About this previous year paper
The uploaded file is a B.Tech (Semester III) Theory Examination 2018–2019 question paper for the subject LASER SYSTEMS AND APPLICATIONS, with Subject Code ROE033.
The document contains 2 printed pages, carries 70 marks, and has a duration of 3 hours.
This examination paper tests the fundamental and applied understanding of laser physics, laser types, laser-tissue interaction, optical coherence, holography, medical applications of lasers, and construction of advanced laser devices.
PAGE 1 — STRUCTURE & CONTENT
Page 1 contains the exam title, general instructions, and SECTION A.
SECTION A — Short Questions (2 × 7 = 14 Marks)
Students must answer all seven short conceptual questions. These questions focus on basic definitions and numerical understanding in laser physics.
Topics include:
Fermi–Dirac Distribution Function
Understanding electron distribution in energy states.
Temporal Coherence
How consistent a wave remains over time; essential for laser operation.
Duty Cycle Calculation
A numerical question involving:
Laser diode emitting 150,000 pulses per second
Pulse duration 30 ns
Ruby Laser Dye
Basic knowledge of ruby laser medium.
Laser Beam Divergence
Factors affecting beam spread.
Population Inversion
Core requirement for laser action.
Spontaneous vs Stimulated Emission
Fundamental difference between natural radiation and induced emission.
These questions evaluate a student’s foundational grasp of laser physics principles.
PAGE 2 — APPLICATION-BASED & EXPLANATORY QUESTIONS
Page 2 contains SECTION C, which includes long, diagram-oriented, explanatory questions worth 7 marks each.
QUESTION 6 — Laser Construction & Working (7 Marks)
Students must attempt any one part:
(a) Dye Laser Working with Schematic Diagram
Construction of dye laser
Principle of operation
Tuning mechanisms (e.g., grating, prism tuning)
Importance of organic dyes as active medium
(b) Excimer Laser Construction & Applications
Working principle of excimer lasers (XeCl, KrF, etc.)
Energy transition between excited dimers
Applications in:
Microelectronics LASIK eye surgery
Material processing Lithography
This section tests understanding of complex laser systems used in modern industries.
QUESTION 7 — Medical Applications & Holography (7 Marks)
Students must attempt one of the following:
(a) Lasers in Medicine
Explains:
How lasers are useful in Ophthalmology and General Surgery
Applications like: Retinal photocoagulation
LASIK Laser angioplasty
Tissue ablation & cutting Benefits of precision, minimal bleeding, sterilization capability
(b) Principle of Holography
Students must describe:
Basic principle of holography Construction of a hologram
Reconstruction using reference beam Use of coherent laser light
Real vs virtual image formation
This section tests advanced conceptual clarity on how lasers interact with human tissue and how coherent light can create 3D holographic images.