Build to Order Concave Holographic Diffraction Gratings

Concave holographic gratings function as both a dispersing and focusing element in monochromators and spectrographs. These gratings contain two focusing elements: the substrate, and the groove curvature. As a result, an instrument designer can replace a lens system by using concave gratings, leading to a reduction of optics in a system, and thus, cost. Another advantage of a system based on concave gratings is decreased optical aberrations such as coma and astigmatism. Concave holographic gratings make possible short radii gratings with low ƒ/# and flat-field imaging suitable for array spectrographs.

Works as both a dispersing and focusing element
Reduced astigmatism in flat-field spectrographs
High spectral imaging resolution in Rowland Circle spectrographs
Reduced astigmatism in constant-deviation monochromators

Concave holographic gratings for are listed below in increasing groove frequency (grooves per mm) for several applications. Click on a Catalog Number to view grating efficiency curves. Request a quote by clicking the quote link. For the gratings listed in this table, the figure at left defines the following parameters:

α – incidence angle
r – distance from entrance slit to grating center
β – diffraction angle
r' – distance from grating center to image

The angles α and β are measured from the grating normal; their algebraic signs are opposite if they lie on opposite sides of the normal.

Master Grating Options for Flat-Field Spectrographs

By suitably curving the grooves on the grating, usually by holographic means, adequate spectral resolution can be achieved on a line instead of a circle. This lends itself naturally to use with linear or area detector arrays. While astigmatism is reduced, which increases throughput, the resolution of a flat-field spectrograph is never as great as for a Rowland Circle spectrograph. The advantage of flat-field spectrographs lies in achieving compact spectrometers with no moving parts.

Spectral resolution is optimized for a planar spectrum.

Search:

Catalog Number	Grooves per mm	Imaging Range mλ₁, mλ₂ (nm)	Reciprocal Linear Dispersion (nm/mm)	Entrance Slit r and α (mm, deg)	λ₁ focus r' and β (mm, deg)	λ₂ focus r' and β (mm, deg)	Input f/no	Ruled Area (mm)	Substrate Size (mm)	Request a Quote
52056BK-*-028C	200	290-1020	32.3	151, 5.0	153,2,-8.3	153,2,-17.0	3.5	Φ44	Φ50	Quote
52A16BK-*-307C	230	380-1080	31.2	137.4, -5.73	138.3,10.8	134.5,20.4	2.0	Φ68	Φ69.9	Quote
52066BK-*-018C	233.9	190-400	33	148, 3.0	116-5.6	113, -8.4	2.5	Φ60	Φ63.5	Quote
52A15BK-*-224C	278.3	350-1050	30	88.0, 6.37	118.14, -12.02	111.13, -23.77	2.5	Φ40	Φ45	Quote
52067BK-*-040C^†	282.7	190-545 545-900	14.5	235, -5.3 252, 0.4	219, 8.4	228, 14.3	3.9 4.2	Φ60	Φ63.5	Quote
52104BF-*-216C	310	470-680	33	100.9, -5.22	101, 13.7	101.7, 17.6	3.3	Φ32	Φ35	Quote
52146BK-*-332C	318	380-720	78.2	40.307, -2	41.86, 9.348	43.56, 15.737	1.5	Φ26	Φ28	Quote
52A14BK-*-221C	367.43	200-800	25.7	88.00, 7.03	104.91, -11.29	97.90, -24.60	2.5	Φ40	Φ45	Quote
52A14BK-*-234C	367.43	200-850	25.7	88.00, 7.03	104.91, -11.29	97.90, -24.60	2.5	Φ40	Φ45	Quote
52A25BK-*-255C	400	380-730	83	30, -5.66	31.96, 14.52	34.19, 23	1.2	Φ24	Φ26	Quote
52A16BK-*-324C	405	380-780	31.2	137.4, -5.73	137, 14.7	129.8, 24.6	2.0	Φ68	Φ69.9	Quote
52097BK-*-207C	430	250-800	24.9	86.4, 6.0	88.6, -12.24	85.4, -26.6	2.9	Φ35	Φ37	Quote
52097BK-*-208C	430	450-850	24.9	86.4, 6.0	85.4, 17.3	83.6, 28.0	2.9	Φ35	Φ37	Quote
52097BK-*-209C	430	300-850	24.9	86.4, 6.0	86.1, 13.5	83.6, 28.0	2.9	Φ35	Φ37	Quote
52112BK-*-261C	432	190-840	26.15	86.4, 6.0	89.4, -10.7	85.4, -26.7	3.6	Φ24	Φ25	Quote
52107BK-*-214C	435.9	190-680	19.5	111.48, 5.5	111.64, -11.82	108.25, -22.45	2.2	Φ51	Φ55	Quote
52057BK-*-014C	435.9	190-400	19.5	109, -6.1	114, 10.9	113, 16.3	2.3	Φ47	Φ50.8	Quote
52066BK-*-001C	454.27	285-720	17	130, 11.3	130, -3.8	128, 7.36	2.2	Φ58	Φ63.5	Quote
52101BF-*-212C	477	200-850	31	86.9, -6.7	60.9, 12.2	70.3, 30.8	3.5	Φ19	Φ20	Quote
52101BK-*-211C	477	200-850	31	86.9, -6.7	60.9, 12.2	70.3, 30.8	3.5	Φ19	Φ20	Quote
52114BK-*-323C	489.87	200-800	24	77.36, 6.65	66.98, -12.35	78.0, -30.52	2.4	28 x 28	30 x 30	Quote
52099BK-*-317CL	580	340-800	16	98.2, 0.00	100.5, 11.37	100.8, 29.54	3.5	37 x 27	40 x 30	Quote
52129BK-*-358C	586.23	340-800	19.8	90.8, -10.78	74.9, 22.7	74.0, 41.0	3.2	28 x 28	37 x 37	Quote
52105BF-*-198C	660	340-805	10.1	112.5, 4.9	122.3, -18.0	133.7, -38.0	3.0	Φ38	Φ40	Quote
52034BK-*-004C	664	340-700	18	80, -13.3	80, 0.2	84, -13.6	2.7	Φ29	Φ32	Quote
52001BK-*-021C	792.8	380-780	4.5	231, 3.0	223, 14.4	258, 34.5	2.4	Φ95	Φ100	Quote
52140BK-*-279C	800	325-800	10.7	86.3, 0	85, 18.2	104.5, 43.82	2.7	28 x 28	30 x 30	Quote
52066BK-*-002C	813.5	380-705	9.5	130, 22.3	128, -4.0	129, 11.2	2.2	Φ60	Φ63.5	Quote
52049BK-*-012C	1300	340-650	7.8	94, -31.1	99, 4.3	97, -19.1	2.9	Φ38	Φ42	Quote
52064BK-*-008C	1803.8	753-784	1.2	345, 67.5	387, -25.8	394, -29.4	6.3	50 x 50	Φ62.5	Quote
52071BK-*-007C	2197	277-313	1	575, 4.9	288, -43.9	296, -50.6	10.5	Φ55	Φ70	Quote
† This flat-field spectrograph grating is designed to produce two aberration-corrected spectra in the same place (using different entrance slit locations).

Showing 1 to 31 of 31 entries

Master Grating Options for Rowland Circle Spectrographs

A "classical" concave grating (one whose grooves are straight, parallel and equally spaced) can be generated on a ruling engine or by recording a laser interference pattern in photoresist (to form a holographic grating). If the object (e.g., entrance slit or fiber) is placed on the Rowland circle (whose diameter equals the radius of curvature of the grating blank), high spectral imaging resolution is obtained.

The detectors or output fibers must be located on the Rowland circle, since that is where the slit images are focused. While the images are narrow in the spectral direction, they suffer from a large amount of astigmatism inherent in this type of grating system.

The entrance slit and diffracted spectrum lie on the Rowland Circle, which also passes through the center of the grating surface.

Search:

Catalog Number	Grooves per mm	Concave Radius (mm)	Recommended Spectral Region	Ruled Area (mm)	Substrate Size (mm)	Request a Quote
52102BF-*-315C	390	350	300 nm-1 μm	Φ48	Φ50.8	Quote
52102BF-*-316C	390	350	300 nm-1 μm	Φ48	Φ50.8	Quote
52088BK-*-257C	678	83.7	200 nm-800 nm	Φ32	Φ38	Quote
52A02BF-*-356C	900	750	120 nm-500 nm	Φ75	Φ80	Quote
52011BK-*-003C	1200	498.1	300 nm-900 nm	Φ60	Φ63.5	Quote
52A02BF-*-556C	1500	750	120 nm-500 nm	Φ75	Φ80	Quote
52071BK-*-025C	1760	352	200 nm-1.1 μm	Φ65	Φ70	Quote
52017BK-*-009C	1800	750	250 nm-900 nm	Φ59	Φ63.5	Quote
52021BK-*-032C	2160	998.8	210 nm-350 nm	Φ59	Φ63.5	Quote
52017BK-*-247C	2400	750	200 nm-700 nm	Φ59	Φ63.5	Quote
52017BK-*-434C	2400	750	200 nm-700 nm	Φ60	Φ63.5	Quote
52017BK-*-482C	2400	750	150 nm-800 nm	Φ60	Φ63.5	Quote
52017BK-*-484C	2400	750	150 nm-800 nm	Φ60	Φ63.5	Quote
52A23BK-*-375C	2400	398.8	200 nm-700 nm	Φ33	Φ35	Quote
52017BK-*-520C	3600	750	150 nm-500 nm	Φ60	Φ63.5	Quote
52011BK-*-521C	3600	498.1	150 nm-500 nm	Φ60	Φ63.5	Quote
52011BK-*-530C	3600	498.1	180 nm-500 nm	Φ60	Φ63.5	Quote

Showing 1 to 17 of 17 entries

Master Grating Options for Constant-Deviation Monochromators

Curving the grating grooves can also reduce aberrations in monochromators, in which only a small part of the spectrum is viewed at a time; wavelengths are scanned by rotating the grating. Again, astigmatism is usually reduced (though for part of the spectrum only) to increase throughput, but the resolution is less than for a Rowland Circle spectrograph.

The angle between the slits remains constant as the grating is rotated to scan wavelengths.

Search:

Catalog Number	Grooves per mm	Nominal Blaze Wavelength (1st Order Littrow)	Imaging Range mλ₁, mλ₂ (nm)	Reciprocal Linear Dispersion (nm/mm)	Entrance Slit r (mm)	Exit Slit r' (mm)	Deviation Angle 2K (deg)	Input f/no	Ruled Area (mm)	Substrate Size (mm)	Request a Quote
52073BK-*-037C	570	2 μm	1100-2500	10	203.9	184.1	38	2.4	Φ84	Φ90	Quote
52073BK-*-278C	1140	1 μm	550-1200	3	201	182.7	38	2.3	Φ84	Φ90	Quote
52094BK-*-096C	1198	300 nm	200-1000	7	105	100	34.7	2.5	38 x 38	42.4 x 42.4	Quote
52094BK-*-097C	1198	450 nm	350-1590	7	105	100	34.7	2.5	38 x 38	42.4 x 42.4	Quote
52094BK-*-098C	1198	375 nm	200-900	7	105	100	34.7	2.5	38 x 38	42.4 x 42.4	Quote
52105BK-*-226C	1200	250 nm	200-800	8.5	100	94	61.6	3.6	Φ36	Φ40	Quote
52111BK-*-228C	1200	350 nm	200-800	8.5	100	94	61.6	3.1	28 x 28	32 x 32	Quote
52085BF-*-249C	1200	250 nm	200-600	7	99.3	103.5	28	3.5	29 x 29	33 x 33	Quote
52085BF-*-251C	1200	250 nm	200-600	7	99.3	103.5	28	3.5	29 x 29	33 x 33	Quote
52085BF-*-364C	1200	225 nm	200-600	7	99.3	103.5	28	3.5	29 x 29	33 x 33	Quote
52085BF-*-433C	1200	225 nm	200-600	7	99.3	103.5	28	3.5	29 x 29	33 x 33	Quote
52027BK-*-006C	1200	200 nm	200-800	8.5	100	94	61.6	3.6	30 x 30	32 x 32	Quote
52057BK-*-020C	1200	450 nm	325-950	7	91.1	117.7	51.2	2.5	Φ47	Φ50.8	Quote
52057BK-*-022C	1200	350 nm	325-950	7	91.1	117.7	51.2	2.5	Φ47	Φ50.8	Quote
52057BK-*-238C	1200	275 nm	200-800	8.5	100	94	61.6	2.5	Φ45	Φ50.8	Quote
52052BF-*-023C	1350	250 nm	190-700	8	91.3	91.3	45	2.3	Φ40	Φ45	Quote
52093BK-*-095C	1500	250 nm	200-800	8	74.73	80	47.1	3.7	24 x 24	28 x 28	Quote

Showing 1 to 17 of 17 entries

Features

Typical Spectral Images with Concave Holographic Gratings

Concave gratings have an advantage over conventional plane grating systems in that concave gratings perform both imaging as well as dispersion (wavelength separation). This reduces the cost of the optical components in the instrument, reduces alignment time, and perhaps minimizes reflective and refractive energy losses as well. Typical spectral images are shown at three wavelengths from (a) a Rowland Circle spectrograph, (b) a flat-field spectrograph, and (c) a constant-deviation monochromator. Note that resolution (image width) degrades as astigmatism (image height) is reduced.

Catalog Part Number System

All standard Richardson gratings have a part number according to the following format:

AA BBB CC DD - EEE x

AA indicates the type of grating (e.g., diced, plano, grism).
BBB indicates the size of the grating substrate.
CC indicates the substrate material
DD indicates the type of coating
EEE indicates the master grating groove parameters
x indicates the master grating type (e.g., ruled, holographic, echelle)

Please see Diffraction Grating Part Number System for additional information.

Grating Substrate Material Options

The standard substrate material for small and medium-sized gratings is specially annealed borosilicate crown glass. Low expansion material can be supplied on request. Float glass may be used for small, diced gratings. In addition, replicas may be furnished on metal substrates, such as copper or aluminum, for applications with extreme thermal conditions. The substrate material codes CC are given below:

Substrate Material Code CC	Substrate Material
AL	Aluminum
BF	Borosilicate float or equivalent
BK	BK-7 glass or equivalent
CU	Copper
FL	Float glass
FS	Fused silica or equivalent
LE	Low-expansion glass
SP	Special glass (unspecified)
TB	BK-7, transmission grade
TF	Fused silica, transmission grade
UL	Corning ULE® glass
ZD	Schott Zerodur®

Diffraction Grating Coating Options

All reflection gratings include a standard aluminum (Al) reflectance coating (Coating Code "01"). Gratings can also be replicated in gold (Au), or overcoated with magnesium fluoride (MgF₂) or silver (Ag), to enhance reflectivity in certain spectral regions. The coating material codes DD are shown below:

Coating Code DD	Coating Material	Application
01	Aluminum (Al)	General purpose applications.
02	Gold (Au)	Offers higher reflectivity in the infrared.
03	Magnesium Fluoride (MgF₂)	Used to prevent oxidation of aluminum (Al) coatings, which helps maintain high reflectivity in the ultraviolet over time.
06	Protected Silver (Ag)	Offers higher reflectivity in the visible and near infrared. Silver is protected from tarnishing by a dielectric coating, which helps maintain reflection over time.

Custom Diffraction Gratings

Newport is pleased to discuss special and unusual applications that are not addressed by our build to order catalog diffraction gratings. In some instances, none of the hundreds of master gratings we have in stock meet specifications, so a new master may be required. Please see Custom Diffraction Gratings for additional information on our capabilities.