Detailed solutions are given to Laser light is highly intense than the convectional light. An attempt is made to include the important types of problems at the undergraduate level. Question. The energy (E) is therefore found from. Typically, lasers are thought of as emitting li… The length of the cavity is equal to 1 m. 1. ���.P��Z1j�������Ծ�܃��Y�4��b��� � �E�>"�e1�[b�M�����#"^�+��3JD��-���u.qUg�{*��^rz��N�~Z�����ٌG�)s�����r� << E�����z6��Cf.�+So�f���(�Q�g�)��L�7���F��c��?��3�*P�#wR���x��`�_����P�䮤��C�lJ���O��`�����)�@�_�'*�:�%&z���3X]P�߀S��a�8 This is because of coherence and directionality of laser. By taking into account the different wavelengths, the power is equal to. Solution of Problem 4.12 Problem 4.13 A laser emitting at 0=850nm has a gain spectral width of = 32 nm and a peak gain of g(0) 50/cm , Plot g() equation 4.41. A ring laser cavity is composed of 4 identical mirrors with a reflection coefficient equal to 0.99. The solution for non … >> g�?>�^7�À��K̵*�trX�M-�������K���'���H��)X���ۦ�"Z�@c�ʯ=�),6�+�
�W�ԯ��bC�ZR 43 0 obj Determine the value of the gain needed in the amplifying medium to obtain laser oscillation. The peak power is the energy of the pulse divided by its duration: 2. endstream The frequency is therefore equal to. In a ring lasercavity, the beam passes through the medium only once each turn. %PDF-1.5 << ��xH���&�/?��KO: There is a broad range of materials that can be cut with a laser: wood, plastic, cardboard, textile... Laser cutting works by directing the output of a high-power laser through optics. If the cavity is moved by dL, the frequency will change by dî where The problem can be solved by using the formula that links the divergence of the beam and the waist size: where t��܊�ͦ���?��DKN����,P#0��I�#EJ���d&M?3��O*�������?��|�>|4Xb�^�S2*���6��~{�ڡ�^��h
�l��t�������gj9�YZL��O�,m��/������/?O�*����A��sGw�y�:$���a
Y;�$�\��"�ǀ�gp�|�M(I���#�O�l�ZyG*$�SU!�bh�dEX GL�����sVt��qJ*yd�Q�HwT �=[�\4b���OlI� are the pump frequency and the laser frequency respectively. fronts in recent years. An one milliwatt He-Ne laser is highly intense than the sun intensity. 72 0 obj Today’s theme is the high-frequency word in laser cutting-carbon steel. In addition, it is important to note that when cutting 5mm carbon steel plate with the laser cutting machine, it needs to replace 7.5 “focal length laser lens. The period between each pulse is equal to, During this period, only one pulse is emitted. The calculation is the same as for the previous question: this time N=0.33! . 69 0 obj What is the radius of the beam at the waist (considering the waist and the laser are in the same plane)? Calculate the number of longitudinal modes that can oscillate in this cavity. xڝ�wTT��Ͻwz��0�z�.0��. and laser, concentrated on a very small area, in order to cut or engrave a material. g� �����oc�n/�~ X�'a�ؠ���ӗ������S%%r^{) 9=r9�6D�O�.9�O��b_'>o�8��N]ݯ����ܔ�� ��ٞ���9oUW��^� ������,(X0*������`���t7f�7��[
h���m�n$v���^�>Ǒ��r�~�Kc�}�8~�ε�t�5�������
H[��F*�����!��g��i�B�����σKm�|(-�L�Yf�JN��r��tf!����L��F߅h&"��>Ňn�_�I�B�
�? Calculate the peak power of the pulses. If nothing is done, the laser is unlikely to oscillate. A Q-switched laser emits pulses of 10µJ of duration 1 ns. Case study: Diode-pumped Nd: YAG Laser; Lesson questions. x��Z͎�6��)��J�~�� ^ S��S�r�Ԯ�۶�U=$��^�������6�i���\�h�3���Lj���?% They direct the laser beam generated on a small zone of the material. Electromagnetic waves are related. Problems and solutions Session 1. Calculate the average output power of the laser. What is the radius of the beam at the waist (considering the waist and the laser are in the same plane)? The linear cavity is 30 cm long. at >> stream when laser oscillation occurs. )ɩL^6 �g�,qm�"[�Z[Z��~Q����7%��"� ����rh�c��6��Ĩo�jl�4��n����;�]`��!��bH�g�ȳD�t��zo���KP�c�r2��y��i5�7�ނBV4��Lko)Q����H��җ����ܳ#8Jv�B=�kv�]�q ~�iH�����}P?�م��.M 峩�b�Q,�J��t@0 /Length 2594 stream /Filter/FlateDecode ��� k��p�N����+�.��sKq������qV�CX|�m��Y�8���fɞ��^=�s�E\� Determine the fraction of the population found in this level compared to the ground state population at a temperature of 300 K. Boltzmann's constant is equal to 1.38.10-23JK-1, The conversion from cm-1 to joules is given by: Laser light is usually spatially coherent, which means that the light either is emitted in a narrow, low-divergence beam, or can be converted into one with the help of optical components such as lenses. ��3�������R� `̊j��[�~ :� w���! In the worst case, the central frequency of CO2 is situated exactly in the middle of the two longitudinal modes. There are no other energy levels nearby. �jN�jWma��]-`ȏl�D?��W@;��&�%�/}vIh�\��ņv�CD�N����湣-�|u_��2��u\d��i��7� �N�� As the gap in frequency is given by the above formula, the distance that the cavity mirror must be moved is equal to: It is possible to make this fine adjustment by using a piezoelectric actuator. 1. �=��&�[�L�B�F��;���la��]�B�i3֏��9!�hcYD�ٿ�6��Ю�5H��6����h
֢�-6���6{a�S��0QS�8�)���q��*<5I��� �[������5)T��>\�h) ������1�7�M��Q����/��ɹxr΅�6��c���[�����"�@���Q���s�
�zhQp�,Lr0u����bC�"Z���ɪMJ���3���bC��AP!�z"�n��OMT-ݭ�%��3