— Blaze angle and alignment — Polarization — Coating — Specifications — ML Series Gratings - Original and Replicated

The output wavelength of a molecular or dye laser can be tuned by rotating a Littrow mounted grating around an axis parallel to the grooves. The grating equation:

nl = d(sin i + sin i’)

where n is the order of diffraction, l is the diffracted wavelength, d is the grating constant (the distance between successive grooves), i is the angle of incidence measured from the normal and i’ is the angle of diffraction measured from the normal, reduces to nl = 2d sin i for the Littrow configuration.

The angle of incidence (i) is adjusted to select the output wavelength while creating a narrow gain profile.

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BLAZE ANGLE AND ALIGNMENT
Because the ML series of gratings are designed for peak polarized efficiency, the groove angle is not equivalent to the Littrow blaze angle of the grating. As a result, when using a He-Ne laser for preliminary grating alignment, the brightest He-Ne order will not correspond to the blaze wavelength of the grating. The grating must be aligned using the calculated He-Ne order that corresponds to the wavelength of interest, regardless of its relative intensity.

The blaze arrow marked on the side or back of the grating should be oriented as shown above.

POLARIZATION
Typical efficiency curves illustrate that, in all cases, orienting the polarization of the E vector (P-Plane) perpendicular to the grooves (E^) increases the efficiency over a specific wavelength region. This should be considered when optimizing the figure of merit (Q) of a cavity, particularly when it is polarized by auxiliary components such as Brewster angle windows.

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COATING
ML gratings can be overcoated with gold, increasing the reflectivity at 10.6 microns by approximately 1%, but the damage threshold in high power applications may be reduced. No damage threshold minimums apply for overcoated gratings.

Specifications

Clear Aperture		³90%
Groove Parallelism to Edge		± 0.5°
Dimensional Tolerances		± 0.5 mm
Thickness:
Originals		10 mm ± 0.5 mm
Replicas		9.5 mm ± 0.5 mm
Damage Threshold:
Original Gratings:
CW Laser		1 KW/cm2
Pulsed Laser (100 nsec pulse)		7 J/cm2
Replicated Gratings:
CW Laser		250 W/cm2
Pulsed Laser (200 nsec pulse)		3.5 J/cm2

Summary ML Grating Specifications
MODEL NO.	GROOVES / MM	MIN. POLARIZED ABS. EFFICIENCY	OPTIMUM RANGE ()	ANGULAR DISPERSION (nm/mr)	Eff Curve
ML-301	75	≥ 88%	9.0 - 11.0	12.3
ML-302	100	≥ 88%	9.0 - 11.0	8.5
ML-303	150	≥ 88%	9.0 - 11.0	4.2
ML-304	135	≥ 88%	9.0 - 11.0	5.2
ML-401	150	≥ 88%	5.0 - 6.0	6.1
ML-402	300	≥ 82%	5.0 - 6.0	2.0
ML-501	300	≥ 80%	2.5 - 3.0	3.0
ML-502	450	≥ 85%	2.0 - 4.0	1.6
ML-601	300	≥ 80%	2.5 - 4.0	0.35
ML-701	90	≥ 88%	16.0 - 20.0	7.7

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ML Series Gratings - Original And Replicated
ML gratings are normally used as end reflectors for tuning molecular lasers. Original gratings are ruled directly into an aluminum coating deposited on a kanigen coated copper substrate, resulting in an inherently higher damage threshold than the replicas which are replicated onto a Pyrex® substrate.
 

Squares
SIZE	25 x 25 mm		30 x 30 mm		50 x 50 mm		58 x 58 mm		Eff Curve
MODEL NO.	ORIGINAL CAT NO.	REPLICA CAT NO.	ORIGINAL CAT NO.	REPLICA CAT NO.	ORIGINAL CAT NO.	REPLICA CAT NO.	ORIGINAL CAT NO.	REPLICA CAT NO.
ML-301	5-3012	5-3112	5-3019	5-3119	5-3015	5-3115	5-3016	5-3116
ML-302	5-3022	5-3122	5-3029	5-3129	5-3025	5-3125	5-3026	5-3126
ML-303	5-3032	5-3132	5-3039	5-3139	5-3035	5-3135	5-3036	5-3136
ML-304	5-3042	5-3142	5-3049	5-3149	5-3045	5-3145	5-3046	5-3146
ML-401	5-4012	5-4112	5-4019	5-4119	5-4015	5-4115	5-4016	5-4116
ML-402	5-4022	5-4122	5-4029	5-4129	5-4025	5-4125	5-4026	5-4126
ML-501	5-5012	5-5112	5-5019	5-5119	5-5015	5-5115	5-5016	5-5116
ML-502	5-5022	5-5122	5-5029	5-5129	5-5025	5-5125	5-5026	5-5126
ML-601	5-6012	5-6112	5-6019	5-6119	5-6015	5-6115	5-6016	5-6116
ML-701	5-7012	5-7112	5-7019	5-7119	5-7015	5-7115	5-7016	5-7116
PRICE($)*	710.00	180.00	1,100.00	190.00	1,430.00	290.00	1,820.00	350.00

* Prices are in USD and are list prices only.

Diameters
SIZE	25 mm DIA.		38 mm DIA.		50 mm DIA.		Eff Curve
MODEL NO.	ORIGINAL CAT NO.	REPLICA CAT NO.	ORIGINAL CAT NO.	REPLICA CAT NO.	ORIGINAL CAT NO.	REPLICA CAT NO.
ML-301	5-3011	5-3111	5-3017	5-3117	5-3014	5-3114
ML-302	5-3021	5-3121	5-3027	5-3127	5-3024	5-3124
ML-303	5-3031	5-3131	5-3037	5-3137	5-3034	5-3134
ML-304	5-3041	5-3141	5-3047	5-3147	5-3044	5-3144
ML-401	5-4011	5-4111	5-4017	5-4117	5-4014	5-4114
ML-402	5-4021	5-4121	5-4027	5-4127	5-4024	5-4124
ML-501	5-5011	5-5111	5-5017	5-5117	5-5014	5-5114
ML-502	5-5021	5-5121	5-5027	5-5127	5-5024	5-5124
ML-601	5-6011	5-6111	5-6017	5-6117	5-6014	5-6114
ML-701	5-7011	5-7111	5-7017	5-7117	5-7014	5-7114
PRICE($)*	760.00	240.00	1,200.00	365.00	1,565.00	495.00

* Prices are in USD and are list prices only.

ML Series Gratings - Original And Replicated
ML gratings are normally used as end reflectors for tuning molecular lasers. Original gratings are ruled directly into an aluminum coating deposited on a kanigen coated copper substrate, resulting in an inherently higher damage threshold than the replicas which are replicated onto a pyrex substrate. 

Rectangles
SIZE	12.5 x 25 mm		25 x 50 mm		"1 x .825"		Eff Curve
MODEL NO.	ORIGINAL CAT. NO.	REPLICA CAT. NO.	ORIGINAL CAT. NO.	REPLICA CAT. NO.	ORIGINAL CAT. NO	REPLICA CAT. NO.
ML-301	5-3610	5-3810	5-3013	5-3113	5-3018	5-3118
ML-302	5-3620	5-3820	5-3023	5-3123	5-3028	5-3128
ML-303	5-3630	5-3830	5-3033	5-3133	5-3038	5-3138
ML-304	5-3640	5-3840	5-3043	5-3143	5-3048	5-3148
ML-401	5-4610	5-4810	5-4013	5-4113	5-4018	5-4118
ML-402	5-4620	5-4820	5-4023	5-4123	5-4028	5-4128
ML-501	5-5610	5-5810	5-5013	5-5113	5-5018	5-5118
ML-502	5-5620	5-5820	5-5023	5-5123	5-5028	5-5128
ML-601	5-6610	5-6810	5-6013	5-6113	5-6018	5-6118
ML-701	5-7610	5-7810	5-7013	5-7113	5-7018	5-7118
Price  ($)*	575.00	120.00	995.00	230.00	710.00	130.00

* Prices are in USD and are list prices only.

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