IJSRSET1844229 | Received : 20 March | Accepted : 31 March 2018 | March-April-2018 [(4) 4 : 941-944] © 2018 IJSRSET | Volume 4 | Issue 4 | Print ISSN: 2395-1990 | Online ISSN : 2394-4099 Themed Section : Engineering and Technology 941 Laser Damage Threshold Data (For 1000 Nm) Of Diethyl 3, 3′- [(2, 4-Dichlorophenyl) Methylidene] Bis (1h-Indole-2- Carboxylate) Nlo Crystals K. Senthilkannan Edayathangudy G S Pillay Arts & Science College Nagapattinam, Tamil Nadu, India ABSTRACT Anisotropic - Crystalline materials have some important patterns of applications relatively with non crystalline materials. Here Diethyl 3,3′-[(2,4-Dichlorophenyl) Methylidene] Bis (1h-Indole-2-Carboxylate) Crystals are of main applications such as Opto electronic and frequency response, nlo applications. The XRD data make known that Diethyl 3,3′- [(2,4-Dichlorophenyl) Methylidene] Bis (1h-Indole-2-Carboxylate) Crystals have Chemical formula as C29H24Cl2N2O4 and Crystal system is Monoclinic, Space group is P21/c and parameters are a, b, c (Å) as 9.777, 15.939, 17.582 and β is 101.94. If it is used as 1000 nm as the wavelength, % of LDT rating is 8.57% and possibility of not probable damage and Laser fluence will be 25.5 kJ/m 2 and Filter LDT will be 29.5k J/m 2 . Keywords: NLO Laser Damage Threshold I. INTRODUCTION A crystalline material is a solid material in which the component atoms are arranged in a definite pattern and whose surface regularity reflects its internal symmetry. The definition of a solid appears obvious, a solid is generally thought of as being hard and firm. Figure 1. Power Vs Time plot Fluence and intensity on the surface of the component are critical parameters, the area of the laser spot is also critical. Even very high-power lasers may be transmitted through or reflected off of a durable optical filter if the spot size is sufficiently large to reduce the fluence and/or intensity. The diameter of a laser spot with a Gaussian profile is most accurately measured at the 1/e 2 intensity points as shown in the diagram below. Lasers: LDT is generally specified in terms of pulse fluence for ―long-pulse lasers.‖ Long-pulse lasers have pulse durations in the nanosecond (ns) to microsecond (µs) range, with repetition rates R typically ranging from about 1 to 100 Hz. Most Semrock filters have LDTLP values on the order of 1 J/cm 2 , and are thus considered ―high-power laser quality‖ components. An important exception is a narrowband laser-line filter in which the internal field strength is strongly concentrated in a few layers of the thin-film coating, resulting in an LDTLP that is about an order of magnitude smaller. As an example, suppose a frequency-doubled Nd:YAG laser at 532 nm emits 10 ns pulses at a 10 Hz repetition rate with 1 W