Gratings - Infrared Laser Gratings

Molecular Laser (ML) - 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  
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. EFF. CURVE
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
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
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"  
MODEL NO. ORIGINAL CAT. NO. REPLICA CAT. NO. ORIGINAL CAT. NO. REPLICA CAT. NO. ORIGINAL CAT. NO. REPLICA CAT. NO. EFF. CURVE.
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
Price  ($)* 575.00 120.00 995.00 230.00 710.00 130.00  

* Prices are in USD and are list prices only.

COATINGS
Gold overcoat that enhances reflectivity in the IR is available for an additional charge.  No damage threshold minimums apply for overcoated gratings. 
Gold Overcoat:  $60.00

* All gratings are measured in the Littrow mounting configuration

* All gratings utilize an aluminum (Al ) reflective coat

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 below.

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.

Also available as original gratings, ruled directly into an aluminum or gold coating deposited on a copper substrate resulting in an inherently higher damage threshold . They are recommended for use with high power lasers.

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

 

Efficiency Curve Key

  • All gratings are measured in the Littrow mounting in 1st order
  • All gratings utilize an aluminum (AI) reflective coat

Grazing Incidence

Grazing incidence is a simple and inexpensive optical configuration that can tune and increase the resolution of a dye laser. A holographic grating, functioning as an end reflector in a dye laser cavity, is positioned so that laser radiation strikes the grating almost perpendicular to the grating normal. As the angle of incidence approaches 89 degrees, a relatively large area of the grating is illuminated by the laser beam, increasing angular dispersion and resolving power significantly. The sizes of the grazing and mirror (12.7 x 50.8 mm) are optimized for grazing incidence. The grating is fixed and tuning is achieved by rotation of the mirror. The laser beam is diffracted twice in grating incidence, resulting in a two fold increase in resolution. Low grating efficiency is characteristic of the grazing incidence configuration but is compensated for by the high gain of the dyes used.

Grazing Incidence Gratings And Mirror
REPLICATED HOLOGRAPHIC GRATING (12.7 x 50.8 mm)
GROOVES/MM BLAZE λ (nm) NORMAL (TF) UTF-P (pulsed) UTF-CW (Continuous)
1200 Vis 5-2401 5-2406 5-2410
1800 Vis 5-2402 5-2407 5-2411
2400 Vis 5-2403 5-2408 5-2412
3600 UV 5-2404 5-2409 5-2413
Price ($) * 129.00 159.00 199.00
 
MIRROR: Used in conjunction with grazing incidence gratings (above) for double pass high resolution tuning of dye lasers.
12.7 x 50.8 mm 5-2405 Price ($) * 89.00

* Prices are in USD and are list prices only.

All dimensions in millimeters.

Grazing Incidence - Specifications

 

 

Specifications
Grating:
Grooves per mm   1200, 1800, 2400 or 3600
Thickness   9.5 mm ± 0.5 mm
Resolution   50% to 90% of theoretical
Efficiency at Grazing Incidence:
            Single Pass   Approx. 24%
            Double Pass   Approx. 4%
Mirror:
Coating - AlSiO
Thickness - 9.5 mm ± 0.5 mm

 

 

Custom

Optometrics operates several modern master diffraction grating production laboratories, producing both interferometrically controlled classically ruled and holographically recorded replication masters to optimize its OEM customers’ instrument performance. Hundreds of standard replication masters are inventoried for fast delivery of many common designs. Optometrics also supports new OEM customers in need of regenerating less efficient grating replication masters, resulting in improved quality, manufacturing efficiencies, and lower costs. Many OEM’s further benefit from Optometrics’ related products, pre-aligned spectrometer sub-assemblies and precision optical replication expertise for critical mirror surfaces.

 

Optometrics’ core technologies of mechanical ruling, holographic recording, photolithography and optical thin film coatings have also positioned the company as a leading supplier of patterned optical coatings, polka-dot beamsplitters, wire grid polarizers, and specialty mirrors.

Optometrics offers its OEM customers additional services:

  • Kanban stocking arrangements
  • Bar coding capabilities
  • Specialized packaging services
  • Customer names coded for confidentiality
  • Higher level pre-aligned optical assemblies

The company is also proud of its ability to support customers in all phases of the product development cycle.

 

Polarization

Typical efficiency curves illustrate that, in all cases, orienting the polarization of the E vector (P-Plane) perpendicular to the grooves 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.

Grating End Reflectors for Dye Lasers

The output wavelength of the dye laser can be tuned by turning the Littrow mounted diffraction grating end reflector about an axis parallel to the grooves. The equation relating wavelength to angle of incidence on the grating is nλ = 2d sin i. Using this relationship, one can calibrate the mirror mount micrometer to i and, using a grating as one of the reflectors in a dye laser, cause the spectral line width of the output to be reduced to a narrow region around the Littrow wavelength. Maximum reduction is attained by increasing dispersion to the practical limit. As can be seen from the equation for angular dispersion,

this limit is approached for the high blaze angle characteristic of echelles and finely spaced echellettes. Even greater selectivity can be attained by adding a Fabry-Perot etalon to the grating-mirror cavity. The efficiency of the spectral condensation in organic dye lasers is quite high, with figures of 70% being typical.

Gratings are normally used in one of two configurations: Littrow or grazing incidence (see figure below).

GRAZING INCIDENCE GRATINGS
Grazing incidence is a simple and inexpensive optical configuration that can tune and increase the resolution of a dye laser. A holographic grating, functioning as an end reflector in a dye laser cavity, is positioned so that laser radiation strikes the grating almost perpendicular to the grating normal. As the angle of incidence approaches 89 degrees, a relatively large area of the grating is illuminated by the laser beam, increasing angular dispersion and resolving power significantly. The sizes of the grazing and mirror (12.7 x 50.8 mm) are optimized for grazing incidence. The grating is fixed and tuning is achieved by rotation of the mirror. The laser beam is diffracted twice in grating incidence, resulting in a two fold increase in resolution. Low grating efficiency is characteristic of the grazing incidence configuration but is compensated for by the high gain of the dyes used. 

 

LITTROW SERIES GRATINGS
SPECIFICATIONS
Dimensional Tolerances - ±0.5mm
Thickness Tolerances - ±0.5mm
EFFICIENCIES
   Roled - 60 - 80% at blaze
       Holographic - 45 - 65% at peak
Clear Apertore - 90%
Groove parallelism to edge - ±0.5°

GROOVES
PER MM

BLAZE λ
(nm)

BLAZE
ANGLE

DISPERSION
(nm/mr)
{@ 500 nm}

12.5 x 25 x 6 CAT. NO 25 x 25 x 9.5 CAT. NO. 30 x 30 x 9.5 CAT. NO. 50 x 50 x 9.5 CAT. NO.
RULED
1200 300 10° 2' 0.82 3-4131 3-2131 3-3131 3-5131
1200 500 17°  26 0.79 3-4151 3-2151 3-3151 3-5151
1200 750 26°  45 0.74 3-4171 3-2171 3-3171 3-5171
1200 1000 36°  52 0.67 3-4111 3-2111 3-3111 3-5111
1800 500 26°  45 0.50 3-4851 3-2851 3-3851 3-5851

   Price($)*

75.00 99.00 105.00 159.00

         
            * Prices are in USD and are list prices only.

GROOVES PER MM BLAZE ANGLE BLAZE λ (nm) DISPERSION (nm/mr) @ 500 nm
ECHELLES
31.6 Echelle 63 14.37
316 Echelle 63 1.44
79 Echelle 75 3.28
79 Echelle 63 5.75

 

Gratings Ruled in Gold

We design and rule custom Gratings directly in gold for IR (4 to 12 microns) laser applications.  Gold gratings are particularly important to IR lasers since their increased efficiency allows more of the generated light to be used.  Their resistance to degradation allows them to be used in high power applications that might damage gratings having a thin gold coating over aluminum, for example. These gratings are available on both INVAR and ceramic substrates - if you are interested in working with other materials please contact us for more information.

Capabilities

  • Custom gratings ruled directly in gold on special substrates in various materials and mediums for 4-12 micron laser applications.
  • Standard molecular laser gratings on aluminized copper substrates.


Specifications
  Grooves/mm   70 - 450
  Optimum Range (µ)   4.0 - 12.0
  Substrate Materials   Copper, Invar, Ceramic or Silicon
     Clear Aperture   90%
  Groove Parallelism to Edge   ±0.5°
  Dimensional Tolerance   ± 0.5 mm
     Thickness Tolerance   ± 0.5 mm
     Typical Peak Efficiency (Polarized)   ³95%

* Custom sizes, rulings and substrates are available on request.

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