The “Spectrometer Exhibit: Instruments that Separate Light into the Colors of the Rainbow” was held at the Osaka Science Museum. I was thrilled to visit the exhibit, due to the fact that they were presenting measuring instruments that I use on a daily basis. One of the displayed items that particularly caught my eye was a spectrometer used in the early 20th century. More than half of the spectrometer’s housing was formed of wood, and a photographic plate was used for recording the spectra. Today the photographic plate has been replaced by a CCD camera, and the rotating mechanism of the optical element is now controlled electrically. Despite this, the internal construction is not much different from modern apparatuses. In fact, the device even employed quartz for the internal prism and lenses, a clever solution that allows passage of ultraviolet light while enabling analysis of a broader range of light wavelengths. This spectroscope was displayed alongside emission spectra of the various chemical elements that were acquired at the time the spectroscope was in use. It was startling how vivid the spectra appeared on the photographic plates. As I gazed at the images, I began to speculate how the scientists using these apparatuses in those days must have felt catching a glimpse of a world no one else had seen. Another part of the exhibit I found of great interest in addition to the displays of equipment were images of fireworks against the backdrop of a night sky in which the light had been separated into its spectral components.
Viewing this exhibit took me back to the Super Light School (Science School for Kids) at the Photonics Center. I participated in the first ever installment of the school. The elementary kids who took part in the class and I built a spectroscope to observe familiar forms of light, such as sunlight and fluorescent light. I was nervous in the days leading up to the class because I don’t ordinarily have many opportunities to speak with elementary kids, so I used some close connections to get some advice from an elementary school teacher. When visiting the teacher’s school I was astonished at how small the desks and chairs in the classroom were, bringing up altogether different worries from a physical perspective. I had prepared vivid slides with colorful rainbow schemes to attract the kids’ attention, but the teacher advised me to be careful about using too much color as brilliant colors can make some kids feel ill, so I revised my presentation at the last minute. Thanks to the advice I received from numerous people, I was able to enjoy myself in the class, albeit still being somewhat nervous. The spectrum shown on this page was acquired with the spectrometer that we used in the Super Light School. While the spectrometer is formed of a simple construction of pieces cut from a CD and cardboard paper, we were able to observe common sunlight separated into a brilliant rainbow of colors.
While light is so common in our everyday lives, we don’t often have an opportunity to get to know the science of light. Through exhibitions, like this spectrometer exhibit, the Light School, and the activities performed by everyone at the Photonics Center, it is my hope that the science of light will become more accessible to everyone.

大阪市立科学館で「分光器展 ～光を虹色に分ける機器～」が開催されていました。日常的に使用している計測機器が紹介されるとあって、嬉しくなって見学に行ってきました。展示物の中で一際目をひかれたのは、20世紀前半に使用されていた分光器でした。筐体の半分以上は木製で、スペクトルの撮像には写真乾板が用いられていました。今では写真乾板はCCDカメラに置き換わり、光学素子の回転機構は電動制御になっています。それでも、内部の仕組みは現代の機器とほとんどかわりありません。むしろ、分析できる光の波長の幅を広げるため、内部のプリズムやレンズに、紫外光を透過しやすい石英を用いる工夫がなされているほどでした。この分光器が現役の時代に取得した、様々な元素の発光スペクトルも併せて展示されていました。写真乾板に映し出されたスペクトルの鮮明さには驚かされました。当時この機器を使って、これまで誰も見た事のない世界を垣間見ていたのだろうかと、想像を膨らませながら眺めていました。機器の展示の他にも、夜空に打ち上がる花火を、光の色毎に分けてスペクトルで表示する映像などもあり、興味深くながめていました。

 

こうした展示を見学していると、スーパー光塾(こども科学の教室)のことを思い出しました。私が参加させて頂いたのは当時まだ第一回目の時です。参加してくれた小学生と一緒に分光器を作って、太陽や蛍光灯などの身近な光を観察しました。開催前は、普段小学生と話をする機会があまりないことを心配し、友人のつてを頼って小学校の先生にアドバイスを頂いたりもしました。訪問させて頂いた学校の教室にある机や椅子の小ささに驚き、物理的な視点からして違う事に改めて気づかされました。興味を持ってもらおうと、虹色のカラフルな配色をちりばめたスライドを作っていたのですが、色酔いしやすい子もいるので色を使いすぎないほうがよいのではとアドバイスを頂き、急いで修正を入れたりもしました。色々な方にアドバイスを頂いたおかげで、当日は緊張しながらも、楽しみながら進行できたように思います。口絵の写真は、その光塾で用いた分光器を使って取得したスペクトルです。CDの切れ端と厚紙だけのシンプルな構成ですが、見慣れた太陽の光が、鮮やかな虹色に分かれるのを観察できました。

 

光は日常にありふれていますが、光の科学にふれあう機会は多くはありません。今回のような展示会や光塾、さらにはセンターの方々の活動を通して、光の科学がより身近なものになるとよいなと思います。

 

 

博士研究員　安藤 潤