The refractive indices of crystal fragments 50–200 μm in size can be measured for light wavelengths between 365 and 1100 nm with a spindle-stage refractometer. Established methods from optical crystallograpy are used to orient a crystal on the microscope spindle stage and then to match its refractive index to an immersion fluid. The refractive index of the fluid for the wavelength of light and matching temperature is determined by comparison of a reference crystal on a second spindle axis with the fluid under the match conditions. Investigations of new nonlinear-optical crystals admirably demonstrate the advantages of measuring the refractive index to ±0.0004 in small single crystals.
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All wavelengths were not available for all solids at the time of this study.
Method: S.S., spindle stage; Co., company supplied; M.D., minimum deviation.
Cargille glasses: supplied refractive-index data are limited to the visible region between 435.8 and 656.3 nm.
Table 4
Sellmeier Coefficients [Eq. (2)] Determined from Refractive-Index Data of New Nonlinear-Optical Crystalsa
Compund
n
A
B
C
D
l-Arginine chloride monohydrate
α
2.35693
0.01673
−0.01375
−0.00553
β
2.56983
0.02473
−0.00761
−0.00570
γ
2.64700
0.02357
−0.01656
−0.01459
l-Arginine bromide monohydrate
α
2.42018
0.01712
−0.02117
−0.01294
β
2.60613
0.03251
0.00318
0.00518
γ
2.68036
0.02281
−0.03029
−0.01299
l-Arginine fluoride
α
2.21633
0.01445
−0.00972
−0.01098
β
2.41384
0.01425
−0.03726
−0.02328
γ
2.48299
0.01868
−0.01612
−0.01855
l-Arginine acetate
α
2.31685
0.01606
−0.02124
−0.01105
β
2.35076
0.01555
−0.02464
−0.01214
γ
2.45789
0.01824
−0.02463
−0.01347
l-Arginine diarsenate
α
2.35711
0.01426
−0.01995
−0.01861
β
2.45055
0.01487
−0.02927
−0.01912
γ
2.53786
0.02245
−0.01068
−0.01564
K2La(NO3)5·2H2O
α
2.20094
0.01426
−0.03134
−0.00618
β
2.31901
0.02001
−0.02474
−0.00586
γ
2.38504
0.02085
−0.02694
−0.00873
K2Ce(NO3)5·2H2O
α
2.21109
0.01410
−0.03458
−0.00639
β
2.33882
0.01934
−0.03335
−0.00793
γ
2.40514
0.01941
−0.03715
−0.01357
Refractive-index data are tabulated in Appendix B.
Table 5
Comparison of Measured and Calculated PM Angles (θ) in New Nonlinear-Optical Crystals
Process: 2ω = second-harmonic generation; 3ω = third-harmonic generation; and types I and II refer to the mixing schemes, where type I refers to the case in which two input waves travel polarized along a slow vibration direction and the resultant wave travels polarized along a fast vibration direction (S + S → F) and type II refers to the case in which two input waves travel polarized along a slow and a fast vibration direction and the resultant wave travels polarized along a fast vibration direction. For mixed frequencies, the higher-energy input wave is the slow polarized wave (F + S → F).
Axis is the reference direction from which θ is measured in the reported plane. The (A), (B), and (C) loci correspond to Fig. 3.
Ref 26.
Table 6
Refractive Indices of MgCO3 Measured by Minimum Deviation at 25°C
λ (nm)
ne
no
1130
1.50629
1.68526
1064
1.50673
1.68665
900
1.50722
1.68805
800
1.50809
1.69051
700
1.51073
1.69718
600
1.51297
1.70254
565
1.51404
1.70483
532
1.51523
1.70760
500
1.51663
1.71081
450
1.51943
1.71722
400
1.52342
—
365
1.52730
1.73561
Table 7
Sellmeier Coefficients [Eq. (2)] for MgCO3 Data Given in Table 6
n
A
B
C
D
ne
2.267040
0.0081835
−0.0093924
−0.0036005
no
2.849137
0.0191492
−0.0176812
−0.0190330
Table 8
Refractive Indices Measured by Spindle-Stage Refractometry for New Nonlinear-Optical Crystals
n
Compound
λ(μm)
α
β
γ
l-Arginine chloride monohydrate
0.3650
1.5800
1.6631
1.6876
0.4005
1.5715
—
1.6753
0.4872
1.5590
1.6360
1.6588
0.5461
1.5541
1.6285
1.6514
0.6476
1.5473
1.6214
1.6427
0.7500
1.5443
1.6158
1.6375
0.8500
1.5417
1.6124
1.6341
1.0500
1.5382
1.6082
1.6287
l-Arginine bromide monohydrate
0.3650
1.6050
—
—
0.4005
1.5943
1.6750
1.6893
0.4872
1.5803
1.6561
1.6693
0.5461
1.5739
1.6480
1.6621
0.6476
1.5674
1.6384
—
0.7500
1.5641
1.6329
1.6481
0.8500
1.5606
1.6296
1.6441
0.9500
1.5582
—
—
1.0088
1.5568
1.6257
1.6403
l-Arginine fluoride
0.4005
1.5200
1.5893
1.6153
0.4872
1.5092
1.5744
1.6014
0.5461
1.5043
1.5693
1.5946
0.6476
1.4988
1.5623
1.5875
0.7500
1.4955
1.5581
1.5835
0.8500
1.4931
1.5551
1.5798
0.9500
1.4907
1.5520
1.5780
1.0088
1.4898
1.5508
1.5750
l-Arginine acetate
0.3650
1.5681
1.5788
1.6199
0.4005
1.5585
1.5692
1.6095
0.4872
1.5456
1.5560
1.5932
0.5461
1.5392
1.5508
1.5881
0.6476
1.5335
1.5441
1.5811
0.7500
1.5305
1.5404
1.5762
0.8500
1.5266
1.5376
1.5726
0.9500
1.5249
1.6354
1.5700
1.0500
1.5227
1.5336
1.5689
l-Arginine diarsenate
0.3650
1.5749
1.6098
1.6491
0.4005
1.5672
1.6000
1.6383
0.4872
1.5551
1.5868
1.6229
0.5461
1.5499
1.5813
1.6161
0.6476
1.5444
—
1.6082
0.7500
1.5405
1.5709
1.6026
0.8500
1.5376
1.5675
1.5998
0.9500
1.5350
1.5656
1.5963
1.0500
1.5329
1.5631
1.5942
K2La(NO3)5·2H2O
0.3650
1.5297
1.5820
1.6063
0.4005
1.5201
1.5702
1.5936
0.4872
1.5062
1.5530
1.5756
0.5461
1.5008
1.5460
1.5682
0.6476
1.4950
1.5387
1.5601
0.7500
1.4915
1.5341
1.5556
0.8500
1.4891
1.5306
1.5518
0.9500
1.4872
1.5285
1.5496
1.0500
1.4857
1.5269
1.5475
K2Ce(NO3)5·2H2O
0.3650
1.5340
1.5912
1.6142
0.4005
1.5238
1.5775
1.5999
0.4872
1.5098
1.5597
1.5811
0.5461
1.5041
1.5524
1.5732
0.6476
1.4983
1.5443
1.5653
0.7500
1.4947
1.5398
1.5603
0.8500
1.4924
1.5365
1.5567
0.9500
1.4905
1.5343
1.5542
1.0500
1.4890
1.5324
1.5519
Tables (8)
Table 1
Possible Reference Crystals for Spindle-Stage Refractometry
All wavelengths were not available for all solids at the time of this study.
Method: S.S., spindle stage; Co., company supplied; M.D., minimum deviation.
Cargille glasses: supplied refractive-index data are limited to the visible region between 435.8 and 656.3 nm.
Table 4
Sellmeier Coefficients [Eq. (2)] Determined from Refractive-Index Data of New Nonlinear-Optical Crystalsa
Compund
n
A
B
C
D
l-Arginine chloride monohydrate
α
2.35693
0.01673
−0.01375
−0.00553
β
2.56983
0.02473
−0.00761
−0.00570
γ
2.64700
0.02357
−0.01656
−0.01459
l-Arginine bromide monohydrate
α
2.42018
0.01712
−0.02117
−0.01294
β
2.60613
0.03251
0.00318
0.00518
γ
2.68036
0.02281
−0.03029
−0.01299
l-Arginine fluoride
α
2.21633
0.01445
−0.00972
−0.01098
β
2.41384
0.01425
−0.03726
−0.02328
γ
2.48299
0.01868
−0.01612
−0.01855
l-Arginine acetate
α
2.31685
0.01606
−0.02124
−0.01105
β
2.35076
0.01555
−0.02464
−0.01214
γ
2.45789
0.01824
−0.02463
−0.01347
l-Arginine diarsenate
α
2.35711
0.01426
−0.01995
−0.01861
β
2.45055
0.01487
−0.02927
−0.01912
γ
2.53786
0.02245
−0.01068
−0.01564
K2La(NO3)5·2H2O
α
2.20094
0.01426
−0.03134
−0.00618
β
2.31901
0.02001
−0.02474
−0.00586
γ
2.38504
0.02085
−0.02694
−0.00873
K2Ce(NO3)5·2H2O
α
2.21109
0.01410
−0.03458
−0.00639
β
2.33882
0.01934
−0.03335
−0.00793
γ
2.40514
0.01941
−0.03715
−0.01357
Refractive-index data are tabulated in Appendix B.
Table 5
Comparison of Measured and Calculated PM Angles (θ) in New Nonlinear-Optical Crystals
Process: 2ω = second-harmonic generation; 3ω = third-harmonic generation; and types I and II refer to the mixing schemes, where type I refers to the case in which two input waves travel polarized along a slow vibration direction and the resultant wave travels polarized along a fast vibration direction (S + S → F) and type II refers to the case in which two input waves travel polarized along a slow and a fast vibration direction and the resultant wave travels polarized along a fast vibration direction. For mixed frequencies, the higher-energy input wave is the slow polarized wave (F + S → F).
Axis is the reference direction from which θ is measured in the reported plane. The (A), (B), and (C) loci correspond to Fig. 3.
Ref 26.
Table 6
Refractive Indices of MgCO3 Measured by Minimum Deviation at 25°C
λ (nm)
ne
no
1130
1.50629
1.68526
1064
1.50673
1.68665
900
1.50722
1.68805
800
1.50809
1.69051
700
1.51073
1.69718
600
1.51297
1.70254
565
1.51404
1.70483
532
1.51523
1.70760
500
1.51663
1.71081
450
1.51943
1.71722
400
1.52342
—
365
1.52730
1.73561
Table 7
Sellmeier Coefficients [Eq. (2)] for MgCO3 Data Given in Table 6
n
A
B
C
D
ne
2.267040
0.0081835
−0.0093924
−0.0036005
no
2.849137
0.0191492
−0.0176812
−0.0190330
Table 8
Refractive Indices Measured by Spindle-Stage Refractometry for New Nonlinear-Optical Crystals