Measuring CD Pit Spacing with a Laser: Applying Fundamental Physics Principles and the Diffraction Grating Method
Abstract
Purpose of the study: This study aimed to measure the distance between data pits on a Compact Disc (CD) by utilizing its reflective surface as a diffraction grating. When a laser beam strikes the CD, the alternating pits and lands create a diffraction pattern of bright and dark fringes. The pit spacing can then be determined from this pattern and compared with literature values.
Methodology: A red laser was used as the light source, and the resulting diffraction pattern was analyzed using simple Python code based on the diffraction principle. This approach provides an efficient and low-cost method to perform quantitative analysis using readily available tools.
Main Findings: The measured distance between pits on the Compact Disc was 1.607 ± 0.017 µm, with an accuracy error of 0.004%. The results closely matched reported literature values, though slight deviations may have arisen from parallax errors, the difficulty of identifying the laser’s exact reflection point, or ruler precision. From these results, it can be seen that a simple basic physics experiment can easily performed by students because the equipment and procedures are simple yet still produce good results.
Novelty/Originality of this study: This work demonstrates that meaningful physics experiments can be conducted with everyday materials and simple instruments, offering a time- and cost-efficient way to explore fundamental concepts such as diffraction. The study highlights the potential of using familiar objects like compact discs to make physics learning more engaging and accessible for students and young researchers.
References
S. Soeharto and B. Csapó, “Evaluating item difficulty patterns for assessing student misconceptions in science across physics, chemistry, and biology concepts,” Heliyon, vol. 7, no. 11, 2021, doi: 10.1016/j.heliyon.2021.e08352.
D. Woitkowski, “Tracing physics content knowledge gains using content complexity levels,” Int. J. Sci. Educ., vol. 42, no. 10, pp. 1585–1608, 2020, doi: 10.1080/09500693.2020.1772520.
J. J. Barreiro, A. Pons, J. C. Barreiro, J. C. Castro-Palacio, and J. A. Monsoriu, “Diffraction by electronic components of everyday use,” Am. J. Phys., vol. 82, no. 3, pp. 257–261, 2014, doi: 10.1119/1.4830043.
K. Herlina, B. A. Wicaksono, D. Andra, and I. D. P. Nyeneng, “Development of a simple and low-cost light diffraction props for teaching and learning optics during covid-19 outbreak,” J. Pendidik. MIPA, vol. 23, no. 2, pp. 437–447, 2022, doi: 10.23960/jpmipa/v23i2.pp437-447.
F. Bouquet, C. Dauphin, F. Bernard, and J. Bobroff, “Low-cost experiments with everyday objects for homework assignments Low-cost experiments with everyday objects for homework assignments,” no. June 2023, 2019, doi: 10.1088/1361-6552/aaf6d6.
L. Sayre et al., “Ultra‐thin GaAs solar cells with nanophotonic metal‐dielectric diffraction gratings fabricated with displacement Talbot lithography,” Prog. Photovoltaics Res. Appl., vol. 30, no. 1, pp. 96–108, Jan. 2022, doi: 10.1002/pip.3463.
Y. Wang, X. Fu, Y. Chen, L. Qin, Y. Ning, and L. Wang, “The development progress of surface structure diffraction gratings: from manufacturing technology to spectroscopic applications,” Appl. Sci., vol. 12, no. 13, p. 6503, Jun. 2022, doi: 10.3390/app12136503.
J. E. Kettler, “The compact disk as a diffraction grating,” vol. 367, no. 1991, pp. 25–27, 2012, doi: 10.1119/1.16553.
H. H. Peek, “The emergence of the compact disc [History of communications],” IEEE Commun. Mag., vol. 48, no. 1, pp. 10–17, 2010, doi: 10.1109/MCOM.2010.5394021.
A. Anžel, D. Heider, and G. Hattab, “The visual story of data storage: from storage properties to user interfaces,” Comput. Struct. Biotechnol. J., vol. 19, pp. 4904–4918, 2021, doi: 10.1016/j.csbj.2021.08.031.
J. A. Cope, “The physics of the compact disc,” Phys. Educ., vol. 28, no. 1, pp. 15–21, 1993, doi: 10.1088/0031-9120/28/1/003.
N. Bonod and J. Neauport, “Diffraction gratings: from principles to applications in high-intensity lasers,” Adv. Opt. Photonics, vol. 8, no. 1, p. 156, 2016, doi: 10.1364/aop.8.000156.
Massachusetts Institute of Technology, Department of Physics, Experiment 9: Interference and Diffraction. 2006, pp. 1–9. [Online]. Available: https://ocw.mit.edu/courses/8-02-physics-ii-electricity-and-magnetism-spring-2007/80de81c8897a6835c7771736d6385fa3_experiment9.pdf
Panchbhaya, “Single-slit diffraction,” in Applications of the Wave Nature of Light, vol. 2, 2015. [Online]. Available: https://panchbhaya.weebly.com/uploads/1/3/7/0/13701351/phys12_c10_10_2.pdf
E. Kannatey-Asibu, Principles of Laser Materials Processing. 2008. doi: 10.1002/9780470459300.
S. E. Huether, “How lasers work,” AORN J., vol. 38, no. 2, pp. 207–215, Aug. 1983, doi: 10.1016/S0001-2092(07)64322-1.
C. Grecco, J. D. Vollet-Filho, M. T. Carvalho, and V. S. Bagnato, “Physics of lasers and LEDs: basic concepts,” in Lasers in Dentistry: Guide for Clinical Practice, 2015, pp. 1–10. doi: 10.1002/9781118987742.ch1.
T. E. Coan, “Diffraction and ompact discs,” 1999. [Online]. Available: https://www.physics.smu.edu/kehoe/1301S06/cd_diff.pdf
A. Bansal and D. Arora, “Compact disks: what, why and how,” DESIDOC Bull. Inf. Technol., vol. 22, no. 4&5, pp. 17–27, 2002, doi: 10.14429/dbit.22.4.3574.
Z. J. Mausolff TerraPower and Z. Mausolff, “Experimental determination of the storage capacity of a CD,” APS, vol. 2, no. May, pp. 1–11, 2016, doi: 10.13140/RG.2.1.4990.2968.
M. H. Chuang, “An optical model and experimental analysis of a reflective diffraction grating,” J. High Sch. Sci., vol. 9, no. 1, 2025, doi: 10.64336/001c.130794.
F. Akbar, A. Khalifah, and M. Abdullah, “Physics Model for Rope Jumping Game,” J. Penelit. Pendidik. IPA, vol. 7, no. 2, pp. 281–286, 2021, doi: 10.29303/jppipa.v7i2.559.
E. Sulistri and Masturi, “Analisis interferensi cahaya laser terhambur menggunakan cermin datar ‘berdebu’ untuk menentukan indeks bias kaca [Interference analysis of scattered laser light using a ‘dusted’ plane mirror to determine the refractive index of the glass],” J. Fis. Unnes, vol. 3, no. 1, pp. 1–8, 2013, doi: 10.15294/jf.v3i1.3958.
A. Khalifah and M. Abdullah, “Physics of bamboo rifle,” Phys. Educ., pp. 1–14, 2021, [Online]. Available: http://arxiv.org/abs/2201.08693
F. Akbar and M. Abdullah, “A Sarong rolled around a body demonstrates that the force for separating two sheets joined by folding and rolling is very large,” Phys. Educ., vol. 55, no. 6, pp. 1–23, 2020, doi: 10.1088/1361-6552/abae24.
R. Rusdiana, Q. Nada, R. Sinaga, and M. Abdullah, “Wind flows and pressure on the Joglo roof , one of Indonesia ’ s traditional houses : a simulation and numerical study,” in ITB Graduate School Conference, 2022, pp. 74–87. [Online]. Available: https://gcs.itb.ac.id/proceeding-igsc/index.php/igsc/article/view/75
R. Lydia Ellyana and D. Sugeng Santoso, “Penggunaan keping Compact Disc (CD) sebagai kisi difraksi untuk menentukan indeks bias zat cair [The use of Compact Disc (CD) discs as diffraction gratings to determine the refractive index of liquids],” J. Teor. dan Apl. Fis., vol. 12, no. 02, 2024, doi: 10.23960/jtaf.v12i02.395.
A. N. Setiawan and L. Saefullah, “Simplified analysis of CD-ROM as an emergency solar panel alternativ,” JPSE (Journal Phys. Sci. Eng., vol. 8, no. 2, p. 89, 2023, doi: 10.17977/um024v8i22023p089.
M. G. Nugraha and K. H. Kirana, “Profil keterampilan berpikir kritis mahasiswa fisika dalam perkuliahan eksperimen fisika berbasis problem solving [Profile of critical thinking skills of physics students in problem-solving-based physics experiment lectures],” in Prosiding Seminar Nasional Fisika 2015, 2015, pp. 201–204. [Online]. Available: https://journal.unj.ac.id/unj/index.php/prosidingsnf/article/view/4709
M. G. Nugraha, S. Utari, D. Saepuzaman, F. N. Solihat, and K. H. Kirana, “Development of basic physics experiments based on science process skills ( SPS ) to enhance mastery concepts of physics pre-service teachers in Melde ’ s law Development of basic physics experiments based on science process skills ( SPS ) to enhance maste,” J. Phys. Conf. Ser., vol. 1280, no. 052075, 2019, doi: 10.1088/1742-6596/1280/5/052075.
W. H. Kristiyanto, “Teaching physics in scientific information disclosure era through daily physics learning teaching physics in scientific information disclosure era through daily physics learning,” in Journal of Physics: Conference Series, 2022. doi: 10.1088/1742-6596/2392/1/012028.
A. C. Ricardo, C. M. Diniz, and C. J. Villas-Bôas, “Interference between electromagnetic and mechanical waves,” pp. 1–7, 2025, [Online]. Available: http://arxiv.org/abs/2508.06683
J. E. Greivenkamp, “Interference,” in Geometrical Optic, Arizona: College of Optical Sciences, 2004. doi: 10.1117/3.547461.
M. Born and E. Wolf, Principles of optics, 7th ed., vol. 3, no. 1. 1980. [Online]. Available: https://api.pageplace.de/preview/DT0400.9781139632607_A23868457/preview-9781139632607_A23868457.pdf
R. Dai, J. C. Fritchman, Q. Liu, Y. Xiao, H. Yu, and L. Bao, “Assessment of student understanding on light interference,” Phys. Rev. Phys. Educ. Res., vol. 15, no. 2, p. 20134, Oct. 2019, doi: 10.1103/PhysRevPhysEducRes.15.020134.
S. Purwaningsih, N. Lestari, E. Yuversa, and C. Riantoni, “Using a diffraction grid to measure the wavelength of a POF laser,” JIPF (Jurnal Ilmu Pendidik. Fis., vol. 8, no. 2, p. 130, 2023, doi: 10.26737/jipf.v8i2.4007.
M. Dobosz, “Refraction techniques for continuous laser beam deflection: an overview,” Precis. Eng., vol. 91, no. October, pp. 522–535, 2024, doi: 10.1016/j.precisioneng.2024.10.009.
Studyphysics.ca, “Lesson 30 : Diffraction & Interference Young ’ s Double Slit Experiment.” pp. 1–8, 2011. [Online]. Available: https://www.studyphysics.ca/2007/30/07_emr/30_diffraction_interference.pdf
S. Johnson, “Unit 102-9 : Interference and Diffraction,” in Physics for the Life Sciences II Activity Guide, no. Updated, 2013. [Online]. Available: https://www.sfu.ca/phys/102/ActivityGuide/pdf/Unit102-9.pdf
J. Braat, P. Dirksen, and A. J. E. M. Janssen, “Diffractive Read-Out of Optical Discs,” 2003, pp. 45–85. doi: 10.1007/978-3-540-46022-0_3.
J. E. Kettler, “The compact disk as a diffraction grating,” Am. J. Phys., vol. 59, no. 4, pp. 367–368, 1991, doi: 10.1119/1.16553.
S. Supliyadi, Khumaedi, “Percobaan kisi difraksi dengan menggunakan keping DVD dan VCD [Diffraction grating experiment using DVD and VCD discs],” J. Pendidik. Fis. Indones. 6, vol. 6, pp. 26–29, 2010, [Online]. Available: http://journal.unnes.ac.id
S. D. Asysyifa, H. Kuswanto, and Y. Arinda, “Designing compact disk as an alternative diffraction grating experiment,” Int. J. Recent Sci. Res., vol. 10, no. D, pp. 30693–30695, 2019, doi: 10.24327/ijrsr.2018.0906.2236.
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