彩虹科学!- Spectrophotometry

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Introduction: Science With Rainbows! - Spectrophotometry

关于:茶在哪里?(以前命名为“dentdentarthurdent”)

Rainbows, natural phenomena that produce beautiful spectrums of coloured light in the sky, inspire myth and legend and art and give happiness to millions of people. Just as natural rainbows are created by how sunlight plays through water droplets in the atmosphere, we can artificially create our own rainbows using prisms. There are many scientific applications of rainbows, and one is 'Spectrophotometry'!

A spectrophotometer is a scientific instrument used to measure how different wavelengths of light (the different colours of light seen in the rainbow are different wavelengths) are absorbed by a sample. This analysis can tell us all sorts of things, and these instruments (first made in the 1940s) have played a huge role in modern science, especially biochemistry.

In this Instructable, we're going to make a basic Arduino-powered spectrophotometer, using a little prism to create and use our own rainbow. We'll make a lot of use of 3D printing, and also learn about lots of other things along the way.

项目视频提供了该项目的简短概述,但请通过可指示您的完整说明进行阅读!

Step 1: What You Will Need

These are the components I used to build my prototype. Please read onto the next step to read a more full explanation of how a spectrophotometer works, and how we can make our own at home!

Main Components

  • Triangular prism (30mm each side)
  • Arduino Uno
  • LDR (light dependent resistor)
  • 16-Bit LED pixel ring
  • 9g Servo
  • 迷你试管
  • DC-DC boost converter 5V-9V
  • USB cable (one end cut off, and the power lines soldered to the boost converter)
  • Wall plug that can supply 5V DC 0.5A
  • USB cable to connect Arduino to PC

小组件

  • 球轴承
  • Toggle switch
  • Momentary push button
  • E10灯丝灯泡
  • Bulb holder
  • 10K OHM电位器(或更大)

消耗品

  • Heatshrink
  • 标题销
  • Hookup wire
  • 焊接
  • Electrical insulative tape
  • 3D打印灯丝

Supporting

  • Windows PC
  • 3D打印机(我的印刷床是210x210mm)

Software

  • Arduino IDE
  • CAD软件如果要修改文件并查看程序集

第2步:彩虹和科学

分光光度计如何工作?
从根本上,分光光度计测量相对于波长物质的传动特性。那么这是什么意思?不同颜色的光(你可以看到的彩虹的颜色)具有不同的“波长”,这就是使它们似乎与我们的眼睛不同的颜色。我们知道不同的材料和化学品彼此不同地吸收和传递不同的波长 - 我们看到一个绿叶出现为绿色,因为光谱的绿色部分是叶子不吸收的主要部分,因此它被向后传递给我们的主要部分眼睛。分光光度计产生光谱,然后通过样品选择性地通过该频谱(例如红灯)的一部分,然后测量记录的光强度。反过来这样做,对于可见光谱内的光线中的每种波长(或每种颜色)的每个频段允许您测量该物质如何吸收各个部分的频谱,从而从您绘制吸收图表。这种分析可以告诉你很多关于一种物质或化学反应,这就是它是这样一个有用的科学工具!在研究这一点时,我读到了一个诺贝尔的化学版权所有的化学版表示,分光光度计是“可能是对生物科学进步的最重要的仪器”。我必须承认,我真的不需要在家里的分光光度计,但我认为尝试使用基本组件和arduino尝试一个非常有趣的项目。 So here goes!

上面的图像显示了我在壳体的尺寸范围内产生棱镜和光源之间所需的角度,以在壳体的尺寸内产生右尺寸和正确的位置。

Sidenote:Herschel的红外实验
红外线是电磁谱的组成部分,其刚刚超出了我们可见光光谱的红色末端。对人眼看不见的,红外线在我们的生活中起着巨大的作用 - 我们太阳的一半以上的能量到达地球作为红外光线,这让我们温暖我们并帮助我们的星球我们所需要的条件。威廉·赫歇尔(William Herschel)是18世纪的德国德国/英国天文学家,是第一个注意到红外线存在的人,他只是用一个简单的棱镜来做这件事,就像你所愿意这样做的那种说明。如果您愿意,您可以尝试在使用棱镜对分光光度计进行复制。

Herschel pointed a beam of strong sunlight into a darkened room, and angled his prism it so a beautiful rainbow shined out from it. He then took a thermometer, and noticed that when holding it in the dark region beyond the red part of the spectrum, there was a noticeable increase in temperature, although there was no visible light there at all! He wasn't looking for it, but with this simple observation he'd just discovered a whole previously unknown type of light!

Step 3: Richard of York Gave Battle in Vain

这个小助记符就是我如何教导彩虹的颜色'理查德 - 红色, - 橙色,约克 - 黄色,给予 - 绿色,战斗 - 蓝色,Indigo,Vain-virte'和参考一小英语历史赛段 - 参考Richard,Duke Of Richard,Richard的失败,在1460年在Wakefield的战斗中,在玫瑰战争的早期,在Wakefield的战斗中。我发现像这样真正令人满意的历史参考,所以我以为我会和你分享这个。

我们的分光光度计设计
Let's now have a look at our design, and discuss the main components.

  • The Prism - we shall use a simple triangular prism to generate our spectrum. The prism assembly will be held in bearings and be able to rotate, this will allow only a part (or single colour) of the light spectrum to be shined through through a narrow slot and into the sample.
  • 伺服马达驱动,一个微型9 g伺服马达会l rotate the prism assembly to point different parts of the spectrum through the slot towards the sample.
  • 测试tube hole - a mini test tube holding the sample will be inserted into this deep hole in the housing. One one side of the test tube will be this narrow slot from which light will pass through the sample, and on the other side of the test tube will be mounted the light sensor which will record readings and pass those to the Arduino microcontroller. I initially used a BH1750, but later changed this to a Light Dependent Resistor (LDR).
  • 光源 - 对于这种设计,我们将使用9V割炬电池。它安装在一个小组件中,该小组件在灯泡(涂覆在锡箔)后面的抛物线反射器以保持直射,并且前面具有小槽,使得只能出现窄光束。这允许光精确地被引入棱镜。

那么这些是设计的关键组件!

Step 4: She's a Rainbow

打印的所有.stl文件以及.step文件(如果要对设计进行修改,您可以导入CAD软件)将上载到这个grabcad页面I created to store the files. I strongly recommend you open this assembly to see for yourself all the detail of the assembly, so it's easier to understand how it all fits together. As well as the files for the spectrophotometer itself, this also includes the mini test tube rack that I designed to hold my samples.

对我来说,最勇气的复合部分是迄今为止打印主要案件!几乎所有项目的复杂性都包含在该单一部分内,因此正确打印这是如此根本。我的3D打印机(修改过的ANET A6)非常基本,缺乏更复杂的打印机的某些安全功能,所以我不舒服地运行它过夜。因此,我必须使用Slicer软件(Ultimaker Cura)中的设置来将打印时间保持在一天的窗口内。我最终调整它需要12.5小时,但如果我打印到更需要的质量,那将是22岁!

The fun pack of filament colours (PLA filament) I bought came with about 30g of a whole variety of colours (even glow-in-the-dark which you'll definitely see appear in a future project!). This I used to add the rainbow spectrum decoration to the side of the casing, which I think adds a lot to the project in terms of aesthetics. The first photo shows how I built this up - you'll need to fettle the fits a little with a knife/file to make sure they all fit snugly, but I didn't actually need to glue them.

第5步:彩虹连接

Electrical details!

这个项目的接线实际上是相对简单的,你很高兴听到!我没有包含一个原理图,因为它非常简单地描述,你将能够毫无困难地复制它。请记住,项目内有两个不同的电路,9V直流电路(从墙上插头供电),运行灯泡,以及拨动开关,以打开和关闭,以及Arduino电路(通过USB提供电源)从PC),还提供5V DC以运行LED像素环,以及LDR(轻依赖电阻)。

我建议将所有电气连接焊接在一起,并在进行任何其他组件之前将接线建造进入主壳体。在添加任何其他印刷部件之前,接线将已经铺设了布线。你会看到我在电缆长度中允许大量松弛,然后大致放入套管的凹槽中,用电工胶带保持下来。它不需要太整洁,因为所有这一切都将被外壳盖子封闭!

DC-DC升压转换器需要修剪(通过旋转螺钉并使用万用表测试输出)以提供9V,这是割炬电池所需的内容。

A tiny piece of stripboard was cut which was used to make a mini 5V rail and GND rail from the Arduino, to which the other electrical components are interfaced. Please follow the specific instructions for the specific LED Ring you purchase, as there are some very similar models that have slightly different wiring, so I wouldn't want to advise you incorrectly. A 10k potentiometer is used to connect the LDR in a voltage divider circuit, but a larger value would probably be better, as I used this set to the maximum 10k position.

Step 6: Assembly Time!

Time to complete the mechanical assembly. It's going to get quite tight inside the housing!

  • After the prism assembly in is inside, a rubber band is used to go to the servo motor head (the servo motor is super-glued in place on the rails that support it). Due to COVID-19 related lockdown, I couldn't go out to source another in time, so this is an old one from the kitchen that once was wrapped around a bunch of asparagus! This rubber band is a little loose, but it still works.
  • The nuts for the M2.5 bolts are embedded into 9 locations in the housing, and super-glued in place.
  • The Uno and boost converter are just pressed into place, which was nice and easy.
  • 在通过外壳通过USB电源线后,我在内侧缠绕了一点电动胶带,以防止它被拉过孔并损坏连接。
  • The LDR fits into a little plate, that fits into the void originally designed for the form factor of the BH1750 light sensor. This pushes into the housing, but I decided to secure it with extra electrical tape.
  • 在下面,四个小型自粘橡胶脚制造一个漂亮的粘结基底。我认为这为设备的感觉增加了一个很好的质量。
  • The light source assembly, even when printed in black PLA still leaked some light through the sides, so I wrapped black electrical tape around it too, which properly insulated it

第7步:测试!

Please download the attached Arduino code and get it uploaded to your Uno, but make sure to pay attention to the libraries that the code references that you'll need to install into your Arduino IDE if you don't already have them. It's necessary to check the pin attachments too, so make sure they match to how you've wired your system.

测试ing time, and running the code will produce the sequence seen in the video (Section 1 of this Instructable!). Copy the data that comes in from the Serial Monitor in the Arduino IDE into Excel or similar, and you can produce a plot similar to that shown above. This shows the traces from all 8 colour samples I tested (the ones shown in the test tube rack, which are paint in solution). The portion of the plot that is relevant is bounded by the vertical lines, which show the portion of the prism's rotation that the colour spectrum is shining through the sample. Outside of those bounds we're not interested in, and the light recorded is extraneous from other errant light sources. It's interesting to see how the LDR picks up different levels of the different colours of light, and how it shows variation within the spectrum for each colour too. I need to conduct more testing to further understand the response of the LDR to different wavelengths of light (there are different types of LDR which respond differently), and analyse more samples, but I think it's a promising result so far.

第8步:结论:在彩虹的某个地方!

我非常喜欢在这项项目上工作,从开始完成1.5个月,这就是教会我的设计,以及在实验中使用光。

如果我有机会改进,这个项目的版本将使用更亮的光源,使得更多的光可以到达传感器。它还可以使用LDR传感器的较大值(大于10k欧姆)电阻器,使得设备对低光水平的变化更敏感。我会发现一个更好的尺寸橡皮筋来驱动棱镜装配旋转(矿山太松),并用厚厚的墙壁打印外壳或用亚光黑色涂料涂漆,以最小化来自棱镜以外的光源的捕获。

非常感谢你的阅读,I hope that this interested you. If you do your own experiments based on this design, I would love to hear from you how you got on, and improvements that you could make! Please also comment if there are details you need that I've missed out, and I'll do my best to help.

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    15讨论

    0.
    Houtkapper.

    3个月前第8步

    Is it possible to get the files for printing the box and internal bits and pieces.

    0.
    ThirdEarthDesign

    Answer 3 months ago

    The author has already included the files via a link in the Instructable...

    0.
    KevinM75

    3个月前

    Rotating the prism rather than moving the slot is a nice space-saving trick (compared to commercial units like the Cary-60 I use at work)!

    2
    bpark1000

    Tip3个月前

    You would be better to use a photodiode rather then an LDR. LDR's are notoriously nonlinear, and prone to age. You will need an amplifier between the photodiode and the Arduino. To get more dynamic range, have several gain stages (gains factors of 2) and feed each one into different Arduino A/D input. The "highest" one that is not saturated is your output.

    3.
    nflemming2004

    3个月前

    一对夫妻思想:
    -using black filiment and/or spraypainting the interior of your body with flat black paint (I've been told Krylon flat black grill paint is the best cheap stuff out there) will significantly help improve your signal-to-noise in your readings
    - 您可以使用CFL灯泡(或更好的不同颜色的又一个激光指针),其在已知波长的光谱中具有尖峰,以校准系统的波长尺度
    -take a "flat" reading, using a sample tube filled with water, or nothing at all, and then subtract out the flat from all your other scans. This will calibrate your system for the specific bulb you're using as well as the spectral sensitivity of the light sensor.

    1
    Luklev.

    3个月前

    Thanks for the very detailed, well designed and interesting instructables. :)


    I also have a question: can a simple E10 bulb produce light throughout the entire spectrum (from IR to UV), or did you choose it with respect to the visible spectrum only. I ask because full spectrum lights, which are used, for example, in plant cultivation or phototherapy, look different.

    I guess it would be good to do a Herschel's Infrared Experiment here to find out ;)
    0.
    nflemming2004

    Reply 3 months ago

    A standard incandescent bulb will produce light from IR through the visible spectrum (no significant light in the UV though). Though, worth noting that the luminance by wavelength is not uniform, so it would be best to calibrate it (maybe using a test tube with plain water).

    0.
    gbowles

    3个月前

    Great Instructable! Did you ever consider using a photodiode array? I have no idea what they cost but I know it reduces the ambient light problem and it would, potentially, be able to do full spectrum scans in milliseconds with fewer moving parts.

    0.
    jihelb85.

    3个月前

    Hello. I cannot find the electronic assembly diagram.
    Please let me know.

    1
    jbtindie

    3个月前

    伟大的项目,丹尼尔!细节和抛光水平卓越!(这看起来并不像有人被砍在一起的东西,而是购买的全吹制品)。有些(希望有用)关于UX的评论,因为我看了从1:35-2:05的视频观看视频......

    First, when the process starts, all of the lights turn green. My impression while watching, was there isn't a indication that it's doing anything. My suggestion would be to animate the LEDs while processing. Maybe display only one LED at a time, and animate it like a clock (every second, change to the next LED)

    Second, when finished, the LEDs turned red. Red usually means something wrong happened, so I suggest that when finished, change all of the LEDs to green.

    除了一些小的UX问题之外,我认为这个项目很棒。(和梦幻般的工作!)我现在要去看看你在融合360中建造它的其他视频。

    1
    edchamberlain.

    3个月前

    Great instructabale. I like the "Pink Floyd” inspired design!

    1
    Glooraxis.

    3个月前Step 3

    Small detail nothing to do with the project but Richard was the legal king not a claimant. It was Henry who usurped the throne.

    1
    德国顿

    3个月前

    开放科学仪表倡议(OSII)
    Purpose:
    这项倡议的目的是开发科学仪器,可以通过任何人自由建造,利用几乎无处不在的资源以及开放社区的贡献。金宝博比分直播手机版
    License:
    A license must be developed, based on GNU public license V3. The projects should be made publicly available through that license.
    文档:
    仪器文档应在公共存储库上可用,由GitHub,Gitlab或Bitbucket等版本控制系统管理。它应该包括开放格式的3D信息,制造方法的描述,从工厂的评论,材料账单等。
    社区:
    项目must be downloadable by anyone.
    Anyone can join the community.
    Contributors could communicate through many means, but a official forum should be hosted somewhere online.
    贡献:
    Contributions could be submitted to the community as suggestions, requirements or as new branches of the project, like any open source software project. Contributors should keep in mind that more and new functionality can be aggregated to the project at any time.
    About the projects:
    Three dimensional CAD projects should be made using a software that can be easily monitored for modifications by a version control system. Please consider using OpenSCAD and use the forum to share your ideas.
    The projects should be developed with modularity and scalability in mind. Modules should, whenever possible, be interchangeable.
    每个项目都应附有CAD文件,材料清单,可以执行其零件的公司列表,购买原材料的地点列表,贡献者名单等。目录结构应遵循一些非常基本的模板。
    接受后的一些基本结构元素,不应改变该版本或所有已开发的模块也必须改变。
    Project branches:
    New branches can be created following the version control options. Every contributor can download a project, create its own branch and then, maybe, commit it to the main project.
    Interfaces:
    Interfaces should be well thought and developed with scalability, interchangeability and modularity in mind.
    截止日期:
    截止日期可能是有用的,但如果某些东西不收敛,则应尽可能实现分支并开始具有基本元素修改的新建一个新的一个。
    Seeds:
    A good starting point would be a low temperature equipment, but the main initiative should be able to handle arbitrary seeds.
    Creator:
    Eduardo N Hering, physicist, PhD.
    enhering@gmail.com
    Please share.

    1
    Penolopy Bulnick.

    3个月前

    This is such a great project! What program did you use to design the 3D printed parts?

    1
    jessyratfink

    3个月前

    This is amazing! Thank you for sharing :D