obtain a second Euclid's C-Finder, DO NOT repair them. This may cause the bug in which it does not fire, and will show the laser marks only repeatedly even with another weapon out and may not fire. It is possible to fix this issue by removing the affected C-Finder from your inventory then buying or stealing a new one. [已核实]
- Has platform::PC Has platform::Playstation 3 Sometimes if you pickpocket the C-Finder, it will be in barely maintained condition instead of perfect [已核实]
- Has platform::PC Has platform::Playstation 3 Has platform::Xbox 360 The weapon may also fire immediately after loading a save chronologically after the laser was targeted so aim away from everything able to be killed. [已核实]